The long term objective of this research is the development and introduction to medical practice of an effective biocompatible implantable hybrid artificial endocrine pancreas which is capable of significant improvement in the therapy of insulin dependent diabetes. The specific aim of this proposal is to extend and modify CTI's proprietary process for cellular encapsulation to the islets of Langerhans, using a coextrusion method in which the islet tissue is enclosed within the polymeric membrane capsule at the time of its formation. The proposed research program will define conditions of macro-capsule containing physiologically-responsive insulin secreting endocrine tissue. Development of this technology may permit the efficacious use of animal cells in an immunoisolated environment for the early treatment of insulin dependent diabetes and thus impact positively on the prevention of the debilitating secondary complications associated with the disease.