Optogenetic therapy: High spatiotemporal resolution and pattern recognition compatible with vision restoration in non-human primates

Abstract

We select here the vector and genetic construct best suited to provide vision restoration in patients suffering from retinopathies, we demonstrate temporal resolution compatible with high dynamic visual scenes and a visual acuity above legal blindness. Abstract:.Restoring vision using optogenetics is an ideal medical application because the eye offers a direct window to access and stimulate the pathological area: the retina. Optogenetic therapy could be applied to diseases with photoreceptor degeneration such as retinitis pigmentosa. Here, we select the specific optogenetic construct that is now used in the clinical trial and assess the opsin functional efficacy on non-human primate's retinal ganglion cells (RGCs).We chose the microbial opsin ChrimsonR and showed that the vector AAV2.7m8 produced greater transfection in RGCs compared to AAV2, and that ChrimsonR attached to tdTomato (ChR-tdT) is more efficiently expressed than ChrimsonR. The 600 nm light activates the RGCs transfected with the vector AAV2.7m8-ChR-tdT from an irradiance of 10 15 photons.cm -2 .s -1 .Vector doses of 5.10 10 and 5.10 11 vg/eye transfect up to 7000 RGCs/mm 2 in the perifovea, with no significant immune reaction. Furthermore, using a multielectrode array we recorded RGCs responses starting from 1ms stimulus duration. Using the recorded activity we were able to decode stimulus information and estimate a theoretical visual acuity of 20/249, above legal blindness. Altogether, our results pave the way for the ongoing clinical trial with the AAV2.7m8-ChrimsonR-tdT vector for vision restoration in patients affected by retinitis pigmentosa.

Functional ultrasound imaging of the spreading activity following optogenetic stimulation of the rat visual cortex

“…We used the optogenetic actuator ChrimsonR for visual restoration in the cortex, because of its red-shifted opsin properties 17 and because it was already being used for visual restoration in the primate retina 11 and had given promising results in clinical trials 13 . We maximized the optogenetic activation of V1 by using the CaMKII promoter to ensure expression limited to the excitatory neurons of V1.…”

“…Our ability to activate neurons in deep cortical layers highlights the potential value of red-shifted opsin ChrimsonR for optogenetic cortical vision restoration strategies. A key element of visual restoration is the induction of neuronal responses with characteristics matching those resulting from a natural visual stimulus [5][6][7][8][9][10][11] . We show here that the firing rates induced by optogenetic stimulation were similar to those induced by visual stimulation.…”

“…Optogenetics has revolutionized investigation of the central nervous system 1 , providing hope for the treatment of a number of conditions, including deafness 2,3 or vision loss 4 . Optogenetic therapy is already widely applied to retinal cells to restore vision for in vivo light application [5][6][7][8][9][10][11] , and is currently being assessed in two different clinical trials 12,13 . However, different approaches, targeting cells other than those of the retina, are required for diseases causing degeneration of the optic nerve (e.g.…”

In vivooptogenetic stimulation of the primate retina activates the visual cortex after long-term transduction

“…Repairing sensory impairments has always been an overarching goal in medicine. In the particular case of vision loss, considerable progress has been achieved in recent years through the development of various therapeutic strategies, such as retinal prostheses (1)(2)(3)(4), stem cell transplantation (5)(6)(7)(8) and optogenetic therapies (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). All these approaches aspire to restore retinal visual information.…”

“…The accessibility of the targeted cell population, and the maintenance of its structure and integrity after the onset of retinal degeneration are key features. Since the first use of optogenetics to restore vision in blind mice through the expression of channelrhodopsin-2 (Chr2) in RGCs (9), many other studies have been conducted, targeting different cell types in the retina: photoreceptors (10,21), bipolar cells (15,16,18) or retinal ganglion cells (RGCs) (9,11,13,14,17). Importantly, in diseases such as age-related macular degeneration (AMD) and RP, the retinal ganglion cells (RGCs) remain well-preserved during the process of retinal degeneration, even at late stages of the disease, after the death of the photoreceptors (22).…”