Xenotransplantation

The success of organ transplantation has led to an ever-increasing shortfall between the demand for organs and the supply. This has led to extensive investigation of the possible use of animals, especially the pig, as organ donors. However, a number of major barriers to successful xenotransplantation exist. These include immunological, physiological, anatomical, infectious and ethical problems. Of the immunological problems, the most immediate is hyperacute rejection of the organ caused by natural cytotoxic antibodies in man directed at the galactose alpha-1,3-galactose antigen present in all mammals except man, old world monkeys and the great apes. It is in this area in which genetic engineering has been applied most assiduously and essentially this problem is solved, at least in theory. However, many other problems remain to be resolved before xenotransplantation is likely to become a clinical reality.