Islet transplantation in the subcutaneous space achieves long-term euglycaemia in preclinical models of type 1 diabetes

The intrahepatic milieu is inhospitable to intraportal islet allografts^1–3, limiting their applicability for the treatment of type 1 diabetes. Although the subcutaneous space represents an alternate, safe and easily accessible site for pancreatic islet transplantation, lack of neovascularization and the resulting hypoxic cell death have largely limited the longevity of graft survival and function and pose a barrier to the widespread adoption of islet transplantation in the clinic. Here we report the successful subcutaneous transplantation of pancreatic islets admixed with a device-free islet viability matrix, resulting in long-term euglycaemia in diverse immune-competent and immuno-incompetent animal models. We validate sustained normoglycaemia afforded by our transplantation methodology using murine, porcine and human pancreatic islets, and also demonstrate its efficacy in a non-human primate model of syngeneic islet transplantation. Transplantation of the islet–islet viability matrix mixture in the subcutaneous space represents a simple, safe and reproducible method, paving the way for a new therapeutic paradigm for type 1 diabetes.