Tolerance, xenotransplantation: future therapies

Solid organ transplantation is limited by an insufficient number of organs to meet the needs of a growing population of patients with end-organ failure. A second problem is that, after successful transplantation, many organs fail owing in large part to chronic immunologic injury or so called "chronic rejection". In other circumstances, the organ "outlives" the recipient, often because the recipient succumbs to medical conditions related to chronic immunosuppression. This review focuses on two future therapies that could solve these problems, specifically, tolerance induction to permit long-term patient and graft survival and xenotransplantation to provide an unlimited supply of donor organs. The primary focuses are the most promising ongoing transplantation research that could be encountered by clinical surgeons in the near future.