Cardiac xenotransplantation: Clinical experience and future direction

The shortage of human organs has focused research on finding an animal sour ce of replacement organs. The immunological barriers to xenotransplantation are now more clearly defined, allowing retrospective interpretation of pas t clinical experience in humans. Due to physiological compatibilities as we ll as ethical and infectious considerations, pigs have now emerged as the m ost likely source of future xenografts. The introduction of transgenic pigs expressing human complement regulatory proteins and new immunosuppressive regimens have shown early promise in the laboratory, although further advan cements are needed to advance to clinical trials. Additional clarification of infectious risks and patient strategies are remaining obstacles to appli cation in the clinical arena. (Ann Thorac Surg 2000;70:320-6) (C) 2000 by T he Society of Thoracic Surgeons.