GalT knockout pig to baboon xenotransplantation

The success and widespread acceptance of clinical allotransplantation has led to a shortage of cadaveric organs and a resurgence of interest in xenotransplantation. Although swine are generally regarded as the preferred source of xenogeneic organs, the severe immunologic response to swine organs has so far precluded their clinical use. However, we have recently obtained pigs not expressing the alpha 1,3-galactosyltransferase gene (GalT-KO swine). We have reported initial results using GalT-KO swine as donors to baboons which demonstrated survival of a life-supporting renal graft for up to 83 days without rejection when combined with a regimen designed to induce tolerance by vascularized donor thymic grafts. Although further improvements will be needed to warrant a clinical trial of xenotransplantation, the initial results are encouraging. In addition to genetic modification of donor pigs, it is hoped that our tolerance-inducing regimen will allow successful clinical xenotransplantation by overcoming additional xenogeneic immunological barriers.