Given his campaign promises, it seems likely that US President-elect Barack Obama will move quickly after his inauguration on 20 January to lift the Bush administration's restrictions on federal funding for human embryonic stem (ES) cell research. That will be good news for American scientists, if only because they will no longer have to decide between the human ES cell lines best able to answer their questions and the lines for which they can receive federal funds. But perhaps the biggest advantage is that their most important funding agency, the US$29-billion National Institutes of Health (NIH), can now start to lead from the front.

The NIH should not expect to take on the kind of primary leadership role for stem cells that it took for other projects.

The agency has a lot of catching up to do. Since 9 August 2001, when President George W. Bush declared that federal funding could only support work with human ES cell lines already in existence, the NIH has largely had to sit on the sidelines while others stepped in to fill the gap. Several US states launched their own initiatives for funding stem-cell research, complete with peer-review panels and regulatory policies. Meanwhile, in a miracle of organization and diplomacy, the International Stem Cell Forum, a working group chaired by the UK Medical Research Council, coordinated scientists across 11 countries to thoroughly compare and characterize some five dozen ES cell lines, only a few of which could be studied using NIH funds.

Indeed, many of the state, private and international organizations operating during the agency's (relative) absence from the field now have experience and expertise that the NIH lacks — not to mention the capacity and willingness to perform tasks that once might have gone to the NIH by default.

Given this reality, the post-20 January NIH should not expect to take on the kind of primary leadership role for stem cells that it took for projects such as the Human Genome Initiative. But the agency can take the lead in coordinating and facilitating the many stem-cell programmes that are already under way.

As an example, consider the legal complications that can sometimes bedevil research collaborations trying to work across international borders — or even across state lines. Researchers joke that some collaborations require as many lawyers as scientists. The NIH could do much to simplify matters, particularly in helping states to ensure that human stem-cell lines are derived and used under ethical guidelines, including informed consent.

The NIH could also take responsibility for pushing forward the often tedious work needed to address essential questions. How many ES cells would it take to cause a tumour? How can animals be used to predict the behaviour of transplanted cells? When is a cell pluripotent, and to what extent does the pluripotent state vary?

Before the NIH can pitch in, however, it needs to stand back. The agency should review the portfolio of research it already funds to learn where particular effort is needed to push through translational barriers; it should look for fundamental biological questions where progress might have been slowed by researchers shying away from ES cell research. To get this insight, the NIH must reach out to other governmental and private programmes promoting stem-cell research to discover which strategies have been most successful. Those entities, some of which tirelessly tout their successes in public, must also be willing to reveal their mistakes and limitations. With this knowledge in hand, the NIH can then decide how to foster existing efforts, what new projects to establish, and how it can guide scientists in its own labs to fill in the gaps.