BBC News | Allowing scientists to carry out stem cell research using hybrid human-animal embryos “is a step too far and should be banned”, the Commons has been told.
Senior Tory MP Edward Leigh said there was “no evidence yet to substantiate” the claims this could lead to treatment for Parkinson’s and Alzheimer’s.
Gordon Brown has urged MPs to back the work, saying it is a “moral endeavour” that could save thousands of lives.
MPs are voting on a series of reforms to embryology laws that date from 1990.
The measures, part of the Human Fertilisation and Embryology Bill, are aimed at updating laws in line with scientific advances.
They will be voted on in the House of Commons over the next two days.
Ex-minister Mr Leigh opened the debate on Monday, with an amendment prohibiting outright the creation of hybrid “admixed” embryos.
He said he believed the move was “ethically wrong and almost certainly medically useless, and if not useless, there is no evidence yet to substantiate it”.
The bill would allow regulated research using hybrid or “admix” embryos, where the nuclei of a human cell are inserted into an animal egg.
The resulting embryos would be kept for up to 14 days to harvest stem cells.
But Mr Leigh said: “We do not believe that regulation is enough. We believe this is a step too far and therefore should be banned.” “In embryos, we do have the genetic make up of a complete human being and we could not and should not be spliced together with the animal kingdom.”
Labour’s Chris Bryant, a former Anglican curate, said Mr Leigh’s arguments were like those used by church leaders against the smallpox vaccine.
“They were wrong and I think you are wrong today,” he said.
In a separate amendment, Tory shadow health minister Mark Simmonds is calling for true hybrids, made by fertilising a human egg with animal sperm, or visa-versa, to be outlawed.
MPs are being given a free vote on four controversial parts of the bill after warnings that some Catholic MPs and cabinet ministers were ready to rebel.
The other three areas are:
- Saviour siblings: These are babies born from embryos selected because they are a tissue match for a sick older brother or sister with a genetic condition. Debate on Monday from about 1830 BST, with vote at about 2200 BST.
- Role of fathers in fertility treatment: Would end the requirement for IVF clinics to consider the “welfare” of any child created in terms of need for a father. Debate from 1530 BST Tuesday, with vote at about 1830 BST.
- The upper limit for abortion: Amendments have been put down to the bill to cut from 24 weeks the time limit for abortions. Debate on Tuesday from 1830 BST, with votes at about 2200 BST.
The Roman Catholic Church has branded the use of hybrid embryos as “monstrous” and says tinkering with life in this way is immoral.
Catholic bishops in Britain and the Irish Republic have given £25,000 to scientists using adult stem cells, which is less controversial than using immature ones.
Such cells can be used to create brain, skin, heart and other tissue for treating diseases.
After making a strong personal case for using hybrid embryos at the weekend, Mr Brown is expected to be backed on this part of the bill.
Writing in the Observer newspaper, Mr Brown called on MPs to back the use of hybrid embryos, saying such scientific advances could speed up treatment for cancer and conditions such as Parkinson’s and Alzheimer’s disease.
“The scientists I speak to are committed to what they see as an inherently moral endeavour that can save and improve the lives of thousands and over time, millions,” he said.
Mr Cameron said he would be voting in favour of admix embryos and the creation of saviour siblings.
Speaking as he visited Birmingham, he said: “My own approach to this is the law needs updating and the importance of science and research and getting to grips with genetic disease… I want to see the research go forward.”
However, he said he would be voting “against some of the things that won’t be necessary”.
Leading medical research charities, including the Wellcome Trust and the Medical Research Council, have issued an open letter also urging MPs to back such research, saying advances in the “understanding and treatment of diseases must not be closed down”.
Scientists at Newcastle University announced last month that they had created the first part-human, part-animal hybrid embryos in the UK.
They were created by injecting DNA derived from human skin cells into eggs taken from cows’ ovaries which had had virtually all their genetic material removed.
Researchers say these human-animal “admixed” embryos could help solve the current problem of the lack of human eggs from which to generate embryos.
The vote on hybrid embryos and “saviour siblings” will take place on Monday, while the vote on the role of fathers in IVF treatment and abortion limits will be held on Tuesday. If the proposals are approved, the new legislation could come into force next year.