Objective: We all know that the inadequate blood supply is likely contributors to islet death in the immediate posttransplant period and may impair islet survival and function in the long term. One direct reason is that microvascular of the islet are disrupted during islet isolation. Thus, improvement of revascularization of transplanted islets may enhance islet survival and the outcomes of islet transplantation. Heparin, used to inhibit coagulation in clinical islet transplantation, can improve revascularization in the fields of therapeutic angiogenesis. Our hypothesis is to bind heparin on the surface of islet by avidin-biotin technique will improve islet revascularization and decrease risk of bleeding resulting from using heparin systemically. Methods: Rat islets were incubated with tissue factor-P biotin ,avidin and heparin sequentially. The degree of heparinization of the islets was visualized by confocal microscopy. The viability of islet before and after heparinization was tested by AO/PI staining. Insulin secretion in response to glucose stimulation was assessed by a dynamic perfusion system. Heparinized or untreated control islets were transplanted under the kidney capsule in a syngeneic transplantation model. After transplantation, blood glucose and glucose tolerance test was measured. The mean microvascular density under kidney capsule was calculated at the end of the experiment. Results:The fluorescence observed by confocal microscopy certified that islet surface was coated by the heparin completely. The results of AO/PI staining revealed above 92% of the cells were viable, and there was no significant difference of viability between heparinized and control islets. The response to glucose stimulation in heparinized islets is similar with the control, which confirmed that the normal islet function was not affected by the heparinization procedure. After transplantation, heparinized islets lead to superior glucose control and to tolerance as compared with the control islets. The microvascular density of heparinized group was markedly higher than that of the control(13.49[0.81]vs 9.78[0.94],P=.04).Conclusion: islet coated by heparin improved revascularization in islet transplantation without toxicity for islets.

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