Advances in Cell Replacement Therapies for Diabetes

Islet cell replacement therapies have evolved as a viable treatment option for type 1 diabetes complicated by problematic hypoglycemia and glycemic lability. Refinements of islet manufacturing, islet transplantation procedures, peritransplant recipient management, and immunosuppressive protocols allowed most recipients to achieve favorable outcomes. Subsequent phase 3 trials of transplantation of deceased donor islets documented the effectiveness of transplanted islets in restoring near-normoglycemia, glycemic stability, and protection from severe hypoglycemia, with an acceptable safety profile for the enrolled high-risk population. Health authorities in several countries have approved deceased donor islet transplantation for treating patients with type 1 diabetes and recurrent severe hypoglycemia. These achievements amplified academic and industry efforts to generate pluripotent stem cell-derived β-cells through directed differentiation for β-cell replacement. Preliminary results of ongoing clinical trials suggest that the transplantation of stem cell-derived β-cells can consistently restore insulin independence in immunosuppressed recipients with type 1 diabetes, thus signaling the profound progress made in generating an unlimited and a uniform supply of cells for transplant. Avoiding the risks of chronic immunosuppression represents the next frontier. Several strategies have entered or are approaching clinical investigation, including immune-isolating islets, engineering immune-privileged islet implantation sites, rendering islets immune evasive, and inducing immune tolerance in transplanted islets. Capitalizing on high-dimensional, multiomic technologies for deep profiling of graft-directed immunity and the fate of the graft will provide new insights that promise to translate into sustaining functional graft survival long-term. Leveraging these parallel progression paths will facilitate the wider clinical adoption of cell replacement therapies in diabetes care.