Algae genes helped blind man recover some of his vision

A blind man who could only perceive the slightest light can now perceive blurry shapes, thanks to gene therapy and a pair of specially designed glasses.

The man was diagnosed with a condition called retinitis pigmentosa 40 years ago, at the age of 18, according to a new report, published Monday, May 24 in the journal. Nature medicine. People with retinitis pigmentosa wear the genes which, due to numerous mutations, cause the light-sensitive retinal cells at the back of the eye break down, according to the National Eye Institute (NEI).

These genes usually code for functional proteins in the retina, but fail to build these proteins, or to make abnormal proteins that malfunction or produce substances that directly damage retinal tissue. The disease affects about 1 in 4,000 people worldwide, according to the NEI, and can sometimes lead to complete blindness, as happened in the 58-year-old patient in the new study, BBC News reported.

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In an attempt to treat the man’s vision loss, scientists inserted genes encoding a light-sensitive protein into a modified virus, then injected these genetically modified viral vectors into one of his eyes, reported Researchers. The protein, called ChrimsonR, is a technical version of a light-sensitive protein found in unicellular algae, which allows the unicellular organism to sense and move towards sunlight, MIT Technology Review Report.

ChrimsonR belongs to a family of light-sensitive proteins called channelrhodopsins, hence the “H” added in crimson, and has been modified to respond to colors in the reddish end of the color spectrum, namely amber light. By injecting the genes for ChrimsonR in the retina – especially in the retinal ganglion cells, a type of nerve cell that sends visual signals to the brain – the team hoped to make these cells sensitive to yellow-orange light, reported the MIT Technology Review.

Here’s where the special glasses came into play. The glasses pick up changes in the light intensity of the environment and then translate that signal into an intense amber image that is projected directly onto the patient’s retina, in an effort to activate ChrimsonR . Months passed before a significant amount of ChrimsonR accumulated in the human eye and began to impair his vision, but eventually he began to perceive patterns of light with the help of glasses, BBC News reported.

“The patient perceived, located, counted and touched” different objects using his treated eye, alone, and while wearing the glasses, the researchers wrote in the study. For example, the patient could see a notebook and cups placed on a table in front of him, although when asked to count the cups he did not always give the correct number, according to MIT Technology Review.

Before receiving the therapy, the man could not detect any object, with or without glasses, and after the injection, he could only see when wearing the glasses, as they convert all light to an amber tint, reported Researchers.

In addition to the notebook and cups, the patient said he was able to see the painted white lines at a crosswalk, the BBC reported. “This patient was initially a little frustrated because it took a long time between the injection and the moment when he started to see something”, first author, Dr José-Alain Sahel, ophthalmologist and scientist at the University of Pittsburgh and the Paris Vision Institute, told the BBC. The patient started training with the glasses around 4.5 months after his injection and didn’t start reporting improvements in his vision until around 7 months after that, the team reported.

“But when he started reporting spontaneously he could see the white stripes crossing the street, you can imagine he was very excited. We were all excited,” Sahel told the BBC.

Even now, human vision is still quite limited, in that he can only see monochrome images and at a fairly low resolution. But “the results provide proof of concept that using optogenetic therapy to partially restore vision is possible,” lead author Dr Botond Roska, founding director of the Institute of Ophthalmology, told BBC News. molecular and clinical studies at the University of Basel. (“Optogenetics” broadly describes the technique of using light and genetic modification to control the activity of neurons.)

Of course, while these early results are exciting, the study is small as only one patient has received the treatment so far, James Bainbridge, professor of retinal studies at University College, told the BBC. London who was not involved in the study. .

Learn more about research in BBC News and MIT Technology Review.

Originally posted on Live Science.

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