Nine months after US President Barack Obama issued an executive order lifting restrictions on human embryonic stem cell (hESC) research in the United States, scientists can at last start to use taxpayer dollars to study newly added cell lines. In the first two weeks of December, National Institutes of Health (NIH) director Francis Collins approved no fewer than 40 new hESC lines for federal funding, although some carry caveats.

The earliest cells to get a green light from Collins included 11 lines from George Daley's lab at Children's Hospital Boston and two lines from Ali Brivanlou of Rockefeller University in New York. These were deemed to meet the agency's informed consent guidelines, established in July.

“Now, with the federal sources of support, it gives us much more flexibility and many more resources to answer broader questions that we weren't even approaching before,” says Daley.

Reviewers determined that the remaining 27 lines — part of a single submission by Douglas Melton of Harvard University in Cambridge, Massachusetts—met the ethical spirit of the guidelines despite the fact that a randomization technique prevented researchers from matching consent forms to specific donors.

The NIH Advisory Committee to the Director added a proviso that the use of the 27 stem cell lines should be restricted to projects in line with the wording of the informed consent form, which stipulated that the cells be used to study diabetes-related pancreatic cells. Collins, who has the final say, assented to his committee's recommendations.

Robert Streiffer, a bioethicist at the University of Wisconsin–Madison, commended this decision. “The right answer is to insist on informed consent,” he says. “Scientists and people in oversight positions routinely underestimate how important it is to patients and donors that they know at least in broad terms what's happening to the biological samples that they're donating.”

With 40 cell lines added to the NIH registry, 31 grants totaling $21 million that had been funded last year but put on hold pending the agency's review can now go ahead. As Nature Medicine went to press, an additional 85 cell lines had been submitted for review, and 242 more filings had been requested but not yet completed. None of the cell lines eligible for federal funding under former President George W. Bush have yet been approved.