Hybrid Embryo Research Endorsed

The idea of blending human and animal DNA to make "chimeric" embryos for research has long been contentious in the United States, where such experiments are legal if conducted without public funding.

In April 2005, the National Academies -- chartered by Congress to advise the nation on matters of science -- released a report affirming that scientists should be allowed to create such entities if the experiments are approved by special review boards. The advisers came down against the creation of human-monkey or human-ape embryos, as well as experiments in which a human-like brain might develop in a non-human animal.

Legislation introduced in the Senate and House would ban the creation of animal-human hybrid embryos even with private monies -- a move that has raised concerns from scientists and patient support groups in part because it would criminalize an entire branch of biomedical research.

In November, Sen. Sam Brownback (R-Kan.) introduced the Human-Animal Hybrid Prohibition Act, which would amend the federal criminal code to penalize anyone who creates or attempts to create an embryo with human and non-human tissue. It has 18 co-sponsors, including presidential candidate John McCain (R-Ariz.). In April, Rep. Christopher H. Smith (R-N.J.) introduced a companion bill.

Sean Tipton, a spokesman for the American Society for Reproductive Medicine, applauded the British move, saying it "will move science forward by explicitly allowing some research while perhaps bringing some comfort to the public because it will be well overseen."

Staff writer Rick Weiss in Washington contributed to this report.