Improved survival and function of rat cryopreserved islets by coculture with sertoli cells

In order to investigate how to improve the function and survival of cryopreserved islets, we cocultured cryopreserved thawed rat islets with rat Sertoli cells. After thawing, the islets were divided into the Sertoli cell coculture group and the control group. Using light and transmission electron microscopes, we examined the morphology of islets and measured their apoptosis index (AI) and insulin release stimulation index (SI). Moreover, we measured apoptosis protein and mRNA by western-blot and reverse transcription polymerase chain reaction and cytokine concentrations in supernatant by ELISA. We examined islet graft survival time in diabetic mice and detected insulin in grafts by immunohistochemistry. We found that the morphology, AI, and SI of the coculture group were all significantly improved. The relative expression levels of cleaved caspase-3 P20, P11, and caspase-7 in the coculture group were lower than those in the control group. Compared with the control group, the expression level of Bax was decreased, but that of Bcl-2 was increased. After transplantation, islet survival in the coculture group was similar to that of fresh islets but longer than that in the control group. These results suggest that coculture with rat Sertoli cells significantly improves the yield and function of rat cryopreserved thawed islets by effectively reducing islet apoptosis.