Abstract
Although improvements in operative techniques and immunosuppressions have paved the way for increases in the organ donor pool through living donor kidney donations, a vast disparity remains between the number of organs available for transplantation and the demand. Indeed, though progress has been made in the fields of regenerative medicine and stem cell technologies, neither de novo nor regenerated tissues are currently capable of sustaining life in animal models. Xenotransplantation would provide an inexhaustible supply of donor organs. Although there have been reports of severe immunologic response between swine and humans, much progress has been made in the past decade largely because of advances in our understanding of the xenoimmunobiology of pig-to-nonhuman primate transplantation as well as the availability of pigs that have undergone genetic modifications, including the alpha 1,3-galactosyltransferase gene knockout (GalT-KO) swine. The results of preclinical transplantation studies with pig organs or cells have been encouraging when co-stimulatory blockade or more-advanced tolerance-inducing treatment strategies were used. In these studies, the survival times for heterotopic heart grafts were more than a year, for life-supporting kidneys it was approximately three months, and for islets, six months. In this review, we summarize recent progress in the field and discuss strategies for successful clinical trials of xenotransplantation.
