British scientists are to submit plans to create a hybrid embryo — part human, part cow.

They are to develop a way of creating stem cells that does not require human eggs, but the application seems likely to be met with controversy.

The team, from the University of Newcastle, would take a cow’s egg and remove the nucleus. They would then replace it with the nucleus of a cell taken from an adult human, such as a skin cell.

The hybrid would be overwhelmingly human — 99.9 per cent, according to the team, led by Lyle Armstrong, of the North East England Stem Cell Institute. The other 0.1 per cent would be animal.

The embryo would then be allowed to divide for six days, when the team would try to extract stem cells, which have many potential applications in medicine. The hybrid embryo would be destroyed, as all research embryos are, at 14 days.

The application will be made to the Human Fertilisation and Embryology Authority, although it is by no means clear that the research falls within its remit. Some experts claim that hybrids, because they are not 100 per cent human, are outside the law under which the HFEA was established.

In 2000 Sir Liam Donaldson, the Chief Medical Officer, recommended that the mixing of human adult cells with the live eggs of any animal species should not be permitted.

This was accepted by the Government, which said that it would bring forward primary legislation to effect this “when the parliamentary timetable allows”. No such legislation has been through Parliament, although the Government announced a review of the Human Fertilisation and Embryology Act last November.

The Select Committee on Science and Technology of the House of Commons disagreed with Sir Liam, saying that hybrids formed by nuclear transfer — the technique planned by the Newcastle team — may have value for deriving embryonic stem cells for research.

It recommended that any new legislation should define the nature of such embryos, make their creation legal for research purposes if they are destroyed after 14 days and prohibit them from being implanted in a woman.

Dr Armstrong said: “We are very hopeful that the HFEA will grant us permission for this work, which will help us to understand more about how cells behave after the nuclear transfer process.

“At the moment we don’t know if the nuclear transfer process works well enough in humans to create useful embryonic stem cells. We need to carry out many tests to establish this and, as animal eggs are freely available, it makes sense to use these. Stem-cell research promises huge potential medical advantages and we believe we will be working towards our ultimate goal of developing new patient therapies.”

Teams at the University of Edinburgh and Kings College London plan to seek permission for similar work. The HFEA said that it had yet to receive the Newcastle application, and could therefore not comment on it. But it indicated that, given the different opinions expressed on the subject of hybrids, any such application would require careful thought.

Dr Armstrong said that while there was still uncertainty whose responsibility it was, “If it isn’t the HFEA’s, I don’t know whose it is.” He said that it would be a valuable piece of research, aimed at discovering what it is about an egg cell that is able to “reprogramme” an adult cell so that it returns to an embryonic condition.

He said: “Human eggs are in short supply, and most come from women who are undergoing IVF. It’s a much better use of a scarce resource to use them to help them have children.” Cows’ eggs had been chosen, he said, because they are large enough to be easily manipulated, unlike those of, say, a mouse.

CELL HISTORY

The North-East England Stem Cell Institute was given a licence in July that allows women to cut the cost of IVF treatment if they donate some of their eggs for cloning research

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