THE SITUATION: Islet transplantation stands as a promising curative treatment for type 1 diabetes. Improvements of this still experimental procedure were recently obtained through the modification of the immunosuppressive regimen and the increase of the islet mass delivered to the patient. Several centers have now reported rates of insulin-independence of 80% and beyond after one year, although these cohorts of patients are limited, and the results restricted to experienced centers.
Technical aspects: Islet isolation relies upon enzymatic digestion of the pancreas, transplantation is peformed through transhepatic portal vein catheterism, a strong steroid-free immunosuppression is needed.
Limitations: Immune rejection and recurrence of diabetic autoimmunity are major obstacles, requiring a potentially harmful immunosuppression. Viability of pancreatic islets must be improved, since over 50% of cells are non specifically destroyed after their injection. The reproducibility of the islet isolation procedure is insufficient. The major question is the optimal source of tissue, as pancreas donors are scarce.
Indications: Islet transplantation is now considered not only for patients needing immunosuppression for another transplantation (most often kidney), but also for patients with labile diabetes, recurrent life-threatening hypoglycemia or ketoacidosis, responsible for severe deterioration of the quality of life.
Conclusion: In order to reduce the waiting lists of diabetic patients and to improve benefits/risks of the process, progress is required in the fields of organisational strategy, immunomodulation, and research on adult and embryonic stem cells.