Type 1 diabetes mellitus has been treated successfully with whole-organ pancreatic transplant. This is a major operation, with risks of graft vascular thrombosis and graft rejection. Recent interest in isolated pancreatic islet cell transplantation, first reported in 1972, has increased following a Canadian report of the reversal of hyperglycemia in seven consecutive patients. The use of a new immunosuppression regimen and multiple transplants from multiple donors in each recipient appeared to improve outcomes markedly. Unfortunately, the availability of donors is limited, making it imperative to determine how to optimize outcomes while decreasing the number of donors needed. Markmann and associates report their experience with islet cell transplants using the Edmonton, Canada, immunosuppressive regimen.
Nine patients with long-term type 1 diabetes and a history of multiple episodes of dangerous, severe hypoglycemic episodes were given infusions through the portal vein with islets from 15 donors. The same three-drug regimen for immunoprophylaxis that was used by the Canadian group was employed.
Of the seven patients who became insulin-independent, five required a single infusion, while the other two required a second. Of these seven, one patient lost partial graft function after eight months, requiring continued insulin therapy at a lower dosage than was required before the transplantation. No major complications occurred. Mouth ulceration occurred in all patients, with resolution when the dose of rapamycin was reduced. Mild hematologic and liver function abnormalities also were commonly noted. No serious infections occurred.
The authors conclude that single islet cell transplants from one or two donors can achieve insulin independence in persons with type 1 diabetes. Further study is needed to determine the optimal islet cell isolation technique, the transplant technique that maximizes engraftment of transplanted cells, and the safest and most effective post-transplant immunosuppression protocol.