Stem Cell Strides Test Bush Policy
Scientists Push for Use Of Newer Cell Colonies
By Rick Weiss
Washington Post Staff Writer
Tuesday, April 22, 2003; Page A01

A series of important advances have boosted the potential of human
embryonic stem cells to treat heart disease, spinal cord injuries and
other ailments, but researchers say they are unable to take advantage
of the new techniques under a two-year-old administration policy that
requires federally supported scientists to use older colonies of stem
cells.

Now pressure is building from scientists, patient advocates and
members of Congress to loosen the embryo-protecting restrictions
imposed by President Bush, with some on Capitol Hill saying they want
to take up the issue next month.

Stem cells obtained from 5-day-old human embryos can morph into all
kinds of human tissues and appear capable of regenerating ailing
organs. But while newer and safer versions of the cells have recently
been created, the policy imposed by Bush in August 2001 puts those
cells off-limits to any scientist whose work is supported with
federal money.

Supporters of embryo cell research have long grumbled about the Bush
policy but have acknowledged that their complaints were largely
theoretical because there was still plenty to learn from older cells.
The unexpectedly rapid advent of more medically promising cells --
and the possibility of human studies within the next year or so --
have changed that equation, they say, making the Bush policy a real
barrier to progress.

The older cells allowed under the Bush plan are less attractive
researchers because they have been grown in mixtures with mouse tumor
cells. The tumor cells, known as "feeder" cells, secrete crucial,
though as yet unidentified, nutrients that help nourish human embryo
cells. But they can also pass mouse viruses or other microbes to the
human stem cells, which means the stem cells could end up sickening
patients instead of curing them.

Concerned about that risk, the Food and Drug Administration has said
it will demand a daunting array of safety tests and long-term patient
follow-up for any experiments in which patients are given stem cells
that have been in contact with animal feeder cells.

Recently, however, scientists have learned how to grow human
embryonic stem cells without mouse cells. The new stem cell colonies,
or "cell lines," appear ideal for use in clinical trials, scientists
say. But they remain unavailable to the vast majority of U.S. stem
cell researchers -- most of whom depend on federal grant money --
because the 2001 Bush policy requires those scientists to work only
with cells from embryos destroyed before Aug. 9, 2001. The goal was
to prevent further destruction of stored human embryos, but it also
limits researchers to cell lines tainted by contact with mouse cells.

"This is the conundrum we're caught up in as federally funded
researchers under the Bush policy," said George Daley, a Harvard
University stem cell biologist also affiliated with the Whitehead
Institute for Biomedical Research in Cambridge, Mass. "We want to do
the basic research that works towards cures, but we cannot use the
newly derived, latest and best cell lines, which puts us at a
disadvantage."

Yesterday, Sen. Arlen Specter (R-Pa.) sent a letter to Bush urging
the president to expand the current 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 and disorders that
afflict millions of Americans."

In interviews last week, Specter and Sen. Tom Harkin (D-Iowa) said
they would like to hold a Senate hearing on the topic next month. And
Sen. Orrin G. Hatch (R-Utah) said that he is "disappointed at the
number of stem cell lines that have been available" to federally
funded scientists, and that he will work with others on Capitol Hill
"in reexamining the administration's policy."

But foes of embryo cell research said they remain opposed to any
changes.

"We expressed support for the president's policy when he enunciated
it, and I don't believe that Congress will overturn it," said Douglas
Johnson, legislative director of the National Right to Life
Committee.

The White House indicated last week it has no intention of changing
its position.

White House spokesman Scott McClellan said the president's policy was
arrived at with "great care" and is based on advice from leading
scientists that "existing lines [of stem cells] are more than enough
to realize the promise of stem cell research in a way that adheres to
the highest ethical standards."

The president has said he favors research on "adult stem cells,"
which are retrieved from adults but which some scientists believe are
less versatile than embryonic cells.

Under FDA guidelines, doctors will have a difficult time conducting
human studies with stem cells grown with mouse cells -- and the
agency's concerns go beyond the mere possibility of mouse viruses
sickening stem cell recipients.

The bigger concern is that a mouse virus could mix its genetic
material with human viruses already in the patient, creating a new
virus with added virulence and perhaps even a newfound ability to
spread from person to person -- much as is believed to have happened
with severe acute respiratory syndrome (SARS), which is spreading
illness and death around the world. That means stem cell transplants
would pose a potential risk not only to the patient but also to close
contacts and the public at large.

Given those risks, the agency has published a 60-page "guidance"
document that spells out the kinds of tests researchers should do if
they want permission to give patients human cells that have been in
contact with animal cells.

First is the need to conduct many different tests aimed at finding
any viruses that may be lurking in those cells. But researchers are
also instructed to warn patients and their close contacts of the risk
of getting an animal disease; monitor the patients' health for the
rest of their lives; and save blood and tissue specimens for at least
50 years after each patient dies. Researchers are also urged to get
patients to agree to make their medical records available throughout
their lives to the FDA, the Centers for Disease Control and
Prevention and other public health agencies; agree to be autopsied
after death; agree to never donate blood, sperm, eggs or organs; and
agree to abide by travel restrictions, medical isolation or other
actions that health officials may at some point deem necessary.

Clinical scientists and patients have been clamoring for a simpler
approach. And lately their wishes have begun to come true.

It started last fall, when researchers from Singapore published a
landmark report showing that human embryonic stem cells could be
maintained in culture dishes if they were accompanied by cells from
14-week-old aborted human fetuses, instead of mouse cells.

That granted the cells a reprieve from the FDA's rules. But as the
researchers noted in the September 2002 issue of the journal Nature
Biotechnology, there remained "ethical concerns" about using cells
from aborted fetuses.

Then last month scientists at Johns Hopkins University made another
leap, showing that human embryonic stem cells could thrive in a
culture system containing adult human bone marrow cells, which
apparently secrete all the growth factors the stem cells need.

The marrow cells offer "a clinically and ethically feasible method to
vastly expand human embryonic stem cells on a clinical scale,"
concluded Linzhao Cheng and his colleagues in the March issue of the
journal Stem Cells.

Now Cheng and others are scrambling to find other recipes that
support stem cell growth.

"It's probable that many different human cell types can support the
growth of [embryonic stem] cells in the right conditions," Cheng
said. "It's certainly broader than we thought."

Indeed, Australian researchers say they have learned several ways of
growing human embryonic stem cells without animal cells. And Thomas
Okarma, president and chief executive of Geron Corp. of Menlo Park,
Calif., said his company is close to having an all-human culture
system for stem cells. With recent animal studies looking quite
positive, he said, he could imagine human clinical tests beginning as
soon as a year from now.

"That's far ahead of what anyone thought, even us," Okarma said. "So
these production issues are going to become important sooner instead
of later."

But scientists receiving federal grant money are not able to study
any of the newly derived lines under the current Bush policy, because
they come from embryos that were donated to research after August
2001. (Most come from fertility clinics, which are disposing the
embryos at parents' request after successful fertility treatment.)

James Battey, who chairs the stem cell task force at the National
Institutes of Health -- the primary source of federal funds for stem
cell research -- said there is much basic research that scientists
can do on the handful of older embryonic stem cell lines and it is
premature for scientists to be chafing over the Bush restrictions.

The older cells still offer "an enormous research opportunity,"
Battey said. "We're doing everything we can within what's allowed to
move this research agenda forward as quickly as possible."

But opponents of the current policy said the United States stands to
fall behind other countries with access to more advanced cell lines
and more open research policies.

"It seems to me it would be foolish for a physician or researcher to
use possibly contaminated lines in a patient or research protocol
when other lines are available," said Anthony Mazzaschi, associate
vice president at the Association of American Medical Colleges. The
new advances, he said, "will put a great deal of pressure on Bush's
policy."

Daniel Perry, a patient advocate who heads the Washington-based
Alliance for Aging Research, said patients will demand nothing less
than the best cells available.

"There's always been an expectation that the [Bush policy] line would
have to give way as the science progressed," said Perry, also a vice
president for the Coalition for the Advancement of Medical Research,
which advocates for stem cell research.

"Time is not on our side," Perry said of patients awaiting new
therapies, "but the science is."

SOURCE: The Washington Post
http://www.washingtonpost.com/wp-dyn/articles/A7107-2003Apr21.html

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