An immunoisolatory vehicle for the implantation into an individual of cells which produce a needed product or provide a needed
metabolic function. The vehicle is comprised of a core region containing isolated cells and materials sufficient to maintain the cells, and a permselective, biocompatible,
peripheral region free of the isolated cells, which immunoisolates the core yet provides for the delivery of the secreted product or
metabolic function to the individual. The vehicle is particularly well-suited to delivery of
insulin from immunoisolated islets of Langerhans, and can also be used advantageously for delivery of high molecular weight products, such as products larger than IgG. A method of making a biocompatible, immunoisolatory implantable vehicle, consisting in a first embodiment of a coextrusion process, and in a second embodiment of a stepwise process. A method for isolating cells within a biocompatible, immunoisolatory implantable vehicle, which protects the isolated cells from
attack by the
immune system of an individual in whom the vehicle is implanted. A method of providing a needed
biological product or
metabolic function to an individual, comprising implanting into the individual an immunoisolatory vehicle containing isolated cells which produce the product or provide the metabolic function.