Xenotransplantation - Nuffield Council on Bioethics
Xenotransplantation - Nuffield Council on Bioethics
Xenotransplantation - Nuffield Council on Bioethics
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Animal-to-Human Transplants : the ethics of xenotransplantati<strong>on</strong><br />
understood. Nevertheless, the UK company Imutran Ltd have announced their<br />
intenti<strong>on</strong> to start trials transplanting transgenic pig organs into human patients in<br />
1996. 38 <str<strong>on</strong>g>Xenotransplantati<strong>on</strong></str<strong>on</strong>g> of pig fetal neural tissue is currently taking place in<br />
the US. 39<br />
C<strong>on</strong>clusi<strong>on</strong><br />
3.36 To date, attempts to treat people by xenotransplantati<strong>on</strong> have not been successful.<br />
There has been recent progress in overcoming some of the difficulties in preventing<br />
xenograft rejecti<strong>on</strong>, but many obstacles remain. Despite advances in the effectiveness<br />
of immunosuppressive drugs, the levels of immunosuppressi<strong>on</strong> required to prevent<br />
rejecti<strong>on</strong> of primate xenografts leave patients susceptible to lethal infecti<strong>on</strong>s. 40 The<br />
small size of primate organs is also likely to cause problems. Where xenotransplantati<strong>on</strong><br />
of pig organs is c<strong>on</strong>cerned, the first problem is to c<strong>on</strong>trol hyperacute rejecti<strong>on</strong>.<br />
The most promising approach is the development of transgenic pigs c<strong>on</strong>taining<br />
human proteins that inhibit the complement reacti<strong>on</strong> to a xenografted organ. Even<br />
if hyperacute rejecti<strong>on</strong> can be c<strong>on</strong>trolled, there will be other immunological barriers<br />
to acceptance of the xenograft by the recipient. There may also be biochemical and<br />
physiological incompatibilities between pig organs and human beings.<br />
3.37 The current attempts to develop xenotransplantati<strong>on</strong> raise the questi<strong>on</strong>s whether the<br />
use of animals to provide organs and tissue for transplantati<strong>on</strong> is acceptable and, if<br />
so, how their welfare can best be taken into account. These questi<strong>on</strong>s are discussed<br />
in Chapters 4 and 5.<br />
38<br />
Pig-to-human heart transplant slated to begin in 1996 (1995) Nature Medicine, 1:987.<br />
39<br />
Parkins<strong>on</strong>’s pig cure. The Times, 15 December 1995.<br />
40<br />
Starzl T et al. (1994) Clinical xenotransplantati<strong>on</strong>. Xenotransplant, 1:3-7.<br />
36