Isolation, banking, encapsulation and transplantation of different types of Langerhans islets.

INTRODUCTION The discovery of a cure for diabetes is a dream of many medical researchers. The transplantation of Langerhans islets is a potential treatment of choice for patients with type 1 diabetes as a source of endogenous insulin for the recipient. OBJECTIVES The aim of the experiment was to transplant Langerhans islets without immunosuppression. To protect the grafts against transplant rejection, semipermeable membranes could be used. MATERIAL AND METHODS Langerhans islets were isolated from rats and pigs and immunoisolated by encapsulation in alginate-protamine-heparin (APH) or alginate-poly-L-lysine-alginate (APA) membranes. Islets were pooled in a controlled manner. Tests for cryopreservation and biocompatibility were also performed. RESULTS The capsules coated with APH are more resistant than the capsules coated with APA. After transplantation of the islets immunoisolated with APA, euglycemia is maintained longer than after transplantation of the islets immunoisolated with APH. Microencapsulation protects the islets from destruction by the host. CONCLUSIONS It is feasible to treat experimental diabetes by transplantation of encapsulated Langerhans islets without immunosuppression.