Washington

US researchers can at last apply for federal grants to study human embryonic stem cells. The go-ahead came last week when the National Institutes of Health (NIH) published the long-awaited terms under which it will fund such research. In principle, grants submitted now could be reviewed as soon as December and funded in the fiscal year 2001, which starts next October.

The move comes hard on the heels of a similar decision by the British government two weeks ago (see Nature 406, 815 ; 2000). It ends a de facto moratorium on US government support for embryonic stem-cell research, in place since the cells were first cultured successfully two years ago.

But the research allowed by the guidelines could be short-lived. The rules are based on an interpretation of the present laws banning the use of public funds for human embryo research, which could be reversed after this year's presidential elections.

In January 1999, the Department of Health and Human Services said that these laws — which are based on the fact that embryos are destroyed when the stem cells are extracted from them — do not apply to their stem cells, as these are not themselves embryos (see Nature 397, 185; 1999).

In a twist that even some stem-cell supporters find tenuous, the guidelines skirt the destruction issue by funding research only on the cells themselves. Extraction will be funded with private money and will use only surplus embryos that would be discarded after in vitro fertilization treatment. Both anti-abortionists and members of the National Bioethics Advisory Commission, which supports stem-cell research, have criticized the logic behind this.

Hot potato: opposition from anti-abortionists could still shift political views in Washington. Credit: AP

The lack of a strong legal basis, together with opposition from the anti-abortion lobby, is making embryonic stem-cell research — already a volatile issue in the United States — a prominent political lightning rod. US presidential candidate George W. Bush has said through spokesmen that he opposes such research. If elected in November, some fear that he could sign an executive order forbidding it. In contrast, Democrat candidate Al Gore has said he supports stem-cell research.

The US Congress is also sharply split. Although some members have indicated that they would either sue the NIH to stop the research or draft legislation to prohibit it, others are trying to expand it. Senator Arlen Specter (Republican, Pennsylvania), for example, has drafted a bill that would allow federal funding for both use and derivation of embryonic stem cells.

Although the guidelines were issued in draft form last winter, the NIH has tried to defuse the controversy by creating a greater distinction between the derivation and the use of embryonic stem cells, and by applying tighter controls. For example, the new guidelines require, rather than recommend, an institutional review board's approval for the derivation of stem cells from both embryos and fetal tissue.

The most significant modification, says Lana Skirboll, associate director for science policy at the NIH, is that the guidelines now allow donors of embryonic stem cells to be identified — the original guidelines required that their identity be masked.

Knowing the identity of donors could help minimize immune responses when cells are transplanted into other humans and also prevent infectious diseases from being transmitted.

Researchers will also have to specify what types of experiments they intend to perform. If they use stem cells for work not included by the guidelines, they could jeopardize other NIH funding for their institutions.

Scientific societies, including the American Society for Cell Biology and the Federation of American Societies for Experimental Biology have welcomed the guidelines, as have several patient advocacy groups. President Bill Clinton endorsed them, but Pope John Paul II denounced them.

Berg: it is too early to focus only on adult cells.

Opponents say that the NIH should support more work on adult stem cells (see Nature 405 , 6; 2000). David Prentice, professor of life sciences at Indiana State University and a member of Do No Harm, a group that opposes embryonic stem-cell research, says that adult stem cells have been unfairly maligned.

He says that recent research raises questions about the claims that adult stem cells cannot differentiate into as many cell types, or produce as many cells as embryonic ones. “They actually have a lot more promise and they don't have the ethical baggage,” he says.

But Nobel laureate Paul Berg, professor of biochemistry at Stanford University, says concentrating only on adult stem cells would be premature. “This line of research is still in its infancy,” he says.