Severe loss of vision occurs due to retinitis pigmentosa (RP) or age-related macular degeneration (AMD) when degeneration of photoreceptors in the eye occurs. This leads not only to physical impairment, but has a significant emotional and psychological impact on quality of life of the patients as well as family members. The current clinical treatment aimed at vision restoration in RP patients is invasive involving surgical procedure for retinal implants. However, these electrical stimulation based implants are limited by poor resolution, heat production (high current required for higher electrode density), retinal damage over a time period and cellular overgrowth due to surgical implantation. Currently, use of optogenetic sensitization of retinal cells has allowed possibilityof stimulating cells with single-cell resolution. In addition to higher resolution, optogenetics has several advantages over electrical stimulation such as cellular specificity and non-invasiveness. However, clinical translation of optogenetic enabled vision restoration suffers from two major drawbacks: (i) Narrow spectral sensitivity of opsin requiring active stimulation by blue light source having intensity order of magnitude higher than ambient light; and (ii) Lack of approach for controlled-delivery of opsin-encoding genes into spatially-targeted regions of degenerated-retina (e.g. periphery in RP and macula in AMD). To allow ambient- light based stimulation paradigm, we have developed broad-band opsin construct that has broad spectral excitability in the entire visible spectrum. This allows significantly higher sensitivity of broad-band opsin sensitized higher-order neurons in degenerated retina to ambient white light, and therefore, significantly lower activation-threshold in contrast to conventional approach of narrow-band opsin and/or use of intense, narrow- band light based active-stimulation. Further, we have developed a near-infrared (NIR) ultrafast laser-based transfection method and demonstrated non-viral, spatially-targeted expression of opsin(s) in retinal ganglion cell (RGC) layer. The overall objective of this project is to demonstrate enhanced retinal photosensitivity in mice model of RP, allowing bright ambient-level white-light stimulation of retinal ganglion cells, sensitized with broadband-opsin by targeted transfection using NIR ultrafast laser beam. Towards this goal we have following aims: (i) Development of broad-band opsin for wide-band efficient optogenetic stimulation; (ii) Optoporation of broad-band opsin encoding genes to spatially-targeted retinal ganglion cells; and (iii) Non-viral in-vivo optical delivery of plasmids encoding broad-band opsin into spatially-targeted regions of photo-degenerated retina of animal model. Success of this proposal will lead to a new clinical approach for treating patients with RP and AMD by determining degenerated areas, followed by conventional intravitreal injection of broad-band opsin constructs and NIR laser-assisted targeted, non-viral delivery of the constructs to degenerated areas in an efficient and minimally-invasive manner. We believe that such treatment will lead to restoration of high- resolution vision by white-light stimulation of broad-band opsin sensitized RGCs at ambient light level.
Success of this proposal will lead to new clinical approach for treating retinitis pigmentosa and age-related macular degeneration patients by first determining the degenerated areas, followed by conventional intravitreal injection of wide-spectrally activatable broad-band opsin constructs and near-infrared ultrafast laser-assisted targeted, non-viral delivery of the constructs to the degenerated areas in an efficient and minimally-invasive manner. This treatment will lead to restoration of high-resolution vision by ambient white-light stimulation of broad-band opsin sensitized retinal ganglion cells.
| Batabyal, Subrata; Kim, Young-Tae; Mohanty, Samarendra (2017) Ultrafast laser-assisted spatially targeted optoporation into cortical axons and retinal cells in the eye. J Biomed Opt 22:60504 |
| Wright, Weldon; Gajjeraman, Sivakumar; Batabyal, Subrata et al. (2017) Restoring vision in mice with retinal degeneration using multicharacteristic opsin. Neurophotonics 4:041505 |
