First Human Test of Optogenetics Could Restore Sight to the Blind

by: Nathaniel Scharping
A decade-old technique that allows researchers to control brain function in lab animals could partially restore sight to the blind.
In a trial sponsored by RetroSense Therapeutics, a startup company in Ann Arbor, Michigan, doctors will inject a harmless virus loaded with DNA from photoreceptive algae into the eyes of 15 patients suffering from retinitis pigmentosa. The experimental procedure represents the first human test of optogenetics, which is a technique that genetically modifies neurons to make them responsive to light. Doctors from the Retina Foundation of the Southwest will perform the procedure, and attempt to transfer the job duties of photoreceptor cells to different cells in the eye to restore sight.

Giving Cells a New Job

Before our brains build a visual image of our world, a chain of cells in our eyes must convert light into electrical signals that are processed in the brain. Photoreceptor cells in the retina represent the first link in this chain, and they are reactive to photons, or the fundamental particle of visible light.Retinitis pigmentosa causes these cells to degenerate, and patients with this condition lose peripheral and night vision and eventually go blind. The plan is bypass these broken photoreceptor cells and make ganglion cells, which relay signals from the retina to the brain, sensitive to light.
Doctors will inject a virus carrying DNA instructions that will coax ganglion cells into producing a light-sensitive protein called channelrhodopsin — the same protein algae use to detect light. For a decade now, neuroscience researchers have been using this method to alter brain cells in lab animals in order to activate or shut down neural pathways with light. Typically, researchers control neural behavior by implanting fiber-optic cables the shine light onto the desired location in the brain. Testing optogenetic therapy in the eye is an ideal first human trial since the procedure doesn’t require implants or complicated surgery……
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Source: Discover Magazine