The UK government has nixed a proposed ban on the creation of human-animal hybrids, clearing the way for embryologists to create hybrid embryos for stem cell research.
It has instead proposed a draft bill - the Human Tissue and Embryos Bill - that would allow the creation of embryos composed of 99.9 per cent human, 0.1 per cent animal DNA.
Health Minister Caroline Flint says the move is not a "climbdown". She argues that the White Paper that called for a ban on such hybrids was only calling for a "general prohibition", and had always left open the possibility of research to be sanctioned on a case-by-case basis.
According to reports, Flint said: "I honestly don't see this as a back flip...it was an evaluation of a number of different view points. Our position was not to stop this research but to be clear that it's sensitive research, and we have to be sure about what we're going to permit to happen in the future."
The bill still prohibits "true" animal human hybrids - fertilised eggs created by the fusion of sperm and eggs from different species. But it allows for chimeras - the introduction of animal DNA into a human embryo, as well as the creation of cytoplasmic hybrid embryos.
But by removing the outright ban, the bill will free stem-cell research from its dependence on donated human eggs. Researchers hope that with access to a more plentiful supply of research embryos, they will be able to refine therapeutic cloning techniques before working on the more difficult to obtain, purely human embryos.
Last November, researchers applied for permission to implant human DNA into cows eggs, effectively creating a human-bovine hybrid. The resulting embryo would then be grown for a few days, before the stem cells would be harvested and the embryo destroyed.
Under the terms of the bill, all hybrid embryos would have to be destroyed after a maximum of 14 days, and it would be illegal to implant them into the womb. ®