Stem-cell researcher Linzhao Cheng hopes to receive an overdue NIH grant this week. Credit: M. WADMAN

The National Institutes of Health is scrambling to get money out the door after the temporary reversal of a court injunction that abruptly shut down US government funding for human embryonic stem-cell research just 17 days earlier. Meanwhile, affected scientists are trying to keep up with the latest developments in an intensifying legal battle that will determine the future viability of their field.

The 9 September ruling by the Court of Appeals for the District of Columbia Circuit quashed a 23 August decision by federal district court Judge Royce Lamberth to shut down National Institutes of Health (NIH) funding for the research while he considers a lawsuit challenging that funding. In a statement issued after the ban was lifted, NIH director Francis Collins said, "We are pleased with the Court's interim ruling, which will allow this important, life-saving research to continue while we present further arguments to the Court in the weeks to come".

However, the reprieve could end as soon as 20 September — the deadline set by the appeals court for litigants to weigh in on whether government funding should be frozen until the case before Lamberth is decided on its merits. Meanwhile, the two plaintiffs in the case, James Sherley of the Boston Biomedical Research Institute in Watertown, Massachusetts, and Theresa Deisher of AVM Biotechnology in Seattle, Washington, last week filed for a summary judgment, asking Lamberth to provide a swift decision on their suit without a court hearing. Sherley and Deisher, who are supported by religious groups that oppose human embryonic stem-cell research, say that their own work, which involves adult stems cells, is being jeopardized by the NIH's funding policies.

Within hours of last week's ruling, senior NIH officials were advised to speed new grants out the door, fast-track the review of grant applications and fund 24 existing, multi-year grants that are still owed a total of US$54 million in the government's 2010 fiscal year, which ends on 30 September. By late afternoon last Thursday, top NIH administrators had announced to staff, by e-mail, that the scientists the agency supports, on and off its campus in Bethesda, Maryland, could resume their experiments immediately, and that funding and peer review would begin apace.

"I am delighted to see that the NIH took swift action," says Linzhao Cheng, a stem-cell researcher at the Institute for Cell Engineering at Johns Hopkins University in Baltimore, Maryland. Cheng had suspended all hiring, purchases and planning for a large NIH grant that had scored very highly in peer review. He had originally expected to receive funding on 1 September. Still, he says, even if he receives payment this week, "we just cannot do science like this, turning the switch on and off".

Peer review is also suffering, Cheng says. Two weeks ago, he was instructed by the NIH to ignore any grants for projects using human embryonic stem cells as he prepares to participate in a study section next month. He hadn't heard of any change to those instructions by the end of last week. By now it will be difficult, he says, to give human embryonic stem-cell proposals the careful reading they deserve in advance of the meeting on 12–13 October.

Cheng also draws on Maryland state funds for his work, but that is not an option for many other researchers (see 'Looking for other funders'). Meri Firpo, an assistant professor at the University of Minnesota Stem Cell Institute in Minneapolis, says that until the future of federal funding becomes more certain, she will plan for a long-term shutdown. She is currently rewriting an NIH grant, due for submission in October, to exclude human embryonic stem cells. And she is restructuring the projects of students who receive federal support to exclude the controversial human cells. "We are going forward with the same question mark as before," Firpo says.

The uncertainty extends to stem-cell res­earchers based on the NIH campus. Although several are hurrying to expand valued cell lines while they can, some are switching to work with induced pluripotent stem cells, which are not derived from embryos. "No one is willing to take any risks at this point and start any big experiments," says one on-campus researcher, "because it's possible that in two weeks all experiments with these cells will really be shut down for a long time."

As the legal battle continues, proponents are pressing for Congress to pass a bill that would explicitly make it legal for the NIH to fund human embryonic stem-cell research. While rejecting a request to stay his ruling, Lamberth wrote, "Congress remains perfectly free to amend or revise the statute."