Embryonic Stem Cells' Safety Weighed by FDA Advisers (Update2)
By Elizabeth Lopatto
April 10 (Bloomberg) -- Embryonic stem cells that may cure diseases
also carry new risks, from the danger improper cells will be
implanted to the prospect they may travel to the wrong parts of the
body, companies told U.S. advisers today.
Geron Corp., Novocell Inc. and Advanced Cell Technology Inc. appeared
before a Food and Drug Administration advisory panel weighing how to
ensure safety in human tests of the decade-old cell technology. The
companies plan to test treatments in people as soon as this year.
Stem cells are attractive for treatment because they can grow and
change into other cell forms. That can also bring unintended
consequences, including creation of tumors. Because stem cells can
last a lifetime, the FDA is asking the companies and scientists how
long patients should be followed and how best to monitor them during
studies.
``We've talked about how long we need to monitor people for, and the
answer is forever,'' said panel member Gordon Weir, a professor of
medicine at Harvard Medical School in Boston, during the meeting.
``We're putting in these cells, and we don't know what they're going
to cause in terms of trouble.''
The FDA may require ``particularly strong'' evidence early in studies
that stem-cell treatments are effective, said Steven Bauer, chief of
the FDA's Cell and Tissue Therapy branch, during the daylong hearing
in Gaithersburg, Maryland. The agency also may require longer trials
of stem-cell therapies than it does for conventional drugs, said
Mercedes Serabian, a supervisory toxicologist for the FDA, after the
meeting.
Mouse Embryos
Scientists discovered ways to get stem cells from mouse embryos about
20 years ago, and in 1998 determined how to obtain them from human
embryos and cultivate them, according to the National Institutes of
Health. Since then, scientists have manipulated embryonic stem cells
in the lab to create different types of tissue cells to treat
disease.
Researchers need to confirm the type of cell they are working with at
every stage of development, said Melissa Carpenter, the vice
president of research and development at Novocell.
``You need to make sure, especially if you're handling multiple cell
products, that the cell product you're delivering is the one you
think you're delivering,'
identify abnormalities in cell cultures before they go into people
and make sure the cells stay where they're implanted, she said.
Producing Insulin
Novocell, based in San Diego, is using stem cells to create insulin-
producing cells for diabetics.
Scientists even face challenges in creating a placebo to mimic the
cloudy solutions that typically contain stem cells, said Jonathan
Dinsmore, general manager and senior vice president of Advanced Cell.
``It's important to use control cells and blind your experimental
team, which is difficult with cell therapy,'' Dinsmore said. Double-
blind studies, in which the researchers and patients don't know who
gets the actual treatment, are considered the gold standard for drug
trials.
Advanced Cell of Alameda, California, is using embryonic cells for an
experimental treatment of eye diseases, including macular
degeneration, a market the company estimates at $28 billion. Macular
degeneration weakens the part of the eye responsible for sharp vision
and affects about 15 percent of people over the age of 75, according
to the National Institutes of Health.
`Tricky to Maintain'
Researchers must carefully store the fragile cells, Jane Lebkowski,
the senior vice president of regenerative medicine at Geron, told the
panel.
``Anyone who has used embryonic stem cells knows that these cells can
be tricky to maintain,'' Lebkowski said.
Geron, of Menlo Park, California, is attempting to treat spinal cord
injuries by turning stem cells into a type of nerve cell that
insulates the spinal cord.
Geron rose 61 cents, or 13 percent, to $5.40 at 4:30 p.m. in Nasdaq
Stock Market composite trading. Advanced Cell Technology was
unchanged at 12 cents in over-the-counter trading. Novocell is
closely held.
There are two types of stem cells. Embryonic cells, created shortly
after conception, can become any other cell type in the body. Their
use is controversial because harvesting them destroys the embryo. Use
of so-called adult stem cells, which exist in tiny numbers within
grown organs, are more limited and able to morph only into certain
types of cells.
Having considered embryonic cells today, the advisers will hold a
hearing tomorrow on use of adult cells. The panel will also discuss
possible rule changes for designing studies of other biotechnology
products, including gene therapy.
To contact the reporter on this story: Elizabeth Lopatto in
Gaithersburg, Maryland, at elopatto@bloomberg.
Last Updated: April 10, 2008 18:49 EDT
http://www.bloomber
pid=20601124&
«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»«¤»¥«¤»§«¤»¥«¤»§«¤»¥«
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
____________________________________________
«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»«¤»¥«¤»§«¤»¥«¤»§«¤»¥«
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch format to Traditional
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___
No comments:
Post a Comment