In developing countries, the problem is even worse because resources are in far shorter supply. At the meeting, held in Geneva on Oct. 30, Professor Jeffrey Platt of Duke University said every conceivable way to increase the amount of organs available for transplant in the United States has been tried but all have fallen well short of the demand. Platt denied that the need for organs could be met by using dialysis and other mechanical procedures. While recent xenotransplant attempts used organs and tissue from baboons, most of the current focus is on genetically altered pigs. Pigs have internal organs that are large enough for humans, and they breed rapidly.
Pigs also raise fewer ethical concerns than primates since they are already consumed for food.
Scientists think they have found a way avoid the severe rejection that usually accompanies an organ or tissue transplant from animal to human. By developing pigs that carry a human gene, researchers believe that organs taken from the hybrid animals will not be attacked by the recipient's immune system. The experts said they also had discussed with scholars of Islam and Judaism the implications of introducing pig tissue into those who follow these faiths. The scholars told them that the Koran and the Old Testament speak about the pig only in dietary terms and do not forbid introduction of porcine material for other reasons. There are still concerns among scientists about the risk of infections crossing species barriers.