Eye cell implants may ease Parkinson’s – study

By Andrew Stern

CHICAGO (Reuters) – People with Parkinson’s disease showed
marked improvement after surgeons implanted in their brains
chemical-producing cells taken from the eye of a dead donor,
researchers said on Monday.

Cells from the inner, or pigment, layer of the eye’s retina
make levodopa, which Parkinson’s patients commonly take in pill
form to replace lost production of the neurotransmitter
dopamine.

Dopamine allows the brain to control and smooth the body’s
movements.

For most patients, the levodopa pills lose their
effectiveness over five years or less, and larger and larger
doses are needed to keep at bay the involuntary movements and
shaking symptomatic of the disease.

Many people on the drug develop involuntary writhing or
dance-like movements.

The retina cells were cultivated and implanted in the
brains of six patients with advanced Parkinson’s, researcher
Natividad Stover of the University of Alabama said.

One year later, the patients scored 48 percent higher on
tests of movement and coordination, and the improvement was
sustained after two years, Stover wrote in the journal Archives
of Neurology.

“The implants were well tolerated,” the report said.
“Improvement was also observed in activities of daily living
(and) quality of life.”

Parkinson’s is a degenerative disease in which key brain
cells that produce dopamine die off. Symptoms start with
tremors and rigidity and patients can end up paralyzed. The
cause of the disease that attacks 2 percent of men and 1.3
percent of women is unknown, and there is no cure.

Some scientists have viewed implanting fetal stem cells
into the brains of Parkinson’s patients as a promising avenue
to restoring dopamine production. But preliminary human trials
were disappointing, and animal experiments have yielded mixed
results.

Other treatments showing promise include deep brain
stimulation with implanted electrodes, drugs that promote brain
cell growth, and gene therapy.

The researchers said a larger study has been started to
test the efficacy and safety of retina cell implants.