Philadelphia - Researchers at the University of Pennsylvania have demonstrated that gene therapy used to restore retinal activity to the blind also restores function to the brains visual center, a critical component of seeing. The multi-institutional study led by Geoffrey K. Aguirre, assistant professor of neurology in Penn's School of Medicine, shows that gene therapy can improve retinal, visual-pathway and visual-cortex responses in animals born blind and has the potential to do the same in humans.

The retina of the eye captures light, but the brain is where vision is experienced, Aguirre said. The traditional view is that blindness in infancy permanently alters the structure and function of the brain, leaving it unable to process visual information if sight is restored. Weve now challenged that view.

The results support the potential for human benefit from retinal therapies aimed at restoring vision to those with genetic retinal disease. Researchers used functional MRI to measure brain activity in blind dogs born with a mutation in gene RPE65, an essential molecule in the retinoid-visual cycle. The same mutation causes a blindness in humans called Leber congenital amaurosis, or LCA. It is the first human eye-retinal disorder slated for gene therapy.

Gene therapy, performed by introducing a working copy of RPE65 into the retina, restored eye function in canines. Yet, it was previously unclear if the brain could receive the restored sight.

The team found that gene therapy to the eye dramatically increased responses to light within the visual cortex of the canine brain. The recovery of visual brain function occurred in a canine that had been blind for the first four years of its life, and recovery was found to persist in another dog for at least two-and-a-half years after therapy, suggesting a level of permanence to the treatment.

Penn scientists then studied the structure and function of the visual
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Contact: Jordan Reese
jreese@pobox.upenn.edu
215-573-6604
University of Pennsylvania
25-Jun-2007