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7/18/04
SENATE SUBCOMMITTEE
ON SCIENCE, TECHNOLOGY, AND SPACE HOLDS HEARING ON ADULT
STEM CELL RESEARCH
The Senate subcommittee on Science, Technology, and Space
held a hearing on 14 July 2004 to assess recent progress
made on adult stem cell research. Subcommittee chairman
Senator Sam Brownback (R-KA), a leading opponent of embryonic
stem cell research, sought to draw attention to adult stem
cells as opposed to embryonic stem cells in order to publicize
progress being made by "non-controversial techniques,"
and by unspoken implication, downplay the need for embryonic
stem cell research. Subcommittee Democrats pointed out the
limitations of adult stem cell research and used the hearing
as a platform to criticize President Bush's limitations
on embryonic stem cell research.
Clinical researchers and their patients presented testimony
on successful therapies using adult stem cells. Dr. Michel
Levesque of the Cedars-Sinai Medical Center in Los Angeles
said that his therapy eliminated a patient's Parkinson's
disease symptoms on the side of the body that was treated.
In this therapy, Dr. Levesque extracted neural stem cells
from the patient's brain, grew them in culture, and injected
them into the area of the brain that had degenerated because
of Parkinson's disease to replace the dead tissue. Similarly,
Dr. Jean Peduzzi-Nelson of the University of Alabama at
Birmingham testified that her studies in rats show that
spinal cord injuries can be healed to an unprecedented extent
by transplanting stem cells into the site of injury from
the injured animal's own olfactory mucosa, a tissue lining
the inside of the nose. Dr. Peduzzi-Nelson said her colleague,
Dr. Carlos Lima in Lisbon, Portugal, has tested this therapy
on several human patients, including three Americans. Two
of these patients testified at the hearing. Both had been
paralyzed as a result of spinal cord injuries for more than
two years, but after the transplantation they are now able
to walk with braces. Dr. Peduzzi-Nelson remarked that this
improvement was better than she had ever observed.
However, these success stories may not be universally replicable.
Dr. Robert Goldstein of the Juvenile Diabetes Research Foundation
testified that adult stem cell therapy does not work to
treat Type I diabetes, in which the pancreatic cells that
produce insulin are destroyed. These insulin-producing cells
are normally replenished by division, not differentiation
from stem cells, so in a Type I diabetic, there is no source
of adult stem cells within the patient's body that could
replace the insulin-producing cells. He said JDRF's strategy
is to fund both adult and embryonic stem cell research in
the hope that something will provide a cure.
Despite Sen. Brownback's attempt to focus on adult stem
cell research, subcommittee Democrats turned the spotlight
on the controversy over embryonic stem cell research. Much
of the debate centered on the limitations of adult v. embryonic
stem cells for therapeutic purposes. Ranking minority member
Ron Wyden (D-OR) cited NIH official statements that, compared
to embryonic stem cells, adult stem cells are 1) not totipotent,
2) often present only in minute quantities, 3) perhaps not
as capable of multiplying, and 4) more likely to have DNA
or other damage. He argued that given these limitations,
President Bush should remove the current restrictions on
embryonic stem cell research because it may hold more promise
for life-saving cures. Dr. Levesque acknowledged that adult
stem cells are hard to isolate, but Dr. Peduzzi-Nelson testified
that often only minute quantities of stem cells are required
for effective therapy, and slow growth in adult stem cells
is advantageous because it is more controlled than growth
in embryonic stem cells. Drs. Peduzzi-Nelson and Levesque
also pointed out that adult stem cells have the advantage
that they will not cause immune rejection because they come
from the patient's own body. Furthermore, they said, embryonic
stem cells can form tumors when implanted.
However, pressed by Sen. Wyden, Dr. Levesque conceded that
it is unknown whether embryonic stem cells will cause immune
rejection, because there is not enough research on them
due to President Bush's restrictions. Dr. Irving Weissman
of Stanford University clarified that only undifferentiated
embryonic stem cells tend to form tumors; differentiated
embryonic stem cells do not. Dr. Weissman described one
advantage of embryonic over adult stem cells: using somatic
nuclear transfer (also known as cloning), researchers could
create embryonic stem cell lines from individuals with genetic
predispositions to develop disorders like juvenile diabetes
and Lou Gehrig's disease. These cell lines would themselves
develop the same disease in culture over time, providing
a unique opportunity to study the molecular and genetic
mechanisms of the disease. Dr. Peduzzi-Nelson used this
point to suggest that the focus on embryonic stem cell research
may be profit-driven. She argued that pharmaceutical companies
want to remove President Bush's limits on embryonic stem
cell research because embryonic stem cell lines (such as
Dr. Weissman described) may be patented and become hugely
profitable, while adult stem cell therapies such as hers
and Dr. Lima's cannot be patented.
11/29/03
From the Society for Neuroscience
LEGISLATIVE ALERT: Contact Congress
to Oppose Part of the Commerce-Justice-State Appropriations
Bill That Would Hamper Stem Cell Research
The federal funding process is nearly complete and language
to be included in a larger Appropriations bill would jeopardize
stem cell research. The amendment, sponsored by Rep. Dave
Weldon (R-FL), would forbid the U.S. Patent and Trademark
Office (PTO) from granting patents on processes and products
derived from embryonic stem cell research and therapeutic
cloning (aka somatic cell nuclear transfer).
By prohibiting these patents, this amendment eliminates
financial incentives for private companies to undertake
this research. There are already government limits to federal
funding for stem cell research. This amendment would create
a disincentive for the private sector to move forward on
such research, as well.
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