Microencapsulation of pancreatic islet cells: a bioartificial endocrine pancreas.

It was about two decades ago that Chang proposed the use of microencapsulated islets as artificial beta cells. By using alginate-poly(L-lysine)-alginate membranes, biocompatible, durable capsules containing viable islet cells can be produced which are impermeable to cells and effector molecules of the immune system, thus providing a total protection to transplanted islets against rejection. The capsule wall contains 93% (w/w) water and can be classified as a hydrogel. Many hydrogels have gained general acceptance as being biocompatible materials. Microencapsulation of pancreatic islets for use as an artificial endocrine pancreas would not only obviate the need for immunosuppressive therapy but also has the potential to prevent the long-term complications of diabetes. Furthermore, the microencapsulation technique can be applied to other types of cells to produce antibodies or enzymes, and to treat a whole range of diseases requiring endocrine replacement therapy.