BioWorld International Correspondent

LONDON - UK stem cell scientists have headed off government plans to outlaw research on human/animal chimeras when a decision on whether to license the use of enucleated animal eggs to generate human embryos as a source of stem cells was deferred to allow time for a public consultation.

The regulator, the Human Fertilisation and Embryology Authority (HFEA), said it needs time to consult because the law is not explicit and human/animal hybrid research would be a significant step change in UK science.

Two of the UK's stem cell research groups have applied to the HFEA for licenses to carry out such work using rabbits' and cows' eggs.

Embryonic stem cell lines derived by putting the nucleus of an adult human cell into the enucleated oocyte of another mammal would have no therapeutic use. But doing the work would enable researchers to refine and practice cloning techniques. That may make them more successful in working with the scarce resource of human eggs.

Oocytes from animals could be used also to generate disease-specific embryonic stem cell lines for use in drug discovery.

The issue of whether or not to grant those licenses was caught up in an overall review of the UK's fertility laws. More than 500 respondents to a consultation on the wider law objected to granting permission to the use of animal eggs in therapeutic cloning, prompting the government to propose outlawing such research.

On the other hand, the UK's position as the international leader in stem cell research would be compromised by a ban.

There also was a question over whether the matter was within the HFEA's jurisdiction.

In the event, the HFEA decided it does have the right to rule on the matter, but also said there should be a public consultation on that issue specifically.

"The issues around hybrid and chimera research are unique and different from mainstream human embryo research," Angela McNab, chief executive of the HFEA, said in a statement. "They have proved challenging, but as the independent regulator, we have a duty to judge this work under the current law.

"From the evidence considered so far, this issue is far from black and white. There is not clear agreement within the scientific community about the need for and benefits of this science. The [HFEA] felt that it is important that we go through the issues and the science thoroughly and test the claims about the benefits of this research," she added.

"In the light of this," McNab said, "the authority felt it would be wrong to make an immediate judgment on these complex and controversial matters before we have built up a proper body of evidence."

Aisling Burnand, chief executive of the BioIndustry Association, welcomed the decision, saying, "There is widespread scientific and public support for this ground-breaking medical research.

"Preventing the research would dash the hopes of millions of patients," Burnand added. "It would also completely undermine the government's support for stem cell research and its commitment to establishing the UK as a world-leading location for innovative scientific research."

The consultation is expected to be completed in the third quarter of 2007.