Immune system suppressing drugs such as cyclosporin have made human organ transplantation possible by restricting attack on the transplanted organ while sparing the immune system's most life-saving benefits. But the challenges facing researchers trying to adapt animal organs for transplantation into humans, a process called xenotransplantation, are much more steep. Duke University scientists are systematically evading the immune system's defenses to make xenotransplantation a practical option for the almost 4,000 people who die each year waiting for human organs. The prospect of using animal organs to save people is a goal Duke immunologist Jeffrey Platt believes is worth pursuing. He is looking to pigs, an animal that supplies humans with food and leather, for that ready organ supply.
Surgeons already use pig heart valves to replace human heart valves that wear out.
In addition, much is already known about raising pigs, and there is a ready supply of the animals. The idea of using animal organs as substitutes for failing human organs has been attempted in the past. The results were dismal. Within minutes, an animal organ is recognized and targeted by protein sentries that circulate in the blood. These sentries flag the animal tissue and set in motion a cascade of events, involving the complement system, that cut off the blood supply to the organ and basically starve it to death.