There are many more individuals with end stage kidney failure, heart failure, chronic lung disease, or liver failure who would benefit from a transplanted kidney, heart, lung or liver than are available. Similarly, there are many people with unstable, difficult to control diabetes that could benefit from a ready source of pancreatic insulin-producing islet cells.
Today the only option for more organs available for transplant is to encourage more individuals to pre-certify their desire for organ donation should they die in a traffic or other accident.
But another approach, still in the future but gaining traction, is to use organs from an animal – known as xenotransplantation.
Most efforts in xenotransplantation focus on the pig, in part because the organs are near to the same size as humans and the physiology is similar. Very real progress has been made in recent years. The steps required to make this approach effective include genetic modification of the pig so that the human immune system will no longer “reject” the transplanted organ. This has included removing the genes that produce the most important pig carbohydrate antigen that human immune cells recognize. Another step has been to add genes that create certain protective proteins in the complement regulatory system (another part of the body’s mechanism to eradicate “foreign” materials like bacteria, viruses or a cancer.) So far, these steps have been major advances but not sufficient so further efforts will be necessary in order for say, a pig heart or kidney to be successfully transplanted into a primate and eventually into a human. But the progress is real, exciting and promising. Stay tuned.