Blind Mice See the Light
Researchers engineer sight into a broken visual circuit
Source: “Light-Activated Channels Targeted to O.N. Bipolar
Cells Restore Visual Function in Retinal Degeneration”
Botond Roska et al.
Nature Neuroscience 11: 667-675
Results: Blind mice that had been genetically engineered to produce a light-sensitive protein in their retinas developed a rudimentary sense of vision. The mice responded to moving patterns, displaying an ability to resolve fine visual details about half as well as normal mice.
Why it matters: People with macular degeneration or retinitis pigmentosa, two leading causes of blindness in the United States, lose vision when photoreceptor cells degenerate. The new results raise the possibility of a therapy that would enable their eyes to detect and respond to light even in the absence of photoreceptors, partially restoring sight.
Methods: Researchers inserted a gene for a light-sensitive protein found in algae into the retinas of mice that lacked photoreceptors. Embedded in the membranes of retinal cells that normally relay signals from photoreceptors to the brain, the protein acts as a channel that opens when hit with light. That allows positively charged ions to flood into the cells, triggering a signal that ultimately reaches the brain.
Next steps: The cells engineered to produce the light-sensitive protein normally turn on in response to light. The researchers would like to apply their approach to cells that shut off in the presence of light, adding another layer of complexity to the restored visual system. But they must first find a way to deliver a second light-sensitive protein specifically to those cells.