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A procedure
using cells from the retina of the human eye is showing promise
as a treatment for patients with advanced Parkinson's disease,
according to researchers at Emory University in Atlanta.
Parkinson's
disease results when nerve cells in the brain stop producing
the neurotransmitter dopamine, a chemical that sends signals
to nerve cells in the brain that control muscle movement.
Cells from the retina produce dopamine as well as levodopa,
a chemical that is the main ingredient of Sinemet, the standard
treatment for the disease. Levodopa changes into dopamine
in the brain, creating new pathways for muscle control.
Retinal
pigment epithelial (RPE) cells are harvested from donor eyes
and prepared by a pharmaceutical company. One donor eye can
treat as many as 100 patients.
Researchers
inject the retinal cells into the damaged movement center
(putamen) in the brains of Parkinson's disease patients. Approximately
350,000 cells, mixed with microscopic gelatin beads, are placed
in five different areas of the putamen. Dopamine begins to
be produced within one month.
"This
is the first human intracerebral retinal cell implantation
study in the world and we are encouraged by the results so
far," said Dr. Ray Watts, professor of Neurology at Emory
University School of Medicine and co-author of the study.
The procedure has been performed on six patients with advanced
Parkinson's disease, who showed notable improvement in their
motor functions and a reduction of the intensity of their
muscle tremors by as much as 40 percent, according to the
study presented at the annual meeting of the American Academy
of Neurology. Improvement has been noted in their tremor,
stiffness, slow movement and balance. Fifty percent of the
patients have also shown improvement of dyskinesia, involuntary
movements caused by medication.
Investigators
have seen none of the side effects found in other experimental
techniques using neurological cells from aborted human embryos.
Source:
Medical Week staff,
week of April 21, 2002
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