A Novel Approach to Increase Human Islet Cell Mass While Preserving β-Cell Function

Abstract

Human islet expansion in monolayer culture leads to loss of function and senescence. By maintaining the 3-D configuration of islets in fibrin gels, it is feasible to expand ␤-cells in response to hepatocyte growth factor (HGF) while preserving physiologic glucose responsiveness both in vitro and in vivo after transplantation into nude mice. Islets were cultured free floating with or without growth factors and nicotinamide and in fibrin gels with the same conditions. Proliferation was observed only in islets cultured in fibrin gels and the cocktail; total insulin increased by threefold, with a concomitant increase in ␤-cell mass by morphometry. Insulin release after glucose challenge was also preserved. Islets in fibrin gels gave rise in vivo to large grafts rich in insulin and glucagon, and grafts from free-floating islets were smaller with fewer endocrine cells. Circulating human C-peptide levels were higher than in the mice receiving free-floating islets. In summary, fibrin allows for HGF-mediated cell proliferation while preserving glucose responsiveness in an environment that preserves cell-cell contacts. Limited islet ex vivo expansion under these conditions may improve recipient-donor tissue ratios to equal the functional results of whole-organ transplants. Diabetes 51: 3435-3439, 2002

Sustained insulin secretory response in human islets co-cultured with pancreatic duct-derived epithelial cells within a rotational cell culture system

“…However, there are limitations because of the nature of the biomaterials employed. While several of the more effective substrates support longterm glucose responsiveness in vitro, the use of these materials poses technical problems for the retrieval of cells for subsequent transplantation [16], and if co-transplanted, the poor rate of vascularisation within such artificial scaffolds would inevitably impede the flow of nutrients and metabolites within the islet graft, leading to central necrosis and cell death [17]. Thus, whilst effectual in vitro, the use of artificial matrices is at present incompatible with clinical islet transplantation and must await further development.…”

Fibrin supports human fetal islet-epithelial cell differentiation via p70s6k and promotes vascular formation during transplantation

“…Previous reports indicate that culturing human adult islets in fibrin for 1 week followed by transplantation of the cells resulted in improved graft size, reduced ductal structures, and significantly increased c-peptide levels compared with animals that received free-floating cultured islets. 25 It was postulated that the angiogenicpromoting effects of fibrin are what led to such results. These effects have also been observed when a fibrin hydrogelislet composite was subcutaneously transplanted in mice.…”

“…28 Indeed, transplantation of human fetal pancreatic cells into athymic diabetic mice leads to normo-glycemia 29 and the use of fibrin may assist in graft survival and function. 25,30 Therefore, the objective of this study is to analyze whether fibrin can promote human fetal pancreas differentiation and proliferation in vitro and in vivo as well as the potential mechanisms involved. We hypothesize that fibrin will promote differentiation of human fetal pancreatic progenitor cells into insulin producing cells through integrin αVβ3 receptor upregulation, and stimulate angiogenesis and cell proliferation.…”

“…24 Furthermore, three-dimensional (3D) fibrin culture of isolated human islets significantly enhanced β cell function and survival. 25 Fibrin is able to support a 3D cellular environment 26 and promote angiogenesis, 27 which may be beneficial for human fetal pancreatic islet cell growth and maturity during culture and/or transplantation. 7 Transplantation of human fetal pancreata has been suggested as a treatment alternative for diabetes due to its reduced immunogenic nature.…”

Gene Therapy Progress and Prospects: Gene therapy for diabetes mellitus

“…Transfer of the gene for these proteins increased islet numbers, size and insulin content at least partly through decreased apoptosis. [56][57][58] This approach aims at enhancing islet yield for transplantation and could be an adjunctive measure for optimizing cadaveric islet transplantation. Clinical trials on this approach have not been reported.…”