Retinal Cell Implants for Parkinson's

A preliminary study suggests that implants of cells from the human retina improved motor symptoms in patients with Parkinson's disease (PD), and they appear to be safe and well tolerated.

Parkinson's disease is a neurodegenerative disorder characterized by tremor, rigidity, postural instability, and slowed ability to start and continue movements. Most patients with PD require treatment with levodopa to control symptoms three to five years after a diagnosis of PD. However, disease progression and long-term oral treatment with levodopa may lead to the development of motor fluctuations and dyskinesias, which is difficulty or distortion in performing voluntary movements.

Human retinal pigment epithelial (RPE), the pigment cell layer found in the inner layer of the retina of the eye, produces levodopa and can be isolated from post mortem human eye tissue, grown in culture, and implanted into the brain attached to microcarriers.

Natividad P. Stover, M.D., of the University of Alabama (Birmingham, AL, USA) and colleagues conducted an open-label pilot study to evaluate the effect of unilateral implantation of human RPE cells attached to gelatin microcarriers. Six patients with advanced PD received cell implants, which were inserted into the brain tissue. The researchers performed efficacy evaluations at one and three months after surgery, and then at six, nine, 12, 15, 18 and 24 months. The results were reported in the December 2005 issue of Archives of Neurology.

"The implants were well tolerated,” the authors reported. "We observed an average improvement of 48% at 12 months after implantation. Improvement was also observed in activities of daily living, quality of life, and motor fluctuations; no off-state dyskinesias were observed.



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