A federal judge’s decision to block the Obama administration's stem cell research expansion efforts was met with surprise and disappointment by Harvard scientists, who say that the ruling brings back the harsh restrictions enacted by the Bush administration on human embryonic stem cell research.

"I think it was a surprising ruling that could represent a step backwards," said Leonard I. Zon, Harvard Medical School professor who directs the Stem Cell Program at Children’s Hospital Boston. “Federal dollars have been available for embryonic stem cell research during this administration and it has greatly stimulated the field.”

Zon added this ruling will force scientists to separate and segregate experiments based on how they are funded, which they say may negatively affect research developments.

Royce C. Lamberth, chief judge of U.S. District Court for the District of Columbia, ruled Monday to hinder the Obama administration’s efforts to expand stem cell research in a case brought by a broad coalition of plaintiffs, including adult stem cell scientists who oppose embryonic stem cell research.

Lambert said in his 15-page opinion that the Obama administration’s stem cell research policy, which reverses prior restrictions and expands federal funding on human embryonic stem cell research, violates federal law prohibiting the destruction of embryonic stem cells for research.

He added that former MIT researcher James L. Sherley ’80 and other scientists who study adult stem cells face “increased competition for limited federal funding” and that the policy would injure [their] ability to successfully compete” for funding from the National Institutes of Health.

Harvard scientists say it is unclear whether the decision will affect grants awarded to researchers or future funding, and the University is waiting to hear from the Justice Department and the NIH.

“This has cast a net of uncertainty over the field in terms of what can and cannot be funded by the National Institutes of Health,” said Kenneth R. Chien ’73, a Medical School professor and leader of the university-wide Cardiovascular Stem Cell Biology program within the Harvard Stem Cell Institute.

Zon said that the potential of stem cell research at Children’s Hospital will likely be curtailed by limited funding for embryonic stem cell research. Although private philanthropy provides a substantial amount of monetary support, he added federal funding is pivotal for research development.

It is important to have both in order to conduct effective research,” Zon said.

Kevin Casey, Harvard’s associate vice president for governmental relations did not respond to a request for comment yesterday. He told the Boston Globe on Tuesday the University was “disappointed at this preliminary halting of this research, as it will slow progress that so many who suffer afflictions are relying on.”

Douglas A. Melton, co-chair of the Department of Stem Cell and Regenerative Biology and co-director of the Stem Cell Research, called the ruling a “great disappointment not only to students and researchers, but also to patients.”

“I’m hoping that this will be a temporary halt and not a prohibition,” he said.

Melton also contested the plaintiffs’ claim that their work would suffer from competing for funds also offered to scientists that work with human embryonic stem cells.

“The only scientists that would be hurt by the competition are those whose work is not competitive,” Melton said.

Steven H. Aden--senior counsel for the Alliance Defense Fund, a nonprofit group of Christian attorneys and co-counsel in the suit--said in a statement Monday that the federal government should not use taxpayer money to fund embryonic stem cell research, especially in difficult economic times.

“The American people should not be forced to pay for experiments--prohibited by federal law--that destroy human life,” he said.

--Staff writer Barbara B. DePena can be reached at barbara.b.depena@college.harvard.edu.