April 28 (HealthDay News) -- By implanting specialized cells found in the human eye into areas of the brain damaged by Parkinson's disease, researchers were able to reduce symptoms and improve quality of life in people with moderate to severe Parkinson's.

The new treatment, dubbed Spheramine, reduced symptoms experienced when people were off their Parkinson's medications by 44 percent for as long as four years of follow-up. Quality-of-life measurements were up about 23 percent, according to the study, expected to be presented April 29 at the American Association of Neurological Surgeons' annual meeting, in Chicago.

"This is a promising study on a form of therapy that is different from anything out there," said the study's lead author, Dr. Roy Bakay, a professor of neurological surgery and the A. Watson and Sarah Armour Presidential Chair at Rush University Medical Center in Chicago.

"This therapy may be beneficial in itself, or it may be used as additional therapy," added Bakay, who was at Emory University in Atlanta at the time of the study.

Spheramine is made from cells called human retinal pigment epithelial cells (hRPE) that are found naturally in the human eye. By combining these cells with microscopic gelatin beads called microcarrier support matrix (MSM), the Emory researchers were able to produce Spheramine, a targeted therapy for Parkinson's. Spheramine can be implanted in the brain, where the eye cells naturally begin to produce levodopa. The researchers believe the levodopa is then turned into dopamine, a neurotransmitter lacking in people with Parkinson's.

"Spheramine is not stem cells. There's no requirement for immunosuppression, and these cells are easily harvested from eye banks and are readily available," Bakay said.

The new study included six patients with moderate to severe Parkinson's disease, a progressive brain disorder that causes tremors and other motor difficulties that worsen as the disease advances. Parkinson's affects as many 1.5 million Americans, according to background information in the study.

There are few effective treatments for Parkinson's, and those that do work often have unpleasant side effects and may stop working over time.

Patients selected for the study were chosen based on their responsiveness to levodopa and the severity of their symptoms when they were off their medication. Using MRI-guided stereotactic surgery, the researchers implanted Spheramine into areas of the volunteers' brains that appeared to be most affected by Parkinson's.

After 12 months, there was a 48 percent improvement in symptoms. At 48 months, that number had dropped to 44 percent, but Bakay said the researchers were pleased that the treatment maintained effectiveness for that long.

The only significant side effect seen in this small study was a transient headache, he said.

Dr. Bruce Silverman, a neurologist at Providence Hospital and Medical Center in Southfield, Mich., said the new study "showed that there was clinical improvement over a sustained period of time. The study was based on small numbers, but it shows some promise."

He added that the study needs to replicated with a larger group of patients.

Bakay said the researchers have recently completed a larger, double-blind study, and results of that trial should be available by the end of this year or early 2009.

SOURCES: Roy Bakay, M.D., professor, neurological surgery, and the A. Watson and Sarah Armour Presidential Chair, Rush University Medical Center, Chicago; Bruce Silverman, D.O., neurologist, Providence Hospital and Medical Center, Southfield, Mich.; April 29, 2008, presentation, American Association of Neurological Surgeons' annual meeting, Chicago