Harvard in particular has been trying to advance stem cell research recently—creating its Stem Cell Institute last year, which circumvented Bush administration regulations on newly-created stem cells by using independent funds for its experiments. Douglas A. Melton—Cabot professor of the natural sciences and co-director of the Stem Cell Institute—has been outspoken in lobbying for stem cell studies both in Boston and in Washington.

Melton was out of town yesterday and could not be reached for comment. But he told The New York Times earlier this week that Romney’s stipulations would “set science back significantly.”

He added that creation of stem cells was necessary to explore the “root causes” of diseases such as Alzheimer’s and diabetes.

Charles Jennings, executive director of the Stem Cell Institute, declined to comment yesterday, stating the he could not comment until the University issued public statement.

But Director of the Division of Medical Ethics at Harvard Medical School Dan W. Brock challenged the logic behind Romney’s comments yesterday, saying that Romney’s distinction between types of cell development is arbitrary.

“In in vitro fertilization, we already allow the creation of embryos that will be destroyed by allowing the creation of more than necessary, so we’ve already accepted the principle that some embryos won’t be used for reproduction,” he said.

“It’s hard to make a case—five days after conception—that embryos have any of the properties of a human being, such that it is morally important how you treat them,” Brock added.

Brock estimated that currently about 400,000 extra cells are available from in vitro experiments. Romney also proposed that none of those stem cells be used without express permission from the donors in his letter to Travaglini yesterday.

—Zachary M. Seward contributed to the reporting of this story.

—Staff writer Risheng Xu can be reached at xu4@fas.harvard.edu.