Prospects for xenotransplantation of the liver.

A severe shortage of human livers for allotransplantation has sparked interest in the potential use of animals in lieu of humans as a source of livers, that is xenotransplantation. Xenotransplantation might also provide a means by which recurrence of hepatitis might be averted. Among the types of xenografts that might be undertaken are extracorporeal "xenoperfusion" or perfusion of devices containing xenogeneic hepatocytes, auxiliary liver transplants, bridge liver transplants, and hepatocyte transplants. The hurdles to xenotransplantation of the liver include the immune response of the recipient against the graft, incompatibility of the graft with complex physiologic and biochemical systems of the recipient, and the possibility of transferring infectious agent from the graft to the recipient. Recent progress in characterizing and overcoming these hurdles has encouraged some optimism regarding the ultimate application of xenotransplantation for the treatment of human disease.