The Scientist / BioMed Central
April 25, 2003

Senators urge stem cell expansion
Letter to the president cites recent research making new
uncontaminated lines possible.
By Ted Agres

Citing recent research advances, Sen. Arlen Specter (R-Penn.) and
other senators are urging President Bush to expand eligibility
requirements for federal funding of human embryonic stem cells
(HESC).

"With the discovery of a way to grow human stem cells without mouse
cells, it is possible to use new stem cell lines that have never been
exposed to mouse cells and are safe for use in humans," Specter wrote
in an April 21 letter to the president.

Under existing policy, federal funds for HESC research are available
only for a limited number of cell lines established before August 9,
2001. Of some 78 stem cell lines initially identified as meeting the
eligibility criteria, only 11 lines are presently available for
researchers, Specter noted. Many scientists and politicians have
argued that this number inhibits meaningful research. And because the
currently qualified stem cell lines have been grown using mouse
feeder cells, there is the potential for mouse viruses and other
contaminating proteins to be passed to human cells, making potential
clinical trials risky and difficult to conduct.

However, in the March issue of Stem Cells, Linzhao Cheng, an oncology
professor at the Johns Hopkins University School of Medicine in
Baltimore, and his colleagues describe growing HESC using a culture
of adult human bone marrow cells. This method "may provide a
clinically and ethically feasible method to expand HESC for novel
cell therapies," they concluded.

Last September, Mark Richards and other researchers at the National
University of Singapore reported use of human fetal and adult
fibroblast feeders to support prolonged growth of existing HESC in
Nature Biotechnology.

"These recent developments underscore the need to expand your August
9, 2001 policy so that doctors and scientists can use these new safer
stem cell lines and realize the promise of stem cell research to cure
diseases," Specter wrote to Bush.

Specter is chairman of the Senate Appropriations Subcommittee on
Labor, Health and Human Services, and Education and has been a
prominent research supporter. He, Sen. Tom Harkin (D-Iowa), and Sen.
Orrin Hatch (R-Utah) hope to hold hearings next month on the matter.

The three are among senators who have sponsored legislation to permit
research cloning to develop therapies (S 303). In February, the House
passed a bill prohibiting cloning for any purpose, including for
research (HR 534). Companion legislation (S 245) has been introduced
by Sen. Sam Brownback (R-Kan.). Neither Senate bill has been acted
upon.

Specter's letter demonstrates that "we're beginning to see some
political pressure based on what scientists had predicted all along —
that the president's policy of August 2001 is inadequate to move the
research forward," said Sean Tipton, spokesman for the Coalition for
the Advancement of Medical Research (CAMR), an advocacy group for
stem cell research and somatic cell nuclear transfer.

But Jim Battey, director of the stem cell task force at the National
Institutes of Health (NIH), said there is no need to change the
administration's funding policy because more basic research is needed
before any clinical trials can begin. "I think we're years away from
any clinical trials involving cells derived from HESC," he told The
Scientist. "There's just too much basic biology that we'll need to
understand to do these clinical studies safely and carefully."

Some of the basic issues include directing differentiation toward
specific cell types, controlling cell proliferation after
transplantation, and insuring proper cell functioning and immune
response survival, said Battey. "These are basic science questions
that can be as easily addressed with cells that are grown on mouse
feeder layers as the cells that are grown on human feeder layers."

Additionally, NIH is supporting research that would make existing,
federally available cell lines in a completely "feeder-free" medium.
"In the long run, that is the best thing to do in terms of culturing
cells that ultimately will be used in clinical trials," Battey said.
"The last thing the stem cell research field needs is to have a
disaster because somebody proceeded too fast without enough available
basic information."
Links for this article
L. Cheng et al., "Human adult marrow cells support prolonged
expansion of human embryonic stem cells in culture," Stem Cells,
21:131-142, 2003.
http://stemcells.alphamedpress.org/cgi/content/full/21/2/131 

M. Richards et al., "Human feeders support prolonged undifferentiated
growth of human inner cell masses and embryonic stem cells," Nature
Biotechnology, 20:933-936, September 2002.
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nbt/journal/v2
0/n9/full/nbt726.html 

T. Agres, "And in this corner," The Scientist, February 7, 2003.
http://www.biomedcentral.com/news/20030207/04/ 

T. Agres, "House passes anti-cloning measure," The Scientist,
February 28, 2003.
http://www.biomedcentral.com/news/20030228/07/ 

E. Russo, "Clone hearings continue," The Scientist, January 30, 2003.
http://www.biomedcentral.com/news/20030130/05/ 

 
SOURCE: The Scientist / BioMed Central
http://www.biomedcentral.com/news/20030425/03/

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