Superiority of Fresh Islets Compared With Cultured Islets

Introduction. It has recently been reported that the outcomes of islet transplantation with short periods of culture are comparable with those of freshly isolated islets. To clarify the influence of culture, fresh islets were compared with cultured islets in terms of quality. Materials and Methods. The quality of freshly isolated islets was compared with that of cultured islets with CMRL 1066 including 10% allogeneic serum, CMRL 1066 including 0.5% human serum albumin, or Miami medium. We evaluated static glucose stimulation tests, insulin/DNA contents, ADP/ATP ratios, and an intraportal transplantation model into syngeneic diabetic rats. The expression of inflammatory mediators in the islets was examined using Western blotting for tissue factor (TF), which is the initiator of detrimental instant, blood-mediated, inflammatory reactions (IBMIR). Results. Although the survival rate was similar in all groups, the stimulation index upon glucose challenge and the insulin/DNA ratio were significantly higher among fresh islets. Most importantly, the expression of TF on islets was significantly lower in fresh islets, suggesting that culture enhanced TF-dependent IBMIR after transplantation. In an in vivo transplantation model, the curative rate and insulin production by the recipient liver was considerably greater in the fresh islet group. Conclusions. Isolated islets without prior culture showed results superior to cultured islets.