US scientists fear that President George Bush's decision to limit publicly funded human embryonic stem-cell research to existing cell lines could put universities at the mercy of private suppliers.
Last week's ruling followed months of deliberation in which officials weighed the field's promise against opposition from religious groups.
But US researchers said that restricting research to current cell lines could allow organisations holding them, many of which are biotechnology firms, to extract onerous licensing terms. It could also drive more top US scientists abroad to countries with more liberal laws on stem-cell research.
The National Institutes of Health offered legal advice to help universities strike deals.
Douglas Melton, professor of molecular and cell biology at Harvard University, said the NIH must do more to prevent commercial interests hijacking research. "The time is ripe for the president to bring his influence to bear on suppliers. Depositing cells with the NIH to be distributed with boilerplate (licensing) agreements would give unrestricted rights to researchers," he said.
Advocates of more public funding outlined plans to roll back White House restrictions. Republican senator Arlen Specter said he would proceed with a bill to fund more embryonic stem-cell derivation. Mr Bush said he would veto such legislation.
Sue Shafer, assistant vice-chancellor for research at the University of California, San Francisco, said the funding caveats maintain the threat that US stem-cell researchers might defect abroad. UCSF lost its top researcher, Roger Pedersen, to Cambridge University last month.
Peter Andrews, of Sheffield University, was the first UK researcher to work with animal stem cells. He said: "The advantage for UK scientists remains the clearer legal environment for work with ES cells and the ability to derive new lines."
Three UK groups, at Newcastle, Sheffield and Edinburgh universities, are licensed under the Human Fertility Act of 1990 by the Human Fertilisation and Embryology Authority to derive stem cells from human embryos for research into infertility and birth defects.
The terms of the act were extended in January to cover the understanding and treatment of disease. The Centre for Genome Research at Edinburgh has sought a licence under the new terms and is awaiting approval from the HFEA's licensing committee. Professor Andrews said his group planned to apply also. Professor Pedersen will work on established stem-cell lines until his HFEA licence is approved.
But UK research could still face difficulties. Although new legislation allows therapeutic cloning, the HFEA can grant licences only for research using surplus IVF embryos pending the completion of a judicial review.
The Pro Life Alliance, an anti-abortion group, has challenged the Department of Health, saying the Human Fertility Act of 1990 is inadequate to cover cloning.
The alliance has also argued that the HFEA is not the right body to oversee stem-cell research given that once stem cells have been removed from an embryo, they are no longer under the authority's jurisdiction.
In Canada, the Institutes of Health Research are expected to deliver regulatory guidelines for federally funded researchers on the use of embryonic stem cells by the end of this year.
Its discussion paper recommended that projects using embryonic and foetal tissue stem cells should be fundable only if they first go through an ethical review and that researchers should not be allowed to create embryos.
- The University of Wisconsin is to sue Geron Corporation over intellectual property rights to embryonic stem cells developed with funding from the biotechnology company, which, in exchange, got commercial rights to develop the university's five stem-cell lines.