Channelrhodopsins provide a breakthrough insight into strategies for curing blindness

Abstract

Photoreceptor cells are the only retinal neurons that can absorb photons. Their degeneration due to some diseases or injuries leads to blindness. Retinal prostheses electrically stimulating surviving retinal cells and evoking a pseudo light sensation have been investigated over the past decade for restoring vision. Currently, a gene therapy approach is under development. Channelrhodopsin-2 derived from the green alga Chlamydomonas reinhardtii, is a microbial-type rhodopsin. Its specific characteristic is that it functions as a light-driven cation-selective channel. It has been reported that the channelrhodopsin-2 transforms inner light-insensitive retinal neurons to light-sensitive neurons. Herein, we introduce new strategies for restoring vision by using channelrhodopsins and discuss the properties of adeno-associated virus vectors widely used in gene therapy.

Visual Responses of Photoreceptor-Degenerated Rats Expressing Two Different Types of Channelrhodopsin Genes

“…ERGs and VEPs were recorded as described previously12151638. Briefly, rats were dark-adapted overnight.…”

“…Safety studies were also performed in rats and marmosets11, which showed that no immunological responses12 were induced by the continuous expression of a ChR2 gene that was derived from the unicellular green algae Chlamydomonas reinhardtii 1314, rather than from a human source. Gene therapy using ChR2 thus represents a potential method for restoring vision in blind patients15. However, ChR2-expressing rats exhibiting photoreceptor degeneration could only detect wavelengths less than 540 nm because of the limitation of the ChR2 action spectrum16.…”

Establishment of Gene Therapy Using Channelrhodopsin-2 to Treat Blindness

“…24.6 ). The shortening of the P1 latency is derived from a short-cut in the transmission of inner retinal cells (Tomita et al 2009b ). These results indicate that ChR2 is a useful tool for restoring vision.…”

Proceedings of the First International Optogenetic Therapies for Vision Symposium

“…Readers interested in more specific details of the field are referred to the published reviews on the subject of optogenetics and visual restoration. [1][2][3][4][5][6][7][8][9] An issue of Nature in 2010 focused on optogenetics as ''Method of the Year'' also contains an excellent explanatory video of the technique in the f o l l o w i n g l i n k : h t t p : / / w w w . y o u t u b e .…”