Transplantation of pancreatic islets.

The currently limited supply of human pancreatic glands, and the fact that multiple glands may be required to isolate sufficient numbers of islets to treat a single patient, indicate that techniques must be further developed and refined for xenografting of isolated islets from animal sources to diabetic patients. An increasing body of evidence using immunoisolation techniques strongly suggests that this will be achieved during the next few years. Several different types of systems employing selectively permeable membranes and matrix supports for cells have been successfully tested in animals, including devices anastomosed to the vascular system as arteriovenous (AV) shunts, tubular membrane chambers, and spherical micro- and macrocapsules. Results in diabetic animals indicate that these systems can function for periods of several months to > year without the use of any immunosuppression. Our data suggest that this approach has the potential not only to allow the transplantation of islets across wide species barriers, but that it can be achieved using injectable microreactors fabricated from biodegradable polymers. The use of these various immunoisolation systems to transplant islets and other cells and tissues offers the opportunity to revolutionize current therapy for many human disease.