Pig organ transplants 'too risky' for humans

The prospects for animal to human transplants - once held out as the solution to the worldwide shortage of donor organs - have been thrown into doubt after a government watchdog declared that it may never be possible to protect the public from the danger of infection with animal viruses.

The prospects for animal to human transplants - once held out as the solution to the worldwide shortage of donor organs - have been thrown into doubt after a government watchdog declared that it may never be possible to protect the public from the danger of infection with animal viruses.

In its third annual report, the UK Xenotransplantation Interim Regulatory Authority (UKXIRA), set up by the Government to monitor the research, says the use of animals for transplants has not lived up to its early promise.

Drug companies have scrambled to invest in the new technology, which was predicted to be worth billions of pounds. But UKXIRA says safer technologies, such as those based on stem cell research using human embryos, may ultimately yield greater benefits. Transplant patients who receive pigs' hearts and lungs risk passing an unknown number of animal viruses to the general population.

The report said: "The evidence of efficacy [for xenotransplantation] has not advanced at the rate predicted ... The likelihood of whole-organ xenotransplantation being available within a worthwhile time-frame may be starting to recede. Stem cell technology may yet provide alternative solutions to any or all of the conditions mentioned above."

The regulator was set up by the Government three years ago to oversee the development of animal-human transplantation. Reviewing the latest research, it concluded that it was "prudent" to assume that the risks to humans from animal viruses existed.

The report said: "The potential for infectious agents to be passed from the source animal, via the transplant, to human recipient and from the patient into the wider population is still a major concern.

"Until such time as research is able to produce more definitive answers on safety ... it is prudent to assume that all forms of xenotransplantation carry a risk of some degree."

A breed of "humanised" pigs with a human gene to help transplant patients stop rejecting their organs has been bred in Britain although no clinical trials of animal-human transplants have so far been conducted in this country.

Five years ago the British company Imutran - now owned by the multinational drug company Novartis - took the world by surprise when it said it was ready to put a pig's heart into a human. But the report said the early promise about the potential for the technology have not been borne out by tests.

Sarah Kite, of the British Union for the Abolition of Vivisection, said: "There has been a lot of scientific hype leading people to believe that successful animal transplants are just around the corner. But now the regulator is saying that this is not the case and there are serious concerns about safety."

MPs last night said that animal-human transplantation was no longer a viable alternative to solve the shortage of human organs for transplant.