Scientists Partially Restore Blind Sight with Breakthrough Therapy

By injecting a genetically engineered virus into the eye, scientists have restored useful vision in a 58-year-old man with retinitis pigmentosa, a hereditary eye disease. Men who had been blind for decades could see small objects such as staple boxes, tumblers, and notebooks when they wore their own goggles.

Breakthroughs are described in Papers published in Nature Medicine on Monday. It relies on optogenetics, a new field of biological research aimed at controlling nerve cells through light.

“These are very exciting results,” says Raymond Wong, a stem cell biologist at the University of Melbourne who is developing treatments for eye diseases that are not relevant to the study.

Although the potential therapeutic benefits are immeasurable, Wong says the technology has been used in only one patient so far.It forms part of Ongoing clinical trials Test the safety and tolerability of gene therapy. Through continuous testing and improvement, we find that this technique helps visually impaired patients navigate their daily tasks more effectively.

How did they do it? By redesigning the cells of the eye to make them more sensitive to light.

Eye computer

I’m reading this article on a mobile device or computer screen because the retina performs complex decoding. According to Boton Roska, a biomedical researcher at the University of Basel and author of a new study, the retina is like a “biological computer behind the eye.”

Like onions, this computer has layers. Light is filtered through the eye and interacts with specialized photoreceptor cells called rod cells and cone cells at the bottom of the computer. They signal another specialized cell called the retinal ganglion cell at the top of the computer.

However, in retinitis pigmentosa, the bottom layer is scrambled. Genetic variation can cause rods and cones to malfunction or die. There are dozens of different mutations that can lead to retinitis pigmentosa. The disease affects 1 in 4,000 people worldwide. According to the National Institute of Health.. Often this results in patients with tunnel vision, and eventually most patients lose vision.

That was the case with a 58-year-old patient who was at the center of a new study. “His retina was unable to detect important signals,” said Jose Alain Sahel, an ophthalmologist at the University of Pittsburgh and lead author of the study.

The patient’s photoreceptor cells are not functioning, but his retinal ganglion cells are functioning. These cells usually receive signals from rod and pyramidal cells and pass them on to the brain. It is these cells that researchers have targeted in optogenetic treatment.

“Optogenetics is the science of taking non-light-sensitive cells and introducing genes that make them light-sensitive,” says Philip Lewis, a biomedical engineer at Monash University.

The team created a viral vector similar to that used to deliver the COVID-19 vaccine. It delivers amber or red light-sensitive genes to ganglion cells. When a gene is delivered to the eye, it makes a specific light-sensing protein known as channelrhodopsin. It is usually made by algae and helps organisms look for sunlight.

“They redesigned the upper layer of the retina into a new photosensitive layer,” Lewis points out.

One vision

Patients need to wear goggles to restore vision. Goggles convert incident light into a monochromatic image and project it onto the redesigned cells of the retina in real time. “There is no delay in the process,” Roska said.

Goggles are important and act like non-functional rods and cones. Without goggles, the patient is completely blind.

After the injection, the man was unaware of any significant changes in his eyesight for several months. Then, “voluntarily”, he began to report that he was able to see the white stripes on the pedestrian crossing while wearing the goggles, Sahel said.

The patient underwent several tests in the laboratory.Released by the team two video It shows a patient trying to find a large item like a notebook and a small item like a tumbler with goggles on and off. They also showed that the visual system of the brain was activated during the experiment by installing a device that measures brain waves.

Lewis states that the improvement in visual function is very localized and the patient needs to scan around to find the object. This may be related to how gene therapy was performed on the retina. The closer it is to the injection site, the better the uptake, so these ganglion cells may respond much better than other areas. Fortunately, the improvement in vision lasted for almost two years, up to 20 months after the injection.

Roska further eased expectations at a press conference last week, pointing out that current devices do not allow patients to see faces or read books, because the resolution is not high enough.

“This treatment did not restore the patient’s vision to normal levels, but some basic vision level restorations help visually impaired patients navigate their daily work and improve their quality of life. It helps to make a big improvement, “says Wong.

Scientists are looking at competing interests, along with lead author Sahel, who declares economic benefits to GenSight Biologics, who developed the methodology. Roska serves as an advisory board to the company.

See the future

The study included only one patient because the pandemic impaired the ability of the research team to train and test other people enrolled in the clinical trial.

“They are telling us what they are seeing, and they are telling us how they are using their restored vision,” Sahel says. “Patients are more than ever really partners in the trial.”

As the pandemic begins to decline, researchers hope to begin training other patients enrolled in the trial and evaluate how goggles can help. The planned completion date is the latter half of 2025.

Not only does it restore vision for people suffering from retinitis pigmentosa Optogenetics Has already revolutionized medicine, and according to Lewis, “its potential is still being explored.”

Scientists have been trying to induce or deactivate nerve cells using electrical stimulation for decades. However, electrical stimulation is not well controlled. It’s like trying to control lightning to the brain. They stimulate the area, but not certain cells.

Optogenetics allows researchers to genetically engineer specific nerve cells to respond to light stimuli. This gives more control over cell activity and allows researchers to study the brain more accurately. Accuracy is important.In an animal model of Parkinson’s disease, scientists Techniques can be used to regulate athletic behavior.. Altering the specific activity of nerve cells with light can provide a therapeutic strategy for combating disease.

“It’s clear that light will play a major role in the future of health care and treatment,” says Lewis.