[Islet cell and pancreas transplantation in diabetes: status 1996]

Replacement of the patient's islets of Langerhans either by pancreas transplantation or by isolated islet transplantation is the only treatment of type I diabetes mellitus to achieve an insulin-independent, constant normoglycemic state. The penalty for this benefit is the need for immunosuppressive treatment in the recipient with all its potential risks. Thus, indications for pancreas or islet transplantations at present exist almost only in patients with end-stage renal disease waiting on dialysis for a kidney graft or in diabetics with already established kidney graft being and going to be obligated to immunosuppression for this reason, respectively. Pancreas transplants alone are primarily performed in only highly selected non-uremic patients with extreme problems of the diabetes. Recent studies demonstrated that pancreas transplantations finally delay the progression of diabetic secondary complications and probably prolong patient's life expectancy. Furthermore, there is no doubt on the dramatic improvement of quality of life. However, pancreas transplantation confers a certain risk and has its complications whereas islet transplantation is a rather minor procedure associated with only small risk, if any. Islet transplantation offers the possibility to alter in vitro the islet immunogenicity and antigenicity, to induce an immunotolerant state or to encapsulate the islets so as to introduce only temporary immunosuppressive treatment of the recipient or to obviate the need for immunosuppression after islet allo- or xenotransplantation. The effectiveness of this concept was demonstrated in animal experiments and may successfully be transferred into the clinical situation. In that case the indications for islet transplantations may be extended to nonuremic type I diabetics including diabetic children. This group of patients is ultimately targetted at by this treatment concept. But, up to now, islet transplantations have been performed only simultaneously to or after kidney transplantations. However, the progress during the last years period has provided evidence that islet transplantation may in principle establish insulin independence also in man albeit prolonged insulin independence has been achieved in only a small number of cases. The state-of-the-art of clinical islet transplantations in type I diabetes mellitus is presented based on a recent analysis of the data of the International Islet Transplant Registry kept in Giessen. Our own experience at the Giessen Transplant Center with transplantations of isolated adult islets of Langerhans in type I diabetic patients is supplementary provided.