NEW YORK, Nov 22 (Reuters Health) -- A decade after human embryonic brain
cells were transplanted into the brain of a 69-year-old man with Parkinson's
disease, the cells still survive and are releasing dopamine, a brain chemical,
researchers report.
"This is the first report to demonstrate... that grafts of fetal human
midbrain tissue not only store dopamine but can release it in a (normal)
manner," and continue to relieve Parkinson's disease symptoms, Dr. Paola Piccini
of the Imperial College School of Medicine in London, UK, told Reuters Health.
Parkinson's disease is a brain disorder characterized by slowness of
movement, rigidity, and tremors. A type of brain cell, the neuron that produces
dopamine, is lost in an area of the brain called the basal ganglia, which
controls voluntary movements. Drugs that replace dopamine can be used to treat
the disease, but they eventually fail and also produce debilitating side
effects.
In the December issue of Nature Neuroscience, Piccini and colleagues in
the UK and Sweden describe how they used an imaging technique to measure
dopamine release from the transplanted neurons.
The Parkinson's patient who was studied had responded well to the
transplanted cells that were implanted only into the right side of the brain.
Therefore, the researchers were able to compare the function of the transplanted
and nontransplanted sides of the brain. Five healthy people were studied for
comparison.
The investigators found that the ability of the patient's brain cells to
store dopamine on the transplanted side of the brain was restored to the same
levels observed in the healthy volunteers. In contrast, the nontransplanted side
stored dopamine at only 12% of normal levels.
Piccini's group also found evidence that the transplanted neurons were
releasing dopamine. Peak dopamine levels were increased by 2- to 10-fold,
according to the report.
There were no signs of transplant rejection, even though the patient had
not received any immune system therapy for over 4 years.
"Our intention is now to explore other sources of (dopamine-releasing)
tissue," Piccini said in the interview with Reuters Health. "Success in this
area should make transplantation available to a far wider population of
Parkinson's disease patients."
