New technologies for bioartificial organs.

Abstract

Each year several hundred thousand Americans die because of organ failure. Organ transplantations have achieved remarkable success, but the source of human organs is limited. Only a small portion of patients can benefit annually from this method of treatment. Immunoisolated living cells as bioartificial organs can be transplanted into humans without the need for immunosuppression and its accompanying side effects. Immunoisolation allows cells from nonhuman species to be used, thereby overcoming the limited supply of human cells available for encapsulation, and the capsule can serve as an ideal cage to keep animal viruses from contacting the human host. To achieve this promise, we have incorporated the pore size distribution into a new design of capsule for the immunoisolation of living cells. In this model the capsule wall is thicker and the pores are bigger than in the current systems. The larger pores will allow the immune system to enter the membrane, and the smaller pores inside the membrane will act as the traps to prevent or delay most of the immune system from passing all the way through to the inner volume of the capsule where the living cells reside. Limited animal studies have supported the advantages of this new entrapment model over the current model. Systematic studies to determine optimal capsule design for human transplantation are now feasible.