Abstract
Purpose: :
To test the hypothesis that a transduction of the channelrhodopsin-2 gene, a microbial-type rhodopsin gene, into retinal ganglion cells of genetically blind rats will restore functional vision.
Methods: :
We made an adeno-associated virus vector type 2 including the channelrhodopsin-2 gene fused to a fluorescent protein, Venus (AAV2-ChR2V). The AAV-ChR2V was injected intravitreally into the eyes of 6-month-old RCS (rdy/rdy) rats. Visual function was evaluated periodically by recording visually evoked potentials (VEPs) with various stimulus patterns and optomotor responses. The expression of ChR2V in the retina was investigated histologically.
Results: :
VEPs could not be recorded from 6-month-old untreated RCS rats. In contrast, VEPs were markedly elicited from RCS rats injected with AAV-ChR2V at 6 weeks post-injection. The VEPs of RCS rats injected with AAV-ChR2V were first detected at 2 weeks after the injection. Thereafter, the amplitude progressively increased up to 6 weeks post-injection. The RCS rats with ChR2V and non dystrophic rats did not respond to 40 Hz and 50 Hz stimuli frequencies. However, VEPs were detected with stimuli <20 Hz of light simulation in both types of rats. The optomotor responses were significantly stronger after the AAV2-ChR2V injection. The expression of ChR2V was observed mainly in the retinal ganglion cells.
Conclusions: :
These findings demonstrate that blind rats can regain their visual function by the transduction of the ChR2V gene into the retinal ganglion cells.
Keywords: retinitis • gene transfer/gene therapy • regeneration