Researchers at the University of California, Berkeley, have announced that
they have demonstrated that by inserting a gene for a green-light
receptor into the eyes of blind mice, a month later, they were navigating
around obstacles as easily as mice with no vision problems.
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Originally Posted by University of California. Berkeley
The researchers say that, within as little as three years, the gene therapy -- delivered via an inactivated virus -- could be tried in humans who've lost sight because of retinal degeneration, ideally giving them enough vision to move around and potentially restoring their ability to read or watch video.
"You would inject this virus into a person's eye and, a couple months later, they'd be seeing something," said Ehud Isacoff, a UC Berkeley professor of molecular and cell biology and director of the Helen Wills Neuroscience Institute. "With neurodegenerative diseases of the retina, often all people try to do is halt or slow further degeneration. But something that restores an image in a few months -- it is an amazing thing to think about."
About 170 million people worldwide live with age-related macular degeneration, which strikes one in 10 people over the age of 55, while 1.7 million people worldwide have the most common form of inherited blindness, retinitis pigmentosa, which typically leaves people blind by the age of 40.
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Originally Posted by University of California, Berkeley
In their trials in mice, the UC Berkeley team succeeded in making 90 percent of ganglion cells light sensitive.
Isacoff, Flannery and their UC Berkeley colleagues will report their success in an article appearing online March 15 in Nature Communications.
To reverse blindness in these mice, the researchers designed a virus targeted to retinal ganglion cells and loaded it with the gene for a light-sensitive receptor, the green (medium-wavelength) cone opsin. Normally, this opsin is expressed only by cone photoreceptor cells and makes them sensitive to green-yellow light. When injected into the eye, the virus carried the gene into ganglion cells, which normally are insensitive to light, and made them light-sensitive and able to send signals to the brain that were interpreted as sight.
"To the limits that we can test the mice, you can't tell the optogenetically-treated mice's behavior from the normal mice without special equipment," Flannery said. "It remains to be seen what that translates to in a patient."
In mice, the researchers were able to deliver the opsins to most of the ganglion cells in the retina. To treat humans, they would need to inject many more virus particles because the human eye contains thousands of times more ganglion cells than the mouse eye. But the UC Berkeley team has developed the means to enhance viral delivery and hopes to insert the new light sensor into a similarly high percentage of ganglion cells, an amount equivalent to the very high pixel numbers in a camera.
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Story here at ScienceDaily :-
https://www.sciencedaily.com/release...0315095808.htm
"Restoration of high-sensitivity and adapting vision with a cone opsin", by Barry et. al. Nature Communications :-
https://www.nature.com/articles/s41467-019-09124-x