Xenotransplantation: state of the art.

Today, at the beginning of the xenogeneic era of transplantation, only simple and single observations about comparative physiology and biochemistry, and even anatomy, are known. Very few data exist which in addition inform about mechanisms after successful xenotransplantation. Nothing is known about phenomena following successfully suppressed hyperacute xenogeneic rejection. Neither the elimination of single factors nor the mitigation of whole systems have led to clinically relevant survival times. Pig organs transplanted into nonhuman primates survived a maximum of 22 days. The hope that transgenic manipulation and modification would be useful to prolong survival times of xenogeneic grafts still waits for evidence. But, within a short time, xenotransplantation could enable patients to receive a life-saving animal organ as an alternative to an allograft. Xenotransplantation would, as a new dimension in medicine, shorten if not eliminate waiting lists. Therefore, scientists must vigorously develop xenografting as a viable alternative for transplantation.