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Stem
Cell Research May
Lead to Parkinson's Therapy
Excerpt
By
E. J. Mundell, Reuters
Health
NEW YORK (Reuters Health)
- Stem cells might someday be used as ``seeds'' for the harvest
of transplantable brain cells that could slow or reverse Parkinson's
disease, according to researchers in Sweden.
``Stem cells, for their ability to proliferate and differentiate
into all possible cells in an individual, hold that therapeutic
potential,'' explained researchers Goncalo Castelo-Branco and
Dr. Ernest Arenas of the Karolinska Institute in Stockholm. Their
findings were presented Sunday in San Diego, California at the
annual meeting of the Society for Neuroscience.
Parkinson's disease is a chronic, progressively debilitating
illness caused by the death of cells deep within the brain that
produce dopamine, an important chemical that helps transmit nerve
impulses. Preventing the loss of these dopamine-producing neurons,
or replacing them once they are gone, is the ``Holy Grail'' of
Parkinson's research.
Scientists have long known that the transplantation of neurons
from fetal brain tissue into the brains of Parkinson's patients
can help halt progression of the disease. But this technique is
impractical since it ``raises both technical and ethical problems,''
according to the researchers.
A solution would be to somehow direct stem cells to develop into
dopamine-producing nerve cells in the laboratory, then harvest
and transplant these cells into the brains of patients who need
them. But just what conditions are necessary to transform stem
cells into this highly specialized type of cell?
``This is precisely the key question that we are trying to solve,''
Castelo-Branco and Arenas told Reuters Health. The Swedish team
has engineered embryonic stem cells to express a protein called
Nurr 1. Nurr 1 acts as a kind of chemical ''antenna,'' helping
the stem cell pick up signals from other brain cells that would
instruct it to develop into a dopamine-producing neuron. Identifying
the exact source of that signal is the next stage in the investigators'
research.
``In the future we hope to be able to identify the molecule(s)
involved and then induce (the growth of) as many midbrain dopamine-producing
neurons as we want,'' the researchers explained. The result, ideally,
would be laboratory-based brain cell ``farms''--a limitless source
of transplantable neurons.
The procedure already appears to be working in mice, according
to the study team, who say they have also been successful in ``increasing
the efficiency'' of the technique in stem cells sourced from human
embryos.
Much more research needs to be done, however, and the therapeutic
use of laboratory-grown brain cells for Parkinson's patients is
still years away. But Castelo-Branco and Arenas are optimistic
that the technique might someday be used to treat other brain
diseases, as well.
Huntington's disease--an inherited, degenerative neurological
disorder--is one likely candidate, they say, because the disease
``affects a defined population of neurons.'' Any effective treatment
for this fatal illness ``would be very important,'' the researchers
conclude.
In a related study, researchers at Thomas Jefferson University
in Philadelphia, Pennsylvania, say they have successfully directed
stem cells from human bone marrow to grow into brain cells under
laboratory conditions.
In a statement, lead researcher Dr. Lorraine Iacovitti said her
team has ``identified factors that get 100% of adult human bone
marrow cells converted to neurons very quickly,'' although they
have not yet been able to create brain cells capable of producing
dopamine.
Another problem remains: All of the new neurons appear to revert
back to undifferentiated stem cells within a few days. ''The bigger
problem to solve is how to keep them differentiated,'' Iacovitti
said.
But she believes the findings hold great promise for Parkinson's
patients. ``The major advantage of using adult human bone marrow
stem cells is that each person can be his own donor,'' she pointed
out.
Reference
Source 89
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