SCIENCE – At 58, he regains his sight. Blinded by a degenerative genetic disease, a patient was able to partially recover his sight thanks to an innovative technique combining gene therapy and light stimulation, reports a study published on Monday, May 24 in the journal Nature Medicine.
This is the first time that this technique, called
optogenetics, has made it possible to obtain partial recovery of visual
function, say the researchers behind this clinical trial, which involved
French, Swiss and American teams.
The patient in the study has retinopathy pigmentosa, a
degenerative genetic disease of the eye that destroys photoreceptor cells in
the retina, leading to progressive loss of vision that usually progresses to
blindness.
While he could only perceive the presence of light,
therapy now allows him to locate and touch objects, according to the study.
In normal vision, photoreceptors in the retina use
proteins capable of reacting to light energy, opsins, which deliver visual
information to the brain via the optic nerve.
Locate, touch objects
In order to restore sensitivity to light, the patient
was injected with the gene encoding one of these proteins, called ChrimsonR,
which detects amber light, the study describes.
Almost five months after receiving the injection, to
give his body time to produce this protein in sufficient quantity, he performed
various exercises, equipped with dedicated glasses fitted with a camera.
Designed for the occasion by the researchers, these
glasses make it possible to project amber-colored images on the patient’s
retina.
“Seven months later, the patient began to report signs
of visual improvement”, explain in a press release the Institut de la Vision
(Sorbonne University / Inserm / CNRS) and the Parisian hospital of
Quinze-Vingts, specializing in ophthalmology. “With the help of the glasses, he
can now locate, count and touch objects”.
In a first test consisting of perceiving, locating and
touching a large notebook and a small box of staples, he managed to touch the
notebook in 92% of the cases but could only grasp the box in 36% of the tests.
A second exercise consisting of counting cups on a
table was successful almost two out of three times (63%).
For the third test, a cup was alternately placed or
removed from the table and the patient had to press a button indicating whether
he was present or absent, while his brain activity was measured using a helmet
of electrodes. electroencephalography.
Optogenetics revolutionizes
research
A software interpreting the recordings of the electrodes
was able to say with an accuracy of 78% whether the cup was present or not,
confirming “that the brain activity is indeed linked to the presence of an
object, and therefore that the retina is not. more blind, ”says Professor
Botond Roska, one of the researchers who led the study.
“If optogenetics, a technique that has already existed
for twenty years, has revolutionized fundamental research in neuroscience (…),
this is the first time internationally that this innovative approach has been
used in humans and that its clinical benefits have been demonstrated ”,
underline the two French organizations, which conducted the clinical trial in
association with the University of Pittsburgh (United States), the Institute of
Molecular and Clinical Ophthalmology of Basel (Switzerland), the Streetlab
company and the French biotech GenSight Biologics.
One in 3,500 people affected
Retinopathy or retinitis pigmentosa affects one in
3,500 people, according to the European Orphanet database, and can start at any
age, with a greater frequency of occurrence between 10 and 30 years.
The genes responsible are very numerous, but certain
mutations are frequently found in people with the disease.
“Blind people with different types of
neurodegenerative diseases of photoreceptors” but retaining “a functional optic
nerve” will be “potentially eligible for treatment,” explains Professor
José-Alain Sahel, founder in 2009 of the Institute of vision, dedicated at
retinal diseases. “But it will take time before this therapy can be offered”.
Gensight Biologics, specialized in gene therapies for
the treatment of neurodegenerative diseases of the retina, “intends to launch a
phase 3 trial soon to confirm the effectiveness of this therapeutic approach”,
he adds.
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