Stem Cells May Treat Parkinson`s
Embryonic stem cells injected into the brain corrected the symptoms of Parkinson`s disease in rats by transforming into neurons that made dopamine, a key brain chemical.
Jan 08 8:18 AM ET
Posted on: 01/08/2002
Stem Cells May Treat Parkinson's
By PAUL RECER, AP Science Writer
WASHINGTON (AP) - Embryonic stem cells injected into the brain
corrected the symptoms of Parkinson's disease (news - web sites) in rats by
transforming into neurons that made dopamine, a key brain chemical.
In a study appearing Tuesday in the Proceedings of the National
Academy of Sciences (news - web sites), researchers at Harvard Medical School (news - web sites) and
McLean Hospital in Belmont, Mass., showed in tests that in rats
whose brains had been chemically damaged, embryonic stem would
spontaneously convert to correct the Parkinson's symptoms.
Some experts said the study was significant because it showed
embryonic stem cells may be used to treat brain disorders, but they
cautioned that the cells also possibly could cause tumors.
Dr. Ole Isacson, senior author of the study, said that if
further experiments are successful, there could be human trials of
the technique in about five years.
Federally funded research on human embryonic stem cells is
limited because producing such cells requires the death of human
embryos. President Bush (news - web sites) last summer approved some such research,
but limited it to cell colonies that already exist - about 60 cell
Many researchers believe that embryonic stem cells hold the
promise of creating new organs or cells to replace or renew ailing
hearts, livers and other organs. Some earlier laboratory studies
have suggested that embryonic stem cells could be directed to
transform into curative cells for such diseases as Alzheimer's,
Parkinson's or diabetes.
In the current study, researchers demonstrated that the
embryonic cells could spontaneously correct some symptoms of
To conduct the study, scientists first caused rats to develop
Parkinson's symptoms by injecting into their brains a toxin that
killed neurons that typically die during the course of that
The researchers then injected embryonic stem cells that had been
extracted from early mouse embryos and were capable of growing into
any type of cell.
About nine weeks after the injections, the embryonic stem cells
converted to neurons that make dopamine, a brain chemical lacking
in Parkinson's disease patients, Isacson said.
The injected stem cells, said Isacson, grew into the type of
neurons that typically die in the brains of Parkinson's patients.
One of the symptoms the Parkinson's rats had was a tendency to
turn aimlessly in their cages, up to 10 times a minute, after they
had been injected with amphetamine. Nine weeks after the stem cell
injections, Isacson said, the rats' tendency to turn was stopped.
The researchers also conducted imaging tests and found that
blood flow was restored to parts of the brains that had died from
the Parkinson's effect.
Dr. Arlene Y. Chiu of the National Institute of Neurological
Disorders and Stroke said Isacson's study was an important advance
because it showed that embryonic stem cells will grow into specific
neurons in the brain.
But she noted that five of the 19 animals used in the study also
developed tumors and cautioned that this was a problem that must be
solved before the technique could be used on humans.
"One of the great fears about using undifferentiated stem cells
is that they will develop tumors," said Chiu.
She said Isacson reduced this problem by injecting only about
1,000 stem cells into each of the test animals. In some earlier
studies, researchers injected more than 100,000 cells and many test
animals developed tumors.
On the Net:
Parkinson's information: http://www.ninds.nih.gov/index.htm
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