Functional porcine islets, free of known pathogens, can serve as a source of insulin producing cells for the treatment of experimentally induced insulin dependent Diabetes Mellitus. Porcine islets can be conformally coated (microencapsulated) with a covalently linked, stable permselective membrane while maintaining islet viability and function. The PEG conformal coating is immunoprotective in a discordant xenograft animal model (porcine islets to rat). [on SciFinder (R)]