Pigs and other animals that are genetically engineered to produce organs which will not be rejected by human patients are a real possibility in the near future, according to Paul Corris, a respiratory consultant, at the Freeman Hospital in Newcastle upon Tyne.
The lungs of a transgenic pig, which has had its genes manipulated to produce human proteins on the surface of its lung, could soon be used in clinical trials, he said, adding that the technology would be available within a decade.
American surgeons have already used monkey hearts as short-term transplants, but Dr Corris believes it will be ethically more acceptable to use a domestic animal, such as a pig, which although not as related to man can be 'humanised' to prevent tissue rejection. 'Pigs are a compromise in terms of being closely enough related to man to make it possible in terms of size. At the same time society is used to eating pigs.'
Dr Corris said work was already under way in smaller animals to perfect the techniques that are necessary to make a pig's lung acceptable for transplantation. 'All the cells (of a transplanted organ) have little markers on them that the recipient's immune system can recognise as foreign,' he said.
The genetic engineers aim to change these markers and make them more human. 'You're actually kidding the human immune system that you're putting in something that is 'like' rather than something that is 'different'.'
In Britain there are between 120 and 150 heart-lung transplants and single lung transplants each year. There are about 250 patients on waiting lists due to the shortage of suitable lungs. 'The lung is more vulnerable to trauma and infection than other organs used in transplantation,' Dr Corris said. They can only be stored for about six hours after the death of a donor.
In addition to genetically engineering pigs to provide more lungs for transplants, scientists are trying to develop new drugs that will make tissue rejection of transplanted organs less likely.
Baroness Thatcher, the former Prime Minister, and Lord Armstrong of Ilminster, a former Cabinet Secretary, were criticised at the meeting for acting as advisers to the tobacco industry. Lord Armstrong has been recruited to the board of British American Tobacco and Baroness Thatcher has been associated with Philip Morris Inc, the company that makes Marlboro cigarettes.
Professor John Moxham, a respiratory researcher at King's College School of Medicine in London, said it was 'appalling' that the industry was recruiting people with 'influence and knowledge' to help market a lethal product.
British Association for the Advancement of Science: