For about 40 years he had lost his sight due to retinitis pigmentosa, genetic degenerative eye disease. Now at the age of 58 he has managed to recover part of his sight and count, identify, albeit in a blurred way, and touch objects thanks to theoptogenetics, the technique that uses pulses of light to control the activity of cells, previously modified to respond to light stimuli. The case, one of the first in which this technique is used in humans, is described in the journal Nature Medicine by the group of the University of Pittsburgh, led by Jos Sahel and Botond Roska. Before the treatment, the man could only detect some light, but could not perceive movement or detect objects. Now he sees and counts objects and he said he was able to see the pedestrian crossing as well. His vision is still limited and requires him to wear special glasses that send pulses of light to the treated eye.
What is retinitis pigmentosa
Retinitis pigmentosa is a neurodegenerative disease of the eye that destroys photoreceptors, the light-receptive cells in the retina, leading to blindness. At the moment there are no approved therapies, other than gene therapy which works only in the early stages of the disease and which has so far only been successful in a particular type of genetic lesion of this pathology.
The long studies
Researchers have been working for more than a decade on optogenetic therapies to restore vision in people with degenerative eye diseases, such as retinitis pigmentosa. The therapy involves the use of a light-sensitive protein to make nerve cells emit a signal to the brain when hit by a certain wavelength of light. Traditional gene therapies can stop or slow the progression of degenerative eye diseases, but they do not help people who have already lost their sight. Optogenetic therapy instead it can help people who have lost sight due to many degenerative photoreceptor diseases, regardless of the genetic changes that cause them, such as macular degeneration, which affects millions of people around the world. Optogenetic therapy, on the other hand, cannot be used for glaucoma or diabetic retinopathy, in which the ganglion cells of the retina are damaged.
How does it work
In the case described, the researchers, including the Italians Angelo Arleo of the Sorbonne University e Francesco Galluppi of the French National Research Council, after testing the technique on monkeys, they switched to humans in a phase 1 / 2a study. With an injection into the eyeball of one of the two eyes, they brought in a virus, rendered harmless, used as a shuttle to carry the gene of the ChrimsonR protein, which makes cells sensitive to light impulses. The virus infected the retinal ganglion cells, making them sensitive to the light that send the fiber to the optic nerve. Because daylight wasn’t enough to activate them, the scholars adopted an ingenious solution, he explains Fabio Benfenati, director of the research center of the Italian Institute of Technology (Iit) in Genoa. They made the man wear gods hi-tech goggles, equipped with a camera capable of capturing images from reality, transforming them into light pulses and projecting the latter onto the retina in real time. In this way the cells modified and made more sensitive to light were activated. The technique was well tolerated by the patient who was able to recognize, count, locate and touch various objects of 10-20 centimeters with the treated eye. The vision is not quite like the natural one – he adds – because the patient has a narrow field of vision and to widen it he has to move his head, but it is still a promising approach. one of the first cases on which optogenetics is tested in humans and compared to gene therapy, it can also be used in more advanced stages of the disease. The authors point out that the new technique is not a cure for blindness: For now all we can say is that there is a patient … with a functional difference. It is a milestone along an encouraging road that can lead us to even better results.
May 25, 2021 (change May 25, 2021 | 16:25)
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