Human embryonic stem cells can live on indefinitely when carefully cultured under just the right conditions. The legal and legislative environments for these cell lines, however, has gotten a lot less hospitable in recent weeks.

After a federal judge placed an injunction on federal funding for all human embryonic stem cell (hESC) research in late August scientists and advocates faced rules that were far more stringent than those under the George W. Bush administration. A temporary lift of the injunction, issued September 9 by a federal appeals court, has done little to solidify the field's future.

The fate of many projects now hangs on language in a congressional budget amendment that was passed years before the first human embryonic stem cell was isolated.

The legislation in question, the 1996 Dickey–Wicker Amendment, prohibits federal funds from being used for any work that would harm or destroy a human embryo. Rather than being voted on annually, the amendment is attached to a slew of other National Institutes of Health (NIH) legislation and gets renewed as part of a batch.

Under Dickey–Wicker, President Bush allowed federal funding for research only on stem cell lines that had already been derived (but prevented the government from backing the further destruction of any embryos). And President Barack Obama pushed the amendment's limitations by asking the NIH in 2009 to allocate funds for still more lines of cells.

But in his interpretation of the amendment, Chief Judge Royce Lamberth of the U.S. District Court for the District of Columbia ruled on August 23 that embryonic stem cells belong in the same legal basket as embryos themselves because, he argued, creating a cell line requires destroying an embryo. In contrast the U.S. Department of Health and Human Services (HHS) has argued that, in part because the cell lines can be maintained indefinitely and do not require subsequent embryo destruction, those cell lines and embryos are distinct, thus allowing for federal funding.

Lamberth's ruling gives the amendment a different legal spin. "I'm sort of in the thick of this and this never ever occurred to me as a possibility," says Doug Melton, a professor at the Harvard Stem Cell Institute whose work uses human embryonic stem cells that fall under the injunction. Others called Lamberth's ruling "draconian" and "a serious setback."

The sticky Dickey–Wicker Amendment
Although the direction of federal policy had seemed to be clear under the Obama administration, the law underlying it has proved not to be.

Until last month, few officials saw much need to alter the amendment. A 1999 interpretation of Dickey-Wicker, written by then counsel for the HHS, Harriet Rabb, held that embryonic stem cells in themselves did not classify as embryos and thus were not subject to funding limitations under the legislation. "It seemed it was working," says Richard Hynes, a professor for cancer research at the Massachusetts Institute of Technology, of the accepted interpretation.

And over the years, Congress had tried to clarify the language from outside of the amendment, twice passing a bill, known as the Stem Cell Research Enhancement Act—introduced in 2005 and 2007 by Diana DeGette (D–Colo.) and Mike Castle (R–Del.). The bill would have allowed for federal backing of embryonic stem cell lines that were derived from unneeded embryos that would otherwise be discarded after fertility treatments. Congress passed the bill twice, but President Bush vetoed it both times.

As Congress returns from summer recess this week, Michael Werner, a partner at Washington D.C. law firm Holland & Knight and executive director for the Alliance for Regenerative Medicine says he expects to get a better sense of whether legislators will try to push through another clarifying bill. Given the surprise nature of the recent injunction, Hynes suggests that both a legislative and legal route will need to be taken in parallel to ensure federal funding in the future. DeGette's bill was reintroduced in Congress earlier this year, and has recently been pushed to the top of the lawmakers' agenda.

Research redefined
The ethical and scientific debates about the merits and hazards of human ESC research remain thorny, and many scientists agree that other kinds of stem cells—namely, adult stem cells and induced pluripotent stem cells—cannot replace the embryonic kind. Neither alternatives wholly bypass some of the key ethical issues or have been shown to be as biologically flexible as hESCs. The legal arguments currently center in part on just where the research itself starts and ends. In the August 23 decision to impose the injunction, Lamberth explained that "the question before the court is whether ESC research is research in which a human embryo is destroyed," he wrote in his opinion. "The court concludes that it is."

But as human ESC research supporters note, federal funds are not used to derive the stem cells, a process that destroys the embryo. Rather, they are used only to maintain the cell lines and perform further experiments. Hynes explains that although some unneeded embryos from fertility services end up adopted by new parents, most fertilized eggs from in vitro services are left sitting in freezers.

The government argued in a September 8 court document that a line of inquiry "does not mean that each research project includes the projects and actions that preceded it—including projects that were performed by different scientists." And the hESCs currently being used in research, the government has argued, are from lines that had been derived previously, through projects funded by other entities.

Lamberth's interpretation leaves Melton wondering, somewhat facetiously, if embryonic stem cell research led to the discovery of a gene, "does that mean that no one could ever think about the gene [or] write a paper about it?"

The legal case has also opened questions about the function of peer review and intensity of competition for federal grant dollars. The two scientists who brought the case forward work on adult stem cells and have asserted that they face unfair competition for limited government funds if the NIH continues to increase its funding of hESC research. As supporters of human ESC research have pointed out, however, embryonic stem cell research has received about 25 percent ($131 million) of the money the government awards among the three types of stem cell research for the current fiscal year. The two plaintiffs, Theresa Deisher and James Sherley, had until late Tuesday to file a response to the temporary stay, and the government will have until September 20 to reply.

Embryonic influence
Federal dollars are not the only funds that back stem cell research. Some states, institutions and private companies have put money toward the work, but the NIH is a substantial contributor—as well as a barometer for the industry. Investors "look to other signs whether this is technology worth investing in," Werner says. "If they see that it is going to be prohibited by the courts or shut down, this provides a disincentive." He asserts that, "Long term, it's not tenable if the NIH isn't involved."

The NIH issued a statement on Friday saying, "We are pleased with the court's interim ruling." But not everyone is confident that the temporary stay instituted by the appeals court will last.

"While I am relieved that the injunction has been stayed, I worry that the future of human ES cell research remains at risk," comments George Daley, an associate professor of pediatrics at Children's Hospital Boston who works with human ESCs. "We need a clear statement from the Congress."

But coming into a contentious election cycle with many other major priorities on the national agenda, pushing through new legislation on embryonic stem cell funding might be tricky. "Right before elections Congress often gets kind of partisan anyway," Werner says. "So that's not an environment typically conducive to compromise and working things out." Although many polls have shown that Americans favor continued research using human ESCs to look for cures for diseases such as diabetes and Parkinson's, many conservative groups advocate against any use of the cell lines.

For some researchers, the question of continuing ESC research is in itself an ethical imperative. "I think it's morally offensive to prevent those embryos from being used and throw them down the drain," Hynes says. "The people who are most damaged by this down the road will be the patients and their families," he says.

A congressional hearing on the issue is scheduled for September 16.