Leshner Tells U.S. Senate Panel That “Full Range” of Stem Cell Research Is Needed

All promising avenues of human stem cell research should be explored, including techniques that both do and do not involve the use of early-stage embryos, AAAS CEO Alan I. Leshner and other witnesses told a Senate subcommittee hearing on 27 June.

Leshner and the others were commenting on a bill co-sponsored by U.S. Sens. Rick Santorum and Arlen Specter, both Pennsylvania Republicans, to promote research on alternative methods to create stem cells. Such cells are capable of becoming different types of cells in the body and hold promise for the treatment of degenerative conditions such as diabetes and Parkinson’s disease.

“We believe that the great clinical promise in stem cells makes it critically important to support research on a wide range of approaches toward deriving cells that have the potential for replacing damaged or deteriorating parts of the body,” Leshner said. But he said the most promising methods to date appear to be derivation of stem cells from excess embryos at in-vitro fertilization (IVF) clinics or from early-stage embryos through a process called somatic cell nuclear transfer.

Santorum, who testified in favor of his legislation, opposes methods of deriving stem cells that destroy human embryos. The Santorum-Specter bill would encourage alternative methods discussed in a report last year by the President’s Council on Bioethics. They include derivation of stem cells from non-viable embryos at IVF clinics; extraction of a single cell from an early-stage embryo for use in growing stem cells while the embryo itself remains viable for transplantation into the womb; and so-called “altered nuclear transfer,” methods aimed at ensuring that any embryo created by the fusion of an egg and donor DNA from an adult cell will be unable to implant in the uterus.

“The alternatives that are now being developed are, in fact, intriguing, but we really don’t know what their ultimate utility will be,” Leshner said, “and each has potential problems or complications.”

Specter said he backs research on alternative stem cell methods while continuing to push for a vote on legislation he has co-sponsored with Sen. Tom Harkin (D-Iowa) that would authorize federally funded research on new stem cell lines from embryos slated for destruction at fertility clinics. President Bush issued a directive in 2001 that federal dollars could be used for research only on embryonic stem cell lines already in existence at that time. Stem cells from 21 such pre-existing lines are now available, but researchers argue that many of the lines are not useful for their particular research.

The U.S. House of Resentatives passed a bill last year that would, like the Specter-Harkin bill, loosen President Bush’s restriction on human embryonic stem cell research. Senate Majority Leader Bill Frist (R-Tenn.) has said he will bring the Specter-Harkin bill to the Senate floor this summer. He also is expected to bring the bill on alternative stem cell methods to the floor then as well.

Harkin said he has no real quarrel with Santorum’s effort to spotlight alternative stem cell methods. “The best thing that can be said about the bill we’re discussing today, S. 2754, is that it does no harm,” Harkin said at the hearing. He said he feared, however, that some who oppose embryonic stem cell research will use the bill “as a decoy” to prevent passage of a bill to loosen the restrictions on federal funding. Leshner said AAAS supports efforts to ease those restrictions.

Santorum acknowledged that none of the proposed alternative methods have yet to produce viable human stem cells lines for general research use. But, he said: “We think this is a very promising area to be explored.”

Harkin asked James Battey, chair of the National Institutes of Health Stem Cell Task Force, whether NIH is able to fund research on alternative stem cell methods. “NIH already is in a position to support animal research on alternative model systems,” Battey said. In fiscal year 2005, he said, the agency spent $38 million on human embryonic stem cell research using the approved cell lines and $198 million for research on stem cells from sources other than human embryos, such as those derived from adult bone marrow and nervous system cells.

Stephen Strom, a professor in the department of pathology at the University of Pittsburgh School of Medicine, told the Senate panel about his laboratory’s research on cells in the human placenta that appear similar to embryonic stem cells in their ability to generate a wide variety of tissues. The cells, called amniotic epithelial cells, have the capacity—under the right conditions in a culture dish—to renew themselves and to turn into the three types of germ layers, or body cells, Strom said. Such amniotic cells “may be a useful and non-controversial source of stem cells for cell transplantation and regenerative medicine,” Strom said.

Battey said it is impossible to say now which potential source of stem cells may produce the sort of benefits many scientists and health advocates are hoping for. “I concur with the argument that we need to look at all types of stem cells,” Battey said.

Leshner said the embryonic stem cell issue has more than just clinical implications. “Many of the countries with whom we cooperate and compete, both scientifically and economically, are intensively pursuing human embryonic stem cell research,” he said. “Countries like Great Britain, Singapore, South Korea, Israel and those in Scandinavia have very advanced programs.” Given the potential health and economic benefits of stem cell research, Leshner added, “I hope we will do all we can to ensure that the full range of approaches are studied to their scientific and ethical limits.”

Earl Lane

29 June 2006