Type 2 diabetic subjects manifest both disordered insulin action and abnormalities in their pancreatic islet cells. Whether the latter represents a primary defect or is a consequence of the former is unknown. To examine the -cell mass and function of islets from type 2 diabetic patients directly, we isolated islets from pancreata of type 2 diabetic cadaveric donors (n ؍ 14) and compared them with islets from normal donors (n ؍ 14) matched for age, BMI, and cold ischemia time. The total recovered islet mass from type 2 diabetic pancreata was significantly less than that from nondiabetic control subjects (256,260 islet equivalents [2,588 IEq/g pancreas] versus 597,569 islet equivalents [6,037 IEq/g pancreas]). Type 2 diabetic islets were also noted to be smaller on average, and histologically, islets from diabetic patients contained a higher proportion of glucagon-producing ␣-cells. In vitro study of islet function from diabetic patients revealed an abnormal glucosestimulated insulin release response in perifusion assays. In addition, in comparison with normal islets, an equivalent number of type 2 diabetic islets failed to reverse hyperglycemia when transplanted to immunodeficient diabetic mice. These results provide direct evidence for abnormalities in the islets of type 2 diabetic patients that may contribute to the pathogenesis of the disease. Diabetes 53: 624 -632, 2004
The MELD score is a relatively poor predictor of posttransplant outcome. In contrast, a model based on four pretransplant variables (recipient age, mechanical ventilation, dialysis, and retransplantation) had a better ability to predict outcome. Our results support the use of MELD for liver allocation and indicate that statistical modeling, such as reported in this article, can be used to identify futile cases in which expected outcome is too poor to justify transplantation.
We found that an induction immunotherapy regimen consisting of rabbit anti-thymocyte globulin (Thymoglobulin) and the monoclonal antibody to CD20 rituximab (Rituxan) promoted long-term islet allograft survival in cynomolgus macaques maintained on rapamycin monotherapy. B lymphocyte reconstitution after rituximab-mediated depletion was characterized by a preponderance of immature and transitional cells, whose persistence was associated with long-term islet allograft survival. Development of donor-specific alloantibodies was abrogated only in the setting of continued rapamycin monotherapy.
The Food and Drug Administration (FDA) held an open public workshop in June 2010 to discuss the current state of science related to antibody-mediated rejection (AMR) in kidney transplantation. Desensitization, acute AMR and chronic AMR (CAMR) were considered in the context of clinical trial design. Participants discussed experiences with HLA antibody detection and quantitation and the utility of monitoring donorspecific antibodies (DSAs) to inform the management of patients with AMR. The role for animal models was discussed. Diagnostic and prognostic features of histology were presented, followed by discussion of sensitivity and specificity of various criteria. The published literature on treatment of acute AMR was summarized, which consisted of case series and limited data from controlled clinical trials. Considerations for future clinical trials were presented, including endpoints and statistical evaluations of outcome. Although many issues need further consideration, the meeting enabled an important exchange of ideas between experts in the field.
The Food and Drug Administration (FDA) held an open public workshop in September 2011 to discuss the current state of science related to the effects of ischemia reperfusion injury (IRI) on outcomes in kidney transplantation. Topics included the development of IRI and delayed graft function (DGF), histology and biomarkers, donor factors, recipient factors, organ quality and organ preservation by means of cold storage solutions or machine perfusion. Various mechanisms of injury and maladaptive response to IRI were discussed as potential targets of intervention. Animal models evaluating specific pathophysiological pathways were presented, as were the limitations of extrapolating animal results to humans. Clinical trials of various drug products administered in the peritransplant period were summarized; a few demonstrated early improvements in DGF, but none demonstrated an improvement in late graft function. Clinical trial design for IRI and DGF were also discussed.
This report confirms the efficacy of the Edmonton immunosuppressive regimen and indicates that insulin independence can often be achieved by a single transplant of sufficient islet mass.
A number of parameters are differentially correlated with outcome in HCV- and HCV+ recipients of orthotopic liver transplantation. These findings may not only have practical implications in the selection and management of liver transplant patients, but also may shed new insight into the biology of HCV infection posttransplant.
Recent improvements in isolated islet transplantation indicate that this therapy may ultimately prove applicable to patients with type I diabetes. An obstacle preventing widespread application of islet transplantation is an insufficient supply of cadaveric pancreata. Non-heart-beating donors (NHBDs) are generally not deemed suitable for whole-organ pancreas donation and could provide a significant source of pancreata for islet transplantation. Isolated pancreatic islets prepared from 10 NHBDs were compared with those procured from 10 brain-dead donors (BDDs). The success of the isolation for the two groups was analyzed for preparation purity, quality, and recovered islet mass. The function of NHBD and BDD islets was evaluated using in vitro and in vivo assays. On the basis of the results of this analysis, an NHBD isolated islet allograft was performed in a type I diabetic. The recovery of islets from NHBDs was comparable to that of control BDDs. In vitro assessment of NHBD islet function revealed function-equivalent BDD islets, and NHBD islets transplanted to non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice efficiently reversed diabetes. Transplantation of 446,320 islet equivalents (IEq) (8,500 IEq/kg of recipient body weight) from a single NHBD successfully reversed the diabetes of a type I diabetic recipient. Normally functioning pancreatic islets can be isolated successfully from NHBDs. A single donor transplant from an NHBD resulted in a state of stable insulin independence in a type I diabetic recipient. These results indicate that NHBDs may provide an as yet untapped source of pancreatic tissue for preparation of isolated islets for clinical transplantation.
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