Improved transgenic organs for transplant from animals to humans may result from controversial cloning experiments currently under way.
Researchers at the Roslin Institute and PPL Therapeutics in Scotland this week introduced the world's press to Dolly, a seven-month-old lamb who is an identical clone of her mother.
Dolly was created by scientists at Roslin, part of the Biotechnology and Biological Sciences Research Council, who took a cell from the udder of her genetic mother and implanted that in another sheep's egg from which the nucleus had been removed. The resulting embryo was grown inside a third sheep.
The breakthrough could offer long-term help to scientists trying to produce transgenic animals and even transgenic organs for transplantation to humans, says Dr Ron James, PPL chief executive. But it also raises ethical questions.
PPL is doing trials with milk from transgenic sheep. The milk contains a human protein which is expected to help cystic fibrosis sufferers. These sheep have been bred normally with human DNA injected into the single sheep cell. But in only 5 per cent of cases does the divided cell incorporate the protein correctly. Dr James says that by cloning genetically manipulated adult cells, the task of setting up a founder population, with identical genetic material, would be made more efficient.
Genes can be taken from, as well as added to cells. In the long term, says Dr James, it may be possible to remove certain genes, for example those which, when in sheep milk, cause allergies in some babies, and clone a founder population from which to breed.
Ian Wilmut, leader of the research team at the Roslin Institute, added that the use of such techniques on humans would face "enormous technical and practical difficulties and it would be socially unacceptable."
PPL says it has established collaborative links with the Royal Postgraduate Medical School in London and is at the earliest stages of looking at transgenic pig organs.