Islet transplantation: a realistic alternative for the treatment of insulin deficient diabetes mellitus

Abstract

Diabetes mellitus is a devastating disease and the WHO [World Health Report, World Health Organization, 2002] (World Health Organization) expects that the number of diabetic patients will increase to 300 million by the year 2025. Type 1 diabetes results from an autoimmune-mediated destruction of the insulin-secreting beta-cells in the islets of Langerhans of the pancreas, whereas Type 2 diabetes is a disease of the older population which is due to systemic insulin resistance and reduced insulin secretion by the pancreatic beta-cells. Surgical resection of the pancreas may also cause insulin-dependent diabetes depending on the size of the remaining pancreas. The long-term complications of diabetes are a direct result of the constantly elevated levels of blood glucose in the absence of an effective insulin treatment. Recent prospective studies such as the diabetes control and complication trial (DCCT) [N. Engl. J. Med. 329 (1993) 977] and the UK prospective diabetes study [Lancet 352 (1998) 837] have convincingly demonstrated that improved blood glucose control in all type diabetes reduces the risk of the development of the secondary complications of diabetes. Despite intensive insulin therapy, most individuals with insulin deficient diabetes are unable to maintain a blood glucose level in the normal range at all times. Therefore, the only way to ensure the long-term health of patients with diabetes is find a way of maintaining constant normoglycemia. It seems logical that the replacement of the islet tissue itself, either by transplanting a vascularized pancreatic allograft or by transplanting purified pancreatic islet cells, offers a better approach than simply replacing insulin that has been lost. In this article, we outline the major achievements made recently in the development of therapeutic islet transplantation applications and offer an explanation as to why islet transplantation seems to be an ideal solution for absolute insulin deficient diabetes.