Pancreas and Islet Transplantation

Pancreas and Islet Transplantation Edited by

Nadey Hakim St Mary’s Hospital London UK

Robert Stratta UT Medical Group Memphis USA

Derek Gray Churchill Hospital Oxford UK

1

Whilst every effort has been made to ensure that the contents of this book are as complete, accurate and up-to-date as possible at the date of writing, Oxford University Press is not able to give any guarantee or assurance that this is the case. Readers are urged to take appropriately qualified medical advice in all cases. The information in this book is intended to be useful to the general reader, but should not be used as a means of self-diagnosis or for the prescription of medication.

Pancreas and Islet Transplantation

1 Great Clarendon Street, Oxford OX2 6DP Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Bangkok Buenos Aires Cape Town Chennai Dar es Salaam Delhi Hong Kong Istanbul Karachi Kolkata Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi São Paulo Shanghai Taipei Tokyo Toronto and an associated company in Berlin Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States by Oxford University Press Inc., New York © Oxford University Press, 2002 The moral rights of the author have been asserted Database right Oxford University Press (maker) First published 2002 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose this same condition on any acquirer A catalogue record for this title is available from the British Library Library of Congress Cataloging in Publication Data Pancreas and islet transplantation / edited by Nadey Hakim, Robert Stratta, Derek Gray. 1. Pancreas–Transplantation. 2. Islands of Langerhans–Transplantation. I. Hakim, Nadey S., 1958- II. Stratta, R.J. (Robert J.) III. Gray, Derek. [DNLM: 1. Pancreas Transplantation. 2. Islets of Langerhans Transplantation. WI 830 P1876 2002] RD546.P364 2002 617.5′570592–dc21 2001052324 ISBN 0 19 263255 8 (hbk. : alk. paper) 10 9 8 7 6 5 4 3 2 1 Typeset by EXPO, Malaysia Printed in Great Britain on acid-free paper by Biddles Ltd, Guildford & King’s Lynn

Preface

Overwhelming clinical evidence has accumulated to support the contention that pancreas transplantation is no longer investigational and indeed, is now regarded as a treatment of choice for uraemic diabetic patients. The results of pancreas transplantation are at least equivalent, if not superior, to other solid organ transplants. A kidney/pancreas transplant may not only be life enhancing, but life saving, compared to alternative treatment options. It is therefore not surprising that pancreas transplantation will become an increasingly important treatment option in the management of diabetic patients with or without renal failure. This book provides an authoritative account on the current status of all organ pancreas transplantation and other transplantation. Pancreas transplantation has rapidly moved from an experimental procedure asociated with high rates of morbidity and mortality to a mainstream technique with excellent patient and grafit survival. Over 15,000 pancreas transplants have already been performed. However pancreas transplantation’s value must be balanced against the risk of the operative procedure and the innovative long-term immunosuppressive therapy. Therefore, the indications for this procedure and the selection of the patients are critical to ensure low mortality and any improvement in quality of life. Consistent islet allograft success has recently been achieved by using multiple donors and steroid free immunosuppressive regime. Perhaps in the future there will be a role for both islet and pancreas transplantation with islet transplantation reserved for diabetic individuals with a low insulin requirement, while the pancreas transplant may be preferable for those with a high insulin requirement or insulin resistance such as those with type II diabetes. N.H., R.S., and D.G.

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Contents

List of contributors ix 1 History of pancreas transplantation 1

David E. R. Sutherland and Carl G. Groth 2 The nature of the problem: why do we need pancreatic transplantation? 15

Martin Press 3 Experimental models in whole organ pancreatic transplantation 27

Vassilios E. Papalois and Nadey S. Hakim 4 Pretransplant medical evaluation for pancreas transplant candidates 45

Jerry McCauley and Robert J. Corry 5 Indications for kidney and pancreas transplantation and patient selection 59

Konstantinos N. Haritopoulos and Nadey S. Hakim 6 Indications for solitary pancreas transplantation 67

Robert J. Stratta 7 Donor management and selection for pancreas transplantation 79

Eldo Ermenegildo Frezza and Robert J. Corry 8 Procurement and benchwork preparation of the pancreatic graft 89

Nadey S. Hakim and Vassilios E. Papalois 9 Pancreas preservation 95

Hans U. Spiegel and Daniel Palmes 10 Surgical techniques of pancreas transplantation 115

Venkatesh Krishnamurthi and Stephen T. Bartlett 11 Pancreas transplantation with portal-enteric drainage 125

Robert J. Stratta, M. Hosein Shokouh-Amiri, Hani P. Grewal, and A. Osama Gaber 12 Pancreas transplantation: early perioperative management 145

Alan J. Koffron and Dixon B. Kaufman 13 Surgical complications of pancreas transplantation 155

Enrico Benedetti, Pierpaolo Sileri, Angelika C. Gruessner, and Luca Cicalese 14 Medical and urological complications of pancreas and kidney/pancreas

transplantation 167 Phuong-Thu T. Pham, Phuong-Chi T. Pham, and Alan H. Wilkinson

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CONTENTS

15 Diagnosis and treatment of pancreatic rejection 191

Alan J. Koffron and Dixon B. Kaufman 16 Histology of the pancreas transplant 205

David K. Klassen 17 Pancreas transplantation: effects on secondary complications of diabetes

mellitus 219 R. Paul Robertson 18 Pancreas transplantation: long-term aspects and effect on quality of life 229

Robert J. Stratta 19 Immunosuppression and diabetogenicity 247

Rahul M. Jindal, V.K. Revanur, and Alan G. Jardine 20 The economics of pancreas transplantation 277

Robert J. Stratta 21 Gene therapy for diabetes 291

Muralidhar Karanam, Z. Song, and Rahul M. Jindal 22 An historical view of the development of cellular and islet transplantation 305

Derek W. R. Gray 23 Fetal and neonatal pancreatic tissue transplantation 325

Bernard E. Tuch 24 Experimental approaches to the prevention of islet rejection 339

Norma Sue Kenyon 25 Clinical effectiveness of islet transplantation 355

Alberto M. Davalli, Federico Bertuzzi, and Antonio SecchIi Index 369

List of contributors

Stephen T. Bartlett, MD University of Maryland, Department of Surgery, Organ Transplant Baltimore, USA Enrico Benedetti, MD University of Illinois at Chicago, Department of Surgery–Division of Transplantation, 840 South Wood Street, CSB M/C 958 room 402, Chicago, 60612 IL, USA Federico Bertuzzi Department of Medicine, Istituto Scientifico San Raffaele, Milan, Italy Luca Cicalese, MD Department of Surgery, University of Illinois at Chicago, Chicago, USA Robert J. Corry, MD Professor of Surgery, Director Pancreas Transplantation Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, USA Alberto M. Davalli Department of Medicine, Istituto Scientifico San Raffaele, Milan, Italy Eldo Ermenegildo Frezza Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, USA

A. Osama Gaber Department of Surgery (Division of Transplantation), University of Tennessee Memphis, Memphis, Tennessee, USA Derek W. R. Gray D. Phil, FRCP, FRCS The Nuffield Department of Surgery, University of Oxford, Oxford, UK Hani P. Grewal Department of Surgery (Division of Transplantation), University of Tennessee Memphis, Memphis, Tennessee, USA Carl G. Groth, MD, PhD Professor of Transplantation Surgery Karolinska Institute, Huddinge Hospital, Huddinge, S-141 86, Sweden Angelika C. Gruessner, MS, PhD Department of Surgery, University of Minnesota, USA Nadey S. Hakim, MD, PhD, FRCS, FICS, FACS Surgical Director of Transplant Unit, St Mary’s Hospital, Praed Street, Paddington, London W2 1NY, UK

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LIST OF CONTRIBUTORS

Konstantinos N. Haritopoulos, MD PhD FICS Transplant Fellow, Transplant Unit, St Mary’s Hospital, London, UK Alan G. Jardine, BSc MD FRCP Senior Lecturer in Nephrology, Department of Surgery, University of Glasgow, UK Rahul M. Jindal, MD, FRCS, MSc Director of Transplantation University Department of Surgery, Western Infirmary, Church Street, Glasgow G11 6NT, UK Muralidhar Karanam Post-doctoral Scientist, University of Glasgow, Glasgow, UK Dixon B. Kaufman, MD, PhD Northwestern University Medical School, Department of Surgery, Division of Transplantation, Chicago, USA Norma Sue Kenyon, Ph.D Diabetes Research Institute, University of Miami School of Medicine, 1450 NW 10th Avenue, Miami, Florida 33136, USA David K. Klassen, MD Department of Medicine, Medical Director of Transplantation, University of Maryland Medical Systems, 22 S. Greene St.–N3W143, Baltimore, MD 21201, USA, Alan J. Koffron, MD Northwestern University Medical School, Department of Surgery, Division of Transplantation, Chicago, USA

Venkatesh Krishnamurthi, MD Staff Surgeon, Director Pancreas Transplant, Cleveland Clinic Foundations, Northwestern, Ohio, USA Jerry McCauley MD, MPH, FACP Associate Professor of Medicine and Surgery, Director of Transplantation Nephrology, Renal-Electrolyte Division and Thomas E. Starzl, Transplantation Institute, University of Pittsburgh School of Medicine, USA Daniel Palmes, MD Münster University Hospital, Department of General Surgery–Surgical Research, Waldeyer Strasse 1, D-48149 Münster, Germany Vassilios E. Papalois, MD, PhD, FICS Consultant Transplant Surgeon Transplant Unit, St Mary’s Hospital, Praed Street, Paddington, London W2 1NY, UK Phuong-Chi T. Pham, MD Olive View-UCLA Medical Center, Department of Medicine, Division of Nephrology, Sylmar, CA 91342, USA Phuong-Thu T. Pham, MD University of California at Los Angeles School of Medicine, Department of Medicine, Division of Nephrology, Kidney and Pancreas Transplantation, Los Angeles, CA 90095, USA Martin Press FRCP Consultant Endocrinologist, Royal Free Hospital, London, NW3 2QG, UK

LIST OF CONTRIBUTORS

V.K. Revanur, FRCS Registrar in Surgery, Department of Surgery, University of Glasgow, UK R. Paul Robertson, MD Scientific Director/CEO, Pacific Northwest Research Institute, 720 Broadway, Seattle, WA 98122, USA Antonio Secchi Department of Medicine, Istituto Scientifico San Raffaele, Milan, Italy M. Hosein Shokouh-Amiri Department of Surgery (Division of Transplantation), University of Tennessee Memphis, Memphis, Tennessee, USA Pierpaolo Sileri, MD Department of Surgery, University of Illinois at Chicago, Chicago, USA Z. Song Post-doctoral Scientist, University of Glasgow, Glasgow, UK Hans Ulrich Spiegel, MD Münster University Hospital, Department of General Surgery–Surgical Research, Waldeyer Strasse 1, D-48149 Münster, Germany

Robert J. Stratta, MD Department of Surgery (Division of Transplantation), University of Tennessee Memphis, 956 Court Avenue, Suite A202, Memphis, TN 38163-2119, USA David E. R. Sutherland, MD, Ph.D. Professor of Surgery, Head, Division of Transplantation Director, Diabetes Institute for Immunology and Transplantation, Department of Surgery, University of Minnesota, Minneapolis, Minnesota, USA Bernard E. Tuch Professor of Medicine and Director of the Pancreas Transplant Unit, Prince of Wales Hospital and the University of New South Wales, Sydney, Australia Alan H. Wilkinson, MD, FRCP Professor of Medicine, Department of Medicine, Division of Nephrology, Medical Director, Kidney and Pancreas Transplantation, University of California at Los Angeles School of Medicine, 200 UCLA Medical Plaza, Suite 365, Los Angeles, CA 90095, USA

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Chapter 1

History of pancreas transplantation David E.R. Sutherland and Carl G. Groth

Introduction The history of pancreas transplantation is intertwined with that of other organ transplants and with the evolution of treatment of diabetes mellitus. Once diabetes was recognized as a consequence of a defect in the internal secretion of the pancreas, the idea of pancreas transplantation took root. From the late 1920s to the mid-1960s, various investigators worked out some of the surgical details of pancreas allotransplantation in dogs [1–8], setting the stage for clinical application [9]. The first pancreas allograft in a human was performed by Drs William D. Kelly and Richard C. Lillihei on 16 December 1966 at the University of Minnesota, a duct ligated segmental graft done simultaneous with a kidney in an uraemic diabetic recipient that resulted in immediate insulin independence (Fig. 1.1). The graft was still functioning 2 months later when the recipient died of sepsis related to surgical complications [10]. Surgical techniques are critical in pancreas transplantation and dominated the seminars organized to forward the field in the decade or two that followed the first case [11,12]. However, from a start where only an occasional pancreas transplant resulted in long-term insulin independence of the recipient [13] to the current highly successful application [14], the development of new immunosuppressants and the evolution of modern antirejection protocols that enveloped the organ transplant field in general were equally important [15-17]. By the mid-1980s, the symposia organized to facilitate the

Fig. 1.1 Technique for segmental transplantation used by Kelly and Lillehei in the first human pancreas transplant [10].

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application of pancreas transplantation reflected the broad interests — surgical, immunological, metabolic — of a maturing discipline [18–20]. The steady improvement in pancreas transplant outcome was documented by the International Pancreas and Islet Transplant Registry (IPTR), founded at the Lyon meeting [11] in 1980 [13,21]. Annual reports have been forthcoming from the IPTR since that time [14]. Patient selection is an important element in the history of pancreas transplantation, with most centres largely limiting its application to diabetic renal allograft recipients who were obligated to immunosuppression in any case. This bias was enforced by the observation that pancreas transplants alone (PTA) in non-uraemic diabetic recipients were associated with a substantially higher rejection rate than simultaneous pancreas kidney (SPK) transplants in uraemic recipients [22], a gap that was narrowed only in the last decade [14]. Nevertheless, a few programmes persisted in the application of pancreas transplantation in nonuraemic diabetic patients [23], accepting the trade-off of immunosuppression to achieve insulin independence per se. The history of the pancreas transplantation can be described in the context of individual contributions to programme development; the evolution, refinements, and physiology or new surgical techniques; antirejection strategies and methods to diagnose rejection episodes; observations on the consequences of euglycaemia on metabolism and diabetic secondary complications; and expansion in application.

Surgical techniques Following the first pancreas transplant with Kelly [10], Lillihei and associates [9,24] went on to perform an additional 13 whole pancreas transplants between 1966 and 1973 (the first five with a cutaneous graft duodenostomy; the next seven with internal exocrine drainage via a Roux-en-Y duodenal jejunostomy (Fig. 1.2); the last with only the papilla of Vater retained for anastomosis to the

Fig. 1.2 Technique of whole pancreaticoduodenal transplant with enteric drainage via a Roux-en-Y limb of recipient bowel, as devised by Lillehei in the initial Minnesota series [9].

D.E.R. SUTHERLAND AND CARL G. GROTH

recipient bowel). Of the first 14 cases at the University of Minnesota, 11 were in consecutive uraemic patients (10 with a simultaneous kidney transplant) and a subsequent three in non-uraemic patients. The complication rate was high, but one patient was insulin independent for over a year and died with a functioning graft after returning to dialysis because of renal allograft thrombosis secondary to arterial stenosis. This was the longest functioning pancreas graft in the world until a series of simultaneous pancreas kidney (SPK) transplants with segmental grafts by Gliedman et al., at Montefiore Hospital in New York beginning in the early 1970s, produced a recipient whose new pancreas functioned (insulin independent) for 5 years [25]. Several surgeons [26–33] scattered around the world performed one or two pancreas transplants in the late 1960s and early 1970s (reviewed in [34,35]), but by the mid-1970s only two centres were systematically offering pancreas transplantation to diabetic patients [36,37]. With the thought that the early failures were related to complications of the graft duodenum, both groups did segmental grafts (body and tail). In Stockholm, Groth et al. [36,38,39] evolved enteric drainage for duct management, while in Lyon, Dubernard et al. [37,40] obliterated the exocrine pancreas by duct injection of a sclerosing synthetic polymer. The latter technique was very safe, although long term-function was still rare. Meanwhile, the University of Minnesota initiated a clinical islet transplant programme with the first case in 1974 [41]. Although clinical islet autografts were successful [42],none of the initial allograft islet recepients became insulin independent [43], and in 1978 pancreas transplants were resumed at the University of Minnesota with a new surgical team [44]. The first few transplants in the new Minnesota series were also segmental grafts with the duct left open into the peritoneal cavity [45]. The very first recipient of an open duct graft (pancreas after kidney, PAK) achieved long-term insulin independence (for 17 years until dying with a functioning graft after being thrown off a horse [46]). However, the open duct technique was technically successfully only half of the time [47], and the University of Minnesota programme went on to use all of the duct management techniques that were extant or subsequently evolved (duct injection, enteric drainage, and urinary drainage) [48]. By the early 1980s, several programmes emerged and forwarded the field. One of the most important developments was modification of urinary drainage by Sollinger et al. [49] at the University of Wisconsin with direct anastomosis of the pancreatic duct to the bladder, remarkedly reducing the acute complication rate that Gliedman et al. [29] had using the ureter. Starzl et al. [50] at the University of Pittsburg resurrected the whole pancreatic duodenal technique of Lillihei et al. [9] for enteric drainage, and shortly thereafter Nghiem and Corry at the University of Iowa reported retention of the duodenum segment for anastomosis to the bladder [51]. Bladder drainage (BD) via the graft duodenum was quickly adapted by most American centres and was the dominant surgical technique for management of the pancreas graft exocrine secretions well into the 1990s [14]. Bladder drainage became popular because even if it did not have a lower complication rate than enteric drainage, the acute morbidity or severity of the complication was less. In addition, for solitary pancreas transplants, a decrease in urine amylase was shown by Prieto et al. to be an early marker for rejection that preceded hyperglycaemia by several days [52]. For SPK transplants, this was not so important, since the elevation of serum creatinine is a marker for rejection in the kidney that usually preceded exocrine or endocrine dysfunction as a sign of concomitant rejection in the pancreas from the same donor, allowing for early treatment and reversal [53]. Chronic complications of BD of pancreaticoduodenal transplants (infections, haematuria, acidosis, and dehydration) lead to the need for enteric conversion in about 10 per cent of cases [14]. The first conversion was reported by Tom et al. [54] from the University of Cincinnati in 1987. Segmental pancreas transplantation did not completely disappear as whole pancreaticoduodenal transplants evolved into a safe technique. Indeed, the fact that a segmental graft could be done at all

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led to the first use of living donors for pancreas transplantation at the University of Minnesota in 1979 [55], and more than 100 have been done since this time (over 10 per cent of the transplants at this institution) [46]. Besides the choice of where to drain (or not drain) the pancreas graft exocrine secretions, there is also a choice as to the site of transplantation and of venous drainage (systemic or portal). Most pancreas transplants are placed in the pelvis with vascular anastomosis to the recipient iliac artery and vein. With the expansion of all organ transplants, techniques were developed to preserve the arterial vessel to both the pancreas and liver when removed and transplanted separately. In the 1980s, several groups reported separately [56–58] the technique of retaining the entire hepatic artery to the liver by using a Y graft of the donor common external internal iliac artery to join the splenic and superior mesenteric arteries feeding a whole pancreas graft. Drainage of segmental pancreas transplant venous effluent into the recipient's portal system was done in a few patients in the 1980s. Calne [59], at Cambridge, was the first, accessing the recipient's splenic vein transabdominally and performing a ductogastrostomy for exocrine drainage. The Barcelona group also used the recipient's splenic vein, but via a retroperitoneal approach with a ducto-uterostomy for exocrine drainage [60]. The portal system was accessed, via the superior mesenteric vein in Stockholm [61,62], and via the inferior mesenteric vein at the University of Minnesota [63], combined with enteric drainage by both groups. In the early 1990s, Rosenlof et al. [64] at the University of Virginia, reported on a series of enteric-drained whole pancreaticoduodenal transplants with anastomosis of the graft portal vein to the recipients superior mesenteric vein (Fig. 1.3), and by the mid-1990s a few groups adapted this technique as their routine [65–67].

Fig. 1.3 Technique of whole pancreaticoduodenal enteric-drained pancreas transplant and portal drainage as devised by Rosenlof et al. [64] at the University of Virginia in 1990.

D.E.R. SUTHERLAND AND CARL G. GROTH

Systemic insulin levels in pancreas transplant recipients are lower with portal venous drainage, and it is thus more physiological, but no studies have shown that portal drainage gives any further advantage over that achieved with systemic drainage in ameliorating secondary complications of diabetes. To summarize the surgical evolution of pancreas transplantation, it went from predominantly whole organ transplantation in the late 1960s and early 1970s to mostly segmental transplantation in the late 1970s and early 1980s and then back to whole organ transplantation. Enteric drainage, duct injection, and BD were successively dominant from the early 1970s to the mid-1980s. The latter still predominates for solitary pancreas transplant, but enteric drainage has now re-emerged as dominant for SPK transplants. [Indeed, the whole pancreaticoduodenal transplant technique with systemic venous and enteric exocrine drainage devised early on by Lillihei (Fig. 1.2) is nearly identical to that currently used by most surgeons, although many forgo a Roux-en-Y limb of recipient bowel.] This shift is explained by the fact that although the immediate technical complications rate is nearly the same for enteric drainage and bladder drainage, the chronic complications rate is higher for bladder drainage. Early diagnosis and treatment of pancreas graft rejection (before hyperglycaemia), however, remains a problem for solitary pancreas transplants (PAK and PTA), while for SPK transplants from the same donor an elevation in serum creatinine is a surrogate marker for rejection likely involving both organs. For solitary pancreas transplants with BD, rejection will always eventually lead to a decline in urinary amylase (UA). Although not entirely specific, UA is 100 per cent sensitive, while an elevation in serum pancreatic enzymes (also not specific) does not always occur (lower sensitivity) [52]. For these reasons, urinary drainage for pancreas transplantation has persisted more than 30 years after its introduction by Gliedman et al. [25] using the ureter and nearly 20 years after direct drainage to the bladder by Sollinger et al. [49].

Antirejection treatment The immunosuppressive regimens used in pancreas allograft recipients are the same as those for other solid organs. From the 1960s to the early 1980s the only universally available maintenance immunosuppressants were azathioprine and steroids. In 1980, 1-year pancreas graft survival rate overall was 20 per cent [13]. Following the introduction of cyclosporin for general use in the mid1980s, 1-year graft survival rates reached approximately 75 per cent for SPK and approximately 50 per cent for PAK and PTA cases [68]. Tacrolimus and mycophenolate mofetil (MMF) came into general use in the mid-1990s [16,17], and current 1-year pancreas graft survival rates are over 80 per cent in all categories [14]. It should be noted that the transplant surgeons instrumental in introducing ciclosporin A, tacrolimus, and MMF, Calne et al.[15], Starzl et al.[16], and Rayhill et al. [17], respectively, were also pioneers and innovators in the surgical techniques for pancreas transplantation [49,50,59]. Also of interest is the fact that the diabetogenic effect of cyclosporin was first reported from its use in pancreas transplant recipients [69]. The other calcineurin inhibitor, tacrolimus, also had this property [16]. Nevertheless, the incidence of drug-induced hyperglycaemia has not been any higher in pancreas transplant recipients than other organ allograft recipients, and long-term insulin independence rates, are highest in pancreas recipients given one or the other of these drugs [14]. The diagnosis and treatment of rejection episodes are based on the same principle as for other organ allografts. Graft dysfunction leads to a tentative diagnosis, a confirmative biopsy is done if possible, and if positive, immunosuppression is temporarily increased. Pancreatic graft biopsies were first done by laparotomy [70], then transcystoscopically for bladder-drained grafts [71], and currently percutaneously, regardless of the surgical technique originally used [72,73].

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Impact of pancreas transplantation on the understanding of pathogenesis of diabetes mellitus and its associated complications Following the introduction of exogenous insulin therapy for the treatment of diabetes in the 1920s, diabetic patients survived to develop complications affecting the eyes, nerves, kidneys, and other tissues. For decades, debates ranged over whether or not the complications were secondary to disordered metabolism. In the early 1980s, the Diabetes Control and Complications Trial (DCCT) was organized to settle the debate. The results, first published in 1993 [74], showed that the lower the glycosylated haemoglobin levels (a reflection of the average blood sugar levels) were in the study patients, the lower the probability that retinopathy, neuropathy, or nephropathy would develop. However, in the 1980s, well before the DCCT study was published, observations in pancreas transplant recipients had already answered the question [75–79]. Since the 1970s it has been known that normal kidneys transplanted into diabetic recipients develop diabetic nephropathy [80]. In 1985, Bohman et al. [75] in Stockholm, showed that in recipients of simultaneous kidney and pancreas transplants in which neither organ was rejected, lesions of diabetic nephropathy did not occur in a transplanted kidney. Shortly thereafter, Bilous et al. [79] at the University of Minnesota, showed that a successful pancreas transplant (PAK) could prevent, reverse, or stabilize lesions in a previously transplanted kidney. The data was confirmed in long-term followup studies in the 1990s [81]. Indeed, Fioretto et al. [82], at the University of Minnesota, showed that lesions of diabetic nephropathy could be reversed in the native kidneys of non-uraemic recipients of pancreas transplants alone. In regard to neuropathy, Solders et al. [76,83] at Stockholm, in studies of recipients of combined pancreas and kidney transplants (SPK) and Kennedy and associates [77,84] at the University of Minnesota, in studies of recipients of successful solitary pancreas transplants, showed neuropathy improved as opposed to its inexorable progression in those with no transplant or with a failed graft. The Minnesota group also showed that neuropathic patients had improved survival probability after successful pancreas transplantation [85]. Finally, Ramsay et al. [78], also at the University of Minnesota, showed that in patients with advanced retinopathy, retinal events occurred in up to 30 per cent during the first 3 years after successful pancreas transplant. Thereafter, they remained stable, while those with failed grafts continued to have retinal events. No patients without disease at baseline developed retinopathy as long as the pancreatic graft functioned. Thus, the scientific principle that the diabetic lesions of the eye, nerve, and kidneys are linked to disordered metabolism was fully established from the observations in pancreas transplant recipients well before the DCCT was completed. Another area of controversy in diabetes mellitus that was enlightened by pancreas transplantation involved the pathogenesis of the disease. By the early 1980s, consistent evidence implicated autoimmunity as responsible for the destruction of ␤-cells in patients with type I diabetes [86]. That this must be the case was finally shown by observations in diabetic recipients of segmental pancreas transplants from their non-diabetic identical twin counterparts carried out at the University of Minnesota in the 1980s [87]. The first three recipients in the identical twin series were done without prophylactic immunosuppression (since isografts cannot be rejected) and all three twin recipients developed biopsy confirmed autoimmune isletitis (no rejection) and recurrence of diabetes mellitus within a few months of the transplant [88]. In contrast, immunosuppressed recipients of identical twin segmental grafts did not develop recurrence of disease [89], indeed, two identical twin recipients have been insulin independent for 9 and 13 years, respectively [46].

D.E.R. SUTHERLAND AND CARL G. GROTH

Although unusual, islet-directed autoimmunity can break through immunosuppression capable of preventing allograft rejection. In 1996, Tyden et al. [90] in Stockholm documented selective ␤-cell destruction in two cadaver pancreas transplants. However, immunosuppression given to prevent allograft rejection is nearly always sufficient to suppress autoimmunity [89], given the rarity of recurrent disease [91]. In summary, observations in pancreas transplant recipients definitely proved both that type I diabetes is an autoimmune disease, and that the diabetic complications which may occur in other organs are secondary to disorder in metabolism.

Evolution of recipient selection and programme development Besides the impact on secondary complications, studies in the 1980s documented an improvement in day-to-day quality of life of a diabetic patient by the insulin independence induced by a functioning pancreas graft [92,93]. Follow-up studies confirmed this benefit [94,95], providing an impetus to consider pancreas (or islet) transplantation at any stage of diabetes. Transplantation of functioning ␤-cells is the most physiological treatment of diabetes mellitus. Ideally it should be simple, with just an injection of isolated islets. The optimism that islet transplantation could be rapidly developed to achieve this simplicity probably delayed the development of clinical pancreas transplantation. However, develop it did and in turn the surprising success of pancreas transplantation (after a rocky start) in part has probably inhibited the development of clinical islet transplantation. Immunological tolerance for clinical application has not yet been developed, and with either pancreas or islet transplantation there is a need for immunosuppression. For this reason, most programmes limited pancreas or islet transplants to uraemic diabetic recipients or renal allografts who are thus obligated to immunosuppression. As the twentieth century ended, approximately 1500 pancreas transplants were being performed annually worldwide (the majority in the United States), of which more than 80 per cent were SPK [14]. During the 1980s, solitary pancreas transplants were routine only at the University of Minnesota [96]. In the 1990s, the number of programmes promoting solitary pancreas transplants has expanded [97,98] and the results in the modern immunosuppressive era have been good [14]. Pancreas (or islet) transplantation in non-uraemic patients should predominate and the foundation for its application has been laid. In regard to islet transplantation, since 1989, several groups have succeeded in establishing insulin independence in occasional diabetic recipients by intraportal islet transplantation [99–102]. Consistent islet allograft success has recently been achieved by using multiple donors and a steroidfree immunosuppression regimen at the University of Alberta in Edmonton [103]. Thus, engrafting an adequate ␤-cell mass appears to be the critical factor for clinical islet transplant to succeed. The challenge now is to achieve consistent success with a single donor. That this should be possible is apparent from the fact that auto islet transplantation after total pancreatectomy can sustain insulin independence [104], as shown by the very first case in the late 1970s [42]. Perhaps there will be a role for both islet and pancreas transplantation, with islet transplantation reserved for diabetic individuals with a low insulin requirement, while pancreas transplant may be preferable for those with a high insulin requirement or insulin resistance such as those with type II diabetes. Pancreas transplantation will also be preferred in individuals diabetic as a result of total pancreatectomy where enteric drainage could be used to correct exocrine deficiency, as was first done in the 1980s [105]. Indeed, if an unlimited supply of ␤-cells for transplantation could be obtained (xenografts or human cell lines), the future of pancreas transplantation could primarily be to correct exocrine deficiency, for which the ground work has already been laid [105,106].

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References 1 Gayet R, Guillamie M. La regulation de la secretion interne pancreatique par un processus humoral, demonstree par des transplantations de pancreas. Experiences sue des animaux normaux. Coll Roy Soc Biol 1927;97:1613–14. 2 Brooks JR, Gifford GH. Pancreatic homotransplantation. Transplant Bull 1959;6:100–3. 3 DeJode LR, Howard JM. Studie in pancreaticoduodenal homo-transplantation. Surg Gynecol Obstet 1962;114:553–8. 4 Bergan J, Hoehn JG, Porter N. Total pancreatic allografts in pancreatectomized dogs. Arch Surg 1965;90:521–6. 5 Largiader F, Lyons GW, Hidalgo F, Dietzman RH, Lillehei RC. Orthotopic allotransplantation of the pancreas. Am J Surg 1967;113:70–8. 6 Merkel FK, Kelly WD, Goetz FC, Maney J. Irradiated heterotopic segmental canine pancreatic allografts. Surgery 1968;63:291–7. 7 Idezuki Y, Feemster JA, Dietzman RH, Lillehei RC. Experimental pancreaticoduodenal preservation and transplantation. Surg Gynecol Obstet 1968;126:1002–14. 8 Sutherland DER. Pancreas and islet transplantation. I. Experimental studies. Diabetologia 1981;20:161–85. 9 Lillehei RC, Simmons RL, Najarian JS, Weil R, Uchida H, Ruiz JO, et al. Pancreatico-duodenal allotransplantation: Experimental and clinical experience. Ann Surg 1970;172:405–36. 10 Kelly WD, Lillehei RC, Merkel FK. Allotransplantation of the pancreas and duodenum along with the kidney in diabetic nephropathy. Surgery 1967;61:827–35. 11 Dubernard JM, Traeger J. Pancreas and islet transplantation workshop. Transplant Proc 1980;12:1–2. 12 Land W, Landgraf R. Segmental pancreatic transplantation international workshop. Horm Metab Res 1983;13:1–104. 13 Sutherland DER. International human pancreas and islet transplant registry. Transplant Proc 1980;12 (No. 4 Suppl. 2):229–36. 14 Gruessner A, Sutherland DER. Pancreas transplant outcomes for United States cases reported to the United Network for Organ Sharing (UNOS) and non-US cases reported to the International Pancreas Transplant Registry. In: Cecka JM, Terasaki PI, eds. Clinical transplants — 1999. Los Angeles: UCLA Immunogenetics Center; 2000:51–69. 15 Calne RY, Rolles K, White DJ, Thiru S, Evans DB, McMaster P, et al. Cyclosporin A initially as the only immunosuppressant in 34 recipients of cadaveric organs: 32 kidneys, 2 pancreases, and 2 livers. Lancet 1979;2:1033–6. 16 Starzl TE, Todo S, Fung J, Demetris AJ, Venkataramman R, Jain A. FK 506 for liver, kidney, and pancreas transplantation. Lancet 1989;2:1000–4. 17 Rayhill SC, Kirk AD, Odorico JS, Heisey DM, Cangro CB, Pirsch JD, et al. Simultaneous pancreas–kidney transplantation at the University of Wisconsin. In: Cecka JM, Terasaki PJ, eds Clinical transplants 1994. Los Angeles: UCLA Tissue Typing Laboratory 1995:261–9. 18 van Schilfgaarde R, Persijn GG, Sutherland DER. International symposium on organ transplantation in diabetics. Transplant Proc 1984;16:565–6. 19 Land W, Landgraf R. The world experience in clinical pancreas transplantation. Transplant Proc 1987;19 (Suppl. 4):1–2. 20 Groth CG, Tyden G, Bolinder J. First international congress on pancreatic and islet transplantation. Diabetes (Suppl. 1)1989;38:1–335. 21 Sutherland DER, Moudry KC. Pancreas Transplant Registry: history and analysis of cases 1966 to October 1986. Pancreas 1987;2:473–88.

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22 Groth CG, Lundgren G, Ostman J, Gunnarsson R. Experience with nine segmental pancreatic transplantations in preuremic diabetic patients in Stockholm. Transplant Proc 1980;12:68–71. 23 Sutherland DER. Pancreas transplantation in non-uremic diabetic patients. Transplant Proc 1986;18:1747–9. 24 Lillehei RC, Ruiz JO, Aquino C, Goetz FC. Transplantation of the pancreas. Acta Endocrinol 1976;83 (Suppl. 205):303–20. 25 Gliedman ML, Tellis VA, Soberman R. Long-term effects of pancreatic transplant function in patients with advanced juvenile onset diabetes. Diabetes Care 1978;1:1–9. 26 Bortagaray MC, Zelasco JF, Bava A. Homotransplante parcial del pancreas en el diabetico. Prensa Med Argent 1970;57:220–4. 27 Teixeira E, Monteiro G, De Cenzo M, Teixeira A, Bergan JJ. Transplantation of the isolated pancreas: report on the first human case. Bull Soc Int Chir 1970;29:337–44. 28 Merkel FK, Poticha SM, Nudelman EJ, Colwell JA, Bergan JJ. Pancreas transplantation in man. I. The donor and recipient operation. Arch Surg 1971;103:205–10. 29 Gliedman ML, Gold M, Whittaker J, Rifkin H, Soberman R, Freed S, et al. Clinical segmental pancreatic transplantation with ureter-pancreatic duct anastomosis for exocrine drainage. Surgery 1973;74:171–80. 30 Connolly JE, Martin DC, Steinberg T, Gwinup G, Gazzaniga AB, Bartlett RH. Clinical experience with pancreaticoduodenal transplantation. Arch Surg 1973;106:489–94. 31 Merkel FK, Ryan WG, Armbruster K, Seim S, Ing TS. Pancreatic transplantation for diabetes mellitus. Ill Med J 1973;144:477–9. 32 Largiader F, Uhlschmid G, Binswanger U, Zaruba K. Pancreas rejection in combined pancreaticoduodenal and renal allotransplantation in man. Transplantation 1975;19:185–7. 33 Brynger H, Blohme G, Claes G, Gustafsson A, Gelin LE. Transplantation of a duct-ligated pancreatic allograft to a diabetic patient. Scand J Urol Nephrol 1975 (Suppl. 29);59–62. 34 Sutherland DER. Pancreas and islet transplantation. II. Clinical trials. Diabetologia 1981;20:435–50. 35 Sutherland DER, Rynasiewicz JJ, Najarian JS. Current status of pancreas and islet transplantation. In: Brownlee M, ed. Handbook of diabetes mellitus. New York: Garland Publishing, 1981:273–416. 36 Groth CG, Lundgren G, Arner P, Collste H, Hardstedt C, Lewander R, et al. Rejection of isolated pancreatic allografts in patients with diabetes. Surg Gynecol Obstet 1976;143:933–40. 37 Dubernard JM, Traeger J, Neyra P, Touraine JL, Traudiant D, Blanc-Brunat N. A new method of preparation of segmental pancreatic grafts for transplantation: trials in dogs and in man. Surgery 1978;84:633–40. 38 Groth CG, Lundgren G, Gunnarsson R, Hardstedt C, Ostman J. Segmental pancreatic transplantation with special reference to the use of ileal exocrine diversion and to the hemodynamics of the graft. Transplant Proc 1980;12 (Suppl. 2):62–7. 39 Groth CG, Collste H, Lundgren G. Successful outcome of segmental human pancreatic transplantation with enteric exocrine diversion after modifications in technique. Lancet 1982;2:522–4. 40 Traeger J, Dubernard JM, Touraine JL, Neyra P, Malik MC, Pelissard C, et al. Pancreatic transplantation in man: a new method of pancreas preparation and results on diabetes correction. Transplant Proc 1979;11:331–5. 41 Najarian JS, Sutherland DER, Matas AJ, Steffes MW, Simmons RL, Goetz FC. Human islet transplantation: A preliminary report. Transplant Proc 1977;9:233–6. 42 Sutherland DER, Matas AJ, Najarian JS. Pancreatic islet cell transplantation. Surg Clin N Am 1978;58:365–82. 43 Sutherland DER, Matas AJ, Goetz FC, Najarian JS. Transplantation of dispersed pancreatic islet tissue in humans: autografts and allografts. Diabetes 1980;29 (Suppl.):31–44.

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44 Sutherland DER, Goetz FC, Najarian JS. Intraperitoneal transplantation of immediately vascularized segmental pancreatic grafts without duct ligation: A clinical trial. Transplantation 1979;28:485–91. 45 Sutherland DER, Baumgartner D, Najarian JS. Free intraperitoneal drainage of segmental pancreas grafts: Clinical and experimental observations on technical aspects. Transplant Proc 1980;12:26–32. 46 Sutherland DE, Gruessner RWG, Dunn DC, Matas AJ, Humar A, Kandaswamy R, et al. Over 1000 pancreas transplants at a single institution. Ann Surg 2000;233:463–501. 47 Sutherland DER, Goetz FC, Rynasiewicz JJ, Baumgartner D, White DC, Elick BA, et al. Segmental pancreas transplantation from living related and cadaver donors: A clinical experience. Surgery 1981;90:159–69. 48 Sutherland DE, Gores PF, Farney AC, Wahoff DC, Matas AJ, Dunn DL, et al. Evolution of kidney, pancreas, and islet transplantation for patients with diabetes at the University of Minnesota. Am J Surg 1993;166:456–91. 49 Sollinger HW, Cook K, Kamps D. Clinical and experimental experience with pancreaticocystostomy for exocrine pancreatic drainage in pancreas transplantation. Transplant Proc 1984;16:749–51. 50 Starzl TE, Iwatsuki S, Shaw BW Jr, Greene DA, Van Thiel DH, Nalesnik MA, et al. Pancreaticoduodenal transplantation in humans. Surg Gynecol Obstet 1984;159:265–72. 51 Nghiem DD, Corry RJ. Technique of simultaneous pancreaticoduodenal transplantation with urinary drainage of pancreatic secretion. Am J Surg 1987;153:405–6. 52 Prieto M, Sutherland DER, Fernandez-Cruz L, Heil JE, Najarian JS. Experimental and clinical experience with urine amylase monitoring for early diagnosis of rejection in pancreas transplantation. Transplantation 1987;43:71–9. 53 Gruessner RWG, Dunn DL, Tzardis PJ, Tomadze G, Moudry-Munns KC, Matas AJ, et al. Simultaneous pancreas and kidney transplants versus single kidney transplants and previous kidney transplants in uremic patients and single pancreas transplants in nonuremic diabetic patients: comparison of rejection, morbidity, and long-term outcome. Transplant Proc 1990;22:622–3. 54 Tom WW, Munda R, First MR, Alexander JW. Autodigestion of the glans penis and urethra by activated transplant pancreatic exocrine enzymes. Surgery 1987;102:99–101. 55 Sutherland DER, Goetz FC, Najarian JS. Living-related donor segmental pancreatectomy for transplantation. Transplant Proc 1980;12:19–25. 56 Sutherland DER, Moudry KC, Najarian JS. Pancreas transplantation. In: Cerilli J, ed. Organ transplantation and replacement. Philadelphia: Lippincott, 1987:535–74. 57 Marsh CL, Perkins JD, Sutherland DER, Corry RJ, Sterioff S. Combined hepatic and pancreaticoduodenal procurement for transplantation. Surg Gynecol Obstet 1989;168:254–8. 58 Delmonico FL, Jenkins RL, Auchincloss H Jr, Etienne TJ, Russell PS, Monaco AB, et al. Procurement of a whole pancreas and liver from the same cadaveric donor (see comments). Surgery 1989;105:718–23. 59 Calne RY. Paratopic segmental pancreas grafting: a technique with portal venous drainage. Lancet 1984;1:595–7. 60 Gil-Vernet JM, Fernandez-Cruz L, Caralps A, Andreu J, Figuerola D. Whole organ and pancreaticoureterostomy in clinical pancreas transplantation. Transplant Proc 1985;17:2019–22. 61 Tyden G, Lundgren G, Ostman J, Gunnarsson R, Groth CG. Grafted pancreas with portal venous drainage. Lancet 1984;1:964. 62 Tydén G, Wilczek H, Lundgren G, Ostman J, Gunnarsson R, Jaremko G, et al. Experience with 21 intraperitoneal segmental pancreatic transplantations with enteric or gastric exocrine diversion in humans. Transplant Proc 1985;17:331–5. 63 Sutherland DER, Goetz FC, Moudry KC, Abouna GM, Najarian JS. Use of recipient mesenteric vessels for revascularization of segmental pancreas grafts: Technical and metabolic considerations. Transplant Proc 1987;19:2300–4.

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64 Rosenlof LK, Earnhardt RC, Pruett TL, Stevenson WC, Douglas MT, Cornett GC, et al. Pancreas transplantation: an initial experience with systemic and portal drainage of pancreatic allografts. Ann Surg 1992;215:586–95. 65 Reddy KS, Stratta RJ, Shokouh-Amiri MH, Alloway R, Egidi MF, Gaber AO. Surgical complications after pancreas transplantation with portal-enteric drainage. J Am Coll Surg 1999;189:305–13. 66 Bruce DS, Newell KA, Woodle ES, Cronin DC, Grewal HP, Millis JM, Ruebe M, et al. Synchronous pancreas–kidney transplantation with portal venous and enteric exocrine drainage: outcome in 70 consecutive cases. Transplant Proc 1998;30:270–1. 67 Philosophe B, Farney AC, Schweitzer E, Colonna J, Jarrell BE, Krishnamurthi V, et al. The superiority of portal venous drainage over systemic venous drainage in pancreas transplantation. Ann Surg 2001;234:689–696. 68 Sutherland DER, Moudry-Munns KC. International Pancreas Transplant Registry Report. In: Terasaki PI, ed. Clinical transplants 1988. UCLA Tissue Typing Laboratory, California; 1989:53–64. 69 Gunnarsson R, Klintmalm G, Lundgren G, Wilczek H, Ostman J, Groth CG. Deterioration in glucose metabolism in pancreatic transplant recipients given cyclosporin (letter). Lancet 1983;2:571–2. 70 Sutherland DER, Casanova D, Sibley RK. Role of pancreas graft biopsies in the diagnosis and treatment of rejection after pancreas transplantation. Transplant Proc 1987;19:2329–31. 71 Perkins JD, Munn SR, Marsh CL, Barr D, Engen DE, Carpenter HA. Safety and efficacy of cystoscopically directed biopsy in pancreas transplantation. Transplant Proc 1990;22:665–6. 72 Allen RD, Wilson TG, Grierson JM, Greenberg ML, Earl MJ, Nankivel BJ, et al. Percutaneous biopsy of bladder-drained pancreas transplants. Transplantation 1991;51:1213–16. 73 Gaber AO, Gaber L, Shokouh-Amiri MH, Hathaway D. Percutaneous biopsy of pancreas transplants. Transplantation 1992;54:548–50. 74 DCCT Research Group. Diabetes control and complications trial (DCCT): The effect of intensive diabetes treatment in long term complications in IDDM. NEJM 1993;329:977–86. 75 Bohman SO, Tyden G, Wilczek H, Lundgren G, Jaremko G, Gunnarsson R, et al. Prevention of kidney graft diabetic nephropathy by pancreas transplantation in man. Diabetes 1985;34:306–8. 76 Solders G, Wilczek H, Gunnarsson R, Tyden G, Persson A, Groth CG. Effects of combined pancreatic and renal transplantation on diabetic neuropathy: a two-year follow-up study. Lancet 1987;2:1232–5. 77 Van der Vliet JA, Navarro X, Kennedy WR, Goetz FC, Najarian JS, Sutherland DER. The effect of pancreas transplantation on diabetic polyneuropathy. Transplantation 1988;45:368–70. 78 Ramsay RC, Goetz FC, Sutherland DER, Mauer SM, Robinson LL, Cantrill HL, et al. Progression of diabetic retinopathy after pancreas transplantation for insulin-dependent diabetes mellitus. NEJM 1988;318:208–14. 79 Bilous RW, Mauer SM, Sutherland DER, Najarian JS, Goetz FC, Steffes MW. The effects of pancreas transplantation on the glomerular structure of renal allografts in patients with insulin-dependent diabetes. NEJM 1989;321:80–5. 80 Mauer SM, Barbosa J, Vernier RL, Kjellstrand CM, Buselmeier TJ, Simmons RL, et al. Development of diabetic vascular lesions in normal kidneys. Development of diabetic vascular lesions in normal kidneys transplanted into patients with diabetes mellitus. N Engl J Med 1976;295:916–20. 81 Wilczek H, Jaremko G, Tydén G, Groth CG. A pancreatic graft protects a simultaneously transplanted kidney from developing diabetic nephropathy: a 1–6 year follow-up study. Transplant Proc 1993;25:1314–15. 82 Fioretto P, Steffes MW, Sutherland DER, Goetz FC, Mauer SM. Reversal of lesions of diabetic nephropathy after pancreas transplantation. New Engl J Med 1998;339:69–75. 83 Solders G, Tyden G, Persson A, Groth CG. Improvement of nerve conduction in diabetic neuropathy: a follow-up study 4 years after combined pancreatic and renal transplantation. Diabetes 1992;41:946. 84 Kennedy WR, Navarro X, Goetz FC, Sutherland DER, Najarian JS. Effects of pancreatic transplantation on diabetic neuropathy. NEJM 1990;322:1031–7.

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85 Navarro X, Kennedy WR, Loewensen RB, Sutherland DER. Influence of pancreas transplantation on cardiorespiratory reflexes, nerve conduction, and mortality in diabetes mellitus. Diabetes 1990;39:802–6. 86 Eisenbarth GS. Type I diabetes mellitus: A chronic autoimmune disease. NEJM 1986;314:1360–8. 87 Sutherland DER, Sibley RK, Xu XZ, Michael AF, Srikanta S, Taub F, et al. Twin-to-twin pancreas transplantation: Reversal and reenactment of the pathogenesis of type I diabetes. Trans Assoc Am Physicians 1984;97:80–7. 88 Sibley RK, Sutherland DER, Goetz FC, Michael AF. Recurrent diabetes mellitus in the pancreas isoand allograft: A light and electron microscopic and immunohistochemical analysis of four cases. Lab Invest 1985;53:132–44. 89 Sutherland DER, Goetz FC, Sibley RK. Recurrence of disease in pancreas transplants. Diabetes 1989;38:85–7. 90 Tyden G, Reinholt FP, Sundkvist G, Bolinder J. Recurrence of autoimmune diabetes mellitus in recipients of cadaveric pancreatic grafts (see comments) (published erratum appears in N Engl J Med 1996;(23):1778). N Engl J Med 1996;335:860–3. 91 Papadimitriou JC, Drachenberg CB, Wiland A, Klassen DK, Fink J, Weir MR, et al. Histologic grading of acute allograft rejection in pancreas needle biopsy: correlation to serum enzymes, glycemia, and response to immunosuppressive treatment. Transplantation 1998;66:1741–5. 92 Nakache R, Tyden G, Groth CG. Quality of life in diabetic patients after combined pancreas-kidney or kidney transplantation. Diabetes 1989;38 (Suppl. 1):40–2. 93 Zehrer CL, Gross CR. Quality of life of pancreas transplant recipients. Diabetologia 1991;34 (Suppl. 1):S145–9. 94 Nakache R, Tyden G, Groth CG. Long-term quality of life in diabetic patients after combined pancreas–kidney transplantation or kidney transplantation. Transplant Proc 1994;26:510–11. 95 Gross CR, Limwattananon C, Matthees BJ. Quality of life after pancreas transplantation: a review. Clin Transplant 1998;12:351–61. 96 Sutherland DER, Chinn PL, Goetz FC, Elick BA, Najarian JS. Minnesota experience with 85 pancreas transplants between 1978 and 1983. World J Surg 1984;8:244–52. 97 Bartlett ST, Schweitzer EJ, Johnson LB, Kuo PC, Papadimitriou JC, Drachenberg CB, et al. Equivalent success of simultaneous pancreas kidney and solitary pancreas transplantation. A prospective trial of tacrolimus immunosuppression with percutaneous biopsy. Ann Surg 1996;224:440–9. 98 Stratta RJ, Weide LG, Sindhi R, Sudan D, Jerius JT, Larsen JL, et al. Solitary pancreas transplantation. Experience with 62 consecutive cases. Diabetes Care 1997;20:362–8. 99 Scharp DW, Lacy PE, Santiago JV, McCullough CS, Weide LG, Falqui L, et al. Insulin independence after islet transplantation into type I diabetic patient. Diabetes 1990;39:515–18. 100 Warnock GL, Kneteman NM, Ryan E. Long-term follow-up after transplantation of insulinproducing pancreatic islets into patients with type I (insulin independent) diabetes mellitus. Diabetologia 1992;35:89–95. 101 Gores PF, Najarian JS, Stephanian E, Lloveras JJ, Kelley SL, Sutherland DER. Insulin independence in type I diabetes after transplantation of unpurified islets from a single donor using 15deoxyspergualin. Lancet 1993;341:19–21. 102 Meyer C, Hering BJ, Grossmann R, Brandhorst H, Brandhorst D, Gerich J, et al. Improved glucose counterregulation and autonomic symptoms after intraportal islet transplants alone in patients with long-standing type I diabetes mellitus. Transplantation 1998;66:233–40. 103 Shapiro AMJ, Lakey JRT, Ryan E, Korbutt GS, Toth E, Warnock GL, et al. Insulin independence after solitary islet transplantation in type I diabetic patients using steroid free immunosuppression. N Engl J Med 2000;343:230–8.

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104 Wahoff DC, Papalois BE, Najarian JS, Kendall DM, Farney AC, Leone JP, et al. Autologous islet transplantation to prevent diabetes after pancreatic resection. Ann Surg 1995;22(4):562–79. 105 Gruessner RWG, Manivel DC, Dunn DL, Sutherland DER. Pancreaticoduodenal transplantation with enteric drainage following native total pancreatectomy for chronic pancreatitis: A case report. Pancreas 1991;6:479–88. 106 Stern RC, Mayes JT, Weber FL Jr, Blades EW, Schulak JA. Restoration of exocrine pancreatic function following pancreas-liver-kidney transplantation in a cystic fibrosis patient. Clin Transplant 1994;8:1–4.

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Chapter 2

The nature of the problem: why do we need pancreatic transplantation? Martin Press

Diabetes is one of the cruellest of diseases. Not only does it shorten life expectancy, but it can seriously compromise quality of life in the process. It remains the most common cause of blindness in people of working age, causes renal failure, impotence, neuropathy, foot ulcers, amputations, and heart disease. This makes it a very expensive disease. In the United Kingdom it accounts for some 9 per cent of the NHS budget [1]. In the United States, 14.6 per cent of the health care budget, amounting to some $100 billion per year, was spent on the 4.5 per cent of the population with diabetes [2]. Of this, half was accounted for by medical costs directly related to diabetes (mostly the treatment of advanced diabetic complications, including haemodialysis, foot ulcers, and amputations) and half by societal costs (including long-term disability and loss of earnings due to blindness, amputations, and premature death). Even without complications, a child who develops diabetes at the age of 7 years will have faced costs of $52 000 by the time he is 40 years old [3]. Patients live their lives in the shadow of these complications. And while they worry about the longterm consequences of hyperglycaemia, the short-term effect is that it makes them feel tired, constantly 'below par'. It affects their driving licence, their life insurance premium, their job, their social life. If they try to improve their control they run into an increased risk of acute hypoglycaemia, which in turn affects their life and can be frankly dangerous, not only to them but to other people (if they become hypoglycaemic at the wheel of a car, for example). It is a miserable disease.

Types of diabetes and their causes Diabetes mellitus is the condition which results from failure of the ␤-cells of the pancreas, the only cells in the body able to produce insulin. It is conventionally divided into type 1, type 2, and secondary diabetes. Secondary diabetes can in turn be divided in two. It can result from either a pancreatic lesion (such as pancreatitis, either acute or chronic, haemochromatosis, or a pancreatic cancer) or from an excess of hormones which result in insulin resistance (e.g. acromegaly due to growth hormone excess or Cushing's syndrome due to corticosteroid excess). By far the most common cause of secondary diabetes is iatrogenic steroid-induced diabetes in patients receiving corticosteroids for arthritis, inflammatory bowel disease, or asthma. Type 1 diabetes, which used to be termed insulin-dependent diabetes mellitus, and before that juvenile-onset diabetes, has its peak onset at puberty but can occur at any age. It is an autoimmune disease in which the ␤-cells are selectively destroyed by a T-cell mediated process. Antibodies, either to insulin itself or to ␤-cell antigens such as GAD (glutamic acid decarboxylase) are markers for the condition. They are frequently positive even before there is any identifiable abnormality of glucose tolerance, and

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often do not stay positive for long after the onset of the disease itself [4], possibly because the destruction of the ␤-cells results in the loss of the antigen. The antibodies probably do not play a direct pathogenic role, but rather reflect the ongoing clinically silent insulitis [4]. It is still unclear which antigens the T cells are responding to or what instigates the autoimmune process, although in non-obese diabetic (NOD) mice, which represent an animal model of type 1 diabetes, knockout of the GAD gene prevents T-cell activation and protects the animals from the development of diabetes [5]. In man, it is believed that the disease results from a combination of genetic and environmental factors. There is disequilibrium with certain HLA haplotypes, but concordance within identical twins is less than 40 per cent [6], implying that while genetic factors may confer a predisposition, environmental factors play at least as great a role. What the (?infectious) factors may be which instigate the autoimmune process in genetically predisposed individuals remains unclear [7]. Whatever the explanation(s) there is currently an epidemic of type 1 diabetes in northern Europe such that the incidence is doubling with each successive generation [8]. Type 2 diabetes was formally known as non-insulin-dependent diabetes mellitus and before that as maturity-onset diabetes. If there is at present an epidemic of type 1 diabetes there is in contrast a global pandemic of type 2 diabetes. While it is appreciated that there is a very strong genetic component of type 2 diabetes, such that there is a near 100 per cent concordance rate in identical twins [9], it is increasingly being appreciated that type 2 diabetes is a heterogeneous, polygenic condition, and different families probably have different genotypes underlying their condition. The prevalence of type 2 diabetes is highest (up to 50 per cent) in American Indians and in South Pacific Islanders. These are populations which have evolved to survive caloric deprivation but who are now affluent and obese. The suggestion is that the 'thrifty' genes which have in the past conferred a survival advantage when food was in short supply, are now responsible for a tendency to gain weight easily and to become insulin resistant as a result [10]. The other major recent observation has been that low birth weight is associated with the development of insulin resistance, hypertension, and type 2 diabetes in later life [11]. While this has been ascribed to the consequences of intrauterine malnutrition [12], it has also been pointed out that, since insulin is the major intrauterine growth hormone, low birth weight and subsequent insulin resistance could both represent different phenotypic manifestations of the same 'insulin-resistant' genotype [13]. Patients with type 2 diabetes are characteristically insulin resistant, and insulin resistance is a characteristic feature of obesity. However, while most patients with type 2 diabetes are overweight, even those patients who are not overweight are insulin resistant. However, this in itself is not sufficient to cause diabetes because so long as the ␤-cells are healthy they can compensate for this. Indeed, all obese and sedentary people are insulin resistant to a greater or lesser extent, but only a small percentage of such people have diabetes. A second lesion appears to be necessary in which the ␤-cells themselves are affected. It is not so much that they 'run out of insulin' as that they appear oblivious to the fact that glucose levels are rising and more insulin is needed [14]. Thus, ␤-cells in patients with type 2 diabetes may retain their ability to respond to other secretagogues such as amino acids or sulphonylureas (and of course the latter are used in the treatment of the condition as a result). Insulin levels are typically only slightly low compared to healthy controls, but they are markedly lower than they would be in a control subject given glucose to cause an equivalent degree of hyperglycaemia. The exact nature of the ␤-cell defect remains unclear, but pulses of insulin secretion lose their normal periodicity [15] and the first phase of insulin secretion in response to an acute challenge is lost [16]. Both the insulin resistance and the ␤-cell secretory defect are exacerbated by hyperglycaemia (Fig. 2.1), thus creating two vicious circles.

MARTIN PRESS

Fig. 2.1 Vicious circles in type 2 diabetes. In type 2 diabetes, hyperglycaemia results from a combination of insulin resistance and ␤-cell dysfunction. Both of these abnormalities are in turn exacerbated by hyperglycaemia. Thus, any therapeutic strategy which improves metabolic control tends to improve both insulin sensitivity and ␤-cell function.

In normal subjects the insulin response to oral glucose is very much greater than to intravenous glucose due to the effect of 'incretins'; hormones secreted by the gut which sensitize the ␤-cell to glucose. The major candidates for the incretins are GLP-1 (glucagon-like peptide 1) and GIP (glucose-dependent insulinotropic peptide), both members of the glucagon superfamily. In type 2 diabetes, secretion of GLP-1 is reduced while its actions are normal, whereas the secretion of GIP is normal but its effects are markedly impaired [17,18]. Infusion of GLP-1 normalizes ␤-cell responsiveness and analogues may in the future be developed for therapeutic use. For the time being, treatment remains with drugs which stimulate insulin secretion, such as the sulphonylureas, or drugs which increase insulin sensitivity, such as biguanides or thiazolidinediones.

Clinical course Type 1 diabetes characteristically has an abrupt onset, but in fact autoimmune destruction of the ␤cells has at that point been going on for months or even years. New-onset type 1 diabetes can thus with equal justification be viewed as 'endstage prediabetes'. On the basis of partial pancreatectomy experiments it is believed that one can manage with only 20 per cent or so of one's ␤-cells, but as soon as the number falls below that level, diabetes presents abruptly, characteristically with polyuria, polydipsia, and weight loss. Type 2 diabetes in contrast is an insidious process whereby insulin resistance appears to be present from the beginning and ␤-cell failure supervenes gradually and progressively over a period of many years [19]. Patients may present with tiredness or infections, but the acute presenting symptoms of type 1 diabetes are absent and patients are frequently totally asymptomatic. On the basis of the incidence of complications at presentation, it is believed that diabetes may have been present for 10 years or more prior to presentation [20]. Furthermore, the United Kingdom Prospective Diabetes Study (UKPDS) has illustrated vividly the fact that even after presentation, type 2 diabetes continues to progress inexorably as the ␤-cells gradually fail [21]. However, in contrast to type 1 diabetes, ␤-cell mass remains normal [22].

Actions of insulin and consequences of insulin deficiency Insulin is the body's major anabolic hormone, and affects not only carbohydrate metabolism but lipid and protein metabolism as well. Thus, patients presenting acutely with type 1 diabetes lose weight

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because they lose muscle and fat, and it is the breakdown of fat, and its metabolism to ketoacids, which results in diabetic ketoacidosis if the condition is not recognized and treated soon enough. Insulin effectively behaves as two distinct hormones with respect to its anabolic and anticatabolic effects respectively, and this is not merely an academic distinction (Fig. 2.2). We have evolved to take in calories as meals rather than grazing continuously. However, when we are not eating, there is a continuing requirement for fuel and the brain in particular cannot utilize anything but glucose to a significant extent. There is thus a need for distinct effects of insulin following a meal, when high levels result in uptake of glucose by muscle and fat in particular, and in a parallel stimulation of fat uptake by adipose tissue under the influence of lipoprotein lipase, an enzyme which is induced by insulin. In contrast, in between meals and particularly overnight, when insulin levels are much lower, the regulation of glucose production by the liver and of free fatty acid release from adipose tissue under the influence of hormone-sensitive lipase, another enzyme regulated by insulin, results in an appropriate rate of release of these fuels to match requirements. Thus, in the postabsorptive state, insulin levels are regulated exquisitely by the pancreatic ␤-cells to maintain exactly the right hepatic glucose production rate to keep fasting glucose levels constant. If the ␤-cells start to fail, the resultant low levels of insulin would normally be the signal to the liver that the subject is hypoglycaemic, and glucose production increases steeply. Similarly, adipose tissue releases greatly increased amounts of free fatty acids which are in turn converted by the liver to ketoacids. Conversely, if the ▪-cells are working normally, the rise

Fig. 2.2 Regulation of blood glucose levels by insulin. A near-constant blood glucose level is maintained despite a constant glucose uptake by the brain, and an intermittent input of large amounts of glucose following a meal. This is achieved by changes in plasma insulin which turns two 'taps'. In the fasting state, when insulin is present at low concentrations, insulin acts predominantly on the liver to regulate glucose production. Following a meal raised insulin concentrations 'turn off' this tap and 'turn on' a tap to increase peripheral glucose uptake, predominantly in muscle.

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Fig. 2.3 Dose-response curves of glucose kinetics as a function of insulin concentrations. Hepatic glucose production is regulated by insulin at low concentrations of insulin (5 to 10 mU/l). This is thus the major determinant of the fasting glucose concentration. Following a meal, insulin concentrations rise by an order of magnitude (to 50 to 100 mU/l). At these levels, hepatic glucose production is completely suppressed and peripheral uptake is stimulated, thus minimizing the hyperglycaemic excursion following food. Because of the steepness of these dose-response curves, even slightly too much or too little insulin will have major effects on the blood glucose concentration in an insulin-treated patient.

in insulin levels following a meal rapidly shuts off hepatic glucose production and free fatty acid release from adipose tissue. It is the steepness of the dose–response curves which should be appreciated (Fig. 2.3). Slight underor over-replacement of insulin results in disproportionate changes in glucose and fatty acid release from the liver and adipose tissue, respectively. Given that the half-life of insulin in the circulation is only 2 to 3 min, and that insulin levels (in a non-diabetic subject) vary continuously to match requirements, the problems involved in the physiological replacement of insulin become obvious. It is surprising that diabetes can be managed as well as it can with 2 to 4 daily subcutaneous injections of insulin.

Metabolic profiles of diabetes and diabetic monitoring Diabetic control is assessed by monitoring glycosylated haemoglobin (HbA1c) every few months and by home glucose monitoring by the patient himself. HbA1c is formed from HbA in the red cells as they circulate. The reaction is non-enzymic and the amount of HbA1c formed is a function of the mean glucose concentration to which the red cells are exposed. Since the red cell survival time is about 120 days, the average age of the red cells in the circulation at any one time is 60 days, and the HbA1c thus provides a guide to what average glucose levels have been over the past 6 to 8 weeks. In some assays, misleading values can be encountered in patients with haemoglobinopathies, and HbA1c values will also be misleading if red cell survival is shortened, for example in a patient with menorrhagia. Some confusion tends to arise because a normal mean blood glucose concentration is about 5 mmol/l and a

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normal level of HbA1c is about 5 per cent. The fact that these figures are numerically identical does not mean that one can translate a given HbA1c into a numerically identical mean glucose level. An HbA1c of 10 per cent translates into a mean glucose level of about 15 mmol/l, although there is considerable variability from one patient to another. This same interpatient variability means that HbA1c cannot be used to diagnose diabetes either. The correct way to use HbA1c measurements is to compare one clinic visit to another in the same patient, in order to ascertain whether diabetic control is getting better or worse. While the HbA1c gives rough guidance on whether diabetic control is adequate, it does not give any information on what to do if it is not. For this one requires the patient's own finger pricks to give information on what glucose levels are at different times of the day. Armed with this information, the aim is to tailor the treatment regimen to the individual patient. It is often possible, just by looking at glucose levels at different times of the day, to tell whether a patient has type 1 or type 2 diabetes. In type 2 diabetes, fasting glucose levels are increased, and, because hepatic glucose production does not fall to zero after a meal, there is an exaggerated rise in glucose level following food. However, the effect is relatively smooth and predictable and varies little from one day to the next. In contrast, type 1 diabetes, in which insulin is totally deficient, is characterized by gross instability and marked day-to-day variability. The incidence of hypoglycaemia, which is rare in type 2 diabetes and virtually always results from too much insulin or too great a dose of a sulphonylurea, is some 20-fold higher in type 1 diabetes since it is not possible with conventional insulin treatment to gauge the dose of insulin required exactly. We teach patients that glucose levels are elevated following food and reduced as a result of exercise or insulin treatment. However, there are clearly many more influences at work than this, and looking at a continuous sensor readout it is often impossible to tell what is causing particular perturbations in diabetic control (Fig. 2.4). One well-recognized influence on diabetic control is the so-called dawn phenomenon, whereby insulin requirements rise between about 4.00 and 8.00 a.m. This appears to result from the effects of growth hormone which is typically secreted as soon as a patient achieves deep sleep at between 11.00 p.m. and 1.00 a.m. These growth hormone peaks induce insulin resistance some 4 h later [23]. If the subject does not have diabetes, the pancreas is able to compensate for this by secreting more insulin but if the ␤-cells are not able to do this, glucose levels will rise. Matters are made worse in the diabetic patient by the fact that this is characteristically the time of day when insulin concentrations are declining as the effects of the previous night's intermediate-acting insulin injection wears off. The effect is most pronounced in teenagers, presumably because they secrete more growth hormone, and is made worse by the fact that growth hormone secretion varies from one night to another. Diabetes is notoriously unstable in teenagers, who tend to get the blame for a phenomenon which is, at least in part, physiological. Insulin resistance is also induced by counter-regulatory hormones secreted during exercise and as a result of hypoglycaemia. The idea that counter-regulatory hormone secretion during hypoglycaemia results in rebound hyperglycaemia (the Somogyi phenomenon) [24] is, however, less of a problem than it might otherwise be because patients with diabetes tend to have impaired secretion of counterregulatory hormones in response to hypoglycaemia [25], but this is a function of how well or badly their diabetes has been controlled.

Insulin regimens While many different types of insulin are available, they can broadly be divided into quick acting and intermediate or long acting. A solution of insulin itself (soluble or regular insulin) will typically start

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Fig. 2.4 Twenty-four hour subcutaneous glucose profile in a patient with type 1 diabetes. The recording is obtained with the MiniMed continuous glucose monitoring system, with a glucose electrode implanted percutaneously into adipose tissue. The arrows represent insulin injections, the first three being preprandial soluble insulin and the fourth a bedtime injection of an isophane insulin. The five circles indicate the patient's own finger-prick blood glucose measurements, which are used in the calibration of the sensor. The sensor tracing indicates that the patient's diabetic control is much worse than he would know from his finger-pricks, with unrecognized episodes of both hypo- and hyperglycaemia. It also illustrates the instability of glucose levels in type 1 diabetes. Clearly there must be other determinants of glucose levels besides insulin, food, and exercise.

to take effect following subcutaneous injection within half an hour. Its peak effect will be seen at 2 to 3 h but a continued effect is seen up to 6 h after an injection. Ultra quick-acting insulin analogues are now also available, which start to act immediately, exert their peak action at 1 to 2 h, and wear off over about 4 h [26]. Intermediate-acting insulins are divided into the isophane and the lente types of insulins. Both have a gradual onset of action with peak effects at 6 to 12 h and a duration of action of 16 to 20 h or more. Insulin analogues which have a less pronounced peak are starting to become available. Intermediateacting insulins come as non-uniform suspensions and considerable variation is seen not only in the amount of insulin actually injected between one injection and the next (depending on how well the insulin is mixed) [27] but also as a result of major differences in absorption rates from one injection to the next [28]. Finally, insulin can be given by insulin pumps. These consist of small battery-operated syringe pumps which are typically worn on the belt or carried in the pocket. The syringe, which contains only quick- or ultra quick-acting insulin, is connected via a tube to a small indwelling subcutaneous catheter. The pump delivers insulin continuously (the basal rate) and thus has advantages over traditional intermediate-acting insulins both in terms of the reliability of absorption [29] and the lack of peaking and waning of the insulin effect. Furthermore, the pump can be programmed to give an increased basal rate during the second half of the night to compensate for

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the dawn phenomenon and mimic a physiological overnight insulin profile. Boluses of quick- or ultra quick-acting insulin are given before a meal via the pump. Current pumps are in no way automatic, however, and patients have to do fingerpricks to 'tell' their pump how much insulin to give. Studies in patients treated with an insulin pump show either an improvement in HbA1c or a reduction in the risk of hypoglycaemia, or both [30–32]. A normal HbA1c is rarely attainable, however, and the risk of longterm complications, while reduced, is far from abolished. Furthermore, any attempt to improve diabetic control further is always limited by an increased risk of hypoglycaemia. Without a pump, the best one can do to approximate a physiological insulin profile is to give an injection of quick- or ultra quick-acting insulin before each meal and a long-acting insulin at bedtime. Patients who wish to be less intensive with their management very often settle for two injections a day, each comprising a mixture of quick- and intermediate-acting insulins. Thus, following the morning injection, the quick-acting fraction covers the hyperglycaemic effect of breakfast and the intermediate-acting insulin covers the afternoon, while following the evening injection the quick-acting insulin covers the evening meal and the intermediate-acting insulin then lasts through the night. The problem with all of these regimens is that they represent only a very poor approximation to the patient's actual insulin needs which vary on a minute-to-minute basis. This is in marked contrast to other endocrine failure syndromes. The hypothyroid patient is perfectly well replaced with a single tablet of thyroxine a day, and even the hypoadrenal patient typically requires two or at most three doses of hydrocortisone per day. These hormones are relatively long acting and requirements vary little.

Does tight diabetic control matter? When insulin was discovered in 1921 and started to be used clinically, it was assumed that this would provide the cure for type 1 diabetes. Certainly, in the sense that people rarely succumbed to what had until then been a fatal disease, this was indeed the case. However, during the 1930s and 1940s patients who did not die from diabetic ketoacidosis nevertheless developed what became known as the complications of diabetes. These included renal failure, blindness, amputations, impotence, and heart disease. Thus, it became apparent not only that diabetes still reduced lifespan but more importantly, that it destroyed quality of life. The question that arose as to whether these complications were the direct result of the hyperglycaemia, or whether they, like the ␤-cell failure, arose from some unidentified underlying metabolic abnormality, has only recently been answered. Seminal studies by Pirart in the 1970s established that patients whose diabetic control was worst, as judged by their blood and urine glucose levels, were indeed at an increased risk from what Pirart described as the triopathy of retinopathy, nephropathy, and neuropathy [33]. He failed to find such a relationship, however, with peripheral vascular disease or coronary heart disease (and the exact relationship between hyperglycaemia and coronary heart disease remains controversial [34]). More importantly, he failed to demonstrate that the relationship between the hyperglycaemia and the complications was one of cause and effect. This would require a randomized prospective trial which finally came in 1993 with the publication of the Diabetes Control and Complications Trial (DCCT) [35]. Some 1441 patients with type 1 diabetes were randomized to be left on their existing insulin regime with one or two injections of insulin per day and an HbA1c of 9.0 per cent, or to be tightly controlled either with multiple injections or with insulin pumps. The aim was to normalize glucose metabolism as far as possible but in the event the study showed vividly the impossibility of normalizing control completely. Although a relationship was shown between glucose levels and the same three complications that Pirart had identified 20 years previously (retinopathy, neuropathy, and nephropathy), the price of bringing the HbA1c down from

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9 to 7 per cent was a three-fold increase in the incidence of severe hypoglycaemia from 19 to 62 episodes per 100 patient years. No data was available on whether macrovascular disease was prevented with intensified control since the patient group was too young. The UKPDS compared different ways of managing type 2 diabetes and concluded that the incidence of coronary heart disease was also a function of the prevalent glucose levels, although no significant reduction could be demonstrated with 'tighter' control, possibly because there was insufficient difference between the 'tight' and 'less tight' study groups [21]. Furthermore, strategies for achieving control which resulted in weight gain (sulphonylureas or insulin) may have substituted one cardiac risk factor for another, since the lowest incidence of coronary heart disease who observed in a small subgroup treated with metformin, the only drug which improves diabetic control without causing weight gain [36].

The practicalities of super tight control It is apparent from these various studies that the degree of diabetic control which is achievable with conventional insulin regimens is quite simply insufficient to prevent diabetic complications. Thus, for example, although patients in the intensively treated group in the DCCT had a significantly reduced risk of microangiopathic complications, 10 to 15 per cent had nevertheless developed microalbuminuria, retinopathy, or neuropathy by the end of the 9-year study period [35]. And this was despite frequent clinic attendances to see doctors, nurses, dietitians, and psychologists, and even more frequent phone calls. The problem in type 1 diabetes is that because the blood glucose is unstable and variance is markedly increased, attempts to reduce the average level to normal inevitably result in hypoglycaemia at times when the glucose level is lowest. This risk is substantially less in patients with type 2 diabetes, because of its lower variance, but in both types of diabetes improved control inevitably results in weight gain.

Closed loop systems In order to achieve tight diabetic control without a concomitant increase in the risk of hypoglycaemia, the only solution is a closed loop system, whereby insulin levels are adjusted on a moment-tomoment basis according to requirements (Fig. 2.5). This is of course only what a healthy pancreatic ␤-cell does. There are only two ways of achieving this in a patient whose ␤-cells are no longer

Fig. 2.5 Schematic illustration of closed loop feedback system for regulation of blood glucose. In the future, such a system may be practical by linking a continuous glucose sensor to an insulin pump. For the present, the only way to achieve this is with a transplant of ␤-cells, either as a whole pancreas or as isolated islets.

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functioning: either by using a continuous glucose sensor attached to an insulin pump, or by transplanting functioning islets, either in a whole vascularized pancreas or as isolated islets. The first approach, with a closed loop insulin pump, was first tried more than 25 years ago [37]. At that time the machines used were enormous and only potentially useful during surgery or labour. Blood glucose levels were sampled ex vivo in blood withdrawn by a slow continuous pump from an arm vein, and the appropriate amount of glucose or insulin, decided by a computer, was infused into the contralateral arm. At the time it was believed that while it would probably be possible to miniaturize the pump and the glucose sensor in due course, there was no prospect of being able to miniaturize the computer! A portable closed loop insulin pump was reported by a Japanese group 15 years ago [38], but there were problems with indwelling sensors in terms of their biocompatibility, stability, and accuracy. These problems seem finally to have been largely overcome [39], but major concerns about the safety and reliability of an implanted closed loop insulin pump mean that this approach is still some years away from routine clinical use. Thus, at present the only available strategy able to provide a closed loop system is ␤-cell transplantation, whether as a whole vascularized pancreas or as isolated islets of Langerhans. The remainder of this book addresses the practicalities of these two approaches.

References 1 Currie CJ, Kraus D, Morgan CL, Gill L, Stott NC, Peters JR. NHS acute sector expenditure for diabetes: the present, the future and excess in-patient cost of care. Diabet Med 1997;14:686–92. 2 Rubin RJ, Altman WM, Mendelson DN. Health care expenditure for people with diabetes mellitus, 1992. J Clin Endocrinol Metab 1994;78:809A–F. 3 Songer TJ. The economic costs of NIDDM. Diabet Metab Rev 1992;8:389–404. 4 Lernmark A, Falorni A. Immune phenomena and events in the islets in insulin-dependent diabetes mellitus. In: Textbook of diabetes, Pickup J, Williams G, ed. Blackwell Science, 2nd edn 1997;15.1–15.23. 5 Yoon J-W, Yoon C-S, Lim H-W, Huang QQ, Kang Y, Pyun KH, et al. Control of autoimmune diabetes in NOD mice by GAD expression or suppression in ␤-cells. Science 1999;284:1183–7. 6 Barnett A, Eff C, Leslie RDG, Pyke D. Diabetes in identical twins. A study of 200 pairs. Diabetologia 1981;20:87–93. 7 Yoon J-W. Environmental factors in the pathogenesis of insulin-dependent diabetes mellitus. In: Textbook of diabetes, Pickup J, Williams G, ed. Blackwell Science, 2nd edn 1997;14:1–14. 8 Bingley PJ, Gale EAM. Rising incidence of insulin-dependent diabetes mellitus in Europe. Diabetes Care 1989;12:289. 9 Newman B, Selby JV, Slemenda C, Fabsitz R, Friedman GD. Concordance for type 2 (non-insulindependent) diabetes mellitus in male twins. Diabetologia 1987;30:763–8. 10 Neel JV, Weder AS, Julius S. Type II diabetes, essential hypertension and obesity as 'syndromes of impaired genetic homeostasis': the 'thrifty genotype' hypothesis enters the 21st century. Perspect Biol Med 1998;42:44–74. 11 Barker DJ, Hales CN, Fall CH, Osmond C, Phipps K, Clark PM. Type 2 (non-insulin-dependent) diabetes mellitus, hypertension and hyperlipidaemia (syndrome X): relation to reduced fetal growth. Diabetologia 1993;36:62–7. 12 Barker DJ. Intrauterine programming of adult disease. Mol Med Today 1995;1:418–23. 13 Hattersley AT, Tooke JE. The foetal insulin hypothesis: an alternative explanation of the association of low birth weight with diabetes and vascular disease. Lancet 1999;353:1789–92. 14 Porte D. ␤-cells in type II diabetes mellitus. Diabetes 1991;40:166–80.

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15 Polonsky KR, Given BD, Hirsch LJ, Tillil H, Shapiro ET. Abnormal patterns of insulin secretion in non-insulin dependent diabetes mellitus. N Engl J Med 1988;318:1231-9. 16 Luzi L. Effect of the loss of first phase insulin secretion on glucose production and disposal in man. Am J Physiol 1989;257:E241–6. 17 Vaag A, Holst JJ, Vølund A, Beck-Nielsen H. Gut incretin hormones in identical twins discordant for non-insulin dependent diabetes mellitus (NIDDM): evidence for decreased glucagon-like peptide 1 secretion during oral glucose ingestion in NIDDM twins. Eur J Endocrinol 1996;135:425–32. 18 Nauck MA, Heimesaat MM, Ørskov C, Holst JJ, Ebert R, Creutzfeld W. Preserved incretin activity of glucagon-like peptide-1 (7–36 amide), but not of synthetic gastric inhibitory polypeptide in patients with type 2 diabetes mellitus. J Clin Invest 1993;91:301–7. 19 Swinburn BA, Gianchandari R, Saad MF, Lillioja S. In vivo ␤-cell function at the transition to early non-insulin dependent diabetes mellitus. Metabolism 1995;44:757–64. 20 Roxburgh MA, Vaughan NJA, New J. Using large cohorts from population based diabetes registers to develop risk equations for type 2 diabetes. Diabetologia 2000;43(Suppl.1):A1. 21 UK Prospective Diabetes Study (UKPDS) Group. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes. Lancet 1998;352:837–53. 22 Rahier J, Sempoux C, Moulin P, Guiot Y. No decrease of the ␤-cell mass in type 2 diabetic patients. Diabetologia 2000;43(Suppl.1):A65. 23 Campbell PJ, Bolli GB, Cryer PE, Gerich JE. Pathogenesis of the dawn phenomenon in patients with insulin-dependent diabetes mellitus: accelerated glucose production and impaired glucose utilization due to nocturnal surges in growth hormone. N Engl J Med 1985;312:1473–9. 24 Somogyi M. Exacerbation of diabetes by excess insulin action. Am J Med 1959;26:169–91. 25 Frier BM, Fisher BM, Gray CE, Beastall GH. Counter-regulatory hormonal responses to hypoglycaemia in type 1 diabetes: evidence for diminished hypothalamic-pituitary hormonal secretion. Diabetologia 1988;31:421–9. 26 Holleman F, Hoekstra JBL. Insulin Lispro. N Engl J Med 1997;337:176–83. 27 Jehle PM, Micheler C, Jehle DR, Breitig D, Boehm BO. Inadequate suspension of neutral protamine Hagedorn (NPH) insulin in pens. Lancet 1999;354:1604–7. 28 Lauritzen T, Faber OK, Binder C. Variation in 125I-insulin absorption and blood glucose concentration. Diabetologia 1979;17:291–5. 29 Lauritzen T, Pramming S, Deckert T, Binder C. Pharmacokinetics of continuous subcutaneous insulin infusion. Diabetologia 1983;24:326–9. 30 Bode BW, Steed RD, Davidson PC. Reduction in severe hypoglycemia with long-term continuous subcutaneous insulin infusion in type 1 diabetes. Diabetes Care 1996;19:324–7. 31 Melki V, Renard E, Lassmann-Vague V, et al. Improvement of HbA1c and blood glucose stability in IDDM patients treated with lispro insulin analog analog in external pumps. Diabetes Care 1998;21:977–82. 32 Boland EA, Grey M, Oesterle A, Fredrickson L, Tamborlane WV. Continuous subcutaneous insulin infusion. A new way to lower risk of severe hypoglycemia, improve metabolic control, and enhance coping in adolescents with type 1 diabetes. Diabetes Care 1999;22:1779–84. 33 Pirart J. Diabète et complications dégénératives. Présentation d'une étude prospective portant sur 4400 cas observés entre 1947 et 1973. Diabète Metab 1977;3:97–107 and 173–82. 34 Barrett-Connor E. Does hyperglycaemia really cause coronary heart disease? Diabetes Care 1997;20:1620–3. 35 The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;329:977–86.

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36 UK Prospective Diabetes Study (UKPDS) Group. Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes. Lancet 1998;352:854–65. 37 Albisser AM, Leibel BS, Ewart TG, Davidovac Z, Botz CK, Zingg W. An artificial endocrine pancreas. Diabetes 1974;23:389–96. 38 Shichiri M, Kawaniori R, Hakui N, Asakawi N, Yamasaki Y, Abe H. The development of wearable-type artificial endocrine pancreas and its usefulness in glycaemic control of human diabetes mellitus. Biomed Biochem Acta 1984;43:561–8. 39 Renard E, Costalat G, Moran B, Kolopp M, Apostol D, Lauton D, et al. First human experience with combined implantation of a long-term i.v. glucose sensor and an i.p. insulin pump. Acta Diabetol 2000;37:166.

Chapter 3

Experimental models in whole organ pancreatic transplantation Vassilios E. Papalois and Nadey S. Hakim

Introduction The first successful pancreas transplant in humans was performed by Kelly and Lillehei on 17 December 1966 in the Department of Surgery at the University of Minnesota [1]. It was a combined transplant of the tail of the pancreas and the kidney to a female diabetic recipient with endstage renal failure. Since then, the results of pancreatic transplantation have dramatically improved. There is a constant effort for improvement of results in all centers that perform pancreatic transplantation worldwide. The improvements include refinement of surgical technique, to minimize the changes of postoperative surgical complications such as graft pancreatitis and thrombosis, methods of drainage of the exocrine portion of the pancreas, the early detection of rejection, and the effect of pancreas transplantation in establishing an insulin-independent status, as well as in preventing or reversing the secondary complications of diabetes. To address these issues, many experimental models in small and large animals have been developed over the years. The importance of the pancreas for glucose control was initially demonstrated in 1890 when Minkowski performed a total pancreatectomy in a dog, which eventually developed diabetes mellitus and died [2]. Later, the discovery of insulin by Banting and Best in 1922, after extensive experimentation in the dog model, was one of the main breakthroughs of medical science in the twentieth century [3]. The first successful experimental allotransplantation of the pancreas in the dog model was performed in 1927 by Gayet and Guillaumie [4]. In the 1950s, the pioneers in the field of experimental pancreatic allotransplantation in the large animal model were Brooks and Gifford [5] and later, in the 1960s, initially De Jode and Howard [6] and later Lillehei [7] pioneered the field. Finally, in the early 1970s, Orloff et al. developed a reliable model for whole organ pancreas transplantation in the rat [8]. Three animals are now used worldwide for experimental pancreatic transplantation — the rat, the dog, and the pig. In this chapter, we present the principles of anatomy and surgical technique for pancreatic allotransplantation in these three animal models, in addition to the most interesting recent experimental developments and the issues raised in relation to pancreatic transplantation.

The rat model Anatomy The pancreas of the rat is more diffuse, softer, and less clearly delineated than the human pancreas. Its location is approximately the same as that of the pancreas in humans, although it is more spread out [9] (Fig. 3.1). The right lobe and body of the pancreas are embedded in the mesoduodenum and the

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Fig. 3.1 Gross anatomy of the rat pancreas showing the right lobe and the body in the mesoduodenum. The left lobe is not shown. Pancreas (P), liver (L), duodenum (D), pancreatic duct (PD).

beginning of the mesojejunum. The left lobe is a branched, flattened part that runs along the dorsal aspect of the stomach, embedded in the dorsal leaf of the greater omentum and along the splenic artery towards the hilum of the spleen. The pancreatic acini are drained by 15 to 40 excretory ducts which fuse to form at least two, and sometimes five to eight, main ducts that open into the bile duct. Often, small ducts open directly into the duodenum. The largest collecting duct is from the left lobe and it is the first duct to enter the bile duct. The arterial blood supply to the pancreas is provided by two main arteries, the superior and inferior pancreaticoduodenal arteries (Fig. 3.2). The superior pancreaticoduodenal artery runs caudally in the mesoduodenum and is a branch of the gastroduodenal artery which, in turn, is a branch of the hepatic artery or, sometimes, a direct branch of the coeliac artery. The coeliac artery in the rat is similar to that of the human, arising from the abdominal aorta as the first unpaired branch. The inferior pancreaticoduodenal artery is a branch of the superior mesenteric artery which, in turn, arises from the aorta as the second unpaired branch 3 to 5 mm caudal to the coeliac artery. The superior and inferior pancreaticoduodenal arteries connect with each other. The splenic artery gives a number of small branches to the left lobe of the pancreas. The venous drainage of the pancreas is into the hepatic portal vein (Fig. 3.3). The superior pancreaticoduodenal vein drains the right lobe and body of the pancreas and is the last tributary to enter the portal vein directly. The inferior pancreatic vein drains the left lobe of the pancreas into one of the splenic veins, which in turn drain into the portal vein. The portal vein in the rat is similar to the human portal vein, draining the superior mesenteric vein, gastrosplenic vein, inferior mesenteric vein, right gastroepiploic vein, and veins from the pancreas. The rat duodenum is relatively longer than the human duodenum and is more mobile, since it is suspended by a mesentery, the mesoduodenum. It arises in the midline from the distal end of the pylorus,

V.E. PAPALOIS AND NADEY S. HAKIM

Fig. 3.2 Arterial vascular supply to the rat pancreas. The right lobe and the body of the pancreas are supplied by a branch of the gastroduodenal (superior pancreaticoduodenal) and a branch of the superior mesenteric (inferior pancreaticoduodenal) artery. The left lobe is supplied by branches of the splenic artery.

Fig. 3.3 Venous drainage of the rat pancreas. The right lobe and body drain directly into the portal vein via the superior pancreaticoduodenal vein. The left lobe is drained via the inferior pancreatic vein which drains into one of the splenic veins, which drain into the portal vein.

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runs transversally towards the right abdominal wall, rises dorsally after an initial curve along the right margin of the liver towards the right kidney, curves as a transfer duodenum towards the mid-sagittal plane, and after another right-angled turn runs cranially as the ascending duodenum.

Technique A variety of injectable anaesthetic agents and inhalant agents have been used for anaesthetizing rats for pancreaticoduodenal transplantation. One of the most classic is an injectable anaesthetic cocktail consisting of ketamine (50 mg/kg), acepromazine (1 mg/kg), and xylazine (5 mg/kg), mixed together in a single solution and given intramuscularly [10]. The depth of anaesthesia is controlled by rigidly monitoring the lead reflex and muscle movement. Operations are performed at a constant room temperature to minimize hypothermia and dehydration. During the procurement of the rat pancreas for pancreaticoduodenal transplantation, the vasculature of the graft consists of a segment of the aorta containing the arteries that ultimately supply the pancreas and duodenum, and a segment of the hepatic portal vein containing the venous tributaries that drain the graft [11]. In the recipient, the graft aortic segment and graft portal vein are anastomosed with the host aorta and inferior vena cava, respectively, below the level of the renal vessels (Fig. 3.4) When transplantation of the pancreas without the duodenum is performed, the pancreatic ducts that enter the bile duct and duodenum are meticulously isolated, ligated, and divided. The small arter-

Fig. 3.4 (a) During the procurement of the rat pancreas for pancreaticoduodenal transplantation, the vasculature of the graft consists of a segment of the aorta containing the arteries that ultimately supply the pancreas and duodenum, and a segment of the hepatic portal vein containing the venous tributaries that drain the graft. In the recipient, the graft aortic segment and graft portal vein are anastomosed with the host aorta (arrow) and inferior vena cava (double arrow), respectively, below the level of the renal vessels. The duodenum of the graft is anastomosed end-to-side to the recipient's duodenum. (indicated by the triple arrow) (b) When transplantation of the pancreas without the duodenum is performed, the pancreatic ducts that enter the bile duct and duodenum are meticulously isolated, ligated and divided. The small arteries and veins between the duodenum and pancreas are ligated and divided and the pancreas is carefully separated from the duodenum. The pancreatic blood vessels in the mesoduodenum are carefully preserved.

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ies and veins between the duodenum and pancreas are ligated and divided, and the pancreas is carefully separated from the duodenum. The pancreatic blood vessels in the mesoduodenum are carefully preserved.

Studies Prevention of post-transplant graft pancreatitis Post-transplant pancreatitis is still a frequently occurring complication of whole organ pancreas transplantation and it is usually attributed to microcirculatory disorders caused by cold ischaemia time and reperfusion injury. Vollmar et al. [12] developed an interesting experimental model for the prevention of reperfusion injury following pancreatic transplantation. They studied the effect of providing nitric oxide (known for its vasodilating nature) on the postischaemic microvascular reperfusion injury that occurs after pancreas transplantation. Heterotopic isogeneic pancreaticoduodenal transplantation was performed in Sprague Dawly rats after 16 h of cold storage of the graft at 4° C in histidine-tryptophane-ketoglutarate (HTK) solution. A second group of rats received intravenous Larginine (a nitric oxide provider) immediately before (50 mg/kg) and during the first 30 min of reperfusion (100 mg/kg). Intravital fluorescence microscopy was used for analysis of functional capillary density, capillary diameters, and capillary red blood cell velocity in exocrine pancreatic tissue during the first 120 min after reperfusion. Histology served for a quantitative assessment of inflammatory response (leucocytic tissue infiltration) and endothelial disintegration (oedema formation). In L-arginine treated animals, functional capillary density of exocrine tissue of pancreatic grafts was found slightly higher after 30 and 60 mins, and significantly higher after 120 min of postischaemic reperfusion, compared with the untreated pancreatic grafts. This was accompanied by a significant increase of capillary diameters. In addition, there was a significant attenuation of both leucocytic tissue infiltration and oedema formation in the L-arginine treated animals, when compared with the non-treated controls. The authors concluded that besides reduction of leucocyte-dependent microvascular injury, L-arginine improves postischaemic microvascular reperfusion, by capillary dilatation. These results suggest that a supplement of nitric oxide during reperfusion is effective in attenuating exocrine microvascular reperfusion injury.

Reversibility of rejection It is well known in pancreatic transplantation that abnormal blood glucose levels usually indicate irreversible rejection. It is very important to know at which stage the rejection progress remains reversible. A very interesting model to investigate this was developed by Konigsrainer et al. [13]. A total of 54 Lewis rats became diabetic after intravenous injection of streptozotosin and they were allotransplanted with whole pancreases from Brown Norway rats. All recipients received orally 50 mg/kg of cyclosporin for 5 days. The animals were divided into six groups. On the sixth day after the transplant, cyclosporin was discontinued in the first group for 2, the second for 4, the third for 6, the fourth for 8, the fifth for 9, and the sixth group for 10 days. Two animals of each group were euthanized at the end of the immunosuppression-free interval for histological assessment of rejection. The remaining animals were treated with intravenous methylprednisolone 7 mg/kg for 3 consecutive days and continuation of cyclosporin at a dose of 15 mg/kg orally for another 3 weeks and they were then euthanized for histological assessment of the pancreatic graft. At the end of the immunosuppression-free interval, the number of animals that became diabetic were as follows: five out of nine in group 4, seven out of 11 in group 5, and eight out of 11 in group 6 and there was evidence of rejection in the pancreatic grafts of all animals (two from each group) that were sacrificed. The severity of rejection correlated to the length of immunosuppression-free interval. The histology returned to normal after

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antirejection therapy in four animals (57 per cent) of group 1, in two animals (28 per cent) of group 2, and in one animal (11 per cent) of groups 3 and 4, respectively. Although there were no animals in groups 5 and 6 with normal graft histology after treatment, there were still four (36 per cent) and three (27 per cent) animals, respectively, that were normoglycaemic and that had pancreatic grafts with well-preserved islets. The authors concluded that hyperglycaemia and severe rejection with endothelitis and isletitis could be reversed. Therefore, they suggested that elevated blood sugars should not be considered as an endpoint for pancreas transplantation and a trial of enhanced immunosuppression is justified in patients with advanced pancreas allograft rejection.

Graft immunoprotection It has been shown that transplantation of the pancreas in combination with the liver can protect the pancreas allograft from rejection [14]. An interesting question that arises from this observation is if ongoing pancreatic rejection could be reversed by subsequent transplantation of the liver. An excellent model to investigate this was developed by Wang et al. [15]. Transplantation was performed between PVG (donors) and DA (recipients) rats. The first group of animals was PVG to PVG pancreas isogeneic grafts. The second group was PVG to DA pancreas allografts, groups 3 to 5 were PVG to DA pancreas allografts followed by liver transplantation on days 2, 4, and 6 respectively, and in group 6 there was PVG to DA pancreas allografts 4 weeks after liver transplantation. The results show that pancreas allografts in group 2 were rejected between the seventh and 13th postoperative day. Liver transplantation prevented subsequent pancreas allograft rejection in group 6. Ongoing rejection was reversed by liver transplantation with subsequent graft acceptance in groups 3 to 5. Significant graft infiltrating lymphocyte apoptosis was demonstrated at 2 weeks in pancreas transplants associated with liver grafting. Graft-versus-host disease was not detected in the pancreas recipients. The authors concluded that although pancreas allografts in the PVG to DA combination rejected rapidly with a median survival time of 9 days, liver transplantation could protect subsequent pancreas grafts from rejection and reverse ongoing pancreas graft rejection with subsequent pancreatic acceptance. Graft infiltrating lymphocyte apoptosis could be associated with the process of graft acceptance.

Prevention of diabetic nephropathy The effect of pancreas transplantation in preventing the progression of diabetes in the native kidneys or the recurrence of diabetes in the transplanted kidney the case of combined kidney/pancreas transplantation is of great importance. Spadella et al. developed a very interesting experimental model to study this [16]. Ninety Lewis rats were randomly assigned to three experimental groups. The first group included 30 non-diabetic control rats, the second group included 30 Alloxan-induced diabetic control rats, and the third group included 30 Alloxan-induced diabetic rats that received isogeneic pancreatic grafts from normal donor Lewis rats. Each group was further divided into three subgroups of 10 rats, which were sacrificed at 1, 3, and 6 months post-transplant, respectively. The kidneys of five rats in each subgroup were studied and 50 glomeruli and tubules from each kidney were analysed by light microscopy by two different investigators in a double-blind study. The presence of glomerular basement membrane thickening, mesangial enlargement, and Bowman's capsule thickening in the kidneys of those rats were measured. There was no significant difference for these three parameters between normal controls, diabetic controls, and rats that received pancreatic transplantation at 1 and 3 months post-transplant. There was significant increase in all these three parameters for the diabetic controls, when compared to normal non-diabetic rats and rats that received pancreatic transplantation at 6 months. However, there was no difference between the normal controls and the rats that received pancreas transplantation. The authors concluded that pancreas transplantation in Alloxan-

V.E. PAPALOIS AND NADEY S. HAKIM

induced diabetic rats prevents the development of kidney lesions, beginning approximately at 6 months after transplantation.

Reversal of vascular complications of diabetes There is insufficient evidence as to whether the transplantation of the whole pancreas can reverse vascular complications associated with diabetes. Pieper et al. [17] investigated whether pancreatic transplantation in experimental diabetes reverses established defects in endothelium-dependent relaxation. Streptozotocin-induced diabetic rats underwent whole organ pancreas transplantation after 12 weeks of disease. Endothelial function was evaluated 4 weeks after transplantation and compared with that of the control and age-matched diabetic animals. Blood was taken for analysis of glucose, insulin, total glycosylated haemoglobin, and plasma amino acid levels. Descending thoracic aortas were isolated, sectioned into rings, and mounted in isolated tissue baths. In precontracted rings, endotheliumdependent relaxation to acetylcholine was performed and compared with endothelium-independent relaxation to nitroglycerine as a control. Pancreatic transplantation normalized the increases in glucose and total glycosylated haemoglobin level and decreased serum insulin levels. Diabetes resulted in impaired relaxation to acetylcholine without altering relaxation to nitroglycerine. Pancreatic transplantation completely restored the defective relaxation to acetylcholine. This study suggests for the first time that one aspect of vascular complications (endothelial dysfunction) is amenable to the surgical intervention of pancreas transplantation.

The dog model Many experimental studies for pancreatic auto- and allotransplantation are using the dog as an experimental model. The first reason is that the dog is an animal which is extremely tolerant to general anaesthesia as well as to intraoperative and postoperative stress. As a result, there are much fewer intraoperative problems as well as postoperative morbidity and mortality resulting in better

Fig. 3.5 Canine pancreatic allograft following vigorous cellular and vascular rejection.

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quantitative and qualitative transplant studies. There is also evidence that, following pancreatic allotransplantation, rejection is much stronger in the dog model [18] (Fig. 3.5). This offers an excellent test for the effectiveness of various new immunosuppressive regimens, as well as of methods for tolerance induction following pancreatic transplantation.

Anatomy The dog pancreas starts from the splenic hilum and extends along the major curvature of the stomach and along a large part of the duodenum. The major difference from the human pancreas is that there is no discreet distinction between head, body, and tail of the pancreas. There is a much more simple distinction between the left part (tail) of the pancreas, which extends from the splenic hilum all the way to the take-off of the splenic artery, and the right part of the pancreas which extends after the take-off of the splenic artery to the pylorus, and from the pylorus all the way along the duodenum (Fig. 3.6). The experimental models for pancreatic transplantation in the canine model are using only the tail which has sufficient islet mass to keep a dog normoglycaemic [18]. The blood supply to the tail of the pancreas comes from the splenic artery which takes off from the coeliac artery. The veins of the tail drain into the splenic vein, which drains eventually into the portal vein. Although this is the vascular anatomy of the tail of the canine pancreas in the majority (77.9 per cent) of cases, there are

Fig. 3.6 The dog pancreas has a left part (tail), which extends from the splenic hilum all the way to the take-off of the splenic artery, and a right part which extends after the take-off of the splenic artery to the pylorus, and from the pylorus all the way along the duodenum. The experimental models for pancreatic transplantation in the canine model are using only the tail which has sufficient islet mass to keep a dog normoglycaemic. The blood supply to the tail of the pancreas comes from the splenic artery which takes off from the coeliac artery.

V.E. PAPALOIS AND NADEY S. HAKIM

anatomical variations [19,20] and knowledge of their existence is vital for proper procurement and transplantation of the segmental (tail) pancreatic graft (Fig. 3.7). In 12.1 per cent of cases, there is an extra vein for the tail of the pancreas that drains directly in the portal vein. In 8.8 per cent of cases, the artery supplying the tail takes off from the superior mesenteric artery. In 0.8 per cent of cases, the artery supplying the tail takes off from the superior mesenteric artery and the vein of the tail drains in the superior mesenteric vein. Finally, in 0.4 per cent of cases, the artery supplying the tail takes off from the superior mesenteric artery and the vein drains directly in the portal vein.

Technique A simple and effective way to anaesthetize a dog is as follows [18]: approximately 45 min prior to the induction of anaesthesia, 5 mg of diazepam are given intramuscularly to the animal. After inserting an angiocatheter in one of the veins of the dorsal aspect of one front limb, 15 mg/kg of sodium phenobarbital is given to the animal followed by intubation and connection to a Harvard anaesthesia machine which provides a respiratory rate of 12 to 14/min giving the animal 300 to 400 cm3 of air each time. An initial intravenous dose of phentanyl (1 cm3) is given prior to the initiation of the operation. During the procedure, 50 mg of sodium phenobarbital (5 per cent concentration) and phentanyl (1 cm3) are given intravenously to the animal every 45 to 60 min. Following the procurement, the vessels of the tail of the pancreas (usually the splenic artery and vein) are anastomosed to the external iliac artery and vein of the recipient by using classic vascular anastomosis techniques (Fig. 3.8). As in clinical transplantation, the exocrine portion of the pancreas can be drained either in the bladder or in the bowel and can also be managed by an intraductal Neoprin injection. However, for experimental purposes only, there are two more methods that can be used for controlling the exocrine portion of the pancreas after the transplantation. The first is a simple ligation of the pancreatic duct. This method is not being used clinically because it eventually leads to the development of fibrotic tissue within the pancreatic graft. However, for experimental purposes, it is very effective because it is very simple and at the same time it takes at least 2 to 4 months for the development of fibrotic tissue, which is a period of time which is usually good enough for completing the observations of most experimental studies. The second method for controlling the exocrine portion of the pancreas is the free drainage of the pancreatic duct into the peritoneal cavity. Clinically this can very shortly lead to pancreatic ascites. Experimentally though, and especially in the dog model, the animal can absorb a large amount of the pancreatic fluid without the development of ascites.

Fig. 3.7 The experimental models for pancreatic transplantation in the canine model are using only the tail which has sufficient islet mass to keep a dog normoglycaemic. The blood supply to the tail of the pancreas (A, PT) comes from the splenic artery (A, SA) which takes off from the coeliac artery (A, CA). The veins of the tail drain into the splenic vein (A, SV), which drains eventually into the portal vein (A, PV). Although this is the vascular anatomy of the tail of the canine pancreas in the majority (A, 77.9 per cent) of the cases, there are anatomical variations and knowledge of their existence is vital for proper procurement and transplantation of the segmental (tail) pancreatic graft. In 12.1 per cent (B) of cases, there is an extra vein for the tail of the pancreas that drains directly in the portal vein (arrow). In 8.8 per cent (C) of cases, the artery supplying the tail takes off from the superior mesenteric artery (arrow). In 0.8 per cent (D) of cases, the artery supplying the tail takes off from the superior mesenteric artery (arrow) and the vein of the tail drains in the superior mesenteric vein (double arrow). Finally, in 0.4 per cent (E) of cases, the artery supplying the tail takes off from the superior mesenteric artery (arrow) and the vein drains directly in the portal vein (double arrow). see overleaf

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Fig. 3.8 The vessels of the tail of the canine pancreas (usually the splenic artery and vein) are anastomosed to the external iliac artery (arrow) and vein (double arrow) of the recipient. The pancreatic duct (PD) is on free drainage into the peritoneal cavity. Clinically this can very shortly lead to pancreatic ascites. Experimentally though, and especially in the dog model, the animal can absorb a large amount of the pancreatic fluid without the development of ascites.

Studies Prevention of cold ischaemia injury Ischaemic injury of the microvascular endothelium during cold preservation causes a disturbance of vascular microcirculation after reperfusion and results in graft failure. In the canine model, the twolayer preservation method (which continuously supplies sufficient oxygen to the pancreas) leads to continued adenosine triphosphate (ATP) production which is essential to maintain cellular integrity and extends the period of preserved pancreatic viability [21,22]. The aim of a study by Kuroda et al. [23] was to clarify the role of the oxygenation of the pancreatic graft by the two-layer method in the viability of the microvascular endothelium during preservation. Following partial pancreatectomy, segmental (tail) canine pancreases were either autotransplanted immediately (with simultaneous completion pancreatectomy) without preservation (control group), preserved by simple cold storage in Euro Collins solution or by the two-layer method using Euro Collins for 48 h, and then autotransplanted. The viability of vascular endothelial cells was evaluated by using the nuclear trypan blue uptake technique. Pancreatic tissue perfusion was measured with hydrogen gas clearance. Although all grafts that were preserved in just Euro Collins solution failed, graft survival for the control and the double-layer method groups was 100 per cent. The percentage of trypan blue positive vascular endothelium in the Euro Collins group was significantly higher compared to the control group. The two-layer method significantly decreased trypan blue uptake compared to the Euro Collins group, although the uptake was still significantly higher compared to the control group. Pancreatic tissue perfusions after 2 h of reperfusion were in inverse proportion to trypan blue uptake. Specifically, pancreatic tissue perfusions in the Euro Collins group were significantly lower than the control group but the two-layer method improved pancreatic tissue perfusions to levels similar to those of the control group. The authors concluded that oxygenation of the pancreas during preservation by the two-layer method protects the microvascular endothelium from cold ischaemic injury. Consequently, pancre-

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atic microcirculation and tissue perfusion can be maintained after reperfusion, resulting in prolonged graft survival.

Differential diagnoses of early rejection versus graft pancreatitis It is particularly difficult to distinguish between early rejection and graft pancreatitis when early rejection produces an elevated serum amylase level. In a study by Suzuki et al. [24], it was investigated if peripancreatic fluid cytology (an alternative diagnostic tool to graft biopsy that has the potential of causing haemorrhage and pancreatic fistula) can differentiate early acute rejection from graft pancreatitis. The dogs used in this study received either a segmental pancreas allograft or autograft. This study included five groups: allografts without immunosuppression (group A), allografts with immunosuppression (group B), autografts without immunosuppression (group C), autografts with immunosuppression (group D), and autografts treated by 45 min of pretransplant warm ischaemia to induce acute graft pancreatitis (group E). A closed section drainage catheter was placed next to the graft to collect peripancreatic fluid daily after the transplant. Peripancreatic fluid cytology was compared to the corresponding histology through the observation period. Peripancreatic fluid cytology performed on day 1 showed similar neutrophil accumulations in all groups. In sharp contrast, on days 3 and 6, group A had dramatically increased mononuclear cell concentrations in peripancreatic fluid cytology, whereas groups B, C, and D showed significantly lower concentrations. Conversely, in group E, numerous degenerating neutrophils with a marked to moderate increase in necrotic tissue fragments were observed by peripancreatic fluid cytology on days 3 and 6. In terms of graft histology on days 3 and 6, group A showed interstitial mononuclear cell infiltration indicting an active rejection process, whereas groups B, C, and D had minimal inflammatory cell infiltration. In group E, graft pancreatitis was histologically confirmed on days 3 and 6. These results suggest that peripancreatic fluid cytology after pancreas transplantation could be a safe, simple, and a useful diagnostic tool for discriminating early graft rejection from post-transplant graft pancreatitis.

Effect of pancreatic transplantation in preventing the development of diabetic complications In experimental models of canine diabetes, retinopathy, neuropathy, and nephropathy have been shown to develop within 5 years. The aim of the study by Hawthorne et al. [25] was to determine in the canine model whether glucose control provided by segmental duct-occluded pancreas autografts could prevent the long-term complications of diabetes. Thirty-five out-bred mongrel dogs underwent segmental pancreas autotransplantation with residual pancreatectomy. Follow-up over 5 years included endocrine, retinal fundus photography, fluorescein angiography, and nerve conduction studies. Long-term survival was achieved in 14 dogs for 4 to 5 years, and in three dogs for 3 to 5 years. Glycosylated haemoglobin levels remained within normal limits. Fundus photography and fluorescein angiography demonstrated the absence of retinal vascular aneurysms, capillary leakage, and obliteration. Retinal digests show no vascular changes and normal endothelial/pericyte ratios. Nerve conduction was normal and histology of nerves revealed normal density of myelinated fibres and absence of intrafascicular vessels and glucogen deposits, with no changes in the spectrum of fibre diameters and ovoids. Renal histology revealed no evidence of nephropathy with normal glomerular basement membranes. The authors concluded that the duct-occluded segmental pancreatic autografts are capable of providing satisfactory metabolic control for up to 5 years, thereby preventing development of long-term microvascular complications of diabetes. This is a very important study which demonstrates the effect of pancreas transplantation in preventing the complications of diabetes without the intervention of the phenomenon of rejection. In humans, as well as in many experiments

V.E. PAPALOIS AND NADEY S. HAKIM

with allotransplantation, the intervention of rejection and early graft loss does not allow the proper study of the effect of pancreas transplantation itself in preventing the long-term complications of diabetes.

The pig model The pig is a large animal suitable for experimental pancreas transplantation due to its anatomy and transplant immunology, both of which are very similar to humans [26]. However, it is an animal very sensitive to anaesthesia and pancreas transplantation (and especially combined kidney and pancreas) can result in significant intra- and postoperative morbidity and mortality.

Anatomy The pig pancreas anatomically looks much like the dog pancreas. The basic anatomical difference is that there is a portion of the pancreatic tissue that takes off from the lobe of the pancreas that runs along the duodenum, and forms a ring that goes around the portal vein.

Technique The technique of giving anaesthesia to the pig is very similar to that described for the dog. The pig pancreas can be procured with a cuff of donor aorta containing the coeliac access and the superior mesenteric artery, and the portal vein would be used for drainage of the graft. However, there is a technique (Fig. 3.9) for combined en bloc procurement of the pancreas and the left kidney for transplantation that decreases preservation, operation, and clamp time [27]. The donor aorta (with coeliac access, superior mesenteric artery, and left renal artery) is procured and is anastomosed en bloc to the recipient's aorta in a side-to-oblique fashion. The portal vein is anastomosed end-to-side to the distal vena cava, and the left renal vein end-to-side to the left common iliac vein. The donor duodenum is usually anastomosed to the bladder to allow monitoring of rejection by measuring of urine amylase. The donor duodenum can also be anastomosed to the bowel. Due to the fact that there is great resemblance between the immunological events following human and pig pancreas allotransplantation, the pig model has been mainly used to investigate the phenomenon of rejection following pancreas transplantation.

Studies Rejection in single versus combined pancreas and kidney transplantation Clinically, the incidence of reversible renal allograft rejection episodes appears to be higher in recipients of simultaneous kidney pancreas (SPK) transplants than in kidney transplants alone (KTA) [28] although other data show that kidney graft survival is similar in SPK and KTA recipients [29]. Conversely, the rate of irreversible pancreas allograft rejection appears to be higher in pancreas transplant alone (PTA) than in SPK recipients [30]. More information to clarify these clinical phenomena could be obtained by monitoring the progress of kidney and/or pancreas allograft rejection in the immediate postransplant period. Therefore Gruessner et al. [31] studied the incidence and histological severity of the rejection process in the pig model following SPK, PTA, and KTA allotransplantation. SPK and PTA recipients were made diabetic pretransplant by intravenous streptosotosin (150 mg/kg) and SPK and KTA recipients underwent native nephrectomy. Cyclosporin, azathioprine, and prednisone were given in tapering doses from the time of transplantation. To ensure that the course of rejection could be observed, the initial doses of the immunosuppressive drugs were reduced

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Fig. 3.9 En bloc procurement of the porcine pancreatic graft (PG) and the left kidney graft (GK) for transplantation. The graft aorta (GA) [with coeliac access (GCA), superior mesenteric artery (GSMA) and left renal artery (GRA)] is procured and is anastomosed en bloc to the recipient's aorta (RA) in a side-tooblique fashion (arrow). The graft portal vein (GPV) is anastomosed end-to-side to the recipient's distal inferior vena cava (RIVC) (double arrow), and the left renal vein (GRV) end-to-side to the recipient's left common iliac vein (RCIV) (triple arrow). The pancreatic graft duodenum (PGD) is anastomosed to the recipient's urine bladder (RUB) to allow monitoring of rejection by measuring of urine amylase. The graft ureter (GU) is anastomosed to the RUB. The PG is placed medially to the caecum.

by 50 per cent at the end of the first week and by another 50 per cent by the end of the second week post-transplant. Grafts were biopsied weekly to grade histological severity of intestinal and vascular rejection. Pancreas allograft biopsies showed a significantly lower incidence of moderate/severe tubulointerstitial rejection in SPK than PTA recipients at 1 and 2 weeks post-transplant. Likewise, 1 and 2 weeks post-transplant, vascular rejection was moderate/severe in significantly fewer SPK than PTA grafts. In contrast to the pancreatic grafts, kidney allograft biopsies did not show any difference in the incidence of moderate/severe tubulointerstitial rejection for SPK and KTA recipients at 1 and 2 weeks post-transplant. However, very importantly, the incidence of moderate/severe vascular rejection was significantly lower in the SPK than KTA renal allografts at 1 and 2 weeks post-transplant. The authors concluded that histological progression of pancreas allograft rejection is less severe in SPK than PTA recipients, suggesting that the kidney downregulates or dilutes the immune attack to the pancreas. In addition, renal allograft rejection is not increased by the addition of the pancreas; if anything the incidence of kidney vascular rejection is decreased by the presence of the pancreas.

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Correlation of rejection of the duodenum with rejection of the pancreas following pancreaticoduodenal transplantation A very interesting study was designed to assess the correlation of rejection of the duodenum and the pancreas [32] since transcystoscopic biopsy of the duodenum of a bladder-drained pancreaticoduodenal graft could provide vital information for the presence and severity of pancreatic rejection. Pancreatic duodenal tissue from pancreaticoduodenal transplants in 32 out-bred Yorkshire landraised pigs was examined. After Streptosotosin-induced hyperglycaemia, the animals were transplanted and treated with prednisone, azathioprine, and cyclosporin. To assure that the phenomenon of rejection will progress, immunosuppression was reduced by 50 per cent weekly and discontinued over 3 weeks. The tissue samples were obtained at necropsy at various time points. Each organ was graded for interstitial rejection and vascular rejection separately as: no, mild, moderate, and severe. All but one animal rejected the organs. The results showed that, concordance of type (interstitial, vascular) and grade of duodenal and pancreas rejection occurred in 47 per cent of cases. Discordant cases usually show higher grades of rejection in the pancreas, but the opposite can also occur. It seems that if duodenal biopsies are positive, they are likely to be representative of pancreatic pathology, but when negative they do not rule out rejection of the pancreas. Finally, interstitial rejection appears to precede vascular rejection, suggesting that factors released during interstitial rejection play a role in endothelial cell activation and vascular rejection.

Differences in rejection grading after simultaneous pancreas and kidney transplantation Clinical observations suggest that recipients of multiorgan transplants from the same donor can express the clinical manifestations of rejection of one organ while the other remains unaffected [33]. If this is the case histologically as well, is a question that needs to be answered. In a well-designed study [34] the authors investigated this phenomenon in 36 diabetic (streptozotocin induced) bilateral nephrectomized immunosuppressed (cyclosporin, azathioprine, prednisone) pig recipients of simultaneous (same donor) pancreas (bladder-drained) and kidney allografts by grading the histological intensity of rejection in biopsies of each organ at definite intervals post-transplant. As in similar previous studies, immunosuppression was gradually reduced to assure that rejection will progress. Interstitial rejection was graded as absent, mild, moderate, and severe in, respectively, 8, 25, 42, and 25 per cent of pancreas versus 4, 12, 27, and 57 per cent of kidney biopsies at 1 week; and 0, 43, 29, and 29 per cent of pancreases versus 10, 0, 30, and 60 per cent of kidney biopsies at 2 weeks. Although the distribution of grades was similar in the two organs the grade of rejection for each pair at 1 week was discordant in 75 per cent (42 per cent differed by 1 and 33 per cent by ≥ 2 grades) and at 2 weeks in 57 per cent (29 per cent by 1 and 29 per cent by ≥ 2 grades) of the recipients. The inability to use the severity of interstitial rejection in one organ to predict the findings in the other is exemplified by the fact that for the two pancreases without interstitial rejection at 1 week, the corresponding kidney showed moderate or severe rejection, and for the one kidney without rejection, the corresponding pancreas showed moderate rejection. Vascular rejection grades (absent, mild, moderate, severe) also showed a similar distribution for the pancreas (57, 30, 9, and 4 per cent) versus kidney biopsies (50, 38, 0, and 12 per cent) at 1 week and 2 weeks (57, 29, 0, and 14 per cent for the pancreas versus 78, 11, 0, and 11 per cent for the kidney biopsies). However, the grading of vascular rejection in organ pairs was disynchronous in 54 per cent of the recipients at 1 week and 29 per cent of the recipients at 2 weeks. No vascular rejection in the pancreas with rejection in the kidney was seen in 23 per cent of the recipients in 1 week and in 0 per cent of the recipients at 2 weeks, while no rejection in the kidney with

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rejection in the pancreas was seen in 23 per cent of the recipients at 1 week and in 29 per cent of the recipients at 2 weeks. These data demonstrated that histologically severe rejection can be present in one organ while the other is not affected. The severity of histological rejection usually varies between the organs of a pair, but there is no consistent pattern whether the kidney or the pancreas is more or less afflicted. This study confirmed in histology the phenomenon of clinical manifestations of rejection of one organ without rejection of the other but further studies are necessary to investigate why the recipient expresses different immunological responses to two organs that come for the same donor and have the same expression of human leucocyte antigen (HLA) antigens. A possible explanation is the expression of different subclasses of antigens in each organ that play an important role in triggering the phenomenon of rejection.

Summary Experimental studies to investigate detection and prevention of graft pancreatitis and rejection following pancreas transplantation as well the effect of pancreas transplantation on the secondary complications of diabetes can be successfully conducted in the rat, dog, and pig model. The rat model has the advantage of using small, less developed animals with relatively small experimental cost; conversely, the results are not always applicable to humans. The dog model offers experimentation with minimum morbidity and mortality and a strong immunological response to allotransplantation which is a really good test for investigating the efficacy of any new immunoregulation method. However, it is not physiologically and immunologically so similar to humans and results from studies in the dog model cannot always be translated in clinical practice. Finally, the pig, although it is a model related to significant morbidity and mortality during experimentation, it is very similar to humans from the physiological and immunological point of view. Therefore, most of the studies in the pig model (especially those related to rejection) can, usually, have clinical application.

References 1 Kelly W, Lillehei R, Merkel F, et al. Allotransplantation of the pancreas and duodenum along with the kidney in diabetic nephropathy. Surgery 1967;61:827. 2 Minkowski O, Mering VJ. Diabetes mellitus after pancreas extirpation. Arch Exp Path Pharmakol 1889;26:371. 3 Banting FG, Best G. The internal secretion of the pancreas. J Lab Clin Med 1922;7:251. 4 Gayet R, Guillaumie M. La regulation de la secretion interne pancreatique par un processus normal demontré par la transplantations du pancreas. Cr Soc Biol 1927;97:1613. 5 Brooks JR, Gifford GH. Pancreatic homotransplantation. Transplant Bull 1959;6:100. 6 De Jode LR, Howard JM. Studies in pancreatic duodenal homotransplantation. Surg Gynecol Obstet 1962;114:553. 7 Lillehei RC, Simmons RL, Najarian JS, et al. Pancreaticoduodenal allotransplantation. Experimental and clinical experience. Ann Surg 1972;172:405. 8 Orloff MJ, Lee S, Charters AC, et al. Long-term studies of pancreas transplantation in experimental diabetes mellitus. Ann Surg 1975;182:198. 9 Orloff MJ, Orloff MS. Whole pancreas transplantation in the rat. In: Cramer DV, Podesta LG, Makowka L, ed. Handbook of animal models in transplantation research, Section III. Boca Raton: CRC Press, 1994.

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10 Orloff MJ, Greenleaf G, Girard B. Reversal of diabetic somatic neuropathy by whole pancreas transplantation. Surgery 1990;108:179. 11 Lee S, Orloff MJ. Techniques of vascular anastomoses and organ transplantation in the rat. Proc Int Macrosurg Soc 1975;1:131. 12 Vollmar B, Janata J, Yamauchi JI, Menger MD. Attenuation of microvascular reperfusion injury in rat pancreas transplantation by l -arginine. Transplantation 1995;67:950. 13 Konigsrainer A, Mark W, Hechenleitner P, et al. At what stage does pancreas allograft rejection become irreversible? An experimental study. Transplantation 1997;63:631. 14 Wang C, Sun J, Wang L, et al. Combined liver and pancreas transplantation induces pancreas allograft tolerance. Transplant Proc 1997;29:1145. 15 Wang C, Sun J, Li L, et al. Conversion of pancreas allograft rejection to acceptance by liver transplantation. Transplantation 1998;62:188. 16 Spandella CT, Mercadante MC, Schellini SA, et al. Effect of pancreas transplantation on the prevention of nephropathy in alloxan induced diabetic rats. Brazil J Med Biol Res 1996;29:1019. 17 Pieper GM, Adams MB, Roza AM. Pancreatic transplantation reverses endothelial dysfunction in experimental diabetes mellitus. Surgery 1998;123:89. 18 Papalois VE. Contribution to the study of experimental pancreatic allotransplantation. PhD Dissertation Thesis, Paschalides Medical Publications, Athens, Greece, 1992. 19 Florack G, Sutherland DER, Cavallini M, et al. Technical aspects of segmental pancreatic allotransplantation in dogs. Am J Surg 1983;146:565. 20 Ortega-Serrano J, Mendoza-Aroca A. Experimental left pancreas autotransplantation in dogs. Anatomical aspects. Res Surg 1990;2:72. 21 Matsamuto S, Kuroda Y, Hamano M, et al. Direct evidence of pancreatic tissue oxygenation during preservation by the two layer method. Transplantation 1996;62:1667. 22 Kawamura T, Kuroda Y, Suzuki Y, et al. Seventy two hour preservation of the canine pancreas by the two layer (Euro Collins solution/perfluorochemical) cold storage method. Transplantation 1989;47:776. 23 Kuroda Y, Fujita H, Matsumoto S, et al. Protection of canine pancreatic microvascular ebdothelium against cold ishemic injury during preservation by the two layer method. Transplantation 1997;64:948. 24 Suzuki Y, Kuroda Y, Tanioka Y, et al. Peripancreatic fluid cytology. Detection of early rejection versus graft pancreatitis after canine pancreatic transplantation. World J Surg 1997;21:880. 25 Hawthorne WJ, Wilson TG, Williamson P, et al. Long-term duct-occluded segmental pancreatic autografts. Absence of microvascular diabetic complications. Transplantation 1997;64:953. 26 Cooper DKC, Ye Y, Rolph L, et al. The pig a potential organ donor for man. In: Cooper DKC, Kemp E, Reemtsma K, White DJG, eds. Xenotransplantation. Heidelberg: Springer-Verlag, 1991. 27 Gruessner RWG, Tzardis P, Schechner R, et al. En bloc simultaneous pancreas and kidney allotransplantation in the pig. J Surg Res 1990;49:366. 28 Nakache R, Mainetti L, Tyden G, et al. Renal transplantation in diabetes mellitus: influence of simultaneous pancreas transplantation on outcome. Transplant Proc 1990;22:624. 29 Sutherland DER, Gruessner A, Moudry-Munns KC, et al. Tabulation of cases from the International Pancreas Transplant Registry (IPTR) and analysis of United Network for Organ Sharing (UNOS) United States of America (USA) Pancreas Transplant Registry Data according to multiple variables. Transplant Proc 1993;25:1707. 30 Sutherland DER, Gruessner RWG, Gillinham K, et al. A single institution's experience with solitary pancreas transplantation: a multivariate analysis leading to improved outcome. In: Terasaki PI, ed. Clinical transplants 1991. Los Angeles: UCLA Tissue Typing Laboratory, 141, 1992. 31 Gruessner RWG, Nakhleh R, Tzardis P, et al. Rejection in single versus combined pancreas and kidney transplantation in pigs. Transplantation 1993;56:1053.

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32 Gruessner RWG, Sutherland DER, Tzardis P, et al. Correlation of rejection of the duodenum with rejection of the pancreas in a pig model of pancreaticoduodenal transplantation. Transplantation 1993;56:1353. 33 Sollinger HW, Stratta RJ, D'Alessandro AM, et al. Experience for simultaneous pancreas-kidney transplantation. Ann Surg 1988;208:475. 34 Gruessner RWG, Nakhleh R, Tzardis P, et al. Differences in rejection grading after simultaneous pancreas and kidney transplantation in pigs. Transplantation 1994;57:102.

Chapter 4

Pretransplant medical evaluation for pancreas transplant candidates Jerry McCauley and Robert J. Corry

Introduction Pancreas transplantation has rapidly moved from an experimental procedure associated with high rates of morbidity and mortality to a mainstream technique with excellent patient and graft survival. The rate of pancreas transplantation increased from less than 200 per year in 1987 to approximately 1000 per year in 1998. [1,2] Recent Medicare funding for simultaneous kidney and pancreas transplantation (SPK) and pancreas after kidney (PAK) transplantation in the United States will likely fuel more rapid growth. The recent proliferation of new immunosuppressant agents will also likely contribute further to improve graft survival in patients with PAK and pancreas transplantation alone (PTA) and increase the rate of transplantation in these patients as well. The medical evaluation prior to transplantation is crucial since many arrive with pre-existing cardiac disease and other complications of diabetes, which may substantially increase the risk of graft loss and death. The indications for pancreas transplantation is in evolution and may be highly affected by the preferences of the transplant centre, improvements in allograft survival related to improved immunosuppression, and surgical technique. The indications for pancreas transplantation are also evolving and are not uniformly accepted by the rapidly growing number of pancreas transplant centres. Likewise, the contraindications for pancreas transplantation are changing as patient and graft survival continues to improve. As with most forms of transplantation, more challenging patients will likely be referred for pancreas transplantation. The medical evaluation of pancreas transplant recipients will certainly become more demanding as the art and science of pancreas transplantation progresses.

Genetics and pathogenesis of type 1 diabetes Evaluation of the potential pancreas transplant recipient must begin with determination of the type of diabetes. The American Diabetes Association (ADA) has recently reclassified diabetes on aetiological grounds, (Table 4.1) [3]. In the revised classification primary and secondary categories of type 1 diabetes have been eliminated. Patients with low or absent insulin production (type 1 diabetics) benefit from replacement of pancreatic ␤-cells capable of producing insulin. Accordingly, type 1 diabetes of the immune or idiopathic type are the most common candidates for pancreatic transplantation. Although most patients with type 1 diabetes are young (< 25 years) at the time of initial diagnosis, type 1 diabetes may develop at any age; even in the geriatric population. The older description of maturity-onset diabetes of the young (MODY) was abandoned for a new classification that identifies the specific genetic defects leading to diabetes. Mutations of the gene hepatic nuclear factor 1␣ and 4␣ are responsible for MODY3 and 1, respectively. A mutation of the glucokinase gene is responsible for

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Table 4.1 Aetiological classification of diabetes mellitus (adapted from Diabetes Care 1998; 21:S5–S19) (1) Type 1 diabetes (a) immune mediated (b) idiopathic (2) Type 2 diabetes (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance) (3) Other specific types (a) Genetic defects of b-cell function (i) chromosome 12, HNF-1a (MODY3) (ii) chromosome 7, glucokinase (MODY2) (iii) chromosome 20, HNF-4a (MODY1) (iv) mitochondrial DNA (b) Others (c) Gestational diabetes mellitus HNF, hepatic nuclear factor; MODY, maturity-onset diabetes of the young.

MODY2. Mutations of mitochondrial DNA results in ineffective conversion of proinsulin to insulin and an effective insulinopenic state. A long list of other specific causes of diabetes form much of the remainder of the new classification of diabetes but most of these patients such as type 2 diabetics are not candidates for pancreatic transplantation. Finally, gestational diabetes retained in the new classification. Autoimmune type 1 diabetes develops after immune destruction of the ␤-cells in the islets of Langerhans of the pancreas [4]. The clinical manifestations of type 1 diabetes was once felt to result from a sudden illness such as a viral infections which initiated rapid destruction of ␤-cells and an immediate need for insulin therapy. It has now become clear that a chronic process of ␤-cell destruction precedes the clinical illness by many years. Hyperglycaemia is an insensitive measure of pancreatic function and mass. At least 70 per cent of the ␤-cells in a normal pancreas must be lost before hyperglycaemia develops [5]. The genetic markers of autoimmune type 1 diabetes are present from birth [6]. These patients are felt to have a genetic predisposition, which is activated by some environmental stimulus. The major gene associated with type 1 diabetes is located on chromosome 6 in association with genes related to immune recognition [4]. Both susceptibility and resistance to type 1 diabetes has been localized to HLA DR and DQ genotypes [7]. Either HLA DR3, DQB1*0201 or HLA DR4, DQB1*0302 is present in greater than 90 per cent of type 1 diabetes. In fact, if patients have both HLA DR3 and DR4, the lifelong risk of type 1 diabetes is even greater. Forty-five per cent of the general white population in the United States have either DR3 or DR4 genotypes [7]. Although this is a common antigen in the American white population, the presence of protective genotypes (DR4, DQB1*0302/DR3, DQB1*0201) and others may account for the low prevalence of type 1 diabetes. Other genes are associated with susceptibility to type 1 diabetes. A recent genome-wide search based upon the human genome project has located at least 20 chromosomal regions associated with susceptibility to type 1 diabetes [8]. It is now clear that the genetic predisposition and clinical expression of type 1 diabetes varies by race and geographical origin. Type 1 diabetes is most prevalent in descendants of northern Europe and less common in other ethnic groups such as those of African, Asian or native North American descent [4,9]. In Europe, the prevalence was demonstrated to have a strong North–South gradient with the highest rate in Finland and the lowest in southern Europe [4,10]. Destruction of pancreatic islet cells is mediated by autoimmune mechanisms. Genetic predisposition does not appear to be sufficient to initiate this process. Patients who are destined to develop type

J.McCAULEY AND R.J. CORRY

1 diabetes have a genetic susceptibility but appear to require an environmental event or multiple events to initiate the autoimmune process leading to isletitis and ultimately leading to destruction of ␤-cells [4]. Potential environmental factors associated with the development of diabetes include viral infection (Coxsackie, enteroviruses, rubella), dietary factors (cow's milk in infant formula, nitrates in drinking water), and others [4].

The evaluation process Simultaneous kidney and pancreas transplantation (see also chapter 5) Approximately 88 per cent of all pancreas transplants are performed as SPK procedures. [1]. Evaluation for the potential SPK transplant recipient is similar to the evaluation for the kidney transplant alone (KTA) recipients with relatively small modification [11]. The protocol for recipient evaluation is detailed in Table 4.2. At our centre, the transplant nurse co-ordinator obtains the initial history. The focus of the history centres on the presentation of diabetes (age at diagnosis for diabetes and immediate need for insulin therapy), the complications of diabetes, prior cardiovascular disease, and factors that might increase the urgency for pancreas transplantation (absence of hypoglycaemic symptoms with documented hypoglycaemia). The history of renal failure is sought in addition to medical or surgical past history. The nurse co-ordinator's preliminary assessment forms the basis for Table 4.2 Pancreas and kidney transplant evaluation protocol at the University of Pittsburgh Professional evaluation

Nephrologist, surgeon, nurse co-ordinator, social worker, dentist

Laboratory studies

General: creatinine, electrolytes, calcium, phosphorus, SGOT, SGPT, GGTP, alkaline phosphatase, total cholesterol, triglyceride, LDL, HDL, amylase, lipase, total protein, albumin, CBC, platelet count, PT, PTT, RPR Diabetes related: C-peptide, hemoglobin A1c

Viral serology

CMV, hepatitis B, hepatitis C, Epstein-–Bart, herpes zoster, herpes simplex, varicella

Other studies

ECG, chest X-ray, PPD and controls, urine C& S

Immunological evaluation

ABO type, HLA typing, DR typing, circulating antibody, quick PRA, crossmatch

Urological evaluation

Ultrasound of kidneys and right upper quadrant

Cancer screening

Women 35 or older: mammogram All women: gynecology examination and Papanicolaou smear Men ≥ 40 years old: PSA All patients ≥ 50 years old: sigmoidoscopy

C & S, Clinitest and Acetest; CBC, complete blood cell count; CMV, cytomegatovirus; GGTP, g-glutanyltranspeptidase; HDL/LDL, low and high-density lipoproteins; PPD, punified protein derivative of tuberculin; PRA, panel reactive antibody; PSA, prostatespecific antigen; PT, prothrombin time; PTT, partial thromboplastin time; RPR, rapid plasmin regain test; SGOT, serum glutamate oxaloacetate transaminase; SGPT, serum glutamate pyruvate transaminase.

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the physician and surgeons evaluation and helps to streamline the process. The nephrologist performs a complete history, physical examination, and reviews medical records with the intention of identifying all previous medical conditions but pays special attention to pre-existing cardiovascular disease and complications of diabetes. The surgeon's evaluation also aim to identify prior medical problems but gives particular emphasis to problems that might cause technical complications with the transplant procedure itself. The social worker's assessment of the patient is crucial given the burden of longstanding diabetes, which may have resulted in depression or other serious psychosocial problems. The laboratory evaluation for pancreas transplant recipients is similar to that for renal transplant candidates. The general laboratory studies, viral serology, and tissue typing is identical. Since pancreas transplantation is only appropriate for patients who are insulinopenic, demonstration of the level of insulin production by the patient's native pancreas is required. An absent or very low C-peptide is considered by most centres to be sufficient to confirm the diagnosis of type 1 diabetes. In addition, a measure of long-term glycaemic control (haemoglobin A1c) is obtained. More specific studies such as nerve conduction velocity, among others, are performed by some centres in an attempt to document the changes in diabetic complications after transplantation. Screening for pre-existing cancers is an important aspect of the medical evaluation of the pancreas recipient. Our policy is to follow the recommendations of major organizations for cancer preventive health services in all of our patients and at times to require screening at earlier ages given the potentially prohibitive risk of mortality for cancers developing after transplantation. The abdominal ultrasound screens for evidence of renal carcinoma and cholelithiasis. An asymptomatic renal carcinoma usually does not require delay in listing for a pancreas transplant outside that needed for convalescence after nephrectomy. At our centre, gallstones are removed prior to transplantation. This approach, however, is not universally accepted. Some centres do not require pretransplant cholecystectomy but remove the gallbladder only if the usual indications are present. Women 35 years of age or older obtain screening mammograms and all sexually active women undergo gynaecological evaluations including Papanicolaou smears. Men 40 years of age or older obtain prostate-specific antigen determinations and all patients 50 years or older perform a screening sigmoidoscopy. The goal of the medical evaluation is to identify risk factors that may adversely affect postoperative morbidity or mortality and to correct or minimize them prior to transplantation. The potential pancreas transplant recipient is known to be at risk for accelerated atherosclerosis due to diabetes but may also have many of the risk factors present in the general dialysis population. The cardiac evaluation of all potential pancreas transplant recipients will be described in detail later in this chapter. During the initial evaluation, however, each of the known risk factors for atherosclerosis should be addressed and the patient should be counseled regarding all modifiable risk factors. The American Heart Association and the International Task Force for Prevention of Coronary Heart Disease have advanced specific measures for primary prevention [12,13]. These measures were not explicitly developed for patients with endstage renal disease (ESRD) but appear prudent until more specific recommendations tailored to these patients are developed. The major elements of these two reports include: (a) smoking cessation; (b) blood pressure control; (c) correction of hyperlipidaemia; (d) increase in physical activity; (e) weight reduction; and (f) oestrogen replacement which is determined on an individual basis. Kasiske et al. reported that approximately 25 per cent of the dialysis patients evaluated for renal transplantation were current smokers, which is similar to the general population [14]. Hypertension is also highly prevalent in the ESRD population including diabetes and has been estimated to be 70 to 85 per cent. Diabetics with severe autonomic neuropathy tend to develop orthostatic hypotension. Once ESRD has occurred and the patients are persistently hypervolaemic, the orthostatic component is attenuated unless they become volume depleted after dialysis. Hyperlipidaemia is also common in

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ESRD patients and may be a particular problem for diabetics who have recently initiated dialysis since the nephrotic syndrome due to diabetic nephropathy may persist. Physical inactivity is very common in ESRD and may be particularly difficult in diabetics with labile blood glucose control. In addition, the other complications of diabetes such as neuropathy, and diffuse atherosclerotic disease may make developing a regular exercise programme challenging. Obesity is a growing problem in the dialysis population and maintaining the appropriate body weight is even more difficult for the diabetic. Tight blood glucose control typically increases body weight, and exercise for the purpose of weight reduction is difficult. Despite the difficulties in controlling these risk factors, any evaluation of the potential candidate for pancreas transplantation should include counselling in these areas. The indications for SPK in patients with ESRD or near ESRD are relatively straightforward (Table 4.3). Once type 1 diabetes has been established, the severity of diabetic complications should be assessed. The American Diabetes Association has recently released a position paper on pancreas transplantation [15]. This group suggested that the potential SPK candidate should: (a) already plan to have a kidney transplant; (b) meet the medical indications and criteria for kidney transplantation; (c) have significant clinical problems with exogenous insulin therapy; (d) not have excessive surgical

Table 4.3 Indications for pancreas transplantation (adapted from ADA [15]) Simultaneous kidney and pancreas transplant

Pancreas after kidney transplant

Pancreas transplant alone

(1) Endstage renal disease with type 1 diabetes with other diabetic compli cations (2) Near endstage renal disease with other diabetic complications (3) Planned bilateral nephrectomy in dia betic with significant other diabetic complications (4) Prior renal transplant which is failing in a type 1 diabetic Prior kidney transplant in type 1 diabetic with other diabetic complications (1) Patients with a history of frequent acute severe metabolic complications requiring medical attention (2) Clinical and emotional problems with insulin therapy that are so severe as to be incapacitating (3) Consistent failure of other therapeutic approaches Other potential indications: (4) Presence of diabetic complications which are progressive and unresponsive to intensive insulin therapy (5) Early diabetic nephropathy associated with other diabetic complications (6) Subcutaneous insulin resistance (7) Following total pancreatectomy (8) Insulin allergy (case report)

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risk for the dual procedure. Although most of these recommendations are self-explanatory, having significant clinical problems with exogenous insulin is less concrete. Patients who have frequent admissions for diabetic ketoacidosis, or extreme lability of glucose control fit into this group. Likewise, those with hypoglycaemia without prodromal symptoms could develop severe brain damage or death if such an event occurs while the patient is unattended. Many consider hypoglycaemic unawareness to be an absolute indication for SPK. Recent animal and human studies suggest that hypoglycaemic unawareness is largely if not completely due to recurrent or chronic hypoglycaemia [16]. When hypoglycaemia is prevented, the awareness of hypoglycaemia frequently returns. The problem of hypoglycaemic unawareness can be present in any patient with insulin-dependent diabetes mellitus (IDDM) but those involved in intensive insulin regimes aimed at normoglycemia are two to four times more likely than patients treated with conventional insulin protocols [17]. In addition to recurrent hypoglycaemia, other risk factors for hypoglycaemia include duration of diabetes, presence of autonomic neuropathy, and strict glycaemic control [18]. Once patients have developed diabetic nephropathy and renal insufficiency, other diabetic complications are almost always present. The diagnosis of diabetic nephropathy, however, is seldom confirmed by renal biopsy in patients with longstanding diabetes. It is usually assumed the renal failure is due to diabetes. Patients without other endorgan complications of diabetes and renal failure may have another underlying renal disease. Those with short duration diabetes (even if the C-peptide confirms type 1 diabetes), absence of retinopathy or other complications are at high risk for having non-diabetic renal disease. Candidates without other diabetic complications but who have renal failure may not be ideal for SPK since the other diabetic complications may not develop in the future. In such atypical cases, a renal biopsy may be useful if the patient does not have longstanding ESRD. Patients with multiple severe diabetic complications including severe atherosclerotic disease also may not be candidates for SPK. Such patients have a very high risk of perioperative complications and may not experience a significant improvement in the quality of life outside of the simple cessation of insulin treatment. Whether pancreatic transplantation reverses the complications of diabetes such as gastropathy or neuropathy, and stabilizes the retinopathy, is controversial [19]. This is largely based upon the lack of randomized studies and limited follow-up in case series. It is, however, generally agreed that the more severe the complication, the less likely it is to fully reverse. If there is little chance of diabetic complications reversing and cardiovascular risk is great, such patients should opt for KA or continue dialysis therapy depending upon the patient's particular clinical situation.

Pancreas after kidney The evaluation of potential recipients for pancreas after kidney (PAK) transplantation is similar to that for the SPK. Approximately 10 per cent of all pancreas transplants are PAK [1]. The PAK patients fall into two groups, those with a prior kidney transplant alone and those with prior SPK in those with a failed pancreas allograft. Since these patients have ESRD, the benefit of a functioning pancreas transplant is similar to the SPK group. In all potential PAK recipients, a detailed evaluation of the current renal allograft must be made. Patients with poor graft function may be candidates for SPK instead. The presence of evidence for significant chronic allograft nephropathy should raise the questions of SPK with removal of the failing renal allograft at the time of the SPK. Patients with marginal renal function and without a recent allograft biopsy should be assumed to have chronic allograft nephropathy. Confirmation of this diagnosis by biopsy is preferred but a clinical picture of a chronically elevated creatinine with or without proteinuria may be sufficient. A 24-h urine collection for creatinine

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clearance and protein should be obtained to better assess the level of renal impairment. No exact cutoff has been determined for creatinine clearance before replacing the prior renal allograft but patients with creatinine clearances less than approximately 30–40 cc/min and significant proteinuria will likely have progressive loss of renal function and require dialysis or transplantation in the future. The added nephrotoxicity of cyclosporin or tacrolimus after the pancreas transplant may accelerate the deterioration in renal function. The decline in glomerular filtration rate (GFR) from nephrotoxicity varies by the drug blood levels achieved and the prevailing renal function at the time of transplantation. Brennan et al. have demonstrated that the serum creatinine and creatinine clearance after a dose of cyclosporin may predict renal function in candidates for PTA and by inference PAK patients with marginal renal function [20]. If it is decided that SPK may be too early (patients with creatinine clearance > 30–40 cc/min), these patients must be followed with periodic assessments of their renal function if they are placed on the waiting list for PAK. If the patient has good allograft function, the evaluation is identical to that for the SPK. For patients who were transplanted greater than 1 year at the time of the evaluation for PAK, all studies should be repeated. This is particularly true for the cardiovascular and immunological evaluations. There has been a growing interest in performing living related renal transplantation followed by PAK (KTA – LD + PAK). Obtaining a planned renal transplant quickly rather then waiting for a pancreas transplant has been particularly attractive to some patients and some transplant centres have offered this option as the preferred approach if a donor is available. For many patients, however, this has been a difficult decision given the superior graft survival of the SPK. A recent cost-utility analysis has demonstrated that SPK is the optimal procedure even if a living kidney donor is available [21]. In this analysis SPK dominated (more effective and less expensive) living related followed by PAK strategy. The major factor causing the KTA – LD + PAK option to be less cost-effective was the inferior graft survival compared to SPK. From this analysis, in order for KTA – LD + PAK to be as costeffective as SPK the former 5-year pancreas survival would need to exceed 86 per cent which has not been possible even in the large volume centres with the best graft survivals. The pre-transplant evaluation of KTA – LD + PAK option is similar to the cadaveric kidney PAK scenario. It is particularly important to inform patients of the predictably inferior pancreas survival if this option is chosen.

Solitary pancreas (see also Chapter 6) Pancreas transplantation alone was performed in only 3 per cent of the patients in the International Pancreas Transplantation Registry [1]. As with all other pancreas transplants, PTA allograft has continued to improve from less than 50 per cent 1-year graft survival in the mid-1980s to 76.6 per cent in 1998 [22]. The indications for PTA are listed in Table 4.3. As with other forms of pancreas transplantation, the ADA has proposed indications for PTA [15]. Unlike SPK or PAK recipients, candidates for PTA do not otherwise require immunosuppression to prevent the renal allograft rejection with their predictable side-effects. There is also the additional surgical risk, which should carry a relatively small morbidity and mortality. Candidates for PTA should not have severe renal insufficiency requiring imminent renal replacement therapy. Such patients would be more appropriate candidates for preemptive SPK. It is expected that candidates for PTA should have near normal renal function and do not have severe disabling diabetic complications. The ADA has suggested that: (a) patients with a history of frequent acute severe metabolic complications requiring medical attention; (b) those with clinical and emotional problems with insulin therapy that are so severe as to be incapacitating; and (c) those with consistent failure of other therapeutic approaches should be considered for PTA. In addition the above recommendations, potential candidates for PTA should have diabetic complications

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which are progressive. Transplantation so early in the course of diabetes that few if any diabetic complications exist would pose significant risk with little certainty of demonstrable benefit. Insulin allergy is an unusual potential indication for PTA. The evidence for this indication is in one case report only [23]. A young woman with longstanding type 1 diabetes developed severe urticaria, which quickly developed into angio-oedema and respiratory distress after treatment with human insulin which she had taken for many years. Beef and pork insulin did not improve the symptoms. Attempts at desensitization were unsuccessful and the fear of a life-threatening anaphylactoid reaction prompted the referral for PTA. Her only diabetic complications included mild retinopathy, one episode of diabetic ketoacidosis, and rare hypoglycaemic episodes. There was no evidence for renal dysfunction. She developed normoglycaemia after the successful PTA without further episodes of insulin allergy. The incidence of insulin allergy has decreased from approximately 50 per cent to 2 and 10 per cent with the advent of human insulin [23]. Allergy to human insulin also occurs and may be due to additives such as zinc, protamine, non-insulin proteins, aggregates of insulin molecules, and animal proteins [23,24]. Pancreas transplantation for this indication should be rare and all other measures should be exhausted if this is the only indication for PTA.

Candidate risk factors for pancreas transplantation The major objective of the pretransplant recipient evaluation is to identify factors which increase the risk of death, graft loss or major morbidity after pancreas transplantation (Table 4.4). Many of the known risk factors are not peculiar to pancreas transplantation but must be considered during the evaluation period. As with renal transplant alone recipients, the following factors must be considered to increase the risk to potential pancreas transplant recipients: (a) increasing age; (b) obesity; (c) adverse psychosocial factors; (d) pre-existing cardiovascular disease; (e) chronic viral infection (hepatitis B or

Table 4.4 Contraindications to pancreas transplantation Absolute contraindications Severe cardiac disease

Severe peripheral vascular disease Malignancy(1)

(1) Coronary artery disease not amenable to anatomical correction (2) Cardiomyopathy with low ejection fraction not corrected by surgical or medical management Aortoiliac disease without possibility of surgical correction Recently diagnosed (requires appropriate waiting period after treatment) (2) Metastatic and untreatable

Relative contraindications (centre specific) HIV infections

Acceptable at some centres if no AIDSdefining illness

Severe diabetic complications unlikely to improve after pancreas transplantation

Only advantage to patient is cessation of insulin and relaxatin of dietary restrictions. Such patients are usually high-risk candidates for cardiac and other complications

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C, parvovirus, HIV); (f) gastrointestinal disorders (peptic ulcers, pancreatitis, diverticulosis); (g) chronic pulmonary disease (chronic restrictive or obstructive disease) chronic fungal disease (histoplasmosis, etc.); and (h) previously treated malignancy. The approach to evaluation of these problems in the renal transplant setting has been examined in great detail and will not be discussed further here. The risk factors specifically affecting pancreas transplant recipients has been examined previously by Gruessner et al [25]. This report retrospectively examined the factors predicting patient and graft survival in addition to the risks for technical complications in KTA, SPK, PAK, and PTA recipients between 1986 and 1993 with 5-year follow-up. Factors considered for the model included: (a) recipient age greater or less than 45 years; (b) obesity; (c) hypertension; (d) blindness in at least one eye; (e) known cardiac disease previous myocardial infarction, coronary bypass, or percutaneous angioplasty; (f) peripheral vascular disease (previous cerebrovascular accident or transient ischaemic attack, bypass, angioplasty, or amputation); and (g) retransplantation (previous pancreas transplant). Patient survival was adversely affected by recipient age greater than or equal to 45 years in the SPK (relative risk (RR) 3.0] and PAK groups (RR 5.86). Recipients of PTA were adversely affected by recipient age. Cardiac disease increased the risk of mortality only in SPK recipients (RR 3.78). For PAK patients only a previous pancreas transplant and peripheral vascular disease increased the risk of death. Manske et al. reported a more pessimistic view of candidate factors after pancreas transplantation [26]. This report summarizes the patient outcomes from 1987 to 1993 in 173 consecutive IDDM patients. This centre offered pancreas transplants to high-risk recipients with advanced diabetic complications and those with underlying cardiac disease although every attempt was made to correct any anatomical lesions prior to transplantation. They also offered living related renal transplantation first followed by pancreas transplantation as the preferred option if possible. In this high-risk group of patients 3-year patient survival was 68 per cent for SPK, 86 per cent for living related, and 90 per cent for KTA. A Cox proportional hazard model (which included type of organ transplant in the model) identified age in 5-year increments (RR = 1.5, P = 0.001), history of congestive heart failure (RR = 2.7, P = 0.03), and SPK (RR = 3.1, P = 0.02) as predicators of increased risk of mortality. During this period the International Pancreas Transplant Registry was reporting 84 per cent, 3-year patient survival for SPK and a response to this study by Secchi et al. emphasized that excellent results were possible with SPK if patient selection differed from the Manske report [27]. These workers emphasize the importance of excluding patients with severe macroangiopathy (previous strokes, severe dilated cardiomyopathy, and amputations). They likewise favoured SPK over living related renal transplant followed by pancreas transplantation given the superior graft survival with the former. Despite this careful evaluation, cardiovascular events were the major cause of death in all groups (13 per cent KTA, 8 per cent in kidney with segmental pancreas, and 6 per cent in SPK). These two reports and the aggregate experience of the International Pancreas Transplant Registry suggest that excellent patient and allograft survival should be the expectation after pancreas transplantation of all types. Performing these procedures in patients with severe diabetic complications and marginally corrected cardiac disease may lead to unacceptable morbidity and mortality.

The cardiac evaluation in the pancreas transplant candidate Cardiovascular disease (CVD) is the leading cause of death in diabetic ESRD patients. Candidates for pancreas transplantation are known to have accelerated atherosclerosis due to diabetes itself, other non-diabetes related factors seen in the general population (smoking, lack of exercise, etc.) and may have an added risk from renal failure. Patients with chronic renal disease appear to have greater risk of developing CVD than the general population. Mortality from CVD has been estimated to be 10 to 20

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times that of the general population [28]. There is no consensus on the nature of the cardiovascular evaluation in the diabetic patient with ESRD. Some centres perform coronary angiography in all patients and others attempt risk stratification, performing angiography in selected high-risk patients. The cardiac evaluation in diabetics is complicated by the high prevalence of silent ischaemia and cardiomyopathy. Studies have found that exercise stress tests with or without thallium or dobutamine echocardiography are of limited predictive value in diabetics [29]. Only 45 per cent of diabetics are capable of reaching 70 to 80 per cent of their maximum predicted heart rate. One recent study, however, suggested that dipyridamole thallium stress tests might be predictive of perioperative cardiac events [30]. In this study only one of 111 (0.9 per cent) patients with a normal study developed a perioperative cardiac event and none of those with fixed defects or reversible defects with less than 50 per cent narrowing of coronary arteries on angiography developed perioperative events. This optimistic view of non-invasive cardiac evaluations has not been the experience of most caring for these patients. Manske et al. have developed an algorithm which attempts to identify low-risk diabetic patients who can safely avoid angiography in the pretransplant evaluation [31]. This group found an 88 per cent prevalence of coronary artery disease in diabetics over 45 years of age and therefore recommended angiography in all diabetics in this group. In young patients without smoking history or ST–T wave changes on electrocardiogram (ECG), or in those with diabetes for less than 25 years, the risk of coronary disease was found to be lower. These patients were recommended to undergo a dipyridamole thallium stress test as the initial study. Any abnormality on this study would require angiography, even in the low-risk group. Although this was a relatively small study, this approach probably represents the most useful way to screen diabetics. Once significant coronary artery disease has been found, anatomical correction by coronary revascularization or angioplasty should be performed before transplantation. Coronary revascularization prior to transplantation in the diabetic has already been shown to decrease the frequency of cardiac events and mortality [32]. Many centres are advocating the use of dobutamine echocardiography as the preferred non-invasive screening study for coronary artery disease in diabetic and non-diabetic renal transplant candidates. It has the advantage of providing information on the presence of ischaemia, wall motion and ejection fraction. As with dipyridamole thallium stress testing this study may not be as accurate in patients with ESRD. Herzog et al. have reported the only study which directly compares dobutamine stress echocardiography (DSE) with coronary angiography [33]. Fifty candidates for renal transplantation underwent DSE followed by coronary angiography. Of these patients 39 (78 per cent) were diabetic with 10 (26 per cent) being type 1 and the remaining type 2. Twenty of the 50 dobutamine studies were positive for inducible ischaemia. Three false negative dobutamine studies were found in patients with more than 70 per cent stenosis and for false negative studies in patients with more than 75 per cent stenosis (including patients with > 70 per cent). The sensitivity and specificity of DSE were respectively 52 and 74 per cent for 50 per cent or greater stenosis, 75 and 71 per cent for stenosis greater than 70 per cent, and 75 and 76 per cent for stenosis greater than 75. The positive and negative predictive values were respectively 70 and 57 per cent for greater than or equals 50 per cent, 45 and 90 per cent for greater than 70 per cent and 60 and 87 per cent greater than 75 per cent stenosis. The authors appropriately conclude that DSE is a useful but imperfect screening test for angiographicallly defined coronary artery disease. Several algorithms have been advocated to screen for coronary artery disease in pancreas transplant candidates. They all attempt to define the low- and high-risk patient and perform angiography as the first diagnostic study only in the high-risk group. Williams has suggested an algorithm which is similar to the Manske approach but attempts to avoid cardiac screening in low-risk patients [34].

J.McCAULEY AND R.J. CORRY

Fig. 4.1

Low-risk patients could potentially avoid a cardiac evaluation altogether if the risk of coronary artery disease appeared to be negligible. Such patients might be placed directly on the waiting list. Our approach to cardiac evaluation (an adaptation of the Manske and Williams approaches) is displayed in Fig. 4.1. In practice, most centres consider a non-invasive stress test to be the minimum evaluation in all pancreas transplant candidates. Patients having a positive stress test require coronary angiography. Those with lesions greater than 70 per cent should undergo angioplasty or coronary artery bypass grafting before being placed on the waiting list. Candidates with inoperable diffuse disease should not be transplanted. Candidates with lesions less than 70 per cent could be approved for transplantation but must be re-evaluated every 6 months to 1 year with a DSE. These patients should also have annual DSE after transplantation. High-risk candidates are those with a prior history of coronary artery disease and/or multiple risk factors. Since the presence of peripheral arterial disease and/or carotid artery disease increases the chances of having coronary artery disease, such patients would be considered to be at high risk and probably should proceed directly to angiography.

Organ allocation system The United Network of Organ Sharing (UNOS) administers the allocation of pancreatic organs in the United States and has devised a system based upon geographical origin of the organ, number of antigen mismatches, and waiting time [35]. Whole pancreata are first allocated locally, regionally, then nationally. The transplant centre in the local allocation scheme can chose a patient waiting for an isolated pancreas, kidney-pancreas (SPK), or solid organ–islet combination from the same donor. If there is a zero antigen mismatched with any patient in the nation, the pancreas is mandated to be allocated to that patient. Within each waiting list, the organs are allocated based upon blood type

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compatibility and waiting time on the transplant list. Blood type O organs are mandated to be transplanted into type O recipients. If the organ is not used at the local level it is allocated regionally then nationally. The organs are allocated by blood type and waiting time in the following sequence: (a) isolated pancreas candidates with one A, B, or DR antigen mismatch, then (b) isolated pancreas candidates with two A, B, or DR antigen mismatches, then (c) isolated pancreas candidates with three A, B, or DR antigen mismatches, then (d) combined kidney pancreas candidates if a kidney is available, then (e) isolated pancreas candidates with four more A, B, or DR antigen mismatches [35]. As mentioned earlier, zero antigen mismatches are mandated to be shared at the national level. If the whole pancreas has not been used locally, regionally, or nationally, it can then be used for islet transplantation. The host organ procurement organization offers the pancreas for islet transplantation locally, regionally, then nationally. At the regional and national levels allocation of the organ is determined by HLA matching, medical urgency, and waiting time. Candidates with zero HLA antigen mismatches receive 3 points, those with one mismatch 2 points, and patients with two mismatches receive 1 point. Potential recipients with three or more antigen mismatches do not receive points. Medical urgency for islet cell transplantation is divided into two groups. Status 1 patients are those who have already received an islet cell transplant within the previous 3 weeks and are considered to be the most urgent. Patients awaiting the first islet cell transplant are assigned to status 2. Patients with the longest waiting time are given 1 point. A fraction of a point is assigned to subsequent patients based upon their waiting time compared to the others on the list.

References 1 1999 Annual Report of the US Scientific Registry for Transplant Recipients and the Organ Procurement and Transplantation Network: Transplant Data: 1989–1998. US Department of Health and Human Services, Health Resources and Services Administration, Office of Special Programs, Division of Transplantation, Rockville, MD: UNOS, Richmond VA. 2 Sutherland D. Pancreas and pancreas–kidney transplantation. Curr Opin Nephrol Hypertens 1998;7:317–25. 3 Annoymous. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care 1998;21:S5–S19. 4 Atkinson MA, Maclaren NK. Mechanisms of disease: The pathogenesis of insulin-dependent diabetes mellitus. N Engl J Med 1994;331:1428. 5 Bonner-Weir S, Trent DF, and Weir GC. Partial pancreatectomy in the rat and subsequent defect in glucose-induced insulin release. J Clin Invest 1983;71:1544–53. 6 McCulloch DK, Palmer JP. The appropriate use of B-cell function testing in the preclinical period of type 1 diabetes. Diabet Med 1991;8:800. 7 Todd JA, Bennett JC. A practical approach to identification of susceptibility genes for IDDM. Diabetes 1992;41:1029–34. 8 Davies, JL, Kawaguchi, Y, Bennett ST, et al. A genome-wide search for human type 1 diabetes susceptibility genes. Nature 1994;371:130. 9 Diabetes Epidemiology Research International Mortality Study Group. Major cross-country differences in risk of dying for people with IDDM. Diabetes Care 1991;14:49–54. 10 Green A, Gale EAM, Patterson CC. Incidence of childhood-onset insulin-dependent diabetes mellitus: the EURODIABAC study. Lancet 1992;339:905–9. 11 McCauley J. Evaluation of the potential renal allograft recipient. Stamford: Appleton & Lange, 1997:43–72.

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12 Grundy SM, Balady GJ, Criqui MH, Fletcher G, et al. Guide to primary prevention of cardiovascular disease: A statement for healthcare professionals from the Task Force on Risk Reduction. Circulation 1997;95:2329–31. 13 Assmann G, Carmena R, Cullen P, Fruchart J, Jossa F, et al. Coronary heart disease: reducing the risk: A world wide view. International Task Force for the Prevention of Coronary Heart Disease. Circulation 1999;100(18):1930–8. 14 Kasiske BL, et al. The adverse effects of cigarette smoking in renal transplant recipients. J Am Soc Nephrol 2000;11(4):753–9. 15 Anonymous. Pancreas transplantation for patients with diabetes mellitus. Diabetes Care 1998;21:S79. 16 Bolli GB. Counterregulatory mechanisms to insulin-induced hypoglycemia in humans: relevance to the problem of intensive treatment for IDDM. J Ped Endo Met 1998;11(Suppl.1):103–15. 17 The DCCT Research Group: Epidemiology of severe hypoglycemia in the diabetes control and complications trial. Am J Med 1991;90:450–9. 18 Kendall D, Rooney DP, Smets YFC, Bolding LS, Robertson RP. Pancreas transplantation restores epinephrine response and symptom recognition during hypoglycemia in patients with long-standing type 1 diabetes and autonomic neuropathy. Diabetes 1997;46(2):249–57. 19 Hricik DE. Combined kidney–pancreas transplantation. Kidney Int 1998;53:1091–102. 20 Brennan DC, Stratta RJ, Lowell JA, Miller SA, Taylor RJ. Cyclosporine challenge in the decision of combined kidney–pancreas versus solitary pancreas transplantation. Transplantation 1994;57(11):1606–11. 21 Douzdjian V, Escobar F, Kupin W, Venkat KK, Abouljoud M. Cost–utility of living-donor kidney transplantation followed by pancreas transplantation versus simultaneous pancreas–kidney transplantation. Clin Transplant 1999;13(1):51–8. 22 1999 Annual Report of the US Scientific Registry for Transplant Recipients and the Organ Procurement and Transplantation Network: Transplant Data: 1989–1998. US Department of Health and Human Services, Health Resources and Services Administration, Office of Special Programs, Division of Transplantation, Rockville, MD; UNOS, Richmond, Virginia, pp. 156. 23 Oh HK, Provenzano R, Hendrix J, El-Nachef MW. Insulin allergy resolution following pancreas transplantation alone. Clin Transplant 1998;12(6):593–5. 24 Simmond JP, Russell GI, Cowley AJ, et al. Generalized allergy to porcine and bovine monocomponent insulins. Br Med J 1980;281(6236):355–6. 25 Gruessner RWG, Dunn DL, Gruessner AC, Matas AJ, Najarian JS, Sutherland DER. Recipient risk factors have an impact on the technical failure and graft survival rates in bladder-drained pancreas transplants. Transplantation 1994;57:1598–606. 26 Manske C, Wang Y, Thomas W. Mortality of cadaveric kidney transplantation versus combined kidney–pancreas transplantation in diabetic patients. Lancet 1995;346:1658–62. 27 Secchi A, Caldara R, Di Carlo V, Guido P. Mortality of cadaveric kidney transplantation versus combined kidney–pancreas transplantation in diabetic patients. Lancet 1996;347:827. 28 Foley RN, Parfrey PS, Sarnak MJ. Clinical epidemiology of cardiovascular disease in chronic renal disease. Am J Kidney Dis 1998;32(5):S112–19. 29 Morrow CE, Schwartz, Sutherland DER, et al. Predictive value of thallium stress testing for coronary and cardiovascular events in uremic diabetic patients before renal transplantation. Am J Surg 1983;146:331–5. 30 Mistry BM, Bastani B, Solomon H, Hoff J, Aridge D, Lindsey L, et al. Prognostic value of dipyridamole thallium-201 screening to minimize perioperative cardiac complications in diabetics undergoing kidney or kidney–pancreas transplantation. Clin Transplant 1998;12(2):130–5. 31 Manske CL, Thomas W, Wang Y, Wilson R. Screening diabetic transplant candidates for coronary artery disease: Identification of a low risk subgroup. Kidney Int 1993;44:617–21.

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32 Manske CL, Wang Y, Rector T, Wilson R, et al. Coronary revascularization in insulin dependent diabetic patients with chronic renal failure. Lancet 1992;340:998–1002. 33 Herzog CA, Marwick TH, Pheley AM, White CW, Rao VK, Dick CD. Dobutamine stress echocardiography for the detection of significant coronary artery disease in renal transplant candidates. Am J Kidney Dis 1999;33(6):1080–90. 34 Williams ME. Management of the diabetic transplant recipient. Kidney Int 1995;48:1660. 35 Annual Report of the US Scientific Registry for Transplant Recipients and the Organ Procurement and Transplantation Network: Transplant Data: 1989–1998. US Department of Health and Human Services, Health Resources and Services Administration, Office of Special Programs, Division of Transplantation, Rockville, MD; UNOS, Richmond, Virginia, pp. 418–19.

Chapter 5

Indications for kidney and pancreas transplantation and patient selection Konstantinos N. Haritopoulos and Nadey S. Hakim

Diabetes mellitus (DM) afflicts 6 per cent of the general population and is currently the third most common disease and the fourth leading cause of death by disease in the United States [1,2]. Of the estimated 16 million diabetic patients in the United States, 4 million take insulin and 1 million have IDDM (insulin-dependent diabetes mellitus) (type I), juvenile onset. Nearly 30 000 new cases of IDDM are diagnosed each year, and the incidence is increasing [2]. The syndrome of IDDM includes not only abnormal glucose metabolism but also specific long-term complications such as retinopathy, nephropathy, and neuropathy [3]. Although exogenous insulin therapy is effective at preventing acute metabolic decompensation and is life-saving, the majority of patients with diabetes will develop one or more endorgan complications during their lifetime [3,4]. Tight glucose control is even more important than previously recognized, as demonstrated by a multicentre trial — the Diabetes Control and Complications Trial (DCCT) [5]. The results of this study demonstrated that intensive control of glucose can significantly reduce (but not reliably protect against) the long-term complications of diabetes. Therefore, in patients who fail other ways of intensive insulin therapy, pancreas transplantation (PTx) may be the best available treatment option because it appears to be the single most effective method in achieving tight glucose control in an ambulatory setting [6]. Nearly 13 000 cases of PTx have been reported to the International Pancreas Transplant Registry (IPTR) and over 170 centres worldwide have performed a PTx [7,8]. This number is probably higher since it is not obligatory for transplant centers not in the United States to report their number of PTx to the IPTR. Insulin independence approaches 82 per cent at 1 year with a 94 per cent patient survival [9]. There are various categories for performing a PTx; either simultaneous pancreas and kidney (SPK), pancreas after kidney (PAK), or pancreas transplant alone (PTA). The majority are SPK transplants (90 per cent), 4 per cent are PAK and less than 6 per cent are PTA [10]. However, unlike liver, lung, and heart transplantation, PTx is not a life-saving procedure and its value must be balanced against the risks of the operative procedure and the inevitable long-term immunosuppressive therapy. Therefore, the indications for this procedure and the selection of patients are critical to ensure low mortality and an improvement in quality of life.

Criteria for pancreas transplantation All recipients should be type I DM, since no benefits have been shown conclusively in type II DM patients because of the peripheral insulin resistance and pre-existing C-peptide secretion [11] (Table

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Table 5.1 Criteria for pancreas transplantation Inclusion criteria ● Presence of IDDM ● Presence of secondary diabetic complications ● Ability to withstand surgery and immunosuppression ● Socio-psychological suitability ● Ability to understand the therapeutic nature of pancreas transplantation ● Ability to understand and comply with the long-term immunosuppression and need for follow-up Exclusion criteria ● Insufficient cardiovascular reserve (a) angiography indicating non-correctable coronary artery disease (b) ejection fraction below 50% (c) recent myocardial infarction ● Malignancy ● Ongoing drug or alcohol abuse ● History of non-compliance with treatment ● Major psychiatric illness ● Active infection ● Age over 65 years ● Lack of well-defined secondary diabetic complications ● Extreme obesity (> 50% of ideal body weight) ● Psychological instability

5.1). C-peptide deficient patients make better candidates for PTx and the majority of pancreas transplant recipients in the United States are C-peptide deficient. However, some IDDM patients that have normal C-peptide levels can achieve good glucose control following PTx [12]. Nevertheless, PTx is an operation that is reserved for patients who have developed secondary complications due to DM. Only 50 per cent of patients with diabetes of 20 years or more will develop severe neuropathy, retinopathy, or nephropathy with 30 per cent progressing to endstage renal failure [7]. In view of the difficulty in predicting those patients who will develop chronic diabetic complications, PTx is currently performed in those patients with established complications. Pancreas transplantation is a difficult operation and to achieve good results it is essential that patients who are possible transplant recipients are in good general health. For the best results, patients should be carefully selected and any pre-existing disease should be scrupulously assessed and evaluated. This is of particular importance in coronary artery disease and, if suspected, it is better to diagnose and treat early by coronary artery bypass grafting before proceeding to PTx [13]. Coronary angiography should be performed in cases in which the history, physical examination, or non-invasive cardiac studies (stress test) reveal an abnormality [14,15]. In addition, angiography of the cerebral arteries is indicated when the carotid Doppler is not normal [16]. Characteristics such as age over 45, diabetes for more than 25 years, a smoking history, longstanding hypertension, previous major amputations due to peripheral vascular disease, or history of cerebrovascular disease are among the usual indications for performing cardiac catheterization [14–15]. A history of previous myocardial infarction, angioplasty, or coronary artery bypass grafting are not necessarily contraindications to PTx. In these cases, stress thallium and echocardiographic imaging in combination with coronary angiography are helpful in defining the operative risk. Echocardiography provides a functional assessment whereas coronary angiography illustrates the anatomical details. Major amputations secondary to severe peripheral vascular disease or severe visual impairment are not considered absolute contraindi-

K.N. HARITOPOULOS AND NADEY S. HAKIM

cations [17]. This is especially true for uraemic patients who can benefit from the reversal of uraemia by an SPK transplant. However, it should be borne in mind that these patients are both unlikely to derive improved function at the endorgan level from the restoration of glucose homeostasis, and that the iliac atherosclerosis these patients are bound to have will potentially complicate the technical procedure. The optimum age of potential recipients should also be considered. There is evidence to suggest that patients who are over 50 years of age with a long duration of diabetes and more advanced diabetic complications have little chance of PTx being able to reverse or stabilize retinopathy, nephropathy, or neuropathy. The situation is quite different in younger patients (less than 50 years old) whose disease may be less advanced and the improvement of diabetic complications more likely [18]. Furthermore, patients who approach 50 years of age represent a high-risk group in terms of patient and graft survival [18–20]. Potential recipients should also be evaluated in regards to their emotional and sociopsychological suitability to undergo a pancreas transplantation. They ought to understand the therapeutic nature of pancreas transplantation as well as the need for long-term immunosuppression and follow-up. Patients who have had a history of non-compliance with treatment are not good candidates for PTx since recipients are required to take their immunosuppression drugs continuously and meticulously. Moreover, contraindications for PTx include untreated malignancy, active infection and HIV seropositivity, severe obesity (over 50 per cent of ideal body weight), an insufficient cardiovascular reserve, as well as age over 65 years.

Recipient groups The degree of nephropathy plays a role in determining the type of pancreas transplantation (Table 5.2). If the creatinine clearance is below 40 ml/min or 0.67 ml/s then an SPK transplant is indicated. If the creatinine clearance is above 40 ml/min or 0.67 ml/s on cyclosporin a PAK transplant is indicated, whereas in cases where the creatinine clearance is above 70 ml/min or 1.17 ml/s then the most suitable Table 5.2 Criteria for selection of candidates for SPK, PTA and PAK transplants Entry criteria for SPK transplant ● Diabetic nephropathy (creatinine clearance < 40 ml/min) ● Patient on dialysis or very close to starting dialysis ● Failure of previous renal allograft Entry criteria for PTA transplant ● Presence of two or more diabetic complications (a) proliferative retinopathy (b) early nephropathy (creatinine clearance > 70 ml/min and proteinuria > 150 mg/24 h but < 3 g/24 h) (c) presence of overt peripheral or autonomic neuropathy (d) vasculopathy with accelerated atherosclerosis ● Hyperlabile diabetes as defined by (a) frequency and severity of episodes of ketoacidosis (b) frequency and severity of episodes of hypoglycaemia (c) hypoglycaemia unawareness (d) impairment of quality of life Entry criteria for PAK transplant ● Patients with stable function of previous renal allograft that meet the criteria for PTA

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operation is a PTA transplant. In those patients who have an intermediate renal function (i.e. clearance between 45 and 70 ml/min or 1.17 ml/s or proteinuria above 2 g/24 h) a ciclosporin challenge test can be performed to assess the functional renal reserve to help determine the type of transplant [21].

Simultaneous pancreas and kidney transplantation This is the preferred procedure in type I diabetics with endstage or near endstage renal disease (ESRD) [22]. Patients with IDDM with impending or ESRD who have minimal or limited secondary complications of diabetes and are between the ages of 20 and 40 years are considered optimal candidates for SPK. One exception to this is the young diabetic patient for whom a suitable living related renal transplant is available. A living related renal transplant offers excellent long-term results with less immunosuppression than is required for SPK transplantation. However, not all IDDM patients with renal failure are acceptable candidates. It has been reported that only 64 per cent of diabetic patients screened are actually accepted for SPK [23], severe cardiovascular illness has been identified as the main criteria for limiting patient selection [24]. Patients who have undergone angioplasty or coronary artery bypass can be accepted if they have adequate left ventricular function without demonstrable ischaemia. Blindness, history of major amputation, or history of cardiac disease are considered to be relative contraindications to SPK [14]. Although these diabetes-related problems are not reversible, a number of patients are well adjusted to these complications and can lead productive lives after dual organ transplantation with facilitated rehabilitation. Another factor that has to be considered is the timing of the transplantation. Pre-emptive transplantation offers the additional advantage of halting the diabetic complications before uraemia develops. Pre-emptive transplantation refers to the use of transplantation for primary renal replacement therapy before dialysis commences. The aim is to take advantage of the possible benefits of transplantation over dialysis. These include improved survival, reduced costs, and reduced morbidity [25]. Furthermore, if the increasing waiting times, the variable progressive nature of diabetic complications along with the diminished survival that IDDM patients have on dialysis are taken into consideration, it can be argued that SPK transplantation should be carefully thought for as a potential treatment for diabetic patients before dialysis.

Pancreas transplantation alone (see also Chapter 6) Ideally, solitary PTx should be performed before the development of diabetic complications such as the need for a kidney transplant. However, at present no reliable markers exist to predict, before the appearance of early lesions, which diabetic patients will develop complications. In a few American centers, including Minneapolis, Omaha, and Wisconsin, PTA has been reserved for those patients with very unstable diabetes or a hypoglycaemic unawareness that is life-threatening [17,26–27]. Indications for PTA include two or more diabetic complications including evidence of early diabetic nephropathy such as microalbuminuria, proteinuria or early histological changes but with relatively preserved renal function (creatinine clearance > 70 ml/min). Other indications may include glucose hyperlability defined as frequent episodes of hypoglycaemia without frank symptoms which lead to a significantly poor quality of life and increased risk of trauma or sudden death. Nevertheless, when non-uraemic diabetics are concerned, the morbidity and mortality associated with the longterm immunosuppression and the surgical procedure itself, must be weighed against the benefits of reversing or halting the progression of secondary endorgan diseases, reducing the risks of hypogly-

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caemic events, and improving quality of life. In summary, PTA is only appropriate in non-uraemic patients where the problems of diabetes itself are perceived to be more serious than the potential problems of immunosuppression. In the diabetic patients whose metabolic control is so fragile that their life is chaotic, PTA may be their only hope for a better lifestyle [28].

Pancreas after kidney transplantation In IDDM patients with a well-functioning kidney transplant, sequential PAK transplant has been advocated because these patients are already receiving chronic immunosuppression. The benefits of a subsequent PAK transplantation are improved quality of life and the fact that a functioning pancreatic allograft will likely prevent or reverse early diabetic changes in the existing kidney transplant. However, only patients with stable and adequate renal transplant function (creatinine clearance ≥ 50 ml/min) should be considered for PAK transplants. Patients with marginal function of their transplanted kidneys should instead be considered for an SPK (or no pancreas) transplant because intensified calcineurin inhibitor therapy used postoperatively can induce renal failure [17]. In Minneapolis, the preferred technique is PAK, advocating a living related renal donation first in order to correct uraemia. Then, 12 months later, a cadaver PTx follows. This sequence maximizes the availability of cadaver kidneys to other patients and improves the recipient’s well being. However, its limitation is the lower rate of pancreas graft survival. However, graft survival rates have improved and it is hoped that with future advances in immunosuppression the survival rates will be ever higher [29].

Living related pancreas transplantation Worldwide, of all pancreas transplants reported to the IPTR between 1966 and 1997 only 105 have been from live donors [30] (Table 5.3). After the kidney, the pancreas was the first solid organ to be transplanted successfully using a live donor [31]. There are certain categories of patients with IDDM who can benefit from PTx from a living donor. These include highly sensitized patients with a low probability of a negative crossmatch against a cadaveric donor, but who have a negative crossmatch

Table 5.3 Criteria for live related pancreas donation Recipients inclusion criteria ● ● ●

Highly sensitized patients with low probability of a negative crossmatch against a cadaveric donor Patients for whom high-dose immunosuppression is undesirable Patients who have been a long time on the waiting list and have had already a kidney transplant that is affected by recurrence of diabetes

Donors exclusion criteria ● History of IDDM in any first-degree relative ● History of gestational diabetes ● Donor age less than the age of diagnosis of IDDM in the recipient plus 10 years ● Body mass index > 27 kg/m2 ● Age > 45 years ● Impaired glucose tolerance or diabetes by the American National Diabetes Data Group criteria ● HbA1c level > 6% ● Glucose disposal rate < 1% during intravenous glucose tolerance tests ● Presence of elevated titre of islet cell autoantibodies

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against a relative. Moreover, diabetic patients who will probably not tolerate high-dose immunosuppression or patients who want to have a minimum dose of immunosuppression can benefit from a very well-matched pancreatic graft from a living related donor. In addition, patients with IDDM and a potential living donor for a kidney transplant who can gain from a successful PTx and wish to avoid a second operation for receiving a pancreatic graft from a cadaveric donor, can receive a pancreas and a kidney from the same living related donor. Furthermore, patients with brittle IDDM and diabetic recipients of a kidney transplant that has been affected by the recurrence of DM and have been on the waiting list for a long time are candidates for a living related pancreas transplant. However, living related pancreas transplantation involves certain risks for the donor as well as the anticipated risks for the recipient. Partial pancreatectomy is by no means an easy operation and a careful selection of potential donors has to be made. Individuals must be excluded from consideration if they meet any of the following criteria: (a) a history of type I diabetes in any first-degree relative; (b) a history of gestational diabetes; (c) age younger than 10 years greater than age of diagnosis of type I in recipient; (d) a body mass index above 27 kg/m2; (e) age older than 45 years; (f) impaired tolerance or diabetes by National Diabetes Group criteria [32]; (g) haemoglobin A1c level above 6 per cent; (h) a glucose disposal rate below 1 per cent during intravenous glucose tolerance tests; or (i) the presence of elevated titre of islet cell autoantibodies. In addition, potential donors who have any of the following criteria should be evaluated by endocrinologists before a decision is made: (a) a glucose value greater than 150 mg/dl; (b) basal, fasting insulin values greater than 20 ␮U/ml; (c) an acute insulin response to glucose or arginine above 300 per cent basal insulin; (d) clinical evidence of insulin resistance; and (e) evidence of more than one autoimmune endocrine disorder [30]. All potential donors have to be advised that none of the current available tests can absolutely exclude the possibility of a later development of diabetes following hemipancreatectomy. Hence, long-term follow-up of the metabolic function of donors is essential. Until 1994 in Minneapolis, living related pancreas transplantation was reserved only for patients without uraemia (PTA) or for diabetic patients who had previously received a kidney transplant (PAK) [33]. The first successful living kidney and pancreas donor transplantation was performed in Minneapolis in 1994 and ever since more than 20 such transplants have been carried out [30,34]. The obvious advantage of a live related SPK transplant is that the recipient does not have to go through two separate surgical procedures. In conclusion, living donor SPK transplants can be done safely and successfully in selected uraemic patients with type I DM.

Conclusion Ideally, pancreatic transplantation should be performed earlier in the course of the disease, before the appearance of secondary complications. As the results of patients and graft survival have considerably improved during the last 5 years, the indications for PTA have become the main subject of debate in pancreatic transplantation. Both the advantages and disadvantages of PTx and insulin therapy have to be carefully considered for specific populations of diabetic patients as well as for each patient individually. In non-uraemic diabetic patients the choice of PTx has to be balanced against the risks of surgery and long-term immunosuppression on one hand and the complications of DM and insulin therapy on the other. At present, candidates for PTx can be selected among the various categories of diabetics. In patients with labile diabetes who have developed secondary complications, or those with frequent hypoglycaemic episodes, PTx with the accompanying immunosuppression is an acceptable alternative. In the future, PTx could be used prophylactically to prevent secondary complications. This could be based

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on the study of genetic susceptibility to complications. Currently, there are no such genetic markers although microalbuminuria has been demonstrated as an early marker of nephropathy in some cases, and elevated Na+/Li+ countertransport has been implicated as a potential marker in predicting the development of nephropathy [35]. Furthermore, candidates for PTA could be selected in the future from the prepubertal diabetic population. It is known that the earlier the onset of diabetes, the greater the risk of complications. PTx can be considered when the patients are mature enough to participate in the choice of treatment.

References 1 Harris M, Hadden WC, Knowles WC, Bennett PH. Prevalence of diabetes and impaired glucose tolerance and plasma glucose levels in the US population aged 20–74 years. Diabetes 1987;36:523–34. 2 Libman I, Songer T, Lapore R. How many people in the US have IDDM? Diabetes Care 1993;16:841–2. 3 Nathan DM. Long-term complications of diabetes mellitus. N Engl J Med 1993;328:1676–84. 4 Clark CM, Lee DA. Prevention and treatment of the complications of diabetes mellitus. N Engl J Med 1995;332:1210–17. 5 The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;29:977–86. 6 Robertson RP. Pancreatic and islet transplantation for diabetes: cures or curiosities? N Engl J Med 1992;327:861–8. 7 Sutherland DER. Pancreas transplants. Br J Surg 1994;81:2–4. 8 Gruessner AC, Sutherland DER. Analyses of pancreas transplant outcomes for United States cases reported to the United Network for Organ Sharing (UNOS) and non-US cases reported to the International Pancreas Transplant Registry (IPTR). In: Cecka JM, Terasaki PI, ed. Clinical transplants 1999. Los Angeles: UCLA Tissue Typing Laboratory, 2000:51–69. 9 International Pancreas Transplant Registry. Worldwide pancreas transplants. IPTR Newsletter 1997;9:1–12. 10 Sutherland DER, Gruessner A, Moudry-Munns K. International pancreas transplant registry report. Transplant Proc 1994;26:407–11. 11 White SA, Nicholson ML, London JM. Vascularized pancreas allotransplantation — clinical indications and outcome. Diabet Med 1999;16:533–43. 12 Sasaki TM, Gray RS, Ratner RE, Currier C, Aquino A, Barhyte DY, et al. Successful long-term kidneypancreas transplants in diabetic patients with high C-peptide levels. Transplantation 1998;65:1510–12. 13 Brayman KL, Weber M. Sutherland DER. Pancreatic and islet transplantation. In: Trede M, Carter DC, eds. Surgery of the pancreas. London: Churchill Livingstone, 1997:637–65. 14 Stratta RJ, Taylor RJ, Lowell JA, Sindhi R, Sudan D, Castaldo P, et al. Clinical transplants 1994. Los Angeles: UCLA Tissue Typing Laboratory, 1994:265–81. 15 Stratta RJ, Weide LG, Sindhi R, Sudan D, Jerius JT, Larsen JR, et al. Solitary pancreas transplantation. Diabetes Care 1997;20:362–8. 16 Dubernard JM, Tajra LCF, Lefrancois N, Dawahra M, Martin C, Thivolet C, et al. Pancreas transplantation: results and indications. Diabetes Metab 1998;24:195–9. 17 Odorico JS, Leverson GE, Becker YT, Pirsch JD, Knechtle SJ, D’Alessandro AM, et al. Pancreas transplantation at the University of Wisconsin. In: Cecka JM, Terasaki PI, ed. Clinical transplants 1999. Los Angeles: UCLA Tissue Typing Laboratory, 2000:199–210. 18 Allen R. Pancreas transplantation. In: Forsythe JLR, ed. A companion to specialist surgical practice — Transplantation surgery. London: Saunders, 1998:167–202.

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19 Stratta RJ. Mortality after vascularised pancreas transplantation. Surgery 1998;124:823–30. 20 Freise CE, Stock PG, Meizer JS. Increased morbidity and mortality of simultaneous pancreas and renal transplantation in patients over 49 years of age. Transplant Proc 1998;30:292. 21 Brennan DC, Stratta RJ, Lowell JA, Miller SA, Taylor RJ. Cyclosporine challenge in the decision of combined kidney–pancreas versus solitary pancreas transplantation. Transplantation 1994;57:1606–11. 22 Shapiro R, Jordan ML, Scantlebury, Vivas CA, Jain A, Chakrabarti P, et al. Simultaneous pancreas–kidney transplantation at the University of Pittsburgh. In: Cecka JM, Terasaki PI, ed. Clinical transplants 1999. Los Angeles; UCLA Tissue Typing Laboratory, 2000:217–21. 23 Stratta RJ, Taylor RJ, Wahl TO, Duckworth WC, Gallagher TF, Knight TF, et al. Recipient selection and evaluation for vascularized pancreas transplantation. Transplantation 1993;55:1090–6. 24 Elkhammas EA, Demirag A, Henry ML. Simultaneous pancreas–kidney transplantation at the Ohio State University Medical Center. In: Cecka JM, Terasaki PI, ed. Clinical transplants 1999. Los Angeles: UCLA Tissue Typing Laboratory, 2000:211–15. 25 Stratta RJ, Taylor RJ, Ozaki CF, Stevenson Bynon J, Miller S, Knight TF, et al. A comparative analysis of results and morbidity in type I diabetes undergoing preemptive versus postdialysis combined pancreas–kidney transplantation. Transplantation 1993;55:1097–103. 26 Gruessner RW, Sutherland DER, Najarian JS, Dunn DL, Gruessner AC. Solitary pancreas transplantation for non-uraemic patients with labile insulin-dependent diabetes mellitus. Transplantation 1997;64:1572–77. 27 Stratta RJ, Taylor RJ, Bynon JS, Lowell JA, Sindh R, Wahi TO, et al. Surgical treatment of diabetes mellitus with pancreas transplantation. Ann Surg 1994;220:809–17. 28 Remuzzi G, Ruggenenti P, Mauer SM. Pancreas and kidney/pancreas transplants: experimental medicine or real improvement. Lancet 1994;343:27–31. 29 Sutherland DER, Gruessner RWG, Najarian JS, Gruessner AC. Solitary pancreas transplants: a new era. Transplant Proc 1998;20:280–1. 30 Gruessner RWG, Kendall DM, Drangstveit MB, Gruessner AC, Sutherland DER. Simultaneous pancreas–kidney transplantation from live donors. Ann Surg 1997;226:471–82. 31 Sutherland DER, Goetz FC, Najarian JS. Living-related donor segmental pancreatectomy for transplantation. Transplant Proc 1980;12:19–25. 32 National Diabetes Data Group. Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance. Diabetes 1979;28:1039–57. 33 Sutherland DER, Gruessner RWG, Dunn D, Moudry-Munns KC, Gruessner A, Najarian JS. Pancreas transplants from living-related donors. Transplant Proc 1994;26:443–5. 34 Gruessner RWG, Sutherland DER. Simultaneous kidney and segmental pancreas transplant from living related donors — the first two successful cases. Transplantation 1996;61:1265–8. 35 Dubernard JM, Martin C, Lefrancois N, Thivolet CH, Dawahra M, Petruzzo P, et al. Advances in pancreas transplantation — 1999 Indications and Contraindications. J Pediatr Endocrinol Metab 1999;12:765–70.

Chapter 6

Indications for solitary pancreas transplantation Robert J. Stratta

Introduction After a decade of controversy surrounding the therapeutic validity of pancreas transplantation (PTX), the procedure has become accepted as the preferred treatment for patients with insulindependent diabetes mellitus (IDDM) and advanced diabetic nephropathy. Vascularized PTX is currently the only available form of autoregulating total endocrine replacement therapy that reliably achieves an insulin-independent euglycaemic state and normal glucose homeostasis resulting in the successful management of diabetes mellitus. Whether PTX represents a treatment or cure for IDDM is debatable. The trade-offs for normal glucose homeostasis are the operative risks of the transplant procedure and the need for chronic immunosuppression. Free islet grafts have the same potential but do not approach PTX in terms of consistency of results. With improvements in organ retrieval and preservation technology, refinements in diagnostic methodology and surgical techniques, advances in clinical immunosuppression and anti-infective prophylaxis, and experience in donor and recipient selection, success rates for PTX have continued to improve. From 1966 through to July 2000, over 14 000 PTXs were performed worldwide and reported to the International Pancreas Transplant Registry (IPTR) [1]. In the last decade, the majority (83 per cent) of PTXs have been performed in combination with a kidney transplant [simultaneous kidney and pancreas transplant (SPK)] in patients with endstage diabetic nephropathy. The current 1-year actuarial patient, kidney, and pancreas (with complete insulin independence) graft survival rates after SPK are 95, 92, and 84 per cent respectively [1,2]. Solitary PTXs comprise the remaining activity, including either sequential pancreas after kidney transplants (PAK, 12 per cent) or PTX alone (PTA, 5 per cent).The current 1-year patient survival rate after solitary PTX is 95 per cent, and the 1-year actuarial pancreas graft survival rates are 73 per cent for PAK and 70 per cent for PTA [1,2]. The differences in graft survival rates between SPK, PAK, and PTA transplants have been attributed to an increased rate of graft loss due to rejection and thrombosis after solitary PTX. PTX should be considered an acceptable therapeutic alternative to continued insulin therapy in diabetic patients with imminent or established endstage renal disease (ESRD) who have had or plan to have a kidney transplant, because the successful addition of a pancreas does not jeopardize patient survival, may improve kidney graft survival, and will restore normoglycaemia [3]. In the diabetic patient with a well-functioning kidney transplant, sequential PAK is advocated because these patients are already obligated to chronic immunosuppression and the additional risk is primarily that of the surgical procedure [4]. The proportion and total number of PAKs performed annually has steadily increased in recent years due to a number of factors: (a) the

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results have continued to improve with advances in immunosuppression (the current 1-year pancreas graft survival rate for PAK patients receiving antibody induction in combination with tacrolimus and mycophenolate mofetil therapy is 83 per cent); (b) living donor kidney transplantation followed by PAK expands the kidney donor pool and permits pre-emptive transplantation as a scheduled event; (c) waiting times for PAK are much shorter than for SPK; (d) increasing the number of solitary PTXs may improve donor utilization and enhance sharing; (e) PAK may be better tolerated with less morbidity compared to SPK (for instance, the patient may be in better medical condition at the time of PAK-not on dialysis); and (f) the results of the kidney may be better when it is not transplanted simultaneous with a pancreas due to less surgical and immunological morbidity [4,5]. Although many transplant centers are experienced in SPK, only a few centers have accumulated experience in PAK. For a patient with diabetes but no uraemia, the choices are between exogenous insulin with the burden of diabetic management and the risk of acute and chronic diabetic complications versus the surgical risk of PTX and medical risks of chronic immunosuppression [6,7]. The Diabetes Control and Complications Trial (DCCT) has clearly shown that improved glycaemic control lowers the risk of secondary diabetic complications [8]. However, intensive insulin therapy did not result in normalization of glycosylated haemoglobin levels, was associated with a three-fold increased risk of severe hypoglycaemia, and was more resource-intensive. The results of the DCCT provide a strong rationale for PTA transplantation provided that the burden of immunosuppression is more benign than the burden of diabetes over the long term. Because of the uncertainty about the relative risk of each treatment option, PTA transplantation is restricted by necessity to those patients who already have demonstrated a propensity to early diabetic complications that are (or predictably will be) worse than the potential undesirable side-effects of chronic immunosuppression [3]. For this reason, most PTA transplants are done in patients with long-term diabetes who have specific problems, such as metabolic lability, neuropathy, or hypoglycaemic unawareness. In selected cases, PTA transplantation may be considered as a treatment option to prevent, stabilize, or reverse secondary complications of diabetes [9]. However, in the absence of glucose hyperlability, establishment of insulin independence alone would not justify the need for chronic immunosuppression if an effect on secondary diabetic complications could not be achieved.

Donor selection Donor selection and organ procurement are of paramount importance to the success of solitary PTX. Most heart-beating donors who have been declared brain dead and are appropriate for kidney, liver, and heart donation are also suitable for pancreas donation (Table 6.1) [10,11]. Although there is some evidence to suggest that donor hyperglycaemia may have an adverse effect on initial and long-term allograft function, the presence of hyperglycaemia or hyperamylasaemia, as such, are not contraindications for pancreas donation. In general, ideal pancreas donors range in age from 10 to 40 years and range in weight from 30 to 80 kg. Management of the multiple organ donor includes aggressive resuscitation to maintain haemodynamic stability, organ perfusion, and oxygenation. Resuscitative efforts usually result in significant hyperglycaemia and intensive control with insulin may have a favourable effect on initial allograft function and survival. Intravenous colloid fluids and mannitol are given to minimize pancreatic edema. Judicious administration of vasopressors such as dopamine is indicated to maintain a systolic blood pressure above 90 mmHg and promote diuresis.

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Table 6.1 Cadaveric pancreas organ donation Indications Declaration of brain death Informed consent Age 6–55 years (ideal 10–40) Weight 30–100 kg (ideal 30–80) Haemodynamic stability with adequate perfusion and oxygenation Normal glycosylated haemoglobin level (only needed in case of severe hyperglycaemia, extreme obesity, or positive family history of diabetes) Absence of infectious or transmissible diseases (i.e. tuberculosis, syphilis, hepatitis, AIDS) Negative serology (HIV; hepatitis B and C) Absence of malignancy (unless skin or low-grade brain cancer) Absence of parenchymal/intrinsic pancreatic disease Contraindications History of diabetes mellitus (type 1 or 2, or gestational) Previous pancreatic surgery Moderate to severe pancreatic trauma Pancreatitis (active acute or chronic) Significant intra-abdominal contamination Major (active) infection Chronic alcohol abuse Recent history of intravenous drug abuse Recent history of homosexuality or high-risk sexual behaviour Prolonged hypotension or hypoxaemia with evidence for significant endorgan (kidney, liver) damage Severe atherosclerosis Inexperienced retrieval team Severe fatty infiltration of pancreatic parenchyma Severe pancreatic oedema Severe obesity (> 150% ideal body weight or BMI > 30 kg/m2) Risk factors Massive transfusions Prior splenectomy Mild to moderate obesity (< 150% ideal body weight, BMI > 27.5 kg/m2) Aberrant hepatic artery anatomy Positive VDRL/RPR serology Prolonged length of hospital stay Donor age above 45 years Cardiovascular or cerebrovascular cause of brain death Mild to moderate fatty infiltration Mild to moderate pancreatic oedema Donor instability Mild pancreatic trauma Mild to moderate atherosclerosis 1 AIDS, acquired immunodeficiency syndrome; 2 BMI, body mass index; 3 HIV, human immunodeficiency virus; 4 RPR, rapid plasma reagin; 5 VDRL, venereal disease research laboratory.

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As the results of PTX have improved and experience has increased, previous contraindications for pancreas donation have become mere risk factors for a successful outcome (Table 6.1). According to IPTR data, the following variables are associated with an increased risk of pancreas allograft thrombosis: (a) donor age above 40 years; (b) cardiovascular or cerebrovascular cause of brain death; and (c) pancreas preservation time above 24 h [1,2]. The results of anecdotal experience suggest that: (a) over 150 per cent ideal body weight or body mass index (BMI) over 30 kg/m2 may be associated with an increased risk of early pancreas graft loss (due to thrombosis, pancreatitis, infection, or primary non-function); (b) a donor liver biopsy with more than 25 to 30 per cent macrovesicular steatosis may be associated with a fatty pancreas leading to an increased risk of early graft loss; and (c) fatty infiltration of the pancreas (as opposed to peripancreatic fat) may be associated with an increased risk of early graft loss [12,13]. Notably, pancreas grafts from female donors over 45 years of age appear to fare better than pancreas grafts from male donors over 45 years independent of age, cause of brain death, or body habitus. The presence of donor obesity or a fatty pancreas may be an underappreciated cause of early graft loss following PTX. However, some overweight donors may have little or no fatty infiltration of the pancreas, while some thin donors may have significant fatty infiltration of the pancreas, so the correlation is not absolute. It is also important to distinguish fatty infiltration of the pancreatic parenchyma from peripancreatic fat deposition. The latter is not uncommon, but is not necessarily associated with an adverse outcome. The most reliable way to make this distinction is to mobilize completely the spleen, body, and tail of the pancreas up into the operative field so that the anterior and posterior aspects of the gland can be carefully visualized and palpated to determine the quality of the organ. There are no data currently available regarding the utility of donor pancreas biopsies, particularly with regard to steatosis. The importance of an experienced retrieval team must be emphasized for the in situ assessment of pancreatic anatomy. Pancreas donors may be categorized as ideal, good, or marginal. By using donor age, weight, and cause of brain death as the three most important factors, one can usually make a rapid and accurate assessment of the quality of the donor pancreas prior to actual intraoperative assessment, which is the second most important factor. Solitary PTX donors need to be either ideal or good. If either the donor or recipient are marginal, there is a greater likelihood of a poor outcome. Unlike SPK, the inherent risk of thrombosis is much higher (two to three times) in PAK and PTA [14]. For this reason, cold ischaemia should be kept to a minimum and serious consideration should be given to routine perioperative anticoagulation in the recipient.

Recipient selection Specific selection criteria for solitary PTX are based on the presence of early diabetic complications or hyperlabile diabetes with adequate cardiac and renal functional reserve [10,11,15]. Indications for PTX include IDDM (type 1 or 2) and the predicted abilities to tolerate the operative procedure, the requisite immunosuppression after transplantation, and possible associated complications (Table 6.2). Patient selection is aided by a comprehensive medical evaluation before transplantation (Table 6.3) performed by a multidisciplinary team that confirms the diagnosis of IDDM, determines the patient’s ability to withstand the operative procedure, establishes the absence of any exclusion criteria (Table 6.4), and documents endorgan complications for future tracking after transplantation [10,11,15]. The primary determinants for recipient selection are the presence of diabetic complications, degree of nephropathy, and cardiovascular risk (Table 6.2). With increasing experience, previous absolute have become relative contraindica-

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Table 6.2 Indications for pancreas transplantation: eligibility guidelines Medical necessity Presence of insulin-treated diabetes mellitus (1) documentation of insulin dose (2) type 1 or 2 diabetes Ability to withstand surgery and immunosuppression (as assessed by pretransplant medical evaluation) (1) adequate cardiopulmonary function (a)cardiac stress testing ± coronary angiography to rule out significant coronary artery disease or other cardiac contraindications (b)patients with significant coronary artery disease should have it corrected pretrans plant (2) absence of other organ system failure (other than kidney) Emotional and sociopsychological suitability Presence of well-defined diabetic complications (any two) (1) proliferative retinopathy (2) nephropathy (hypertension, proteinuria, or decline in GFR) (3) symptomatic peripheral or autonomic neuropathy (4) microangiopathy (5) accelerated atherosclerosis (macroangiopathy) (6) glucose hyperlability, insulin resistance, or hypoglycaemia unawareness with a significant impairment in quality of life Absence of any contraindications Financial resources Type of pancreas transplant Specific entry criteria based on degree of nephropathy (1) simultaneous kidney–pancreas transplant: creatinine clearance below 30 ml/min (2) sequential pancreas after kidney transplant: creatinine clearance ≥ 40 ml/min (on calcineurin inhibitor); > 55 ml/min if not on calcineurin inhibitor (3) pancreas transplant alone: creatinine clearance above 60–70 ml/min and 24-h protein excretion < 2 g Primary determinants for recipient selection are the presence of diabetic complications, degree of nephropathy, and cardiovascular risk GFR, glomerular filtration rate.

tions, and relative contraindications have become risk factors for PTX (Table 6.4). Binocular blindness or a history of a major amputation are not necessarily contraindications for solitary PTX, provided that the patient is well adjusted to these otherwise irreversible diabetic complications. Inclusion and exclusion criteria for PTX are listed in Tables 6.2 and 6.4. Selection criteria for solitary PTX are based on the presence of progressive diabetic complications associated with either hypoglycaemia unawareness or exogenous insulin failure with hyperlabile diabetes resulting in a significant impairment in quality of life despite optimization of insulin therapy [16]. In the absence of indications for kidney transplantation, PTA transplantation should only be considered in patients who exhibit one or more of the following criteria: (a) a history of frequent, acute, and severe metabolic complications (hypoglycaemia, hyperglycaemia, diabetic ketoacidosis) requiring medical attention; (b) clinical and emotional problems with exogenous insulin therapy that are incapacitating; or (c) consistent failure of insulin-based management to prevent acute complications. Diabetic patients with a creatinine clearance above 60 to 70 ml/min and evidence of overt diabetic complications or unawareness of hypoglycaemic

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Table 6.3 Evaluation of the pancreas transplant candidate Interviews and consultations History and physical examination by nephrologist, endocrinologist, and transplant surgeon Ophthalmology evaluation including visual acuity, fluorescein angiography, retinal fundus photography with retinopathy score, and slit-lamp examination Transplant co-ordinator and medical social worker interview including completion or quality of life questionnaire Gynaecology consultation for all females (pelvic examination with Papanicolaou smear) Dental evaluation When indicated, additional evaluations may be required by orthopaedic surgery, podiatry, psychology, psychiatry, neurology, or gastroenterology Cardiovascular, respiratory, and peripheral vascular evaluations Standard testing includes orthostatic vital signs, 12-lead electrocardiogram, chest radiograph, echocardiography, and exercise treadmill, stress thallium, or dobutamine stress echocardiography Additional studies may include arterial blood gases, 24-h Holter monitoring, autonomic and peripheral vasomotor reflexes, Doppler arterial studies, ankle/brachial index, transcutaneous oxygen monitoring, plethysmography, carotid Doppler examination, aortography with run-off, or pulmonary function tests as indicated Cardiology consultation with or without coronary angiography as indicated Metabolic and endocrine evaluation Standard testing includes fasting blood glucose, glycohaemoglobin, and fasting lipid panel (cholesterol, triglycerides and HDL cholesterol) Fasting and stimulated C-peptide levels are used to assess type of diabetes if needed Additional studies may include oral or intravenous glucose challenge, anti-insulin and islet cell antibodies, proinsulin level, and lipoprotein profile Genitourinary/renal evaluation Standard testing includes electrolytes, blood urea nitrogen, serum creatinine, urinalysis with culture, and 24-h urine for protein and creatinine clearance Voiding cystourethrogram and urodynamics when indicated Radiometric glomerular filtration rate if needed In addition, kidney biopsy may be indicated Calcineurin inhibitor challenge test when indicated Hormonal profiles as indicated Evaluation of erectile dysfunction when indicated Serology and immunology evaluation ABO blood type and HLA tissue type Cytotoxic antibodies Viral titres (Epstein–Barr virus, herpes simplex virus, varicella-zoster virus, human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and cytomegalovirus); PCR quantitation when indicated VDRL/FTA test for syphilis Other laboratory tests Complete blood count with differential and platelets, prothrombin time, partial thromboplastin time, chemistry profile, amylase, lipase Abdominal ultrasound of kidneys and gallbladder Mammography in females over 35 years Haemoccult × 3; contrast studies or endoscopy when indicated When indicated, nerve conduction studies, gastric emptying scan, electromyography Hypercoagulable work-up (when indicated) FTA, fluorescent treponemal antibody; HDL, high-density lipoprotein; PCR, polymerase chain reaction; VDRL, Venereal Disease Research Laboratory

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Table 6.4 Absolute and relative contraindications and risk factors for pancreas transplantation Absolute contraindications Insufficient cardiovascular reserve; one or more of the following (1) coronary angiographic evidence of significant non-correctable or untreatable coronary artery disease (2) recent myocardial infarction (3) ejection fraction below 30% Active infection History of malignancy diagnosed within past 3 years (excluding non-melanoma skin cancer) Positive HIV serology Positive hepatitis B surface antigen serology Active, untreated peptic ulcer disease Ongoing substance abuse (drug or alcohol) Major ongoing psychiatric illness Recent history of non-compliance Inability to provide informed consent Any systemic illness that would severely limit life expectancy or compromise recovery Significant, irreversible hepatic or pulmonary dysfunction Positive crossmatch Relative contraindications Age less than 18 or greater than 65 years Recent retinal haemorrhage Symptomatic cerebrovascular or peripheral vascular disease Absence of appropriate social support network Extreme obesity (> 150% ideal body weight or BMI > 30 kg/m2) Active smoking Severe aortoiliac vascular disease Risk factors History of myocardial infarction, congestive heart failure, previous open heart surgery, or cardiac intervention History of major amputation or peripheral bypass graft History of cerebrovascular event or carotid endarterectomy History of hypercoagulable syndrome BMI, body mass index; HIV, human immunodeficiency virus.

symptoms are potential candidates for PTA transplantation (Table 6.2). A creatinine clearance over 60 to 70 ml/min is usually required for PTA transplantation because immunosuppression can cause accelerated deterioration of renal function in those with a lower creatinine clearance before transplantation. In 233 PTA transplants performed at the University of Minnesota, 36 patients (15.4 per cent) subsequently required a kidney transplant [17]. The actuarial probability of this occurrence was 4 per cent at 1 year and 10 per cent at 5 years. This risk was present regardless of whether or not the patient exhibited long-term pancreas function. Diabetic patients that have previously received a renal allograft, whether from a living or a cadaveric donor, are considered potential candidates for PAK if the creatinine clearance is above 40 ml/min on either cyclosporin or tacrolimus immunosuppression [15]. If the patient is not on a calcineurin inhibitor for their kidney transplant, a minimum creatinine clearance of 55 ml/min is recommended (Table 6.2). Adding a calcineurin inhibitor (or increasing the dose for PAK) generally results in a 25 per cent decline in baseline creatinine clearance. It is unclear how to factor the level of proteinuria into the decision analysis, particularly since the use of a

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calcineurin inhibitor will decrease the actual level of proteinuria. However, in the presence of massive proteinuria (> 2 g/day) or nephrotic syndrome, the risk of accelerated nephropathy due to drug toxicity must be considered. In this setting, a trial of high-dose cyclosporin or tacrolimus prior to PTX (cyclosporin or tacrolimus challenge) may be indicated to ascertain the drug effect on the patient’s creatinine clearance, serum creatinine, and protein excretion [18,19]. In general, if the serum creatinine is above 2.5 mg/dl in a male or above 2.0 mg/dl in a female, then it may be ‘too late’ to proceed with a PAK and the patient may have to wait to ‘qualify’ for a pre-emptive SPK [15,20]. A baseline kidney biopsy is important to document, quantify, and monitor the progression of nephropathy after PAK. However, there is little data or experience in using the biopsy results to guide recipient selection. The presence of chronic allograft nephropathy might be a contraindication to proceeding with PAK in a patient with otherwise stable renal allograft function. The cardiac status of each candidate must be assessed carefully because significant (and silent) coronary artery disease is not uncommon in this population. The cardiac evaluation consists of a non-invasive functional assessment such as an exercise or a pharmacological stress test in addition to echocardiography. Coronary angiography is reserved for specific indications such as age over 45 years, diabetes for more than 25 years, a positive smoking history, longstanding hypertension, previous major amputation due to peripheral vascular disease, history of cerebrovascular disease, or cases in which the history, physical examination, or non-invasive cardiac studies reveal an abnormality [10,11,15]. A history of previous myocardial infarction, angioplasty, stenting, or coronary artery bypass grafting are not contraindications for PTX, as excellent outcomes have been reported in patients with previous cardiac interventions [17]. However, sudden cardiac death, in the absence of significant structural heart disease, continues to be a major cause of cardiac mortality after PTX [21]. For this reason, a number of centres are beginning to test cardiac autonomic function in these patients using laboratory evoked cardiovascular tests and 24-h heart rate variability measurements [22]. The new methodology may be able to detect alterations in autonomic function prior to the onset of disabling symptoms. In general, age over 65 years, heavy smoking, a left ventricular ejection fraction below 30 per cent, recent myocardial infarction, and severe obesity (over 150 per cent ideal body weight or BMI over 30 kg/m2) are usually viewed as contraindications for PTX (Table 6.4) [10,11,15]. Most patients below 45 years of age are acceptable candidates for PTX, provided that no significant coronary artery disease is present. Diabetic patients older than 45 years of age are not candidates until proven otherwise, and need to be undergo an extensive cardiovascular and peripheral vascular evaluation. Transplant recipients tend to age at a faster rate than non-transplant patients. For example, a diabetic patient who is 5 to 10 years postkidney transplantation is physiologically much different than a diabetic patient who is the same age and being considered for PTA transplant. A good rule of thumb is to add the number of years after kidney transplantation to the patient’s actual age to calculate physiological age (this also applies to the number of years on dialysis pretransplant). Recipient weight criteria are similar to those used for donor selection. Potential male recipients above 100 kg and female recipients above 80 kg, depending on their height and body habitus, have a higher rate of surgical complications after PTX. For this reason, a BMI over 30 kg/m2 is considered an absolute contraindication and BMI over 27.5 kg/m2 as a relative contraindication for solitary PTX. IDDM is associated with a number of coagulation abnormalities including hyperhomocysteinaemia, activated protein C resistance, increased levels of fibrinogen and von Willebrand’s factor, decreased levels of antithrombin III, and protein S deficiency [23]. In contrast to other

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transplanted organs, the pancreas is susceptible to thrombosis because of its low microcirculatory flow based on collateral circulation. In the absence of the antiplatelet and anticoagulative effects of uraemia, solitary PTX recipients may be uniquely prone to vascular thrombosis [14]. For these reasons, a hypercoagulable work-up is indicated (Table 6.5). Ideally, solitary PTX should be performed before diabetic complications are present and before the need for a kidney transplant [24–30]. At present, there are no reliable early markers to predict, before the earliest complications appear, which diabetic individuals are at risk for progressive complications. Diabetic patients with repeated episodes of ketoacidosis, hypoglycaemia unawareness, or glucose hyperlability may derive immediate benefit from PTA with an enhanced quality of life simply by achieving an insulin-free state with improved counter-regulation. Most PTX recipients find the transition to transplantation easier than continued insulin therapy. In addition to improving quality of life and rehabilitation, there is now compelling evidence that PTX is not only acutely life-enhancing, but chronically life-saving [31]. It is hoped that the beneficial changes in carbohydrate and lipid metabolism that occur early after PTX will translate into long-term improvements in diabetic endorgan complications and decrease the risk of atherosclerotic vascular disease. In addition to correcting dysmetabolism and freeing the patient from exogenous insulin therapy, data on the course of secondary complications after PTX are emerging [9,31]. With regard to nephropathy [32], preliminary evidence suggests that successful PTA transplantation can induce regression of early but not advanced microscopic lesions of diabetic nephropathy and stabilize renal function, while successful PAK can prevent the recurrence of diabetic nephropathy in the kidney transplant. The progression of diabetic retinopathy appears to be less favourably influenced by a functioning PTX. However, with longer follow-up (more than 4 years), data are accumulating to suggest that retinopathy may be stabilized. Peripheral and autonomic neuropathies improve or stabilize in most PTX recipients, which may actually translate into a survival advantage. Improvements in nerve conduction velocity, gastric function, cardiac function, and a beneficial effect on microcirculatory blood flow have been demonstrated [9]. These effects Table 6.5 Hypercoagulation work-up If a patient has a history of any of the following conditions, then the hypercoagulation work-up should be ordered Autoimmune disease (Wegener’s, lupus, polyarthritis) Post-thrombosis (deep venous thrombosis; pulmonary embolism, stroke, myocardial infarction, recurrent dialysis access thromboses) Vasculitis Family history of thrombosis History of thrombosis with loss of allograft The hypercoagulation work-up includes the following tests Prothrombin time, partial thromboplastin time, fibrinogen Antithrombin III activity Functional protein C & S levels Lupus anticoagulant studies Factor V Leiden, factor VII, factor VIII, factor IX activity Anticardiolipin antibody assay Antiphospholipid antibody Thrombin time Homocysteine level

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may place patients at a lower overall risk for the development of peripheral ulcers or amputations. There is also evidence that a functioning PTX may ablate the hyperlipidaemic effects of immunosuppression and actually improve lipid metabolism over time. However, long-term studies are needed to document and characterize fully the effects of successful PTX on the diabetic condition. A history of compliance with medication regimens and scheduled follow-up is an important factor in patient selection. Other exclusion criteria that are applicable to all solid organ transplant recipients include the presence of active infection or recent malignancy, active substance abuse or dependence, recent history of non-compliance or psychiatric illness, and positive human immunodeficiency virus or hepatitis B virus serology (Table 6.4) [10,11,15]. Solitary PTX has assumed an increasingly important role in the treatment of IDDM and currently accounts for more than 20 per cent of PTX activity in the United States. In the future, advances in immunosuppressive strategies and diagnostic technology will only enhance the already good results achieved with solitary PTX. Further documentation of the long-term benefits and effects of PTX may lead to wider availability and acceptance, particularly from a reimbursement standpoint. Effective control of rejection with earlier diagnosis or better prevention may soon permit solitary PTX to become an accepted treatment option in diabetic patients without advanced complications. Such a policy, if applied correctly, might actually reduce the number of diabetic patients requiring kidney transplantation in the future. Other strategies for the treatment of IDDM are being actively investigated, including islet cell and fetal pancreas transplants, gene therapy, implantable insulin pumps, and biohybrid artificial pancreas units. Although any or all of these complementary methods may have a role in the treatment of IDDM in the future, it will be difficult for these alternative strategies to improve on the metabolic efficiency of the vascularized PTX that is achieved at present.

Acknowledgements We gratefully acknowledge the expertise of Joyce Lariviere in the preparation of this manuscript.

References 1 Sutherland DER, Gruessner, AC. International Pancreas Transplant Registry Update. IPTR Newsletter 2000;12:1–23. 2 Gruessner AC, Sutherland DER. Analysis of pancreas transplant outcomes for United States cases reported to the United Network for Organ Sharing (UNOS) and non-US cases reported to the International Pancreas Transplant Registry (IPTR). In: Cecka JM, Terasaki PI, ed. Clinical transplants 1999. Los Angeles: UCLA Immunogenetics Center, 2000, 51–69. 3 Robertson RP, Davis C, Larsen J, Stratta R, Sutherland DER. Pancreas and islet transplantation for patients with diabetes. Diabetes Care 2000;23:112–16. 4 Humar A, Kandaswamy R, Ramcharan T, et al. Pancreas after kidney transplants: a viable alternative to simultaneous pancreas–kidney transplants. Ann Surg 2001; (in press). 5 Humar A, Sutherland DER, Ramcharan T, et al. Optimal timing for a pancreas transplant after a successful kidney transplant. Transplantation 2000;70:1247–50. 6 Robertson RP. Pancreatic and islet transplantation for diabetes — cures or curiosities? N Engl J Med 1992;327:1861–8. 7 Stratta RJ. Vascularized pancreas transplantation: the ultimate treatment for insulin dependent diabetes. Br Med J 1996;313:703–4.

R.J. STRATTA

8 The Diabetes Control and Complications Trial (DCCT) Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulindependent diabetes mellitus. N Eng J Med 1993;329:977–86. 9 Stratta RJ. Impact of pancreas transplantation on complications of diabetes. Curr Opin Organ Transpl 1998;3:258–73. 10 Stratta RJ. Pancreas transplantation. In: Soper NA, ed. Problems in general surgery. New York: Lippincott-Williams and Wilkins, 1998;15(3):43–65. 11 Stratta RJ, Taylor RJ, Gill I. Pancreas transplantation: a managed cure approach to diabetes. In: Wells SA ed. Current problems in surgery, St Louis: Mosby, 1996;33(9):711–808. 12 Stratta RJ. Donor age, organ import, and cold ischemia: effects on early outcome after simultaneous kidney–pancreas transplantation. Transplant Proc 1997;29:3291–92. 13 Stratta RJ. Graft failure after solitary pancreas transplantation. Transpl Proc 1998;30(2):289. 14 Troppmann C, Gruessner AC, Benedetti E, et al. Vascular graft thrombosis after pancreatic transplantation: univariate and multivariate operative and nonoperative risk factor analysis. J Am Coll Surg 1996;182:285–316. 15 Stratta RJ, Taylor RJ, Wahl TO, et al. Recipient selection and evaluation for vascularized pancreas transplantation. Transplantation 1993;55:1090–6. 16 Stratta RJ. Solitary pancreas transplantation: the extreme or the ultimate. UNOS Update 1996;12:22–3. 17 Sutherland DER, Gruessner RWG, Dunn DL, et al. Lessons learned from more than 1000 pancreas transplants at a single institution. Ann Surg 2001;233:463–501. 18 Brennan DC, Stratta RJ, Lowell JA, Miller SA, Taylor RJ. Cyclosporine challenge in the decision of combined kidney–pancreas versus solitary pancreas transplantation. Transplantation 1994;57:1606–11. 19 Lane JT, Ratanasuwan T, Mack-Shipman LR, et al. Cyclosporine challenge test revisited: does it predict outcome after solitary pancreas transplantation? Clin Transplant 2001;15:28–31. 20 Stratta RJ, Taylor RJ, Ozaki CF, et al. A comparative analysis of results and morbidity in type 1 diabetics undergoing preemptive versus post-dialysis combined pancreas–kidney transplantation. Transplantation 1993;55:1097–103. 21 Hathaway DK, El-Gebely S, Cardoso S, Elmer DS, Gaber AO. Autonomic cardiac dysfunction in diabetic transplant recipients succumbing to sudden cardiac death. Transplantation 1995;59:634–7. 22 Cashion AK, Hathaway DK, Milstead EJ, Reed L, Gaber AO. Changes in patterns of 24-hour heart rate variability after kidney and kidney–pancreas transplant. Transplantation 1999;68:1846–50. 23 Kamal K, Powell RJ, Sumpio BE. The pathobiology of diabetes mellitus: implications for surgeons. J Am Coll Surg 1996;183:271–89. 24 Sutherland DER, Stratta RJ, Gruessner AC. Pancreas transplant outcome by recipient category: single pancreas versus combined kidney–pancreas. Curr Opin Organ Transpl 1998;3:231–41. 25 Stratta RJ, Weide LG, Sindhi R, et al. Solitary pancreas transplantation: experience with 62 consecutive cases. Diabetes Care 1997;20:362–8. 26 Gruessner RWG, Sutherland DER, Najarian JS, Dunn DL, Gruessner AC. Solitary pancreas transplantation for non-uremic patients with labile insulin-dependent diabetes mellitus. Transplantation 1997;64:1572–7. 27 Bartlett ST, Schweitzer EJ, Johnson LB, et al. Equivalent success of simultaneous pancreas kidney and solitary pancreas transplantation. Ann Surg 1996;224:440–52. 28 Odorico JS. Current status of isolated pancreas transplantation. Graft 1999;2:82–5. 29 Gruessner AC, Sutherland DER, Gruessner RWG. Solitary pancreas transplants: improving results and factors that influence outcome. Transplant Proc 1997;29:664–5. 30 Sutherland DER, Gruessner RWG, Najarian JS, Gruessner AC. Solitary pancreas transplants: a new era. Transplant Proc 1998;30:280–1.

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31 Stratta RJ, Pancreas transplantation: long-term aspects and effect on quality of life. In: Hakim NS, Stratta RJ, Gray DWR, eds. Pancreas and islet transplantation. Oxford: Oxford University Press, 2002; 89–94. 32 Fioretto P, Steffes WM, Sutherland DER, Goetz FC, Mauer M. Reversal of lesions of diabetic nephropathy after pancreas transplantation. N Eng J Med 1998;339:69–75.

Chapter 7

Donor management and selection for pancreas transplantation Eldo Ermenegildo Frezza and Robert J. Corry

Introduction Pancreas transplantation is a well-established treatment for patients with insulin-dependent diabetes. Over the last decade, the procedure has been refined, and immunosuppressive regimens have improved such that, at major centres, 1-year graft survival routinely exceeds 80 per cent [1]. Recent evidence supports the beneficial effect of pancreas transplantation on the maintenance of normoglycaemia, and the arrest and possible reversal of diabetic complications such as vasculopathy, neuropathy, and nephropathy [2–4]. With improved outcome, the number of patients receiving pancreas transplants has risen steadily. Nearly 1000 transplants were performed in the United States in 1996, as compared to approximately 300 in 1988 [1]. Despite this, the waiting time for a pancreas continues to increase as more candidates are accepted for transplantation, particularly after Medicare’s recent recognition of the procedure. Utilization of pancreas grafts varies from 0 to more than 70 per cent among different procurement regions [5]. The shortage of appropriate organs for transplantation is further compounded by the discarding of relatively normal pancreases, or their lack of retrieval. In an effort to expand our pancreas donor pool, we have liberalized the criteria defining a suitable pancreas donor. There has been a reluctance to use organs from haemodynamically unstable or nonheart-beating donors. With demand for organs far exceeding the supply of optimal donors, we have instituted an aggressive policy that does not exclude organs based on donor age or haemodynamic status. Indeed, had we excluded pancreas from unstable donors or donors over 45 years of age, the number of patients receiving a transplant at our institution would have been halved. With routine surveillance using percutaneous needle biopsy of the transplanted pancreas, some centres are now reporting equivalent survival results among recipients of simultaneous pancreas and kidney (SPK) transplantation and pancreas transplant after kidney (PAK) [6]. We have shown that the use of marginal donor [7] has not adversely affected overall pancreas graft survival at our institution. In fact, it has allowed us to expand our donor pool and virtually double the number of pancreas transplants performed. The most important determinant of pancreas suitability is inspection of the organ by an experienced pancreas transplant surgeon. We avoid transplanting organs with calcifications, extensive fibrosis, or fatty infiltration. Also of importance is determination of the adequacy of the back-table flush, as judged by the quality of the effluent draining from the portal vein. Brisk drainage of solution installed under the force of gravity, free of blood (this sometimes requires placement of a clamp across the splenic hilum), with no evidence of blood within the organ are signs of a good flush. Although these criteria are somewhat subjective, they are superior to rejecting organs, sight unseen, based only on demographics and laboratory values. Therefore, we do

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not restrict use of pancreatic grafts simply based on donor age or haemodynamic status. Adoption of these strategies may allow for a reduction in the number of organs discarded and expand the availability of pancreas grafts for transplantation.

Donor selection All donors without a history of diabetes should be considered eligible. Donor hyperglycaemia or hyperamylasaemia are not considered contraindications. Selection of pancreas donor grafts for transplantation is based principally on: (a) careful inspection of pancreatic parenchyma for evidence of fibrosis and extent of fatty infiltration; (b) examination of the donor vessels for presence and severity of atherosclerotic plaque; and (c) the quality of the back-table venous efflux of chilled flush solution. An immediate return of chilled solution flushed into the organ by force of gravity is considered adequate. Organs with extensive fatty infiltration, calcifications, or fibrosis are not harvested. Pancreas with major traumatic injuries are rejected, although minor injuries, such as capsular tears, are not considered contraindications. Table 7.1 outlines the donor risk factors analysed including donor age, sex, cause of death (gunshot wound, closed head injury, cerebrovascular accident, anoxia, or other miscellaneous causes), vasopressor requirement at the time of harvest, amylase, lipase, and glucose. Table 7.1 and 7.2 summarize the donor and recipient factors that, in our experience, must be considered in assessing the outcome of pancreas transplantation.

Table 7.1 Donor factors analysed to assess pancreas transplant outcome in Pittsburgh experience Risk factor* Age (mean: 29, range: 6–62 years) ≤ 45 years > 45 years Sex male female not recorded Cause of death gunshot wound closed head injury cerebrovascular accident anoxia other not reported Vasopressors None or low dose High dose Laboratory values amylase (mean 136, range 6–1411) lipase (mean 116, range 9–1373) glucose (mean 285, range 100–648) * Including

three non-heart-beating donors.

Frequency (%) 83.9 16.1 46.0 48.2 5.8 24.8 17.5 40.9 8.0 2.9 5.8 62.8 37.2

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Table 7.2 Recipient factors analysed to assess pancreas transplant outcome Risk factor

Frequency (%)

Age (mean: 40, range: 27–58 years) Sex Male Female

46.7 53.3

Operation

SPK PAK PTA

85.4 8.8 5.8

Drainage

Bladder Enteric

21.2 78.8

Complications

Thrombosis Donor-related Donor-unrelated (n = 14) or none (n = 86)

9.5 17.5 73.0

Cold ischaemia time, hr (mean: 17.4, range: 7–31) Laboratory values (48 h peak) Amylase (IU/dl) (mean: 480, range: ≤ 2000 > 400 Lipase (IU/dl) (mean: 2804, range: 79–24,445) ≤ 2000 > 2000 Glucose (mg/dl) (mean: 220, range: 58–826) < 300 > 300

46–2039) 56.9 42.3 58.4 40.9 78.1 21.9

Marginal donors Pancreas donors are considered marginal if they were retrieved from donors over 45 years of age or from donors haemodynamically unstable at the time of harvest. Donors were considered to be haemodynamically unstable if they required high-dose dopamine (> 10 µ/kg/min) or at least two vasopressors at the time of harvest. By these criteria more than 69 per cent of patients with grafts from marginal donors were transplanted in our experience [7]. The oldest graft transplanted was from a 62-year-old donor. Haemodynamically unstable donors represented 32 per cent of the grafts. Only in 4 per cent of case was a pancreas utilized from a donor who was both over age 45 and on highdose vasopressors.

Assessment of the pancreas allograft The ultimate decision depends on the judgement of the transplant surgeon, who is in the best position to assess the suitability of the pancreas based on the recipient’s clinical condition and the complete donor profile provided by the field co-ordinator. Indeed, in many instances the teams can only assess the suitability of the organ by direct visualization or intraoperative biopsy at the time of procurement. The pancreas is inspected for colour and consistency and presence or absence of masses, nodularity, or trauma. On palpation, the normal pancreas is soft and smooth, with no hard nodules and little or no fat. Pale appearance suggests ischaemia, whereas a yellowish colour may reflect other underlying microvesicular or macrovesicular steatosis (fatty infiltration). Fatty infiltration is often a consequence

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of donor obesity, or alcoholism. A large percentage of macrosteatosis is associated with poor graft function. Fatty pancreas should therefore be carefully examined by an experienced surgeon at the time of harvesting to determine the extent and distribution of fat.

The cadaveric donor Cadaveric organ donation begins with the determination of brain death in a given patient and the identification of such an individual as a potential donor. The success of organ recovery depends on a team effort among health-care professionals and personnel from the local organ procurement organization (OPO). The demand for organ transplantation in the United States increased by 16 per cent per year [8]. Unfortunately, the number of organs donated annually has not changed much. Following the enactment of the Organ Transplant Act in 1984, the creation of a single national organization with regional offices, the United Network for Organ Sharing (UNOS), assumed the responsibility for obtaining and distributing donor organs to transplant centres. Several retrospective studies analysed the organ donation patterns in different states, being the reason that each state has a different pattern of urban and rural areas. For this reason, it is not always feasible to compare the result of a Kentucky study [9] with a study performed in Pennsylvania [10] or New Jersey [11]. In fact, the first has more non-urban population than the other two states. Moreover, there are factors that are characteristic for a rural or an urban population in a given region or state. There is a continued need for public education and an examination of the factors that contribute to an insufficient number of donors. These factors range from general distrust of the health-care system to religious myths and misperceptions regarding consent to donation. Such fears are especially common among some minority groups. One study identified three possible causes of the loss of a potential donor: (a) failure to identify a potential donor; (b) failure to ask the family to donate; and (c) family refusal to donate [12]. Investigators in New Jersey attempted to ascertain the reason for a recent increase in organ donations. Several factors seemed to correlate with an increase in the rate of conversion from a potential donor to an active donor. These were: (a) a better application of the paediatric donation New Jersey Bill [13]; (b) the acceptance of brain dead abused children; (c) a door-to-door campaign performed by UNOS in the years 1992 and 1993; and (d) an increase in donation in the Afro-American, Hispanic, and Asian, groups that historically did not donate as much [11]. Interestingly enough, the non-urban hospital area had a better donation than the large urban areas, particularly if there was a level 2 trauma centres. Surprisingly, the presence of a transplant centre in the same areas, did not significantly increase the rate of donation [11]. In general, the diagnosis of brain death precedes any consideration for organ donation. This determination is made independently of the transplantation team. The criteria for brain death are listed in Table 7.3.

Table 7.3 Criteria for establishing brain death [16] The presence of deep coma without induced hypothermia or the use of depressant drugs No spontaneous respiratory motion in the absence of muscle relaxants No spontaneous movements in the absence of decerebration and decorticate posturing No response to deep painful stimuli Absent cranial reflexes, i.e. fixed and dilated pupils, no corneal reflexes, no oculocephalic reflex (doll’s eyes)

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Table 7.4 Contraindications to cadaveric donation [16] Absolute Chronic renal disease Malignant tumour (except primary brain tumours) Positive HbsAg test Positive HIV test Untreated systemic bacterial, fungal, or viral infections Prolonged cold ischaemia

Relative Hypertension Diabetes Bacterial sepsis (treated) Anti-HCV positive Age > 70 years Age < 2 months Prolonged warm ischaemia

ATN, acute tubular necrosis; HbsAg, hepatitis B surface antigen; HCV, hepatitis C virus; HIV, human immunodeficiency virus.

Once a person with irreversible brain injury has been referred, determining the potential donor’s suitability is best co-ordinated by the OPO in consultation with the transplant surgeons. When relative contraindications exist, the donor is sometimes described as marginal (Table 7.4). For example, some centres prefer not to use organs from very young donors because of a higher risk of technical complications and reports of decreased graft survival. However, such organs can be successfully transplanted into selected recipients [for example, first transplant, low body weight, low panel reactive antibody (PRA) level], and should not be routinely excluded from the donor pool. Several centres have reported good results with paediatric kidneys in adult recipients [14,15]. Similarly, organs from donor older than 60 or even 70 years can often be used; however, older donors may have other medical problems (for example, hypertension, cardiac disease) that may make their organs less suitable [16]. The use of organs from hepatitis C virus (HCV) antibody-positive donors has been controversial. A consensus seems to have been reached to transplant these organs into HCV-positive recipients (with appropriate informed consent) in view of the lack of associated morbidity [17–19]. In situations in which a patient has profound, irreversible, neurological injury and strict criteria for brain death cannot be strictly met, some donors can serve as non-heart-beating donors. In these situations, consent is obtained, and the patient is extubated in the operating room; once the heart has ceased beating, the organs are rapidly removed. There are other circumstances in which organs can be recovered from non-heart-beating donors when sudden circulatory arrest takes place in an uncontrolled situation [20,21].

Management of the donor Once brain death has been declared in a potential organ donor candidate, maintenance of organ perfusion becomes the paramount issue in management. Haemodynamic stability and cardiac function must be maintained, as well as physiological electrolyte balance and pH, adequate urine output, glucose level, adequate arterial oxygenation, temperature regulation, and control of infection. Once consent for donation has been obtained from the patient’s family, the organ procurement field co-ordinator undertakes a careful work-up of the candidate. A careful history is obtained with special focus on previous medical history, social behaviour, and other risk factors for transmissible disease. Knowledge of the mechanism of brain death and duration of cardiopulmonary arrest prior to resuscitation is crucial. The pancreas is not among the organs most commonly injured in trauma. Therefore,

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sometimes traumatic injuries are not discovered in time. We suggest, based on this, that the knowledge of peritoneal lavage and or abdominal CT results is important in the work-up of the traumatically injured donor. It is important to know the presence of any pancreatitis in the past or recent history of alcohol use. Minimum laboratory evaluation must include ABO blood type, glucose level, amylase, lipase, liver function tests, electrolytes, complete blood cell count, prothrombin time, partial thromboplastin time, viral serologies for hepatitis, cytomegalovirus, and HIV. Additional laboratory screening is directed by the donor’s medical and social history. Complete cultures should be performed on tissues from donors who have been admitted to hospital for prolonged periods or who have known foci of infection. The above information, together with a summary of haemodynamics and donor vital statistics (age, height, and weight), is used to generate a donor profile to assess suitability of the patient for organ donation. As experience with ‘marginal’ donors has increased [7], it has become apparent that donors should not be summarily rejected on the basis of age, laboratory, or haemodynamic thresholds. The use of the super-rapid in situ cold flush technique has allowed successful use of both livers and kidneys in situations in which cardiac arrest has occurred and there is the capability for immediate retrieval of the organs, but not yet the pancreas. Aggressive intravenous crystalloid infusion is necessary to keep urine output greater than 1 ml/kg/h. Excessive urine losses due to diabetes insipidus may warrant the use of vasopressin, although it may sometimes be desirable instead to replace the high urinary output intravenously. Severe hypernatraemia and hypokalaemia, which can occur in donors with diabetes insipidus, may be avoided by frequent electrolyte monitoring. Persistent untreated hypokalaemia may result in ventricular tachycardia and cardiac arrest. In addition, it is necessary to avoid infections in potential donors [22]. The rapid infusion of large volumes of cold fluids, such as crystalloid solutions, blood, or blood products, can aggravate pre-existing hypothermia and create pancreatic oedema, which is considered a relative contraindication for harvesting. All efforts must be directed at maintaining haemodynamic stability by continuous replacement of blood loss and urine output with crystalloid. Use of adrenergic agonists should be avoided if possible, to minimize peripheral vasoconstriction and reduced renal and hepatic perfusion. Muscle relaxants are usually required to optimize surgical exposure, because spinal reflexes sometimes prevent abdominal relaxation. Full intravenous heparinization (300 U/kg) is performed before cross clamping of the aorta. The need for an anaesthesiologist continues until the time of aortic cross-clamping and in situ hypothermic perfusion [16]. With the development of multiple organ recovery techniques the time to procure each solid organ should be minimized to decrease any unnecessary ischaemic injury. We suggest retrieval of liver and pancreas en bloc to expedite the harvest and avoid the possibility of instability in the donor. The in situ division of the pancreas could create long operating time and is not superior to a well-flushed pancreas divided on the back-table. Brain-dead cadavers are often hyperglycaemic owing to the administration of steroids and intravenous infusion of large amounts of dextrose-containing solutions. Such donors also often exhibit a resistance to insulin and require high doses to restore normoglycaemia. Nevertheless, grafts taken from hyperglycaemic cadaver donors have functioned perfectly in recipients. Hyperamylasaemia is also often present in brain-dead cadavers and is usually not associated with any apparent pancreatic injury. Hyperamylasaemia is a known consequence of isolated brain trauma. Normal function in the recipient without the occurrence of pancreatitis in grafts taken from hyperamylasaemic donors has been documented. Thus the only contraindication to the use of a brain-dead

E. ERMENEGILDO FREZZA AND R.J. CORRY

cadaver as a pancreas donor is a history of diabetes, intra-abdominal trauma with bacterial contamination, direct injury to the pancreas, or abnormalities of the pancreas on gross inspection. Whole or segmental pancreas grafts can be obtained from virtually every cadaver donor, regardless of what other organs are also procured. One should never forgo obtaining a liver from a donor simply to use the pancreas; removal of both organs from the same donor is technically feasible [16].

Complications related to mismanagement of the donor It is very important to be careful during the preparation of the donor and the harvesting of the pancreas. Two common complications that may be related to mismanagement of the donor are graft thrombosis and pancreatitis. Thrombosis and subsequent ischaemic necrosis of the graft are complications that have contributed to graft failure in a number of patients. The high incidence of this problem has been explained by the fact that the pancreas is a so-called ‘low-flow’ organ. Haemodynamic instability prior to the harvesting can be detrimental to the pancreas. Removal of the spleen in combination with postclamping oedema, which, to a varying degree, always follows ex vivo organ preservation, may be sufficient to facilitate the occurrence of thrombosis. Therefore the most important preventive factors are: (a) continued monitoring of the potential donor, with control of any hypotensive episode; and (b) meticulous surgical technique. Graft thrombosis usually presents in the initial 12 to 24 h after transplantation and is signalled by a sudden elevation in the serum glucose level or by failure of the glucose level to fall towards normal. The diagnosis can be confirmed by a radionuclide perfusion scan to delineate flow to the pancreas. If the diagnosis is confirmed, the graft must be removed expeditiously to prevent septic or vascular complications. Pancreatitis may occur early as well as late after pancreatic transplantation. Early postoperative pancreatitis is usually a consequence of: (a) haemodynamic instability prior to the harvesting; and (b) injury to the pancreas during procurement and preservation. After transplantation, there is inevitably a rise in the serum amylase level, which usually peaks after 24 to 48 h. Hyperamylasaemia usually is not associated with abdominal pain and clinical signs of pancreatitis. Treatment of pancreatitis in this setting is the same as for any other form of acute pancreatitis. Pancreatitis in the early post-transplantation period is usually self-limited. Should pancreatitis progress, however, thrombosis may ensue, necessitating removal of the graft, since the inflamed pancreas may become the focus of a septic process, resulting in pancreatic abscess, anastomotic failure, peripancreatic abscess, peritonitis, and pancreatic fistula.

Related pancreas donor The same rationale for use of related donor for kidney transplants also applies to use of related donors for segmental pancreas transplants (Table 7.5). A portion of the body and tail of the pancreas can be removed from a living donor, based on a vascular pedicle of the splenic vessels. The spleen of the donor can survive on collateral circulation, and the remainder of the body, the head, and the uncinate process of the pancreas is sufficient to maintain normoglycaemia in the donor. Criteria that prospective living-related donors must meet before being evaluated are listed in Table 7.5. Prospective donors undergo oral and intravenous glucose tolerance tests. All glucose values during standard oral glucose tolerance tests (OGTT) must be within an arbitrarily defined normal range (fasting < 105 mg/dl, 60-min value 185 mg/dl, 90-min value: 160 mg/dl, and 120-min value: 140 mg/dl) [22,23].

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Table 7.5 Criteria for selection of living related pancreas donors [22] Pre-evaluation Recipient and donor discordant for diabetes for at least 10 years Donor at least 10 years older than age of onset of diabetes in recipient In cases of sibling donation, no family members other than the proband are diabetic Post evaluation Normal oral glucose tolerance test (OGTT)result by criteria of Fajans and Conn and of the Natural Diabetes Data Study Group Delta insulin > 90 IU/ml for sum of 0-, 60-, 120- and 180-min values during cortisonestimulated OGTT minus sum during standard OGTT according to technique of Fajans and Conn No islet cell antibodies Other metabolic parameters normal

Conclusions Simultaneous pancreas–kidney transplantation is now considered an excellent therapeutic option for patients with renal failure secondary to type I diabetes mellitus. Since the first pancreas transplant was performed in 1966 by Kelly and Lillehei, the surgical technique, immunosuppressive therapy, and antibiotic have continually evolved. Patient and graft survival rates after pancreas transplantation (PTX) have approached those of other solid organ transplants. According to the last Pancreas Registry, patient and graft survival rates [24] at 1 year for patient, kidney, and pancreas were 94, 90, and 83 per cent respectively for SPK; 95 and 71 per cent for pancreas transplant alone, and 95 and 71 per cent for PAK transplant. Enteric drainage is becoming more common, increasing from 2 per cent of cases in 1988 to 12 per cent in 1995, to 33 per cent of cases in 1998 [24,25]. The high incidence of morbidity after PTX is possibly related to multiple factors: underlying diabetes mellitus and uraemia (in SKP recipients), heavy immunosuppression (because the pancreas appears to be a highly immunogenic organ), low blood flow based on no collateral circulation, unique complications related to exocrine secretions, and the transplantation procedure involving two hollow viscera (donor duodenum and recipient urinary bladder or small bowel) [26]. Judicious management of the donor could therefore play an important role in the success of the transplant and prevention of early postoperative complications.

References 1 Gruessner A, Sutherland DER. Pancreas transplantation in the United States (US) and in non US as reported to the United Network for Organ Sharing (UNOS) and the international pancreas transplant registry. In: Terasaki PI, Cecka JM, ed. Clinical transplant 1994. Los Angeles: UCLA Tissue Typing Laboratory, 1996;47–9. 2 Gfesser M, Nusser J, Muller-Felber W, Abendroth D, Land W, Landgraf R. Cross-sectional study of peripheral microcirculation in diabetic patients with microangiopathy: Influence of pancreatic and kidney transplantation. Acta Diabetol 1993;30:79. 3 Muller-Felber W, Landgraf R, Scheuer R. et al. Diabetic neuropathy 3 years after successful pancreas and kidney transplantation. Diabetes 1993;42:1482. 4 Wilczek HE, Jaremko G, Tyden G, Groth CG. Evolution of diabetic nephropathy in kidney grafts. Transplantation 1995;59:51.

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5 Stratta RJ, Bennett L. Pancreas underutilization in the United States: analysis of United Network for Organ Sharing data. Transplant Proc 1997;29:3309. 6 Bartlett ST, Schweitzer EJ, Johnson LB, et al. Equivalent success of simultaneous pancreas kidney and solitary pancreas transplantation. Ann Surg 1996;224:440. 7 Kapur S, Bonham CA, Dodson FS, Dvorchik I, Corry RJ. Strategies to expand the donor pool for pancreas transplantation. Transplantation 1999;67:284–90. 8 Davidson MN, Devney P. Attitudinal barriers to organ donation among black Americans. Transplant Proc 1991;23:2531–2. 9 Garrison RN, Bentley FR, Rauqe GH, et al. There is an answer to the shortage of organ donors. Surg Gynecol Obstet 1991;173:391–6. 10 Nathan HM, Jarrell BE, Broznik B, et al. Estimation and characterization of the potential renal organ donor pool in Pennsylvania. Transplantation 1991;51:142–9. 11 Frezza EE, Krefski LRN, Valenziano CP. Factors influencing the potential organ donation: a 6-yr experience of the New Jersey Organ and Tissue Sharing Network. Clin Transplant 1999;13:231–40. 12 Gortmaker SL., Beasley CL, Brigham LE, et al. Organ donor potential and performance Size and nature of the organ donor shortfall. Crit Care Med 1996;24:432–9. 13 New Jersey Bill 1-1277; supplementing P.L. 1967, c. 234. 14 Ratner LE, Flye MW. Successful transplantation of cadaveric en-bloc paired kidneys into adult recipients. Transplantation 1991;51:273. 15 Darris F, Jordan ML, et al. Transplantation of pediatric en-bloc kidneys under FK506 immunosuppression. Transplant Proc 1991;23:3089. 16 Scantlebury VP. Cadaveric and living donation. In: Renal transplantation, Shapiro R, Simmons RL, Starzl TE, ed. Appleton & Lange, 1997. 17 Brunson ME, Lau JY, et al. Non-A, non-B hepatitis and elevated serum aminotransferases in renal transplant patients. Transplantation 1993;56:1364. 18 Stempel GA, Lake J, et al. Hepatitis C: its prevalence in end-stage renal failure patients and clinical course after transplantation. Transplantation 1993;55:273–6. 19 Morales JM, Campistol JM, et al. Transplantation of kidneys from donors with hepatitis C antibody into recipients with pre-transplantation anti-HCV. Kidney Int 1995;47:236–40. 20 Anaise D, Smith R, Ishiman M, et al. An approach to organ salvage from non heart beating cadaver donors under existing legal and ethical requirements for transplantation. Transplantation 1990;49:290–4. 21 Matsuno M, Kozaki M, Sakurai E, et al. Effect of combination in situ cooling and mechanic perfusion preservation on non-heart-beating donor kidney procurement. Transplant Proc 1993;25:1516–17. 22 Sutherland DE, Moudry KC, Najarian JS. Pancreas transplantation. In: Organ transplantation and replacement, Cerilli GJ, ed. Lippincott, 1988. 23 Humar A, Gruessner RW, Sutherland DE. Living related donor pancreas and pancreas-kidney transplantation. Br Med Bull 1997;53:879–91. 24 Gruessner AC, Sutherland DE. Analysis of pancreas transplants for United States (US) and non-US pancreas transplants as reported to the International Pancreas-Transplant Registry (IPTR) and to the United Network for Organ Sharing (UNOS). In: Cecka JM, Terasaki PI, ed. Clinical transplants 1998. Los Angeles: UCLA Tissue Typing Laboratory, 1999:53–71. 25 Sutherland DE, Gruessner A. Pancreas transplant results in the UNOS United States of America Registry compared with non-USA data in the international registry. In Terasaki P, Cecka M, ed. Clinical transplants 1995 Los Angeles: UCLA Tissue Typing Laboratory;1994:47. 26 Reddy KS, Stratta RJ, Shokouh Amiri MH, Alloway R, Egidi MF, et al. Surgical complications after pancreas transplantation with portal-enteric drainage. J Am Coll Surg 1999;189:305–13.

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Chapter 8

Procurement and benchwork preparation of the pancreatic graft Nadey S. Hakim and Vassilios E. Papalois

Donor selection The selection criteria for pancreas donors are similar to those for other solid organs [1,2]. Ideally, donor age ranges between 18 and 45 years and donor weight between 40 to 100 kg. A history of diabetes mellitus, acute necrotizing pancreatitis, and chronic pancreatitis are obvious contraindications. Despite a reported history of pancreatitis, it is always worthwhile examining the pancreas at the time of procurement to assess the suitability of the organ. It should be remembered that after brain death the serum amylase levels are often high in the absence of pancreatitis, and hyperglycaemia may occur in the absence of diabetes. The direct inspection of the pancreas is therefore justified before deciding whether or not to procure.

Multiorgan procurement of the pancreas, liver and kidneys This chapter describes the technique we are using in our institution, which, in contrast to the classical technique [3], requires that most of the dissection for donor pancreatectomy is done after crossclamping and intravascular flushing of the abdominal organs [4,5]. We believe that this technique is faster and minimizes handling of the pancreas and blood loss. This is of great importance since it has been demonstrated that pancreatic manipulation and donor instability are factors associated with post-transplant primary non-function [6] and graft pancreatitis [7]. The cadaver-donor pancreatectomy is usually part of a standard multi organ retrieval. The procurement starts with the dissection of the vascular anatomy shared by the pancreas and the liver. Arterial anomalies in the blood supply of the liver are not uncommon and may influence the decision whether or not to procure the pancreas. Generally, in such situations, priority is given to the liver because it is a live-saving procedure. The hepatic artery is isolated and dissected. It is traced down to its origin at the coeliac axis. During the dissection, the gastroduodenal artery, right gastric artery, and coronary vein are identified, ligated, and divided. After the coeliac axis is identified, the splenic artery is isolated and looped. The left gastric artery is ligated and divided. The coeliac axis is followed down to its origin. The dissection of the hepatoduodenal ligament is completed by isolating the portal vein. The origin of the superior mesenteric artery is isolated, dissected, and looped just above the left renal vein. At this point, a nasogastric tube is advanced into the duodenum. Then 400 ml of antibiotic solution (containing 750 mg cefuroxime, 50 mg amphotericin B, and 500 mg amikacin) are injected and the tube is withdrawn back into the stomach. Contrary to other pancreatic procurement techniques, this is all that is required before intravascular flushing, as the complete dissection of the pancreas takes place after cross-clamping. Heparin

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(70 U/kg) is given intravenously. To prepare for intravascular flushing of the abdominal organs with University of Wisconsin (UW) preservation solution, the aorta is ligated just above its bifurcation and a perfusion cannula inserted into the aorta. The cannula tip is placed between the take-offs of the ligated inferior mesenteric artery and renal arteries. Another infusion cannula is inserted into the inferior mesenteric vein for portal perfusion of the liver. A Kocher manoeuvre is performed to expose the posterior surface of the head of the pancreas as well as the underlying aorta and inferior vena cava. In co-ordination with the thoracic procurement team, the supracoeliac aorta is cross-clamped and both arterial and portal flush begun, the suprahepatic vena cava is divided supradiaphragmatically, and venous return is vented into the chest. Two litres of UW solution are perfused through the aorta and 1 litre through the portal vein. After 1 litre is delivered through the aorta, it is advisable to tighten the vessel loop around the splenic artery to prevent overflushing of the pancreas, which can lead to post-transplant pancreatitis. After flushing is complete, the pancreas and the liver are usually separated in situ. The coeliac axis remains with the liver. The splenic artery is divided just distal to its take-off from the coeliac axis. The liver is removed first, the aorta at the level of the coeliac axis, and the superior mesenteric artery is incised laterally on the left side, so that injury to the renal arteries is avoided. The Carrel aortic patch is divided between the coeliac axis and the superior mesenteric artery. The inferior vena cava is divided proximal to the entrance of the renal veins. The portal vein is divided halfway between the pancreas and the hepatic hilum, with sufficient lengths left for both liver and pancreas. The dissection of the pancreas is done trying to avoid excessive manipulation of the pancreatic parenchyma. The gastrocolic ligament divided from the pylorus to the gastrosplenic ligament, to expose the anterior surface of the pancreas through the lesser sac. The transverse colon is mobilized completely from the hepatic and splenic flexures, which allows good exposure and dissection of the pancreas from the adjacent retroperitoneal structures. All short gastric vessels are divided, separating the stomach from the spleen. The retroperitoneal attachments of the spleen as well as the splenocolic ligament are freed, resulting in complete splenic mobilization. The spleen is used as a handle to avoid injuring the pancreas. The posterior attachments of the pancreas are taken down, with the pancreas separated from the left kidney and the left adrenal gland. Retroperitoneal pancreatic dissection is performed to the level of the aorta. Here coeliac ganglions and lymphatics are divided, exposing the superior mesenteric artery and more distally the left renal vein. The GIA 60 (Gastro-Intestinal Anastomosis 60) stapler is used to divide the duodenum just distal to the pylorus. A second pass of the GIA stapler divides the fourth portion of the duodenum proximal to the ligament of the Treitz. The take-offs of the renal arteries, as well as their relationship to the superior mesenteric artery, are identified. There is no need for an aortic cuff to remain with the superior mesenteric artery. Finally at the level of the ligament of Treitz, the mesenteric root distal to the uncinate process of the pancreas is divided with the TA 90 stapler. The pancreas is removed and inspected on the back-table. The splenic artery can be marked with a 6–0 Prolene suture, making it easy to identify should it retract on the pancreatic tissue. The distal duodenal stump is opened by cutting the staple line. The duodenum is emptied of the residual bile or duodenal contents and restapled with a GIA 60. The entire common iliac artery and its bifurcation is procured en bloc and packaged with the pancreas. The pancreas is preserved in UW solution, kept cold in a box-container, and transported to the recipient hospital.

Vascular variations in combined pancreas/liver procurement If an aberrant right hepatic artery, or even the common hepatic artery, arises from the superior mesenteric, the pancreas can still be procured with the liver. The aberrant artery usually is the first

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branch off the superior mesenteric artery, whereas the origin of the inferior pancreaticoduodenal artery is more distal. In this case, the superior mesenteric artery is divided just distal to the aberrant right hepatic artery, the aberrant branch and its aortic cuff including the take-off of the coeliac axis and the superior mesenteric artery, remain with the liver. If the distal superior mesenteric artery, including the inferior pancreaticoduodenal artery, is preserved, an iliac Y draft can be used for arterial reconstruction of both the distal superior mesenteric artery and the splenic artery. It is necessary to preserve the inferior pancreaticoduodenal artery to provide sufficient blood supply to the head of the pancreas and the duodenum, because the gastroduodenal artery with its main branch, the superior pancreaticoduodenal artery, is usually ligated in combined pancreas/liver procurement. If the inferior pancreaticoduodenal artery is less than 3 mm in diameter and its origin is proximal to the aberrant right hepatic artery, and the liver team needs the proximal superior mesenteric artery, the pancreas procurement should be abandoned. However, if the inferior pancreaticoduodenal artery diameter is more than 3 mm, successful arterial reconstruction using a Y graft may be feasible.

Pancreas without liver procurement If the liver is not procured, dissection of the hepatoduodenal ligament is performed close to the hepatic hilum. The hepatic artery is ligated distal to the origin of the gastroduodenal artery. This provides additional blood supply to the head of the pancreas and the duodenum via the superior pancreaticoduodenal artery. The portal vein is divided proximal to its bifurcation, giving additional length. The aortic cuff encompassing the take-offs of the coeliac axis and the superior mesenteric artery is left intact and remains with the pancreas.

Benchwork preparation of the pancreas for transplantation We describe our own technique of pancreas preparation. The pancreas benchwork preparation begins by removing the spleen. The splenic hilar vessels are stapled with Ethicon vascular staplers. After the spleen is removed, attention is turned to the donor duodenum. The proximal duodenal staple line is over-run with 4–0 Prolene running suture and inverted using a 4–0 Prolene in a Lambert fashion to bury the suture line. Excess distal duodenum is excised by carefully ligating small vessels up to the level of the uncinate process. The mesenteric root which was divided with a TA 90 stapler, is reinforced with a vascular stapler. Any peripancreatic lymphatic tissue or small vessels that have not been ligated previously are identified, ligated or stapled. Unless the coeliac axis and the superior mesenteric artery are procured on a common aortic cuff, the vascular reconstruction has to be done. The splenic artery and the superior mesenteric artery are identified and prepared for reconstruction by removing surrounding lymphatic ganglionic tissue. The most common technique uses an arterial extension iliac Y graft of donor, common, external, and internal iliac artery obtained at the time of procurement (Fig. 8.1). The internal iliac artery of the extension graft is anastomosed end-to-end to the splenic artery of the pancreatic graft with running 7–0 Prolene sutures. The external iliac artery of the extension graft is anastomosed end-to-end to the superior mesenteric artery of the pancreatic graft with running 7–0 Prolene sutures. If a donor graft cannot be used and the superior mesenteric artery has an aortic patch an is of good size, an interposition graft can be used for reconstruction. Depending on the size of the splenic artery, either the donor external or internal iliac artery is anastomosed end-to-end to the splenic artery with running sutures. An arteriotomy is made on the anterior surface of the superior mesenteric artery and an end-to-side anastomosis created between the proximal end of the iliac artery and the superior mesenteric artery with 7–0 Prolene sutures. If the splenic artery is of sufficient length and can be mobilized all the way to

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(a)

(b)

(c)

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(d)

(e)

Fig. 8.1 Bench work.preparation for pancreas transplantation. (A) Placement of four 7–0 prolene stay suture to the superior mesenteric artery of the pancreatic graft prior to its anastomosis with the external iliac artery of the Y graft. (B) anastomosis of the superior mesenteric artery to the external iliac artery with running 7–0 Prolene suture. (C) The Y graft after the completion of the anastomosis of its two limbs to the superior mesenteric and splenic arteries of the pancreatic graft. (D) The portal vein of the pancreatic graft. (E) The pancreatic graft after the completion of the bench work preparation, ready for revascularization.

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the superior mesenteric artery without tension, a direct end-to-side anastomosis can be made between the splenic artery and the superior mesenteric artery. The bench work procedure takes in our hand on average 45 minutes with excellent results and minimal bleeding on revascularization. We believe that the meticulous procurement and benchwork preparation techniques that we described are vital as the transplant procedure can be carried out with minimal difficulties and no complications.

References 1 Papalois VE, Hakim NS. Pancreas transplantation. In: Hakim NS, ed. Introduction to organ transplantation. London: Imperial College Press, 1997:189–200. 2 Papalois VE, Hakim NS. Pancreatic transplantation. Surgery (British) 1998;16:44–8. 3 Sutherland DER, Ascher NL. Whole pancreas donation from a cadaver. In: Simmons RL, Finch ME, Ascher NL, Najarian JS, ed. Manual of vascular access, organ donation and transplantation. New York; Springer-Verlag, 1984:144–52. 4 Papalois VE, Hakim NS. Successful procurement of 50 pancreatic grafts using a simple and fast technique. Int Surg 1998;83:327–9. 5 Papalois VE, Hakim NS. Pancreas and islet transplantation. In: Hakim NS, Danovitch GM Transplantation surgery. London: Springer-Verlag, 2002:211–33. 6 Tropmann C, Gruessner A, Benedetti E, Papalois BE, Matas A, Sutherland DER et al. Delayed endocrine pancreas graft function after simultaneous pancreas–kidney transplantation: incidence, risk factors and impact on long-term outcome. Transplantation 1996;61:1323–30. 7 Benedetti E, Coady N, Asolati M, Dunn T, Stormoen B, Bartholomew A, et al. A prospective randomised clinical trial of perioperative treatment with octreotide in pancreas transplantation. Am J Surg 1998;175:14–17.

Chapter 9

Pancreas preservation H.U. Spiegel and D. Palmes

General section Introduction The evolution of organ transplantation into a clinical reality is due mainly to the development of surgical technique, the introduction of immunosuppressant drugs with better selectivity and fewer sideeffects, and the devising of more effective means of organ preservation and protection. The immense success of organ transplantation has broadened its indications to include conditions which do not threaten life, but where the gain in quality of life outweights the risks of lifelong immunosuppression, for example, pancreas transplants in patients with insulin-dependent type I diabetes mellitus (IDDM) who are not adequately controlled even by carefully adjusted insulin therapy [1–5]. The steadily rising demand for donor organs can no longer be met by the numbers of potential organ donors. New strategies will therefore have to be devised for procuring better supplies of donor organs, for example, enlargement of the donor pool by recruitment of living donors and of ‘marginal’ donors with minor impairment of organ function; adequate utilization of available donor organs must be also ensured. Organ preservation is of crucial importance for two reasons: first, because it provides the time necessary for the complex interdisciplinary co-operation; and secondly, because it enables surgeons to utilize ‘marginal’ donor organs, thereby enlarging the potential donor pool. This section presents an overview of the goals and strategies of organ preservation. The physiological and pathophysiological events occurring during preservation and the demands made on the techniques and solutions will first be outlined in general terms and their clinical relevance to pancreas preservation will then be discussed.

Goals of organ preservation The preservation of organs has two purposes. First, it must ensure the viability of the organs and rapid recovery of their functional capacity. The disorders of function arising after organ transplantation can be divided into three categories. Irreversible loss of function after transplantation is described as ‘primary non-function’ (PNF), whereas irreversible but limited impairment of function is termed ‘primary dysfunction’ (PDF) (Fig. 9.1). If the organs springs into life only after a period of latency, the term ‘delayed graft function’ (DGE) is applied. The second goal is to provide an adequate time for testing donor-recipient compatibility and for the necessary logistical preparations. A distinction is made between short-term organ preservation for up to 24 h, which is adequate for transplantation under emergency conditions. Intermediate-term organ preservation allows this period to be extended for up to 96 h, enabling the transplantation to be performed under elective conditions. Although there have been experimental studies of the successful preservation of kidney, pancreas, heart, and liver over intermediate times, in everyday clinical practice

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Fig. 9.1 Primary non function: causes and aetiology.

intermediate-time preservation has been confined to renal transplants, because of the fear of the dysfunctions mentioned above. Long-term preservation by the freezing of organs aims at an entirely different goal, the creation of an organ and tissue bank which would supply the ideal transplant for the recipient at any chosen time. By extreme lowering of temperature it should be possible to arrest cell metabolism completely. However, only by storage in liquid nitrogen at –196° C cessation of all metabolic activity can be guaranteed. Whereas successful long-term preservation of individual cells and tissues such as cornea, heart valves, and pancreatic islet cells is feasible, difficulties arise in the case of larger solid organs because of delayed penetration of freezing throughout the entire organ and, similarly, problems with uneven thawing. Rapid warming leads to premature activation of metabolism in the outer layers, whereas slow warming may be followed by renewed recrystallization of areas which have already thawed. For this reason long-term preservation by freezing is not an adequate method for solid organs. Consideration will therefore be restricted to the principles and techniques of short- and intermediate-term preservation.

Strategies of organ preservation With the cutting off of the circulation and the onset of ischaemia, viability of the organs is restricted to a period of 30–60 min by lack of oxygen, substrates, and energy and by the accumulation of metabolic endproducts. To maintain viability for the necessary time and to ensure rapid resumption of function after transplantation, two strategies are available. The first strategy is to simulate the physiological milieu of the organ during the extracorporeal phase. Optimal maintenance of an explanted organ during this phase can be guaranteed by continuous perfusion with whole blood, because this provides ideal supplies of oxygen, substrates, and cofactors, coupled with satisfactory elimination of metabolic products. This obvious idea was seized up early in the development of transplant medicine and was put into practice by using heart–lung machines for continuous perfusion of organs with their own blood or by connecting the organs to an intermediate host [6–8]. However, the physiological advantages of perfusing organs with blood came up against various logistical, medical, and ethical problems which precluded its routine use in everyday practice and caused its abandonment. In the technique of bloodless perfusion the organs are perfused with solutions based on cryoprecipitated plasma, human albumin or other colloid materials, so as to circumvent the problems arising from the use of blood. Efforts were also made to maintain aerobic energy metabolism by oxygenation and enrichment with substrates such as glucose, fatty acids, amino acids, phosphates, and adensine.

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The mode of perfusion that comes closest to the physiological situation is continuous or intermittent machine perfusion. This comprises a closed system within which 800–1200 ml of solution is circulated through a heat exchanger and a membrane oxygenator and pumped through the organ at a perfusion pressure of around 30 mmHg. Metabolic endproducts can be removed by regularly changing the perfusion fluid. In everyday practice the use of continuous or intermittent organ perfusion is restricted by the relatively high technical and logistical effort required. Furthermore, it has not proved successful in organs with a pronounced tendency to oedema, such as the pancreas. Lastly, when using perfusion or nutrient solutions based on plasma or human albumin, the possibility of transmitting vital diseases must not be forgotten. The second strategy for organ preservation is to slow down the metabolic processes in the ischaemic or anoxic organ by hypothermia or by drugs, so as to prevent cell death from energy deficit and to maintain the viability of the organ until it has been implanted and reperfusion has been started. The most important item is hypothermia. The use of hypothermia for organ preservation is based on the fact that energy-consuming and autolytic metabolic processes, like all enzymatic reactions, attain their maximum reaction velocity only within a narrow temperature range. If the temperature drops below that range, the reactions will slow down. In human beings and most other warm-blooded animals, cooling by 10° C will slow metabolic activity by a factor of 1.5 to 2.0. This correlation is expressed by the van’t Hoff coefficient Q10: Q10 = (k2/k1)10/(t2–t1, where k1 and k2 denote the reaction velocities at temperatures t1 and t2. This indicates a slowing of reaction velocity by a factor of 12 when the temperature of the organ is reduced to 0° C. From this correlation it is also clear that hypothermia does not completely suppress metabolism, but can merely prolong the interval before the onset of cell death. Yet this is not the only constraint which hypothermia involves. Organs which have been stored in simple Ringer lactate solution, even for a short time show marked cell swelling and massive loss of intracellular potassium and magnesium. To understand the background behind these reactions we must first visualize the physiological situation in a normal cell and the consequences of cold ischaemia. Under physiological conditions the cell is surrounded by a milieu containing high concentrations of sodium and chloride and a low concentration of potassium ions. Furthermore, the extracellular concentration of calcium ions is roughly 1000 times greater than it is in the intracellular space. There is an electrical potential across the cell membrane, with its negative pole in the cell and positive charges on the exterior. Numerous energy-consuming processes serve to maintain this status. The necessary substrate is usually adenosine triphosphate (ATP), which is synthesized in the mitochondria by a process which consumes energy. It in turn supplies energy for the membrane-based Na/K-ATPase, which working against the concentration gradients, pumps three sodium ions out of the cell and two potassium ions into the cell. Among other important proteins is Na/Ca-ATPase, which is responsible for transport of calcium out of the cell, and the voltage-dependent calcium channels. Under conditions of ischaemia and anoxia anaerobic glycolysis comes into action to provide energy by the breakdown of glucose to lactate. Even though this metabolic pathway is considerably less efficient than aerobic glycolysis via the citrate cycle, it is nevertheless adequate to maintain the integrity of the cell in the system described above. However, though organs can tolerate ischaemia for a limited time, after this time has ended further synthesis of ATP is impossible and metabolism comes to a standstill. This leads to uncompensated influx of sodium ions and loss of intracellular potassium.

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Collapse of the membrane potential is followed by massive influx of chloride and calcium. The membrane proteins undergo denaturation and water streams into the dying cell. Hypothermia cannot prevent these processes but can slow them down to a great extent. By the reduction in metabolic rate, the cell is enabled, by using anaerobic glycolysis, to eke out its limited energy reserves for a considerably longer time. The activity of Na/K-ATPase is certainly reduced, but because it is less temperature-sensitive than other enzymes, its residual activity allows it at least partially to maintain the membrane potential. Nevertheless, there is a relative preponderance of ion flows along the concentration gradients, so that in addition to the losses of intracellular potassium and magnesium there is an influx of sodium, carrying with it an influx of water which leads to intracellular oedema. The conditions of hypothermic ischaemia have many effects on intracellular calcium balance. Owing to accumulation of lactate, anaerobic glycolysis leads to the development of intracellular acidosis and consequently to a shift from protein-bound calcium to free Ca2+ ions. The cellular energy deficit leads to the escape of calcium from compartments with high concentrations, such as the mitochondria, into the intracellular space. Loss of the membrane potential results in an increased influx of calcium via the voltage-dependent calcium channels. At the same time the efflux of calcium via the energy-dependent Na/Ca-channels is considerably reduced. The marked increases in intracellular calcium concentration activate phospholipases A1, A2, and C, which catalyse hydrolysis of the phospholipids of the cell membranes. This reaction is detrimental to the transplant in two respects: first, it destabilizes the cell membrane with further accentuation of the electrolyte imbalance; and secondly, these processes cause the liberation of arachidonic acids. The latter are then broken down to eicosanoids, and because of their pronounced chemotactic activity these induce an increased reaction on the part of the non-specific immune system [9]. Ischaemia leads to loss of energy-rich compounds, in particular ATP, and to accumulation of breakdown products in the form of hypoxanthine. This substance is normally broken down to urate by xanthine dehydrogenase. However, under conditions of ischaemia, owing to the deficit of reduced NAD as acceptor, this pathway is diverted via xanthine oxidase. During reoxygenization, the breakdown of hypoxanthine leads to sudden liberation of oxygen radicals. Under ischaemic conditions, therefore, hypothermia can prevent rapid cell death, but there will nevertheless be an intracellular energy deficit, accompanied by electrolyte shifts with intracellular oedema and abnormalities of membrane potential. The damage that occurs during reperfusion is triggered by the influx of calcium, the activation of arachidonic acid metabolism and other biochemical changes.

Principles of organ preservation In the early days of organ transplantation various preservative solutions were developed with the object of mitigating the consequences of ischaemia and hypothermia, and of minimizing reperfusion damage. The ingredients of the solutions used to maintain the physiological milieu and to act upon the pathophysiology of the ischaemia–reperfusion lesion are described in detail below.

Electrolytes The electrolytes added to preservative solutions serve two purposes. First, they are intended to stabilize the cell membrane; and secondly, to prevent the emergence of an osmotic gradient between the extracellular and intracellular compartments during hypothermic storage. Solutions with an electrolyte composition resembling that of intracellular fluid, for example University of Wisconsin (UW) or Euro Collins (EC), have high concentrations of potassium and phosphate and low concentrations

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of sodium and chloride. Because of the absence of concentration gradients between the intracellular and extracellular spaces, they are claimed to avoid the efflux of potassium out of the cell, and hence both to stabilize the cell membrane and to prevent the emergence of an osmotic gradient. Experimental and clinical studies have shown, however, that the electrolyte concentration of preservation solutions is of relatively little importance for their oncotic and cell-protective action. Comparison of the potassium-rich UW and EC solutions with Bretschneider’s histidine–tryptophan– ketoglutarate(HTK) solution, which has an ionic composition almost exactly the same as that of extracellular fluid, showed no differences with regard to the prevention of electrical charge exchanges or of cellular oedema. Furthermore, a high potassium concentration in the extracellular space, for example in UW solution, has proved to be deleterious, because it constricts the blood vessels and damages vascular endothelium. Conversely, addition of magnesium, for example in Marshall’s solution, has proved valuable. Because of the possibility of precipitation with phosphates the addition of calcium to preservation solutions should be avoided.

Impermeants Because the sodium–potassium pump has stopped working, the cell membrane potential drops, and sodium and chloride can therefore stream into the cell without hindrance. The resulting osmotic gradient leads to influx of water, culminating in cellular oedema. The development of cellular oedema can be avoided by adding certain substances to the preservative solutions. These substances can diffuse into the interstitial spaces, but they cannot permeate through the cell wall or at most can penetrate only very slowly. These substances are called impermeants. Large molecules which are not required for energy metabolism or other physiological processes within the cell have proved the most effective substances for this purpose. In the version of UW solution intended for use in heart–lung machines, gluconate (MW 196) has been used with great success, and the same is true of lactobionate (MW 358) added to the UW storage solution. Other polysaccharides and disaccharides such as raffinose (MW 594) in UW solution or mannitol (MW 182) in Marshall’s solution have been used with equal success, whereas the employment of metabolizable monosaccharides such as glucose (MW 180) in the EC solution or the use of colloids alone have proved ineffective. Other substances, which diffuse into the cell much more slowly than simple electrolytes, for example histidine (MW 155) or tryptophan (MW 204) contained in Bretschneider’s HTK solution, have given satisfactory results. Similar effects are produced by the use of citrate in Marshall’s solution or of phosphate in the EC solution [10].

Colloids During the ‘flush out’, that is, the rinsing out of the blood in the transplant at the beginning of perfusion, interstitial oedema frequently arises during continuous machine perfusion or during reperfusion. This oedema compresses the capillaries and hence hinders complete rinsing out of the blood during the ‘flush out’, and causes patchy distribution of the preservative solution and incomplete capillary reperfusion. Attempts have been made to compensate for the transcapillary fluid loss by using colloids, that is, substances of high molecular weight [for example, hydroxyethyl starch (HES) in UW solution or polyethylene glycol in EC solution], which do not escape from the blood vessels and thereby create a colloid-osmotic pressure gradient against the interstitial tissues [11–13]. However, in clinical and experimental practice it soon became evident that the colloid additive, though one of the basic prerequisites for long-term machine perfusion, is not necessary for simple hypothermic storage. Because one of the effects of colloid additives is to increase the viscosity of the

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perfusion solution, one disadvantage, especially during liver perfusion, was inadequate washing out of the larger and smaller bile ducts whose blood supply comes from capillaries alone [14].

Buffers During tissue ischaemia, anaerobic glycolysis and glycogenolysis (Pasteur effect) lead to the accumulation of acid valencies such as lactate. This causes cell damage, affecting the lysosomes and mitochondria in particular. The intracellular acidosis, by its effect on various enzymes such as phosphorlipase A2, also modifies the reactions occurring during reperfusion. There are three measures which can compensate for these effects. By avoiding the use of glucose as an initial substrate for anaerobic glycolysis it was hoped to prevent the development of acidosis from the outset. Furthermore, by alkalinization, as in UW solution, and by the addition of buffer substances such as histidine in HTK solution, any lowering of pH due to tissue ischaemia can be neutralized.

Energy substrates Despite the reduction in cell metabolic activity during hypothermic storage, there is still some consumption of energy, and because of the anaerobic conditions and the lack of substrates, it cannot be completely made good. This leads to ATP breakdown with the emergence of endproducts such as adenosine, inosine, and hypoxanthine, which pass freely through the cell membrane and are hence lost from the cell. When reperfusion begins these substances necessary for ATP synthesis are lacking just when they are needed for regeneration of the sodium–potassium pump and for other energy-consuming functions. Attempts have been made to counteract this pathophysiological mechanism by adding various substances to preservative solutions. Energy-rich precursors such as adenosine in UW solution, adenosine, and ribosine in heart–lung machine UW solution, and phosphate in UW and EC solutions, are added so that they can serve as substrates for ATP synthesis. Another approach is to add allopurinol, as in UW solution, so as to inhibit xanthine oxidase and hence block the breakdown of adenosine nucleotides. However, the value of ATP precursors is still uncertain. Some experiments have shown more rapid ATP regeneration owing to the increased availability of these substances. Conversely, it is known that the absence of these energy precursors enhances ischaemia tolerance [15,16]. Oxygen persufflation is yet another measure which can be used to regenerate cellular energy metabolism, because aerobic glycolysis within the cell provides more energy than is given by anaerobic glycolysis. For this purpose oxygen is introduced into the organ by continuous bubbling via its blood vessels (‘persufflation’), and the oxygen is then allowed to escape by puncture channels made on the surface of the organ with a fine needle. Care must be taken that the organ remains immersed in the preservative solution and does not float up to the surface because of the gas which it contains. Although oxygen persufflation has been shown to slow down ATP breakdown in renal transplants in experimental animals, this procedure has not found favour in clinical practice, first, because of serious technical difficulties which dealing with larger organs; and secondly, because damage to vascular endothelium by reactive oxygen metabolites cannot be excluded [17,18]. During continuous machine perfusion synthetic perfluorochemicals have been used as erythrocyte substitutes with the aim of improving oxygen transport. However, for simple hypothermic storage, these additives have proved useful only in the case of pancreas preservation [19–21].

Oxygen radical scavengers During ischaemia ATP is metabolized to hypoxanthine and xanthine, while xanthine dehydrogenase is converted to xanthine oxidase. The start of reperfusion is followed by oxydation of hypoxanthine and

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xanthine by xanthine oxidase, and the release of oxygen radicals. These damage the cell membrane and lead to chemotaxis and activation of neutrophil granulocytes. Preservative solutions contain ingredients which provide adequate protection from oxygen radicals by three mechanisms. UW solution contains allopurinol which inhibits xanthine oxidase, thus preventing the formation of oxygen radicals. By adding oxygen scavengers, such as glutathione in UW solution or histidine in HTK solution, free oxygen radicals can be captured or reduced in numbers. Lastly, by adding vasoactive substances [prostaglandins, eicosanoids, nitric oxide] efforts have been made to ensure optimum vascular diameters during reperfusion. This will allow an adequate influx of oxygen and nutrients, and will regulate the influx of oxygen so as to keep the formation of oxygen radicals within tolerable bounds [9].

Summary The cell damage caused by ischaemia can be minimized by hypothermia, which will in principle damp down all the energy-dependent reactions of the cell. In addition, the composition of the extracellular fluid to which the ischaemic organ is to be exposed can be adapted to the altered conditions by adding appropriate substances to the preservation solution (Table 9.1) The most important measure is to correct the serious osmotic imbalance associated with hypothermia. Simple lowering of extracellular sodium concentration to the levels existing within the cell, together with reduction of extracellular calcium concentration on the levels in the cytosol, has proved to be inadequate. To prevent cellular oedema it is necessary to add osmotically active substances, which should be so far as possible metabolically inactive. These substances should not diffuse into the cell, or only to a limited extent, and should also take over protective functions (for example, oxygen radical scavengers, buffer substances). Moreover, by buffering the extracellular space, ischaemic damage can be still further reduced, because low pH values during hypothermia lead to a decrease in the activity of certain enzymes, for example phosphofructokinase (Fig. 9.2).

Special section Introduction Diabetes mellitus is the principal cause of chronic renal impairment and blindness in adults and leads to amputations and impotence in more cases than any other disease. Type I IDDM is the most frequent chronic disease of children [22–25]. Diabetes mellitus is not merely a disorder of intermediary metabolism, but also causes specific lesions in blood vessels and the nervous system such as retinopathy, nephropathy, or neuropathy. In the last two decades it has become clear that these ‘microangiopathies’ are mainly due to hyperglycaemia. Acute metabolic decompensation can be averted by exogenous insulin therapy and properly timed injections can often ward off many of the complications of diabetes mellitus. However, even in well-stabilized patients, insulin injections do not always achieve control of intermediary metabolism as good as that provided by physiological endogenous insulin secretion, which reacts to the smallest shifts in glucose concentration. Transplantation of the pancreas is the only mode of treatment for IDDM which offers reliable independence from insulin injections and which can normalize glycated haemoglobin levels. Pancreas transplants, besides improving the patient’s quality of life, also aim to correct the secondary complications of IDDM by ensuring long-term euglycaemia [22–25]. The crucial factor is the transplantation of the cells of the islets of Langerhans; this can be done in three ways [22,23]. The simplest way would

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Table 9.1 Strategies of organ preservation Hypothermia (delays catabolism, which leads to tissue destruction) Organ preservation Physical cell millieu ● osmotically active substances (suppress cell swelling) ● electrolytes (prevent the formation of an osmotic gradient between extracellular and intracellular spaces and stabilize the cell membrane) ● buffer substances (extracellular and intracellular pH neutralization) ● colloids (facilitate the initial flushout; during continuous machine perfusion) Biochemical cell millieu ● metabolites for regenerating energy production ● inhibition of the breakdown of important structural proteins (protease inhibitors) Minimization of reperfusion damage ● reduction of oxygen radical formation (inhibition of xanthine oxidase) ● scavenging of oxygen radicals already formed ● use of vasoactive substances to ensure optimal vascular diameter during reperfusion

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Fig.9.2 Organ preservation: pathophysiology and therapeutic principles. AMP, adenosine monophosphate; ATP = adenosine triphophose, adenosine triphosphate.

be to implant isolated islet cells in the hope that they would colonize the recipient. This mode of therapy is still in a very early clinical stage and demands methods of preparing and processing the pancreas that are completely different from classical organ preservation. [26]. The remainder of this section will be restricted to the preservation of the entire pancreas. A second possibility is to transplant the tail of the pancreas, which contains the majority of the roughly 1 million islet cells. The third possibility is to transplant the entire pancreas. This is normally the method of choice and is usually combined with renal transplantation (simultaneous pancreas and kidney transplantation). There are certain exceptions, such as pancreatic transplantation after the performance of a kidney transplant, usually following a living donation, and the rare cases of isolated pancreatic transplantation in nonuraemic but metabolically unstable patients. These latter forms of pancreatic transplantation differ mainly in that they are performed as ‘bench surgery’ and are summarized elsewhere (Chapter 8).

Pancreas procurement The aim of any organ transplantation is optimal transplant function, and this can be achieved by adequate donor management, the best possible organ protection, and by minimizing organ damage during the implantation. Damage to a transplant may lead to disorders of functions, sometimes amounting to primary failure of the organ (PNF). When there is a shortage of donor organs this problem may be aggravated by the use of transplants with minor pre-existing damage (‘marginal donors’). Because of its filamentous structure and the absence of any capsule, the pancreas has proved highly susceptible to stresses during harvesting and preservation (Table 9.2) [27]. In principle, damage to the donor organ can be divided into five categories as follows.

Pre-preservation injury Even before explantation, potential donor organs can suffer damage from the donor’s previous illness or fatal illness, during hypotensive or ischaemic phases and even in the course of intensive care. Absolute contraindications prohibiting the use of a donor for a pancreas transplant include diabetes

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Table 9.2 Checklist for pancreas preservation Perfusion via

Aorta Superior mesenteric vein, splenic vein Omit intravascular flush

Perfusion pressure and volume

100 cm H2O transarterial, maximum 1000 ml perfusion solution (beware of overperfusion)

Packaging

First bag containing pancreas and preservatives solution without ice (do not forget vessel interponate), organ dish filled with fluid and ice, second sterile bag around the dish

Preservative solution and ischaemia tolerance

EC solution obsolete UW solution is the gold standard, safe limit 12 h cold ischaemia time, cold ischaemia time can be prolonged to up to 96 h by adding prostanoid inhibitors, NO synthetase inhibitors, PAF antagonists and by the two-layer storage technique HTK solution: equally good results at cold ischaemia times of up to 24 h [46]

Special features

Marked tendency to oedema because of absence of capsule (beware of overperfusion, continuous perfusion obsolete, good results from omission of intravascular flush) Preservation solution must also be suitable for multiorgan harvesting and must not compromise any subsequent islet cell isolation Prolongation of cold ischaemia time in connection with pancreas preservation is worthwhile only in connection with renal ischaemia tolerance

NO = nitric oxide; PAF, platelet-activating factor.

mellitus, or a history of acute or chronic pancreatitis. Because of the connection between nicotine abuse and ␤-cell function, even though it is not yet fully clear, a history of smoking is a relative contraindication to the use of such a donor [28].

Harvesting injury Damage may occur during explantation from inexpert dissection of the organ, or from inadequate perfusion and organ cooling, possibly leading to warm ischaemia as well. Because it has no capsule, the pancreas is particularly susceptible to damage from manipulation, ischaemia, or changes in its milieu. If portal perfusion is in progress at the same time, hyperperfusion (> 1000 ml perfusion solution) or the generation of retrograde portal overpressure in the pancreas must be avoided [23,24]. To divert exocrine pancreatic secretion, a segment of duodenum has to be resected and sterilized, but fortunately it will tolerate ischaemia longer than the pancreas [27].

Cold preservation injury The duration of cold ischaemia is critical for transplant function. For example, the incidence of primary organ failure and the retransplantation rate rise significantly with increasing cold ischaemia time.

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Rewarming injury Prolonged warm ischaemia time or inadequate cooling of the transplant during implantation will lead to additional damage.

Reperfusion injury In addition to cold ischaemia time, reperfusion damage plays a crucial part in the inception of primary organ failure. Cardiac problems, which may arise, for example, during liver transplantation because of the escape of preservation solutions with high potassium concentrations into the systemic circulation, can be avoided by the use of washout solutions before reperfusion. [13]

Pancreas preservation Euro Collins solution In the late 1960s Collins inaugurated the era of hypothermic organ preservation by introducing a hyperosmolar solution having an ionic composition almost identical with intracellular fluid, but without colloid additives. With this ‘Collins solution’ he succeeded under experimental conditions in prolonging hypothermic kidney preservation to over 48 h. The first Collins solutions (C2, C3, C4) had high concentrations of potassium, magnesium sulfate, and glucose. Procaine was added to the C3 and C4 solutions to inhibit sodium influx into the cell and phenoxybenzamine was used to induce vasodilatation. As experimental and clinical experience grew, various modifications were made to C3 and C4, resulting in solutions, which was fundamentally similar to C2 (Table 9.3). Phenoxybenzamine and procaine were no longer used as additives. In the event of circulatory stasis, tissue cholinesterase could metabolize procaine to para-aminobenzoic acid, which is nephrotoxic. Phenoxybenzamine rapidly precipitates out of solution. In addition the magnesium additive was withdrawn, because precipitates of magnesium phosphate complexes had often been observed in the early Collins solution. To increase the osmolarity of EC solution, the glucose concentration was raised from 120 to 180 mmol/l. However, the use of glucose as an osmotically active substance proved less than optimal for two reasons. First, long-term preservation of organs with increased glucose permeability, such as liver and pancreas, presents problems, because with the gradual diffusion of glucose into the intracellular space the osmolarity of the solution diminishes and it cannot be relied upon to prevent cell oedema [29–31]. This means that when EC solution is used to preserve the pancreas it gives a maximum ischaemia time of only 4 h before serious cell oedema develops, one of the causes being the intracellular diffusion of glucose [32,33]. This results in the ‘no flow phenomenon’, a condition in which capillary blood flow through the transplant is obstructed by cell oedema. Secondly, glucose is the initial substrate for the anaerobic glycolysis which takes place during hypothermia, and if glucose is available in large amounts it may induce tissue acidosis. Numerous experimental studies have shown that the preservation of organs, in particular of the pancreas, can be optimized by replacement of glucose by other, metabolically inert sugars, such as sucrose or mannitol, and by the addition of HES to raise osmolarity [34]. In 1976 EC solution was recommended as the preservative solution of choice by the Preservation Working Committee, which is made up of members from the transplant centres associated with Eurotransplant. Nowadays, for the reasons stated above it is considered inferior to other preservative solutions such as UW or HTK solution, and is no longer employed for clinical pancreas conservation [35].

University of Wisconsin solution UW solution was developed in 1987 by Belzer and Southard for preservation of the pancreas [33,36,37]. The aims of UW solutions are to minimize cell swelling during hypothermic ischaemia,

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Table 9.3 Constituents of preservation solutions Constituents

EC

Colloids ●

UW

HTK

CR

50

HES

Impermeants ● ● ● ● ● ● ●

glucose mannitol lactobionate raffinose histidine tryptophan ␣-ketoglutarate

Osmolarity

182

10 30 100 30 180 2 1

355

320

57.5 10 7.4

25

310

300

Buffers ● ● ●

PO4– HCO3– pH

7.2

1 7.2

6.8

O2 radical scavengers ● ●

glutathione allopurinol

3 1

3 1

Electrolyte concentrations ● ● ● ● ●

Na+ K Cl– MgSO4 lactate

10 115 15

30 120 5

15 9 50 4

130 5 112 + 28

Additives ● ● ●

adenosine insulin dexamethasone

100 8 0.5

1 +

prevent acidosis, avoid interstitial oedema, capture oxygen radicals, especially during reperfusion, and supply precursor materials for the energy metabolism of the organ. The effects of the various constituents of UW solution are achieved by their presence in the extracellular space and not by equilibration of the transplant to the preservative solution. The solution is viscous (4.8 cP at 1° C) and has an electrolyte composition similar to that of intracellular fluid with high potassium concentrations (135 mmol/l) and low sodium concentrations (35 mmol/l) with a pH of 7.4. The pH is maintained by using phosphate as a buffer. To stabilize the membrane potential magnesium, sulfate and lactobionate are added to calcium chelators. Acting as impermeant substances, HES, lactobionate, and reffinose prevent the emergence of cell oedema during hypothermia. Furthermore, addition of HES — colloid substance — enabled UW solution to be used for machine perfusion of the kidneys. Adenosine is added to aid ATP regeneration (Table 9.3). The importance of the adenosine in UW solution has been shown in many experimental studies in which UW solution, with adenosine in various concentrations, or none at all, was employed [15,16,38]. Although there was no substantial difference between UW solutions containing 1 and 100 mmol/l, complete removal of adenosine from the solution was followed by poorer results. The use

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of allopurinol inhibits both the breakdown of adenosine nucleotides and the generation of oxygen radicals [39]. Furthermore, glutathione additive will capture free oxygen radicals. On prolonged storage, however, the reduced form of glutathione is converted into the oxidative form, and the reducing action of glutathione as an oxygen radical scavenger is lost. When using UW solution which has been in store for some time, it has proved useful to add glutathione immediately before use. In the light of early experience with UW solution under experimental and clinical conditions for liver, kidney, heart and intestine preservation, certain modifications of its composition were made. First of all, HES was considered unnecessary for simple hypothermic preservation. For example, in the successful long-term preservation of rabbit kidneys, a better initial transplant function was demonstrated in kidneys which had been preserved in UW solution free from HES. To maintain osmolarity, in the modified UW solution the concentration of raffinose has been doubled to 60 mmol/l. Secondly, the ratio of sodium and potassium had been reversed, because the high potassium concentrations in the original UW solution (designed to simulate intracellular fluid) proved damaging to cells and had vasoconstrictor effects [40,41]. Besides this, overloading of the systemic circulation with potassium diffusing out of the transplant caused cardiac arrhythmias, sometimes progressing to ventricular fibrillation. Lastly, it proved unnecessary to add insulin or dexamethasone [42]. Since the early 1990s heart, lung, liver, pancreas, kidney, and intestinal transplants have been performed with great success with the modified UW solution. For pancreas preservation under hospital conditions, cold ischaemia times of up to 12 h have been achieved with UW solution. Prostanoid inhibitors [43], NO synthetase inhibitors, and platelet-activating factor (PAF) antagonists, used as additives, prolonged pancreas preservation under experimental conditions for up to 96 h [44]. Using UW solution, ischaemia tolerance times (safe limits) of 18 h for liver and up to 36 h for kidney have been achieved. At present, therefore, it is the preferred perfusion solution and the ‘gold standard’ for multiorgan harvesting [45–47].

Histidine–Tryptophan–Ketoglutarate solution Bretschneider’s HTK solution has been in use since 1961 for experimental work and since 1971 as a cardioplegic solution in open-heart surgery. Its organ protective action depends on the following principles. The impermeant aminoacids histidine, tryptophan and ␣-ketoglutarate retard the unavoidable acidosis due to ischaemia and buffer critically low pH values. In addition, the impermeant aminoacids and the added mannitol maintain cell volume regulation under conditions of ischaemia. Because of the low extracellular sodium concentration (reduced to approximately intracellular levels) together with elevation of potassium concentration to roughly twice the extracellular norm, the load on the cellular ion pumps is relieved. By the omission of glucose, economies are made in inessential energy-consuming processes, such as the utilization of the lactate transport system when the anaerobic glycolysis rate reaches high levels. Finally, histidine, tryptophan, and ␣-ketoglutarate are capable of capturing oxygen radicals, thus minimizing the severity of reperfusion damage (Table 9.1). In contrast to other preservative solutions, the mode of action of HTK solution depends on a socalled ‘equilibration’ of the extracellular compartment, that is, by perfusion with a low-viscosity fluid (viscosity of HTK solution: 1.8 cP at 1° C) the temperature and composition of the extracellular fluid are rendered practically identical with those of the preservation solution [48–50]. Complete equilibration takes time, because the separate constituents of the extracellular fluid shift at different speeds as they come into line with the composition of the preservative solution. Calcium equilibration needs more time than sodium equilibration. This difference in kinetics can be evened out, for example, by adding magnesium, calcium antagonists, and calcium complexing agents. Because the perfusion time for organ equilibration is so much longer than perfusion with ‘single flush-out’ with other perfusion

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solutions, the so-called ‘high volume concept’ of HTK solution has arrised. The amount of perfusion fluid needed for the purpose is calculated from the dry weight of the transplant, among other factors. For example, for complete equilibration of the kidneys (dry weight 250 to 400 g)