WASHINGTON - Scientists urged senators yesterday to join the House in passing a measure to expand embryonic stem cell research, arguing that newer, uncontaminated cell lines now available cannot be used by federally funded investigators under President Bush's policy.
A hearing, held by the Special Committee on Aging, was the first in the Senate since the House passed stem cell legislation late last month in defiance of Bush's veto threat.
The House bill would allow federally funded research on thousands of frozen embryos that are stored in fertility centers and donated by couples who no longer need them.
John D. Gearhart, a Johns Hopkins University developmental biologist and stem cell pioneer, said the current limits on research - which restrict federally funded research on embryonic stem cells to lines that were already in existence at the time of Bush's announcement in August 2001 - are a "logistical nightmare" that is slowing advancements in the field.
"It is essential this bill be passed," Gearhart said.
Embryonic stem cells are thought to be extremely valuable to scientists because they are capable of reproducing into any of the body's more than 200 cell types. Advocates believe research in this field holds promise for treatments and possibly cures for a wide range of diseases, such as Alzheimer's, Parkinson's, diabetes and other debilitating and crippling ailments. But Bush and many religious conservatives oppose the research because embryos are destroyed in the process of deriving the stem cells.
Gearhart, who conducts research on stem cells from embryonic and adult tissues, said the lines available for research under the president's policy lack genetic diversity, are not disease-specific, are not adequate for researchers to apply to a wide variety of diseases and are contaminated with animal cells.
Earlier embryonic stem cell lines, including the 22 available for federal research, were grown with mouse "feeder" cells that helped the stem cells grow but also made them unsuitable for use in human therapies.
Gearhart said colleagues at the University of California, San Diego and the University of Wisconsin, Madison recently published methods for growing embryonic stem cells without such mouse cells.
"We'd rather work on lines that have no feeder layers," he said of the new, "cleaner" cell lines. "These are now available. This is extremely valuable and should be eligible for federal funding if we want to progress."
In the wake of the recent House vote supporting expanded funding, a bipartisan majority in the Senate is pressing Senate Republican leader Bill Frist to bring a similar bill to a vote as soon as possible.
Frist, a physician, supported Bush's 2001 policy but said at the time he would be willing to reconsider the issue if scientific advances warranted it. He said yesterday that he would bring some sort of stem cell bill to the Senate floor but did not specify whether it would be the legislation calling for an expansion of embryonic stem cell research.
Democratic Sen. Edward M. Kennedy of Massachusetts has said that if Frist blocks the bill, supporters of embryonic stem cell research would add the measure to some other legislation coming up for a vote.
Bush has said repeatedly that he would veto any legislation expanding the use of federal funds for embryonic stem cell research. But advocates are hoping a broad show of bipartisan support in both houses would pressure the president to find some sort of compromise or loosen his position.
Yesterday, the Republican chairman of the Aging panel, Sen. Gordon H. Smith of Oregon, an abortion foe, threw his support behind the bill.
Larry Goldstein, a stem cell researcher at the University of California, San Diego, told the panel he was "loath to see the United States cede its historical lead in this field" to countries such as Great Britain, South Korea and Singapore that have made huge investments - and advancements - in the field.