The promise of xenografting.

Advances in understanding the rejection of foreign tissues has renewed enthusiasm about the possibility of overcoming the present organ shortage by transplanting porcine kidneys into humans. Currently, three known forms of organ rejection stand as obstacles to xenotransplantation as a clinical reality--hyperacute rejection, acute vascular rejection, and cellular rejection. Progress in the knowledge of xenoreactive antibodies and of complement, along with new transgenic technologies, have enabled researchers to overcome hyperacute rejection in xenografts. The advances have brought into focus such issues as the ability of the porcine kidney to replace the physiologic functions of the human kidney and the risk associated with the potential transmission of infectious agents from animals to humans. Despite the remaining hurdles to clinical application of xenotransplantation, the rapid pace of research and emerging technologies would seem to make xenotransplantation a renal replacement therapy of great promise.