Santorum said these methods would not involve destroying embryos and would be "non-controversial," but acknowledged that controversy may be unavoidable in such an ethically charged, uncharted scientific field.
"There are some who believe that . . . there is controversy around these new entities - these collections of cells - as to whether it is an embryo or not," Santorum said during a news conference at the University of Pennsylvania. "I feel comfortable, given all of the conversations I have had with a number of bioethicists, that these are appropriate steps to take."
The collaboration between the two senators comes at a crucial time for Santorum, who is in a tough reelection race for a third term against the likely Democratic nominee, State Treasurer Bob Casey Jr.
Casey, who is against abortion, supports federal funding only on existing embryonic stem-cell lines. He has called for more federal funding on research that does not involve destroying human embryos. Casey did not take a position on the bill yesterday, saying he needed more information.
By teaming with Specter, Santorum could gain leverage on an issue with particular appeal to voters in Southeastern Pennsylvania, a politically moderate, must-win area.
Specter has repeatedly said Santorum's reelection is his top priority because he "was indispensable in my victory two years ago."
"I am anxious to find every avenue I can to give him some political leverage which is consistent with my principles," Specter said.
Embryonic stem cells are "pluripotent" - meaning they give rise to all types of tissues in the body - and theoretically have tremendous potential to repair and regenerate tissues. Pluripotent stem cells exist only briefly in a three-day-old embryo, which is destroyed when the stem cells are removed.
Santorum, like some other abortion opponents, has opposed embryonic stem-cell research because he equates destruction of human embryos with murder.
In seeking a middle ground, President Bush in 2001 said federal funding could be used only for research on certain existing stem-cell lines, most of which have died or become unsuitable.
But yesterday, Santorum came out in favor of another "attempt to bridge the gap," namely the 2005 report by the President's Council on Bioethics. This report outlines what it calls "ethically uncontroversial" concepts for getting embryonic stem cells - including creating an embryo engineered so that it could not keep growing.
Santorum and Specter said they began discussing drafting a bill late last year.
"I think Sen. Specter would say [the bill] is not exactly what he wanted. And it raised some concerns for me," Santorum said. "Both of us have compromised."
Specter said his top priority remains Senate approval of the Stem Cell Research Enhancement Act, which would provide federal funding for research on leftover embryos donated by couples undergoing fertility treatment. The bill passed the House last year and could be considered in the Senate this year, along with the Santorum-Specter bill.
It is not yet clear whether concepts outlined in the bioethics council's report will work. Two of them were tested last year in mice. However, instead of solving ethical dilemmas, the experiments unleashed more controversy.
In one experiment, a mouse embryo was cloned using genetic material that had been altered so it could not grow much beyond the stage where stem cells appeared. The embryo was altered so that it could yielded stem cells, but could not grow in a mouse uterus.
Yesterday, lead researcher Rudolph Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Mass., said he was glad that his experiment is spurring legislative debate aimed at funding an acceptable compromise. But at the International Center for Technology Assessment, which neither advocates nor opposes embryonic stem-cell research, bioethicist Jaydee Hanson said making "defective embryos" is no solution.
"Simply redefining something as 'not an embryo' doesn't make it not an embryo," he said.
The other novel approach for obtaining embryonic stem cells involved removing a single cell, called a blastomere, from an eight-cell mouse embryo. Cambridge, Mass., stem-cell researcher Robert Lanza tricked the blastomere into becoming an embryonic stem cell, while the embryo was implanted and developed normally in a mouse. But since a single human blastomere is theoretically able to develop into an embryo, this method, too, raises ethical questions about what constitutes a human life.
The Santorum-Specter bill also calls for funding of research on adult stem cells that "are capable of producing all or almost all of the [body's] cell types."
But adult stem-cell research - which is already funded by the federal government as well as states such as New Jersey and California - has not yet produced pluripotent stem cells.
Contact staff writer Carrie Budoff at 610-313-8211 or email@example.com.