Islet transplantation for diabetes: current status and future prospects

There has been an explosion of interest in developing transplantation strategies to replace the islets lost during the normal progression of diabetes. In large part, the renewed interest is due to the unprecedented success of the 'Edmonton protocol' for Type I diabetics following islet allografting and a modified immunosuppressive regimen. While these data provide a clear and unequivocal demonstration that islet transplantation is a viable treatment strategy, the shortage of suitable donor tissue, together with the debilitating consequences of life long immunosuppression necessitate a concerted effort to develop novel means to enable islet transplantation on a widespread basis. This review outlines several of these possibilities including the development of novel, less toxic immunosuppressants, tolerising the host immune system to accept islet transplants, developing alternative sources of islet cells via gene therapy, stem cell technologies and xenotransplantation, immunoisolation of islets and providing local immunosuppression to islet grafts using Sertoli cells. These possibilities are highlighted in the context of islet cell transplantation as a success, but with need for further refinements before it is a panacea for most patients.