( Discovery promises to make retina spin...)Schepens Scientists Identify Key to Integrating Transplanted Nerve,Cells Into Injured Tissue,Health

BOSTON, April 26, 2007 /PRNewswire/ -- Scientists at the Schepens Eye Research Institute, an affiliate of Harvard Medical School, have identified a key mechanism for successfully transplanting tissue into the adult central nervous system. The study found that a molecule known as MMP-2 (which is induced by stem cells) has the ability to break down barriers on the outer surface of a damaged retina and allow healthy donor cells to integrate and wire themselves into remaining recipient tissue. The finding, reported in the current issue (April 25, 2007) of the Journal of Neuroscience, holds great promise not only for patients with retinal disease, but also for those suffering from spinal cord injuries and neurodegenerative disorders such as Parkinson's and Alzheimer's Diseases.

"This is a very significant finding," says Dr. Michael Young, associate scientist at the Schepens Eye Research Institute and principal investigator of the study. "We believe that it will ultimately make retinal transplantation and restoration of vision a possibility." He adds that transplantation of donor photoreceptors (in whole retina transplants) may prove to be more beneficial than transplanting stem cells alone, as these retinal transplants contain a complete organized supply of cells necessary for proper vision.

The regenerative capacity of central nervous system tissue in adult mammals, including human begins, is extremely limited. This is partly due to the formation of barriers, known as "glial" scars, which are triggered by the body to protect the injured retina or other nerve tissue from further damage. This dense scar tissue throws up a blockade to foreign cells, including transplants meant to heal and regenerate. This is what has made previous attempts to transplant whole donor retinas so difficult, according to Young
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