Another presidential veto loomed on federal funding for embryonic stem cell research in the US this week after Congress gave final approval to the Stem Cell Research Enhancement Act of 2007.

The bipartisan 247-176 vote in the House of Representatives was still short of the two-thirds majority needed to override a presidential veto on the legislation, which would ease the current tight restrictions on federal support for stem cell research using discarded human embryos. President Bush has already vowed to scotch the bill, saying it “puts scientific research and ethical principle into conflict.”

The legislation, cleared on a 63-34 vote by the US Senate in April, revives the Stem Cell Research and Enhancement Act of 2005. The previous version also made it through the Senate and House with bipartisan majorities but was vetoed by President Bush in July 2006. The reconstituted bill would amend the Public Health Service Act so that the federal government could conduct and support research using human embryonic stem cells, subject to restrictions such as embryos donated by in vitro fertilisation clinics having to be surplus to clinical need.

At the moment, federal backing for embryonic stem cell research in the US is severely restricted under an executive order passed by President Bush in August 2001. This limited government funding to research using the 22 or so embryonic stem cell lines then available for study. Researchers say this restricted pool has now been superseded by new stem cell lines with better potential for therapeutic intervention.

Ethical progression

While the Democrats’ control of Congress has given fresh impetus to efforts to push through legislation that would boost funding for embryonic stem cell research, President Bush is standing firm on his moral objections to the practice. In a statement issued in response to the House vote, Bush said recent scientific developments had “reinforced my conviction that stem cell science can progress in ethical ways.”

“I am disappointed the leadership of Congress recycled an old bill that would simply overturn our country’s carefully balanced policy on embryonic stem cell research,” he commented. “If this bill were to become law, American taxpayers would for the first time in our history be compelled to support this deliberate destruction of human embryos. Crossing that line would be a grave mistake. For that reason, I will veto the bill passed today.”

The president’s stance was bolstered by a report in the UK journal Nature that researchers from the US and Japan had managed to reprogramme fibroblast cells from the skin of mice to their embryonic state. Conspiracy theorists are having a field day with the timing of the Nature announcement, which came just on the eve of the House vote.

A few days before the introduction of the Stem Cell Research Enhancement Act of 2007 in January, Nature Biotechnology published a study indicating that stem cells with potential to replace damaged tissue could be harvested from amniotic fluid in the womb.