IN-VITRO AND IN-VIVO EVALUATION OF PROTAMINE HEPARIN MEMBRANE FOR MICROENCAPSULATION OF RAT LANGERHANS ISLETS

Rat pancreatic islets were microencapsulated with multilayer protamine -heparin (PH) membrane. Basal and stimulatory insulin secretion of mic roencapsulated islets was similar to the controlled free islets in vit ro. During the long-term culture (up to 2 weeks) mean insulin release of encapsulated islets did not significantly differ from the mean of f ree ones (the ratio of mentioned means was 54-167%). Empty PH microcap sules transplanted into Wistar rats intraperitoneally and under the ki dney capsule were generally harmless up to 4 months. In only a few cas es traces of fibrotic tissue around capsules entrapped in the omentum were found. No damage of microcapsules structure was observed. The wor st results were obtained in the instance of retroperitoneal transplant ation. We conclude, therefore, that PH membrane was proved to be highl y biocompatible, nontoxic for islets, and did not impair viability and glucose-dependent insulin secretion of Langerhans islets in in vitro culture.