Medicine needs hybrid embryos, scientists say

The Government's intention to ban experiments with hybridised animal-human embryos has come under fierce criticism from MPs, scientists and a phalanx of medical charities.

A letter delivered today to Tony Blair from 223 medical research charities warns that a ban on the creation of "chimera" embryos will hamper efforts to develop effective treatments for many incurable conditions. Scientists have proposed taking DNA from human skin cells and merging it with the cytoplasm - the non-nucleus part of the cell - of the unfertilised egg of a rabbit or cow.

They want to create stem cells from cloned embryos for studying conditions such as Parkinson's disease and motor neurone disease. However, the Human Fertilisation and Embryology Authority (HFEA) has postponed a decision on awarding licences until the Government clarifies its threat to ban such research.

Sophie Petit-Zeman, from the Association of Medical Research Charities, said that there is an overwhelming consensus about the need for such research among medical charities involved with financing studies into serious diseases.

"To our knowledge, a letter to government signed by 223 medical research charities and patient organisations is unprecedented. These groups are urging the Government to sanction research which has the potential to offer vital insights," Dr Petit-Zeman said.

The letter comes on the same day that the Science and Technology Committee of the House of Commons criticises the Government and the HFEA for their opposition to research using chimera embryos.

"We find that the creation of human-animal chimera or hybrid embryos, and specifically cytoplasmic hybrid embryos, is necessary for research," the committee says in its report published today. "We are critical of the HFEA for delaying assessment of applications for licences to create cytoplasmic hybrid embryos for research."

Official concern goes back to a report in 2000 by experts led by Sir Liam Donaldson, the Chief Medical Officer. The report said: "The use of eggs from a non-human species to carry a human cell nucleus was not a realistic or desirable solution to the possible lack of human eggs for research or subsequent treatment."

A subsequent public consultation exercise by the Government attracted about 300 responses, of which 277 were opposed to such research - although the majority were from organised lobby groups.

Nevertheless, the scale of the opposition led the Department of Health to propose a ban, although a White Paper on reforming the Human Fertilisation and Embryology Act confusingly allowed for the creation of hybrid embryos "under licence" for research purposes.

The science and technology committee's report, however, questioned whether the consultation was truly representative.

"We regard the consultation exercise as deeply flawed. All it did was count numbers," said Phil Willis, the Liberal Democrat MP for Harrogate and Knaresborough, who chaired the Commons select committee. "This is a test of the Government's commitment to science. We very much hope that the department will listen and reflect on the committee's conclusions when the draft Tissue and Embryos Bill is published next month," he added.

The Royal Society and other scientific organisations have lent their support to moves to prevent the ban from being included in the forthcoming legislation. Sir Richard Gardner, who is chairman of the society's stem cell working group, said that the embryos should be permitted for the benefit of future research.

"The technique to create human-animal cytoplasmic hybrids ... has only emerged in the past five years," Sir Richard said. "We do not know what possibilities might emerge in the next five years so it is vital that new legislation can accommodate scientific breakthroughs," he said.

Three groups of scientists are known to want licences. Two have had their applications postponed and the third is expected to make an application once the present situation is clarified.

Chimeras: what, how and why

What is a chimera embryo?

A chimera is an organism comprising cells from two different species. In this case, the genetic material of the animal has been almost entirely removed so the embryo is 99.5 per cent human. Technically, the animal-human embryo is neither a chimera nor a hybrid, it is a "cytoplasmic hybrid embryo", or "cybrid".

How are these hybrid embryos created?

The nucleus of an unfertilised egg cell from a rabbit or cow is removed, leaving a shell filled with the cell's non-nuclear cytoplasm. A nucleus from a human skin cell is injected and stimulated with electricity to form a cloned human embryo.

Why do scientists want to create such embryos?

There is a shortage of human eggs. Scientists want to create embryonic stem cells from these embryos. If the human cells are from a Parkinson's patient or someone suffering from motor neurone disease, the resulting stem cells could be used to develop nerve tissue or brain cells, thereby providing an experimental "model" to test treatments.

What are the objections?

Some say that it demeans animals. Others argue that it demeans human life because each embryo is a potential human being. There is no evidence to suggest that the chimeras would ever develop normally in the womb, and in any case, it would be illegal to allow them to develop beyond 14 days.

Is this research allowed elsewhere?

China is leading the way, having already created stem cells from human embryos created from rabbit eggs.

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