Xenotransplantation using pigs as the transplant source holds great promise to resolve the severe shortage of human organ donors. Although stem-cell-derived organ and tissue regeneration have a potential to solve this as well for the future, it still remains as very early experimental phase. Likewise, artificial organs and mechanical devices have been simply used for bridge therapy to transplant. Therefore, xenotransplantation might provide the most imminent solution to the scarcity of human organ donors. In the last two decades, major progress has been made in understanding the mechanisms of xenografts rejection, zoonotic infections including porcine endogenous retrovirus (PERV) and production of genetically engineered pigs including α1,3-galactosyltransferase-deficient pigs. With these elaborations, it is now on the threshold of first clinical application. Particularly promising first target is porcine pancreatic islet xenotransplantation. Graft survival has been prolonged to almost one year in the non-human primate study and is waiting for the development of relatively non-toxic or clinically applicable immunosuppressive or tolerance-inducing regimens. This review highlights the currently known obstacles to translate xenotransplantation into clinical therapies and the possible strategies to overcome these hurdles, as well as current status and future perspective for clinical xenotransplantaion.

Keywords: Xenotransplantation, Porcine, Islet transplantation, Transplant rejection, Immune tolerance