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May 28, 2021/Bio Valley BIOON/---Since the early mid-2000s, optogenetics has become a promising technology to restore the vision of blind patients by virtue of its potential to activate neurons with light.
In recent years, at least two companies have announced the start of clinical trials to test optogenetic-based therapies in humans.
One of these companies recently announced that patients who are blind or almost blind due to retinitis pigmentosa will be treated after treatment.
Can detect light and motion.
In a new case study, researchers from the University of Pittsburgh in the United States and the University of Basel in Switzerland provided detailed evidence for the first time that a person had visual functional recovery after optogenetic treatment.
The relevant research results were published online in the journal Nature Medicine on May 24, 2021, with the title of the paper "Partial recovery of visual function in a blind patient after optogenetic therapy".
The 58-year-old man described in this paper is the first participant in a clinical trial partially funded by GenSight Biologics to evaluate the safety of the therapy, followed by its efficacy.
40 years before participating in the test, the man was diagnosed with retinitis pigmentosa.
Retinitis pigmentosa is a rare genetic disease that causes the photoreceptor cells on the retina to degenerate, leading to blindness.
In order to compensate for the loss of these photoreceptor cells, the authors tried to make existing retinal ganglion cells-under healthy conditions, these cells receive information from the photoreceptor cells through other intermediate cells-to respond to light.
They extracted light-sensitive protein genes from microorganisms and used gene therapy to deliver them to the blind retina.
Specifically, they injected the gene for the artificial light-sensitive channel protein ChrimsonR originally from Chlamydomonas noctigama into the central retina of the patient's most damaged eye.
This light-sensitive protein gene delivered by adeno-associated virus (AAV) vector takes several months to be fully expressed on the cell surface.
Once this happens, you need to activate it with a well-designed goggles, which can detect changes in ambient light and project light pulses onto the retinal cells treated with AAV vectors in real time.
Combining viral vector injections with the use of goggles is not enough to restore vision - this patient still needs vision training to learn to control his eye movements and to associate the visual perception of objects with their physical location.
This is not a plug and play technology.
This is a technology that can achieve visual restoration.
Before treatment, the patient could barely detect light, but seven months after starting training, he reported the first signs of visual improvement.
Picture from Nature Medicine, 2021, doi:10.
In order to rigorously assess the partial improvement in vision, the authors performed different tests in which the patient was asked to perceive, locate, count, and touch one, two, or three objects on a white table under different conditions (A notebook, a staple box or a set of balls).
Without goggles, he could not perform these activities at all, but when his eyes that received viral vector injections were stimulated by the goggles, the success rate of his performance increased significantly --- for example, in tests involving identifying notebooks In, he can perceive, locate and touch this large object with a success rate factor of 92%.
Electroencephalogram (EEG) recording the activity of different neurons further confirmed the patient's performance on these tests.
The authors pointed out that this patient’s vision improvement was limited and could not provide sufficient resolution to recognize faces or read.
This may be partly due to the low dose of viral vector the patient received.
Two other patients received the same dose.
The COVID-19 pandemic does not allow for comprehensive training and assessment of the vision of these two patients, but these authors learned from them that this therapy is safe, which allows subsequent patient cohorts to receive higher doses of treatment .
These authors hope that higher doses of treatment will bring better results.
Reference materials:Reference materials:
José-Alain Sahel et al.
Partial recovery of visual function in a blind patient after optogenetic therapy.
Nature Medicine, 2021, doi:10.