Islet transplantation for type 1 diabetes, 2015: what have we learned from alloislet and autoislet successes?

The therapeutic potential of pancreatic islet allotransplantation, in which human donor islets are used, as a treatment for type 1 diabetes (T1D) has fascinated diabetes researchers and clinicians for decades. At the same time, the therapeutic potential of total pancreatectomy and islet autotransplantation (TPIAT) (in which one's own islets are used) as a preventive treatment for diabetes in patients who undergo total pancreatectomy for chronic, painful pancreatitis has received relatively less attention. This is ironic, since the latter has been much more effective than the former in terms of successful glucose management and duration of efficacy. The reasons for this disparity can be partially identified. TPIAT receives very little attention in textbooks of internal medicine and general surgery and surprisingly little print in textbooks of endocrinology and transplantation. T1D is much more predominant than TPIAT as a clinical entity. Provision of insulin or replacement of islets is mandatory and a primary goal in T1D. Provision of pain relief from chronic pancreatitis is the primary goal of total pancreatectomy in TPIAT, whereas treatment of diabetes, and certainly prevention of diabetes, has been more of a secondary consideration. Nonetheless, research developments in both fields have contributed to success in one another. In this Perspective, I will provide a brief history of islet transplantation and contrast and compare the procedures of allo- and autoislet transplantation from three major points of view 1) the procedures of islet procurement, isolation, and transplantation; 2) the role and complications of immunosuppressive drugs; and 3) the posttransplant consequences on β- as well as α-cell function.