Retinal Cell Implantation Shows Promise And Improvement In Advanced Parkinson's Disease Patients

In this Phase I trial, Dr. Watts and colleagues implanted retinal pigment epithelial (RPE) cells attached to gelatin microcarriers into the brains of six patients with advanced PD. RPE cells, normally found in the back of the eye, are cultured in the laboratory to produce cells for this treatment. These cells provide a source of increased dopamine production.

Dopamine is a neurotransmitter produced by neurons in the brain that is found in steadily decreasing amounts as the disease progresses. The implanted retinal cells serve as a new source of dopamine production in these patients.

"This is the first human intracerebral retinal cell implantation study in the world and we are encouraged by the results so far," Dr. Watts reports. "We’ve been following these six participants for over a year, and we’ve found they’ve improved, on average, nearly 50 percent in motor function."

Improvement is being seen in their tremor, stiffness, slow movement and balance, the most common motor functions affected by Parkinson’s disease. Half of the participants are also showing improvement of dyskinesia, which are involuntary movements that are a result of medications.

The epithelial cells used in the trial were taken from a human donor. Hundreds of millions of cells were grown in cell culture from the donor cells, and they were attached to tiny gelatin beads (or microcarriers) prior to implantation. Surgeons then implanted approximately 325,000 cells in each participant during MRI-guided stereotaxic surgery. The cells were implanted in five different areas of the striatum, the part of the brain that controls movement. The cells then live on the gelatin beads in the striatum and continually provide a source of increased dopamine production. The novel cell product is called Spheramine®, developed by Titan Pharmaceuticals, Inc. and uses Titan’s cell-coated microcarrier (CCM‘) technology.

Participants in the Emory study only had cells implanted on one side of the brain, focusing on the side that was most affected by the disease. This implantation procedure is still investigational and has not been approved by the Food and Drug Administration (FDA) for general use.

Researchers say because it is performed stereotaxically with a needle, there is less risk of infection or bleeding. Participants did not have to take immune suppressant drugs, because the brain is relatively immune protected and these cells appear to have low tendency to produce an immune response when implanted with this microcarrier technique.

The research for this Phase I, open-label trial was supported by a grant from Titan Pharmaceuticals, Inc. and the National Institute of Neurological Disorders and Stroke (NINDS), a division of the National Institutes of Health (NIH).

"This new cell implantation therapy appears to be safe and well tolerated in participants 12 to 15 months following implantation," says Dr. Watts. "We will continue to follow these six participants for months to come. We hope to begin a Phase II controlled trial soon implanting Spheramine on both sides of the brain, instead of just one side."

Parkinson’s disease is a progressive disorder of the central nervous system affecting over one million people in the United States.