One of the major steps toward successful islet transplantation for the treatment of type diabetes is to obtain islets of sufficient number and viability. Using a standardized method of isolating islets, the goal of this study was to analyze the factors influencing the outcome of islet isolation. A total of 104 cadaveric human pancreata were processed for islets by the same team. Data from the islet-processing charts were reviewed retrospectively. The two endpoints were the recovery of islets, viable after 2 days of culture (group V = viable, group NV = nonviable) and the islet yield. Viable islets were recovered in 61% of cases (n = 63). Minimal blood glucose recorded during hospitalization was very significantly lower in group V (124 +/- 5 vs. 148 +/- 9, P = 0.01). Lack of significant medical history in the donor was associated with better viability as compared with various donor predispositions (chi-2 4.21, P = 0.04). Cold ischemia time (8.1 +/- 0.5 hr in group V vs. 9.8 +/- 0.9 hr in group NV, P = 0.07) and collagenase lot (5 lots tested, chi-2 13.1, P = 0.01) also affected the recovery of viable islets. Hospital time was shorter in group V (65.3 +/- 6.8 vs. 80.9 +/- 17.9 hr, P = 0.35). Multivariate logistic regression analyses of viable islet recovery identified minimal blood glucose (P = 0.03) and collagenase lot (P = 0.06) as the most significant risk factors. However, the best multivariate predictive model--which includes blood glucose, collagenase lot, donor age and surgical procurement team--correctly predicted 66.2% of cases only. Multivariate analysis of final islet yield designed hospitalization length, cardiorespiratory arrest, surgical procurement team, and collagenase lot as the best predictors. These data obtained in a large series of pancreata emphasized several donor and technical factors that should target the attention of islet transplant researchers in order to improve islet yield and viability.

Adolescent↗

PubMed1994

Successful engraftment of autologous and allogeneic islets into the porcine thymus.

Work in rodents has shown that injection of pancreatic islets of Langerhans into the thymus can induce donor-specific unresponsiveness to islets subsequently transplanted to extrathymic sites. The overall objective of our investigation is to test this in a large animal (pig) model. In the current study we examined whether autologous and allogeneic adult or fetal islets survive in the porcine thymus. Collagenase-digested adult and fetal porcine islets were injected into the thymic lobes of 5- to 13-month-old, normal pigs. Pigs receiving allografts were given either a standard triple regimen of oral cyclosporine, azathioprine, and prednisone or intravenous anti-lymphocyte globulin (ALG) for immunosuppression. Two pigs of each group that received an allograft or autograft were given no immunosuppression. Biopsies of the grafts were taken at 4, 6, or 12 weeks for examination. Islet survival was assessed by histology with hematoxylin and eosin and insulin staining and by measurement of tissue insulin content using acid alcohol extraction and radioimmunoassay. The insulin content of control thymus was found to be 0.71 +/- 0.29 microU/mg (n = 5). The insulin content of the islet-grafted thymic tissues ranged from 1.57 to 10.65 microU/mg. Since the amounts of injected islets were not equal and not distributed evenly, and only a part of the graft site was used for determination of tissue insulin, thymic insulin contents higher than 1.4 microU/mg (twice that of the control value) were considered to demonstrate the presence of viable islets. With this criterion, we concluded that islets were found to be viable in seven of nine pigs and two pigs which were treated with ALG were shown to be marginally positive. On histological examination, islets were found in the thymus as well as under the thymic capsule, except for the above two pigs. These results demonstrate that the pig thymus supports fetal and adult islet transplants.

Animals↗

PubMed1994

Swine as an allotransplantation model.

Because of their anatomical and physiological similarities to humans, pigs are well suited for solving technical problems associated with clinical transplantation. The availability of genetically defined strains of miniature swine is unique with this species, and has permitted the investigation, in a large animal model, of immunological and genetic aspects of allograft rejection, clinical manifestations associated with bone marrow transplantation, and the feasibility of various approaches for induction of transplantation tolerance. Immunological assays and various reagents are also available in order to pursue these studies.

Animals↗

PubMed1994

Effect of H-2 compatibility in autoimmune destruction of islet allografts from B10 congenic lines to nonobese diabetic mice.

Autoimmune diabetes involves multiple antigens, and both cellular and humoral immune responses. Using CBA (H-2k) C57BL/6 (H-2b), and BALB/c (H-2d) newborn mouse pancreata, we previously demonstrated that acute and strong destruction of islet allografts by anti-islet autoimmunity in the nonobese diabetic (NOD) mouse H-2Kd, Db) is under the influence of major histocompatibility complex (MHC) antigens. In the current study, we have attempted to confirm these results in the absence of minor alloantigenic differences using B10 congenic strains as pancreatic donors. Pancreata from B10.BR (H-2k), C57BL/10SnJ (H-2b), and B10.D2 (H-2d) were transplanted under the kidney capsule of NOD mice within 1 month of diabetes onset. These recipients were immunosuppressed with cyclosporine (CsA) in a dosage that effectively prevents rejection of skin allograft, but not islet isograft destruction that is mediated by anti-islet autoimmunity. On day 10, the grafts were harvested and examined histologically to assess viability. Pancreatic allografts from B10.D2, sharing the H-2Kd with the NOD mouse, showed the strongest lymphocytic infiltration, and neither islets nor beta cells were found in all seven grafts. C57BL/10SnJ grafts, sharing the same H-2Db, also showed severe lymphocytic infiltration, and no intact islets, and only a few beta cells were found, as single cells, in three of eight grafts. In contrast, B10.BR grafts, completely incompatible at the H-2, showed the least infiltration, and normal islets containing many beta cells were found in 10 of 11 grafts. These results again suggested the hypothesis that islet allograft destruction by diabetic NOD mice is MHC restricted.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Issues in clinical islet transplantation.

The Second International Islet Transplantation Symposium was held at UCLA in January, 1993. The symposium, sponsored by the Jerry's Foundation for Diabetes Research was focused on the issues in clinical islet transplantation. The leaders from each of the clinically active programs around the world were invited to discuss their clinical results and ways to achieve higher success rates. The Islet Transplantation Registry revealed there have been 178 islet transplants in human subjects worldwide: 11% of the patients have achieved insulin-independence; however, 20% of the patients have achieved insulin-independence during 1990-1992; 20% of the patients have functioning islet grafts as determined by circulating C-peptide levels; however 65% have functioning grafts during 1990-1992. These patients still require exogenous insulin; however, many demonstrate improved glucose control and decreased insulin requirements, and are considered to have a partially successful transplant. The major issues for clinical success are islet preparation, donor islet number, and prevention of rejection. We are hopeful that islet transplantation will realize its full potential this decade and await the advance in technology that will result in clinical success rates approaching that of solid organ transplantation.

Animals↗

PubMed1994