Eye cell implants improve lives of Parkinson's sufferers

Dec 14 2005

U.S. researchers say that people with Parkinson's disease showed a marked improvement after surgeons implanted in their brains chemical-producing cells taken from the eye of a dead donor.

Apparently 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.

However 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, and many people on the drug develop involuntary writhing or dance-like movements.

Natividad Stover, a researcher at the University of Alabama, says the retina cells were cultivated and implanted in the brains of six patients with advanced Parkinson's disease.

Stover says that one year later, the patients scored 48 percent higher on tests of movement and coordination, and the improvement was sustained after two years.

The research showed that the implants were well tolerated,and improvement was observed in activities of daily living and in the 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 considered implanting fetal stem cells into the brains of Parkinson's patients to be a promising avenue to restoring dopamine production, but preliminary human trials proved to be disappointing, and animal experiments have yielded mixed results.

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

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

The research is published in the journal Archives of Neurology.