A world apart.

This is the first of a 3-part series on the controversial issue of xenotransplantation. After two failed attempts in 1992 the possibility of using animals to supply organs for human transplant receded and the procedure was halted in 1997. But as increasing numbers of patients die while waiting for a human kidney, the idea of xenotransplantion is again attracting interest. Two major problems are the danger of transferring animal viruses to humans and the response of the human immune system to the foreign organ. The programme offers a detailed picture of how a pig farm dedicated to producing transplant organs would be managed. Prof. Robin Weiss (University College, London) comments that a sterile environment for the pigs would not eliminate viruses inherent in their DNA. Also, immunosuppression in the patient to prevent rejection of the animal organ would be breaking down barriers designed to protect humans against animal viruses. However, shortly before xenotranpslant surgery was halted, two patients in Texas were given life support after liver failure by means of pig livers attached outside their bodies. (There is film of this procedure, at a German hospital, in the final programme of the series, Man-Made Pigs.) They were supported in this way for 3 days, until human organs were available. With the donor organ shortage forcing attention once more on the possibility of using animals, one biotechnology company is experimenting with pigs, inbred to eliminate pig viruses. Depending on the success of animal cross-species transplant experiments, xenotranplant experiments could be resumed.