Approaching the clinical application of xenotransplantation.

Interspecies transplantation or xenotransplantation is seen increasingly as a potential approach to overcoming the severe shortage of human organs and tissues for transplantation. Much has been learned recently about the immunologic hurdles of transplanting porcine organs into humans. These hurdles can be addressed, in part, by the genetic engineering of donors and by specific therapies directed at the salient immune events. As we succeed in dealing with the immunologic aspects of xenotransplantation, other issues, including zoonosis, and regulatory aspects will need to be addressed.