Prolonged survival of transplanted islets of Langerhans encapsulated in a biocompatible membrane.

Prolonged survival of islet allografts in streptozotocin-induced diabetic rats was achieved by encapsulating individual islets in protective, biocompatible alginate-polylysine-alginate membranes. A single intraperitoneal transplant of encapsulated islets reversed the diabetic state for up to 1 year. In contrast, a single injection of unencapsulated islets was effective for less than 2 weeks. The microencapsulation procedure, by protecting transplanted tissue from the components of the immune system, has great clinical potential in the treatment of diseases requiring organ transplantation, such as diabetes and liver disease.