xenotransplant

Animal to human transplant. Animals used as organ and tissue sources include pigs and primates. Transplants carried out (with varying degrees of success) include heart, kidney, liver, bone marrow, fetal neural tissue (to treat Parkinson's disease), and fetal islet tissue (for diabetes). The first xenotransplants took place in 1964 (pig heart valves in the UK; chimpanzee kidneys in the USA).

Clinical trials were halted in the USA in 1995 because of fears that diseases could be spread from animals to humans but in 1996 an advisory panel concluded that the benefits were such that this risk was justified. The use of primates as donors was ruled unethical in the UK 1996.

US researchers called for a ban on transplants from pigs in 1997, following the discovery that pigs can carry a virus that can be passed to humans but in 1998 the US Food and Drug Administration (FDA) announced that there would be no moratorium on xenotransplantation. However in April 1999 the FDA announced that there would be a ban on clinical trials involving xenotransplantation from non-human primates to humans (clinical trials involving pig cells will still take place in the USA). In October 2000, the Organization for Economic Cooperation and Development (OECD) and the World Health Organization (WHO) outlined proposals for a watchdog to be set up to monitor trials and to study the risks of xenotransplantation.