Transplantable bioartificial pancreas devices: current status and future prospects

Islet transplantation has become a valuable therapy for patients with diabetes mellitus type 1.However, only selected patients with exhausted insulin therapy characterized by instable metabolic control and repeated severe hypoglycemia are transplant candidates. This strict indication is mainly due to the requirement for lifelong immunosuppression and the critical shortage for donor organs. Therefore, numerous research activities address these issues in order to provide beta cell replacement therapy to a broader cohort of patients with diabetes. The encapsulation of pancreatic islets within mainly alginate-based macro- or microcapsules withvarious physical configurations may allow protecting the islet graft without the need for immunosuppressive agents and moreover expanding the donor pool to animal tissue and novel insulin-producing cells. Despite major advances in encapsulation technology, a significant translation into clinical application is not evident. There are still issues that need to be resolved associated with graft oxygenation, immunprotection, inflammatory response, material biocompatibility, and transplantation site to list some of them. The recent advances in xenotransplantation and particularly in the field of stem cell-derived beta cells have generated a renewed scientific interest in encapsulation. This review aims to provide an overview on current encapsulation technologies as a treatment modality in cell replacement therapy for type 1 diabetes.