Hybrid embryos could be created within months!
Hybrid embryos containing both human and animal material could be created in British laboratories within months.
The controversial research was given a green light yesterday by the UK's fertility regulator.
A shortage of human eggs led scientists to seek permission to make hybrid embryos from human skin cells and animal eggs such as those from cows, which are plentiful in slaughterhouses.
Research: An embryo created in a laboratory
Two teams of scientists are poised to start making cow-human hybrids for research into incurable diseases, with at least one project expected to start by the end of the year.
Stem cell expert Dr Stephen Minger, who wants to use the embryos to study conditions such as Alzheimer's, Parkinson's and motor neurone disease, said the work could "revolutionise drug discovery".
But the decision by the Human Fertilisation and Embryology Authority is likely to be subject to a High Court challenge, with opponents claiming the watchdog is not entitled to rule on the issue.
Josephine Quintavalle, of the campaign group Comment on Reproductive Ethics, said last night: "There is a sense from some people that scientists should never be stopped in their tracks.
"Reproduction with animals has been taboo since the beginning of recorded time and that taboo has remained with us for a reason.
"This is tampering at a very basic level."
Quest: Stephen Minger
Britain is one of the first Western countries to approve such research.
The creation of hybrid embryos is banned in Australia and many European countries but experiments have been carried out in the Far East and the research is allowed in Canada.
The process involves removing the genetic material from the animal egg and replacing it with human DNA.
After being kick-started by an electric current, the egg would develop into an embryo from which stem cells - the body's master cells - can be harvested.
Such cells would be made available to scientists around the world to study the causes of disease and develop potential treatments.
The embryos, known as cytoplasmic, would be more than 99 per cent human.
They would have to be destroyed after 14 days and could not be implanted into women.
Scientists' hopes of using such hybrids were initially jeopardised by plans to outlaw such research under a shake-up of the ageing fertility laws.
But in May, Ministers dramatically changed their minds, with a draft bill approving the creation of hybrids for research into serious diseases as long as it is carried out by scientists licensed by the HFEA.
Yesterday, the HFEA, which is being asked to rule on two applications by scientists before the new law comes into force, approved the creation of hybrids in principle.
The final go-ahead on applications from researchers at King's College, London, and the North East Stem Cell Institute in Newcastle will rest with the authority's licence committee, due to meet in November.
Should it approve the applications, the research in Newcastle is likely to start almost immediately, while the London scientists hope to conduct their first experiments next summer.
The highly complex and labour-intensive nature of the process means that thousands of cow eggs could be used over many months to create just one hybrid embryo.
Critics say there is little evidence such intricate work will yield results and vehemently oppose the destruction of embryos that will be an inevitable part of the experiments.
Comment on Reproductive Ethics is considering a legal challenge based on the belief that the wording of current fertility laws does not give the HFEA the right to rule on the issue.
Anthony Ozimic, of the Society for Unborn Children, said there were 'grave ethical and moral objections' to the research.
"All the evidence suggests these embryos are essentially human," he said. "Yet, they will be cannibalised and killed for their stem cells.
"Patients with degenerative diseases are being exploited.
"They and their families are being sold lies and false hope by the profit-hungry biotech industry."
But Dr Minger, of King's College London, says the work is an essential part of the quest to find new drugs and therapies for devastating illnesses.
He said: "Our techniques could be also be used for various forms of cancer, for cystic fibrosis, for muscular dystrophy.
"If I was someone with Alzheimer's disease, I would say: 'What are they worrying about?'.
"The research is going to be tightly regulated by the HFEA. No cows are going to be killed, the cell lines are only going to be used for research and the embryos aren't going to be implanted."
Dr Belinda Cupid, of the Motor Neurone Disease Association, said: "There is currently no cure for motor neurone disease but allowing the use of hybrid embryos in research may revolutionise future treatment of the disease and other degenerative neurological conditions.
"The case for the use of human-animal hybrid embryos in stem cell research is compelling as it holds the potential to save lives."
The HFEA says a consultation showed the public were "at ease" with the idea when told it could pave the way for therapies for conditions such as Alzheimer's.
Although the embryos are sometimes called chimeras, after the monstrous creatures in Greek mythology, they are technically hybrids.
Chimeras contain two types of cell - one from each "parent" - while the hybrids have only one, in which the genetic material is mixed.