Reversal of diabetes by xenotransplantation of monkey pancreatic islets in rats: an ultrastructural study.

OBJECTIVES: Transplantation of pancreatic islets is considered a potential curative treatment of type 1 diabetes. Electron microscopy plays a major role in the evaluation of pancreatic islets. The aim of this study was to study the reversal of diabetes by xenotransplantation of monkey pancreatic islets into diabetic recipient by functional and structural findings. METHODS: Islets of Langerhans were isolated from monkeys by collagenase digestion method. Two days after the induction of diabetes in rats with streptozotocin, diabetes was confirmed. Freshly isolated islets were transplanted under the renal capsule of the diabetic rats. The recipients received cyclosporin A (30 mg/kg) every day. Fasting plasma glucose was estimated on days 3, 7, and 14 after transplantation. The presence of glucose and ketone in urine was checked. After 14 days, the grafts were removed and processed for light and electron microscopic study. RESULTS: After the induction of diabetes, the mean fasting plasma glucose was 347.20 mg/dL. On day 3 after transplantation, the mean fasting plasma glucose value was 100 mg/dL. The mean fasting plasma glucose was 94.6 mg/dL on day 7 and 94.8 mg/dL on day 14. Histology of the monkey islet grafts after 14 days showed the survival of pancreatic islets. Ultrastructure of the same grafts showed the presence of alpha, beta, and delta granules similar to those of native pancreatic islets with the other cellular organelles. CONCLUSION: The diabetic state of rats can be reversed by xenotransplantation of isolated monkey islets. Ultrastructural study confirms the normal synthesis and release of islet hormones. The released insulin from transplanted monkey islets had lowered the plasma glucose level of recipient rats.