Disclosed herein are devices, methods, and compositions for delivering a therapeutic, e.g., a cell or a therapeutic agent. Disclosed is a device comprising a membrane and a population of non-native pancreatic β cells, wherein said non-native pancreatic β cells exhibit an in vitro glucose-stimulated insulin secretion (GSIS) response to a glucose challenge. Disclosed is a method of treating a condition comprising: placing a device disclosed herein in a subject in need thereof In some cases, said device is configured to remain in said subject for a period of more than six months, said condition is a chronic disease. In some cases, said chronic disease is diabetes.
