Medical researchers are to be allowed to create embryos that are part-human and part-animal after the Government yesterday dropped a proposed ban following a revolt by scientists, charities and patients.

Ministers have accepted that the controversial work should be allowed to go ahead, as first reported by The Times in February, clearing the way for experiments that promise insights into incurable conditions such as Alzheimer’s and motor neuron disease.

A White Paper published in December proposed to outlaw almost all research in which human and animal material are fused to make embryos, provoking outrage in the scientific community.

Though the draft Human Tissues and Embryos Bill published yesterday still includes language that would block this work for now, the document signals clearly that ministers no longer want this to happen.

They have invited an all-party parliamentary scrutiny committee to revise the legislation. The new position has been reflected in the appointment of the panel’s chairman. Phil Willis, the Liberal Democrat MP, also chairs the Commons Science and Technology Committee, which last month issued a scathing report opposing any ban.

The committee will consider whether the Bill should be amended so that most human-animal experiments are permitted under licence from the Human Fertilisation and Embryology Authority (HFEA) or whether separate regulations are needed. Such regulations would be presented to Parliament at the same time as the Bill.

Scientists would be allowed to create “cytoplasmic hybrids” or “cybrids”, in which human DNA is added to an empty animal egg to form an embryo that is 99.9 per cent human.

Two British teams have already applied to the HFEA for permission to do this, to produce laboratory models of diseases such as Alzheimer’s. The regulator is currently consulting the public before ruling.

Chimeras, in which animal cells are added to human embryos, would also be permitted, as would transgenic human embryos with added animal DNA. Only true hybrid embryos, formed when animal sperm fertilise a human egg or vice versa, would be illegal.

The legislation would also exclude embryos that contained more animal than human DNA, which would remain subject to Home Office animal experimentation laws. This resolves concerns that laboratory animals with human genes, such as mice bred as models of Down’s syndrome, could be inadvertently outlawed.

Caroline Flint, the Health Minister responsible for the Bill, said that while the Government had refined its position and clarified language, it had never intended to ban human-animal research. “I honestly don’t see this as a backflip,” she said. “I suppose it’s the difference between saying ‘no, but’ and ‘yes, but’.”

Scientists and patient groups welcomed the Government’s support for the work but questioned why it had not lifted the threat of a ban already.

The original White Paper was widely criticised by scientists as unnecessarily proscriptive, prompting 44 experts including three Noble laureates to write a letter of protest to The Times. It also caused divisions within Government, as the Department of Trade and Industry and Sir David King, the Chief Scientific Adviser, opposed any ban. Sir David said that he was satisfied with the new arrangements.

Hybrid rules

Cytoplasmic hybrid or cybrid Definition Embryo created by placing the nucleus of a human cell into an empty animal egg Proposal Permitted under licence from the HFEA

Human transgenic embryo Definition Human embryo altered by the introduction of animal DNA Proposal Permitted under licence from the HFEA

Human-animal chimera Definition Human embryo altered by the introduction of animal cells Proposal Permitted under licence from the HFEA

True human-animal hybrid Definition Embryo created by fertilising a human egg with animal sperm, or vice versa Proposal Banned, except for testing the viability of human sperm

Transgenic animals Definition Animals or animal embryos altered by the introduction of human DNA Proposal Permitted, subject to Home Office animal experiment regulations

Source: Department of Health

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