Project Summary/Abstract Diabetes is an increasingly important health problem worldwide. Despite recent advances in diabetes care, including long-acting insulin formulations, insulin pumps, and continuous glucose monitors, a majority of diabetic patients cannot achieve currently recommended targets for blood glucose control. Although transplantation of diabetic patients with donor-derived pancreatic islets or intact pancreas effectively restores blood glucose control, such procedures remain rare due to limited source material and the requirement for life-long immunosuppression. To circumvent the first of these obstacles, Regenerative Medical Solutions (RMS) has developed a proprietary protocol for converting induced pluripotent stem cells (iPSC), a virtually unlimited cell source, into islet-like clusters (ILC) of cells that include insulin-producing beta-like cells. To eliminate the need for immunosuppression, iTolerance, Inc, has advanced a product consisting of Fas ligand conjugated microparticles (iTOL-100) that, when co-transplanted with rodent or primate islets, create localized immune tolerance and provide long-term protection from allograft rejection in animal models of diabetes. In this proposed project, RMS will work with the Diabetes Research Institute at the University of Miami to test a combined product consisting of ILC mixed with iTOL-100 as a candidate cell-based diabetes therapeutic that will alleviate the need for life-long immunosuppression. To establish the feasibility of such a combined product, we will first demonstrate in vitro cytocompatibility of the two products (ILC and iTOL-100). Next, the in vivo cytocompatibility and therapeutic efficacy of the combined product will be verified in an immunocompromised mouse model of diabetes. Finally, the ability of the combined product to delay the xenograft rejection response in immune competent diabetic mice will be determined. Together, these studies will lay the groundwork for a Phase II project in which the combined product will be tested for its ability to evade allograft rejection in mice reconstituted with a human immune system, along with other essential studies that will enable clinical translation. The availability of an abundant beta cell-replacement therapy that does not require chronic immunosuppressive medication for long-term allograft tolerance will extend the reach of this form of treatment to the ever-growing numbers of patients who may benefit from it.