New Gene-Based Therapy Partially Restored a Blind Man’s Vision

Retinitis pigmentosa is a rare genetic disease that people are born with- it causes the light-gathering cells in the retina to die resulting in vision loss over time. There is no known cure for retinitis pigmentosa, but scientists announced in their report in the journal Nature Medicine that they partially restored a blind man’s sight by using a new technique called optogenetics.

Before the optogenetic therapy treatment, the man could detect some light but could not see motion or pick out objects- now he can see and count objects, and even reported being able to see the white stripes of a pedestrian crosswalk! His vision is still limited and requires him to wear special goggles, but his results are proof of more effective treatments to come.

For people with degenerative eye diseases, the therapy involved uses a light-sensitive protein to make nerve cells fire off a signal to the brain when hit with a certain wavelength of light. These therapies may halt or slow progression of degenerative eye diseases, but it does not help people who have already lost vision. This is simply because when victims lose their photoreceptors completely- you cannot repair the gene defect from dead cells.

In this new optogenetic therapy treatment, researchers have been experimenting with a radical kind of repair- they are using gene therapy to turn ganglion cells into new photoreceptor cells, even though they do not normally capture light. Scientists are taking advantage of proteins derived from algae and other microbes that can make any nerve cell sensitive to light. In the early 2000s, neuroscientists figured out how to install some of these proteins into the brain cells of mice and other lab animals by injecting viruses carrying their genes. The viruses infected certain types of brain cells, which then used the new gene to build light-sensitive channels. Now, Dr. Sahel and other researchers are using optogenetics to add light-sensitive proteins to cells in the retina. They reason that retinal cells are nerves as well- or in other words, an extension of the brain.

To create their goggles, scientists chose an optogenetic protein that is sensitive only to amber light, which is easier on the eye than other colors, and used viruses to deliver these amber proteins to the ganglion cells in the retina. A special device was used to transform visual information from the external world into amber light that could be recognized by the ganglion cells. The goggles then send a pulse of amber light from that pixel into the eye thus activating parts of the brain involved in vision.

Even though it will take many more positive results from clinical trials before optogenetics can become a standard treatment for some forms of blindness, there is no doubt that this opens up a new world for the lives of individuals with vision impairment. Certainly this is an exciting time for scientists and researchers involved in the field of vision and vision treatment, and I am interested in seeing how optogenetic therapy progresses.







Sources:
https://www.nytimes.com/2021/05/24/science/blindness-therapy-optogenetics.html

https://www.sciencenews.org/article/blindness-retinitis-pigmentosa-gene-therapy-vision-optogenetics

https://www.nature.com/articles/s41591-021-01351-4