A retrievable implant for the long-term encapsulation and survival of therapeutic xenogeneic cells

The long-term function of transplanted therapeutic cells typically requires systemic immune suppression. Here, we show that a retrievable implant comprising of a silicone reservoir and a porous polymeric membrane protects human cells encapsulated in it after implant transplantation in the intraperitoneal space of immunocompetent mice. Membranes with pores 1 µm in diameter allowed host macrophages to migrate into the device without the loss of transplanted cells, whereas membranes with pore sizes under 0.8 µm prevented their infiltration by immune cells. A synthetic polymer coating prevented fibrosis and was necessary for the long-term function of the device. For over 130 days the device supported human cells engineered to secrete erythropoietin in immunocompetent mice as well as transgenic human cells carrying an inducible gene circuit for the on-demand secretion of erythropoietin. Pancreatic islets from rats encapsulated in the device and implanted in diabetic mice restored normoglycaemia in the mice for over 75 days. The biocompatible device provides a retrievable solution for the transplantation of engineered cells in the absence of immunosuppression.