Clinical studies of human islet transplantation.

Recent advantages in techniques for the isolation of human pancreatic islets of Langerhans have led to the introduction of clinical trials of islet transplantation in diabetic patients who are already immunosuppressed because they have received a kidney transplant for end-stage renal failure. This paper describes the techniques used and the outcome in three diabetic patients who have received intraportal islet transplants. The first two patients received islets pooled from multiple cadaveric organ donors, the third patient received islets from a single well major histocompatibility complex (MHC) matched donor. The islet grafts in the first two patients failed rapidly, almost certainly due to rejection. The islet graft in the third patient continues to function after 18 months. Taken together with the worldwide experience, the results of this small series suggest that islet transplantation from a single well MHC matched donor may be optimal. For this approach to be a realistic option, techniques for islet isolation need to be further improved so that large numbers of islets can be regularly isolated from a single pancreas. The collagenase digestion phase of the islet isolation process is the major limiting factor and this area requires further detailed research.