American Journal of Transplantation 2004; 4: 295–298 Copyright C Blackwell Munksgaard 2004 Blackwell Munksgaard doi: 10.1046/j.1600-6143.2003.00375.x Editorial Unraveling the Secrets of Single Donor Success in Islet Transplantation

A. M. James Shapiroa,∗ and Camillo Ricordib preparation and clinical use of this immunosuppressive pro- tocol (7). Furthermore, by restricting donor cold aClinical Islet Transplant Program, , ischemia to less than 8 h (from up to 20 h in the original Edmonton AB, Canada Edmonton series), combined with more restrictive maxi- bDiabetes Research Institute, University of Miami, mal candidate body weight and requirement cut-offs Miami, FL (from upwards of 90 kg and >1.0 U/kg/day in the Edmonton ∗ Corresponding author: James Shapiro, [email protected] series, down to 70 kg and = 0.7 U/kg/day in the ITN trial), five of the first 13 ITN patients (38%) attained insulin inde- Received 10 November 2003, revised and accepted for pendence with a single donor islet transplant, and single publication 21 November 2003 donor success was as high as 75% at one of the centers (8). Preliminary analysis suggests that the two most significant factors affecting clinical success are: (a) the center’s skills in preparation of high-quality, high-yield islets following an Islet transplantation is emerging as an attractive alterna- identical isolation protocol; and (b) the center’s ability to tive to solitary for a highly select maintain the recipient’s immunosuppressant levels within group of patients with severe, labile forms of Type 1 dia- a specified target range after transplantation. betes that had previously tried and failed on intensive in- sulin therapy. The year 2000 marked a dramatic shift in The degree of glycemic control provided by successful islet clinical success with the introduction of the so-called ‘Ed- transplantation is far superior to all forms of exogenous in- monton Protocol’, which built upon many years of inten- sulin therapy available presently, and HbA1C is routinely sive research and extensive collaborations between islet maintained in the normal range after discontinuation of in- groups worldwide (1,2). sulin (4,9). Islet transplantation has thus far proven to be highly effective in completely reversing both hypoglycemic With cumulative combined data in more than 75 islet episodes and lability even in those with partially functioning recipients from Edmonton, Miami and Minnesota since grafts, despite the fact that counter-regulatory glucagon re- 1999, 99% of patients have demonstrated primary sponses are not fully restored (10). These findings recently function, and 96% remained C-peptide positive at 1 year led the Food and Drug Administration’s (FDA) Biological Re- (3). Rates of insulin independence were 85% at 1 year, sponse Modifier’s Advisory Committee to propose an alter- and approximately 70% remained insulin free at 2 years. native definition of islet transplant success as ‘Restoration This combined series of more than 75 cases was associ- of sustained euglycemia, either without exogenous insulin ated with a 0% patient mortality, with no cases of ma- or with reduced insulin requirements’, as the FDA begins to lignancy, cytomegaloviral disease or Epstein-Barr-related explore the possibility of moving forward with a Biologics post-transplant lymphoproliferative disorder to date (3). In License for islet manufacture (3). most of the cases at the Edmonton and Miami sites, islets were transplanted from usually two (or rarely, three) donors Over the past 4 years since the introduction of the ‘Ed- (4). There were no reports of main portal vein thrombo- monton Protocol’, extensive progress has continued, and sis in this series, but 4% of the 75 patients developed currently more than 300 new islet recipients have received a segmental thrombus of a branch portal vein associated treatment on a worldwide basis since 1999 (11,12). This with infusion of less pure islet preparations (Edmonton site expanded experience has not only confirmed the initial only) (5). These excellent outcomes match the current suc- Edmonton findings, but has highlighted important limita- cess rate for solitary pancreas transplantation in the United tions that must be overcome if islet transplantation is to States (6). be more broadly applied as a potential cure for diabetes (4,13,14). The results of islet after kidney transplants ap- Preliminary data from the Immune Tolerance Network’s pear to match the success of islet alone transplants un- (ITN) international nine site trial indicates that Edmonton’s der -based immunosuppression (15–17). The Mi- success has indeed been replicated elsewhere at selected lan group have recently shown that long-term islet graft international centers, with a 90% insulin-free rate noted function (with persistent C-peptide secretion) can not only in three of the centers with long-standing expertise in islet prolong the half-life of a kidney transplant, but may be

295 Shapiro and Ricordi associated with a reduced incidence of diabetic vascular sensitive recipients may have further contributed to the complications and enhanced patient survival (11,18–20). single donor success. The answer likely lies in the combi- nation of these factors. Indeed, single donor islet success Notable progress includes the introduction of the perfluo- has been achieved by a number of other groups using vari- rodecalin (PFC) ‘two-layer’ method for pancreas protection ants of the ‘Edmonton Protocol’, but not to this consistent during transportation and rescue of marginal donors (21– level of success. To go beyond speculation, it would take 25), successful single-donor islet transplants from obese, a large, randomized, stratified, controlled trial to robustly nonheart-beating donors (26,27), and the routine use of define the relative importance of each factor. The islet field islet culture rather than immediate transplantation to fur- would likely be better served however, by a continued se- ther improve the purity, practicality and safety of the proce- ries of iterative pilot trials, all aimed at trying to further dure (22,28–31). The risk of acute bleeding following per- improve the safety, efficacy and availability of islet trans- cutaneous transhepatic access to the portal vein has been plantation. reduced substantially by physical and mechanical ablation of the catheter tract using combinations of coils, thrombo- One of the biggest limitations to advancement in islet trans- static agents or a coagulative laser (30,32). The use of a bag plantation presently is access to high-quality donor pan- rather than a syringe for islet delivery has further improved creas organs. Greater than 70% of cadaveric pancreas or- the sterility and safety of the procedure (33). gans are never recovered in the US, and of the 30% that are, the few that are offered for islet transplantation typi- The most notable recent progress however, has been the cally only become available after being offered and declined emergence of routine, single donor islet transplant suc- by whole pancreas transplant programs across the coun- cess at the University of Minnesota (31). In the current try. The problem with this approach is that it frequently issue of the American Journal of Transplantation, Hering exceeds the 6–8-h ‘shelf-life’ required to optimize the islet and colleagues describe their unprecedented pilot expe- isolation process. The immediate challenges ahead in islet rience with an innovative series of strategies designed transplantation are clear. Accruing data at the major islet to optimize the success with single donor islet transplan- transplant institutions may soon be sufficient to justify a Bi- tation. The authors are to be congratulated both on the ologics License with the FDA (3). This would facilitate the quality and potency of their islet preparations. Donor pan- transition from research to insured clinical care in the US, creas organs were shipped in ‘two-layer’ oxygenated PFCs, thereby preserving valuable research funds to take islet and islets were dissociated using the automated Ricordi transplantation to the next stage. This would also facili- method (2), purified on non-Ficoll-based iodixanol gradients tate a parallel shift in organ allocation policy to allow more and cultured for 2 days in insulin-transferrin-selenium sup- ideal pancreas donor organs to be used for islet isolation, plemented media (28,29). The use of thehOKT3g1 (Ala-Ala) rather than the ‘left-over’ organs that are available currently. was associated with the documented emergence There is a need for reliable, practical, predictive assays of of increased peripheral CD4+ CD25+ ‘regulatory’ T-cell islet function that will consistently define the potency of an populations (31). A substantial body of evidence suggests islet preparation before transplantation. With more than 45 that this antibody may effectively regulate autoimmunity separate IND applications for islet research protocols reg- in , and is therefore a particularly attractive istered with the FDA in the US, and with an estimated 75 agent to test in islet transplantation (34–37). These strate- islet start-up programs worldwide, perhaps it is time to re- gies were associated with improved outcome, with four examine the concept of regionalized islet isolation centers, of six patients achieving and maintaining insulin indepen- with shipment of a high-quality final islet product to a num- dence beyond 1 year after single donor islet transplantation ber of recipient centers (30,38). This would clearly improve (31). Hering’s paper is also the first to demonstrate a clear both the safety and the efficiency of the challenging pro- predictive association between outcome of marginal mass cess required for islet manufacture, thereby making more islet transplants in diabetic nude mice and functional out- islets available to a broader recipient base. Meanwhile, ad- come after clinical transplantation of islets from the same ditional studies are needed to define whether the improved human donor (31). outcome in the Minnesota study was indeed the result of any, or a combination, of the several strategies selected, As others try to unravel the secrets of the single donor or whether the real determining factors could have been islet success reported by Hering and colleagues, it is not related to the selection of from donors with a easy to define whether the dominant factors lie in the high BMI, which yield higher numbers of islets, in combi- optimal selection of initial quality pancreas organs, in the nation with careful selection of lean and insulin-sensitive islet process itself, in the immunosuppressant protocol or recipients. in the recruitment of optimal, insulin-sensitive recipients. Some might argue that the careful selection of young, In the longer term, further improvements in antirejection stable, obese pancreas donors (donor weight range 90– therapies that do not have ‘nonimmunosuppressive side- 159 kg, donor age range 16–39) coupled with a limited du- effects’, strategies designed to induce immunological tol- ration of cold ischemic storage ensured a more potent islet erance, and a means to supply an unlimited cell source for controlled insulin delivery will be the key steps to product. Careful selection of low-weight, relatively insulin-

296 American Journal of Transplantation 2004; 4: 295–298 Editorial define an ultimate cure for diabetes. With a potential 17. Bertuzzi F, Grohovaz F, Maffi P et al. Successful transplantation 300 million people worldwide currently at risk of develop- of human islets in recipients bearing a kidney graft. Diabetologia ing diabetes, and an annual diabetes healthcare cost world- 2002; 45: 77–84. wide of at least $153 billion (US), it is clear that new so- 18. Fiorina P, Folli F, Zerbini G et al. Islet transplantation is associated lutions must be found. Ultimately, an alternative stem cell with improvement of renal function among uremic patients with or xenogeneic source may perhaps address these needs, type I diabetes mellitus and kidney transplants. J Am Soc Nephrol but until such time, advances in islet transplantation con- 2003; 14: 2150–2158. tinue to offer enormous hope to countless thousands of 19. Fiorina P, Folli F, Maffi P et al. Islet transplantation improves vas- prospective candidates. cular diabetic complications in patients with diabetes who un- derwent : a comparison between kidney- pancreas and kidney-alone transplantation. Transplantation 2003; 75: 1296–1301. References 20. Fiorina P, Folli F, Bertuzzi F et al. Long-term beneficial effect of islet transplantation on diabetic macro-/microangiopathy in type 1. Shapiro AM, Lakey JR, Ryan EA et al. Islet transplantation in seven 1 diabetic kidney-transplanted patients. Diabetes Care 2003; 26: patients with type 1 diabetes mellitus using a glucocorticoid-free 1129–1136. immunosuppressive regimen. N Engl J Med 2000; 343: 230–8. 21. Hering BJ, Matsumoto I, Sawada T et al. Impact of two-layer pan- 2. Ricordi C, Lacy PE, Scharp DW. Automated islet isolation from creas preservation on islet isolation and transplantation. Trans- human pancreas. Diabetes 1989; 38: 140–142. plantation 2002; 74: 1813–1816. 3. FDABMRAC Meeting. 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