The potential of genetically engineered pig heart transplantation in infants with complex congenital heart disease.

Despite advances in surgical and medical techniques, complex congenital heart disease in neonates and infants continues to be associated with significant mortality and morbidity. More than 500 infants in the USA are placed on the cardiac transplantation wait-list annually. However, there remains a critical shortage of deceased human donor organs for transplantation with a median wait-time of 4 months. Hence, infant mortality on the heart transplant wait-list in the USA is higher than for any other solid organ transplant group. Orthotopic transplantation of a pig heart as a bridge to allotransplantation might offer the best prospect of long-term survival of these patients. In recent years, there have been several advances in genetic engineering of pigs to mitigate the vigorous antibody-mediated rejection of a pig heart transplanted into a nonhuman primate. In this review, we briefly highlight (i) the history of clinical heart xenotransplantation, (ii) current advances and techniques of genetically engineering pigs, (iii) the current status of pig orthotopic cardiac graft survival in nonhuman primates, and (iv) progress toward pursuing clinical trials of cardiac xenotransplantation. Ultimately, we argue that pig heart xenotransplantation should initially be used as a bridge to cardiac allotransplantation in neonates and infants.