The ripple effect of the federal court ruling against the expanded use of stem cells in research is being felt as strongly at Washington University as it is at research facilities throughout the country.

"It's a pretty disastrous event," said Dr. Steven Teitelbaum, a professor of immunology and pathology at Washington University. "You can't expect science to move forward if you take the hammer out of the toolbox."

The ruling could be a blow to a pair of research projects under way at Washington University, including one comparing the efficiency of reprogrammed adult stem cells — induced pluripotent stem cells — versus embryonic stem cells.

For now, work is continuing on both projects, while the school awaits guidance from the National Institutes of Health. The research is using stem cell lines approved during the administration of President George W. Bush.

On Monday, a U.S. District Court judge ruled that President Barack Obama's 2009 executive order that expanded embryonic stem cell research was illegal, saying the presidential order violates a ban on using federal funds to destroy embryos.

For years, private funding has been used to create embryonic stem cell lines, mostly from discarded embryos from fertility clinics in a process that destroys the embryos. Under Bush, the federal government agreed to fund embryonic stem cell research. But the Bush rules limited federally funded research to 21 cell lines already in existence by 2001.

Under Obama's executive order, federal funds could be used to conduct research on hundreds more stem cell lines that had been obtained with private funds, as long as donors of embryos signed consent forms and complied with other rules.

Researchers were unclear what the court decision would mean for their work.

The ruling will be a disappointment if it rolls back the Obama administration's expanded lineup of available stem cell lines, but will be devastating if it also knocks out the Bush-era lines, said Teitelbaum.

He argued that a total elimination of federal funding for embryonic stem cell research would put American scientists at a disadvantage compared with their counterparts in other countries.

The ruling may cause less damage to research being done at the University of Missouri-Columbia, where Michael Roberts, a professor of animal science and biochemistry, has been working in the area for six years. Roberts has been looking into the causes of preeclampsia, a disease that causes hypertension in pregnant women.

The school uses three of the stem cell lines approved by the Bush administration and has the approval to use one of the lines authorized by the Obama administration. For now, Roberts said, he has switched to nonfederal funding sources as a temporary fix to continue his research while the recent court ruling is deciphered by legal experts. And even if the worst-case scenario becomes reality, his own research should survive, he said.

"Five years ago, I would have said it was a terrible ruling," Roberts said. "But it's not catastrophic for me."

Instead, he said he could rely upon the reprogrammed adult stem cells.

The ruling is not expected to affect the work at the Stowers Institute for Medical Research in Kansas City. A spokeswoman said the private institute did not receive any federal assistance for human embryonic stem cell research.

Researchers at the University of Illinois at Urbana-Champaign could not be reached for comment.

The National Institutes of Health has taken the position that researchers who already have grants can continue with their work, director Dr. Francis Collins said Tuesday. However, research proposals are frozen.

The Justice Department said Tuesday that the Obama administration would appeal the ruling and would ask the U.S. Court of Appeals to lift the preliminary injunction issued Monday.

The Associated Press contributed to this report.