Final Report Summary - RETINAL-GENE-THERAPY (Overcoming translational barriers to gene therapy by novel vector design)
Gene therapy has been applied with success in the clinic over the past decade. The approval of the first adeno-associated virus (AAV) - based gene therapy product (Glybera) in Europe, highlights the need for a greater sophistication of AAV vector as a means to deliver gene drugs. Inherited retinal degenerations are a primary clinical focus of AAV mediated gene therapy. Current delivery methods are efficient for gene delivery to the rodent retina with a large set of AAV that can be applied based on the needs of the disease being targeted. However the applicability of these vectors in human gene therapy depends on our ability to overcome the translational challenges between the rodent and human retinas. The aim of this grant proposal was to evaluate the ability of previously created artificial AAV variants to deliver genes to the non-human primate retina. The most efficient AAV variant selected based on reporter gene delivery in the first part was then evaluated for its therapeutic potential in delivering optogenetic tools in the primate retina. The overall aim was to find suitable variants for application in different gene therapy settings: gene replacement therapies aimed at the outer retina, trophic factor secretion by overexpression of neurotrophin genes and delivery of optogenetic tools to restore light sensitivity to blind retinas after loss of vision.
Based on the progress made in engineering AAV vectors able to transduce the rodent retina pan-retinally and across all layers by rational or combinatorial engineering techniques, within this project we designed and tested combination of new AAVs coupled with strong promoters to target important cell populations in the non-human primate retina. We described a new AAV vector/promoter combination able to transduce foveal photoreceptors by a non invasive injection into the vitreous- the gel like substance that fills the cavity of the eye. We also described an AAV variant based on a different serotype showing a spectacular increase in cone transduction capabilities of one of the vectors tested in the retina of primates when administered underneath the retina- subretinally. We then used these vectors for optogenetics application described in aim 3- showing that it is possible to obtain functional level expression with safe doses of AAV for vision restoration using this approach. We believe the vector developments obtained within the framework of this project will help move the field of retinal gene therapy forward that it be for gene supplementation or other modes of gene therapy. Our results highlight the importance of viral vector development in overcoming surgical delivery challenges, as gene therapy to restore vision becomes a potentially attainable goal for those clinicians who treat inherited retinal degenerations in the clinic.
Prospects of the research career development and reintegration for the fellow have been met with success. The fellow has integrated the Vision Institute, after her post-doctoral experience in UC Berkeley, USA. She transformed her research and has explored new horizons in translational gene therapy, going from rodents to pre-clinical models. The CIG has helped her integration in the institute where she now holds a permanent position.
Based on the progress made in engineering AAV vectors able to transduce the rodent retina pan-retinally and across all layers by rational or combinatorial engineering techniques, within this project we designed and tested combination of new AAVs coupled with strong promoters to target important cell populations in the non-human primate retina. We described a new AAV vector/promoter combination able to transduce foveal photoreceptors by a non invasive injection into the vitreous- the gel like substance that fills the cavity of the eye. We also described an AAV variant based on a different serotype showing a spectacular increase in cone transduction capabilities of one of the vectors tested in the retina of primates when administered underneath the retina- subretinally. We then used these vectors for optogenetics application described in aim 3- showing that it is possible to obtain functional level expression with safe doses of AAV for vision restoration using this approach. We believe the vector developments obtained within the framework of this project will help move the field of retinal gene therapy forward that it be for gene supplementation or other modes of gene therapy. Our results highlight the importance of viral vector development in overcoming surgical delivery challenges, as gene therapy to restore vision becomes a potentially attainable goal for those clinicians who treat inherited retinal degenerations in the clinic.
Prospects of the research career development and reintegration for the fellow have been met with success. The fellow has integrated the Vision Institute, after her post-doctoral experience in UC Berkeley, USA. She transformed her research and has explored new horizons in translational gene therapy, going from rodents to pre-clinical models. The CIG has helped her integration in the institute where she now holds a permanent position.