Vision-Restoring Retinal Gene Therapy Also Strengthens Visual Processing Pathways in Brain; Rapid Regrowth of Unused Brain Connections Seen After Decades of Near Blindness in Treated LCA2 Patients

Since 2007, clinical trials using gene therapy have resulted in often-dramatic sight restoration for dozens of children and adults who were otherwise doomed to blindness. Now, researchers from the Perelman School of Medicine at the University of Pennsylvania (Penn) and The Children’s Hospital of Philadelphia (CHOP), together with colleagues, have found evidence that this sight restoration leads to strengthening of visual pathways in the brain, published in the July 15, 2015 issue of Science Translational Medicine. The article is titled “Plasticity of the Human Visual System after Retinal Gene Therapy in Patients with Leber’s Congenital Amaurosis.” “The patients had received the gene therapy in just one eye (their worse seeing eye), and though we imaged their brains only about two years later, on average, we saw big differences between the side of the brain connected to the treated region of the injected eye and the side connected to the untreated eye,” said lead author Manzar Ashtari, Ph.D., Director of CNS Imaging at the Center for Advanced Retinal and Ocular Therapeutics in the Department of Ophthalmology at Penn. Ashtari is the former Director of Diffusion Tensor Image Analyses and Brain Morphometry at CHOP. “It’s an elegant demonstration that these visual processing pathways can be restored even long after the period when it was thought there would be a loss of plasticity,” said senior author Jean Bennett, M.D., Ph.D., the F.M. Kirby Professor of Ophthalmology at Penn and Director of the Center for Advanced Retinal and Ocular Therapeutics. The team examined ten patients who have Leber’s congenital amaurosis Type 2 (LCA2), a rare disease that afflicts those who inherit one bad copy of an LCA2 gene from each parent.
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