Pancreatic islet transplantation--experimental experience and clinical potential.

New theoretic developments in transplantation biology indicate that it is possible to reduce the immunogenicity of a graft by removing antigen-presenting cells (leukocytes) from the tissue before grafting. Also becoming apparent is that cellular replacement therapy, the grafting of cells or clusters of cells, can be used to treat metabolic disorders such as type I diabetes mellitus. In the past, immune rejection has been a major problem and long-term patient immunosuppression is not warranted in patients with type I diabetes. Results of studies in animals show that under defined genetic conditions, mature islet tissue or immature fetal proislets may be transplanted across major histocompatibility barriers without a requirement for recipient immunosuppression. We are now ready to commence applying this technology clinically. These developments will initially be very experimental and limited in scope but should accelerate as data emerge from the initial trials.