Developing a new AAV-based tool for targeted gene therapy against hearing loss

Project Summary Gene therapy mediated by recombinant adeno associated virusrAAVvectors has been clinically successful for the treatment of certain eye diseasesHoweverno successful clinical outcomes exist to treat hearing lossSince the cochlea is enclosed mostly within the temporal bonelocal viral gene delivery can itself cause hearing lossIn additionthe elaborate structure and exquisite function of the inner ear require coordinated action of diverse inner ear cell typesincluding the sensory hair cellssupporting cellsspiral ganglion neuronsand stria vascularisNo current rAAV gene delivery can specifically target spiral ganglion neuronswhich are the only neuron type to carry auditory information from hair cells to central auditory systemThereforeit would be ideal if rAAVs can target spiral ganglion neurons after a systemic injectionAAVhas recently been found to be able to cross the blood brain barrier after a systemic injectionBased on our previous studies and discussions with potential consumersin this projectwe proposed to make two productsone new AAVbased library with random sequences in Cap open reading framesandat least one rAAV specifically targeting spiral ganglion neuronsTo achieve these goalswe have set up specific milestones in our two aimsIn Aimwe will make a novel AAVbased vector in which the expression of capsid proteins is coupledbut not fusedto green fluorescent proteinand then we will make random mutagenesis of the Cap gene to generation of the rAAV viral libraryIn Aimour collaborators will inject this rAAV viral library into the mouse tail vein and isolate specific rAAV DNA from spiral ganglion neurons two weeks post injectionThe process will be iterated to enhance the targeting specificity of rAAV capsid protein variants to SGNsThe novel parts of our technology areusing a strategy to co express GFP with rAAV capsid proteinswhich allows direct recovery of cell specific rAAV Cap open reading framefocusing on AAVwhich can cross the blood brain barrier after a systemic injectionandworking with our collaboratorsspiral ganglion neurons will be targeted without requirement of prepurification and pre labellingIf successfulthis project will not only establish a neuronal specific targeting tool for cochlear gene therapybut also provide an rAAV library for screening other rAAVs able to target other types of cells in the auditory systemThusthis project will not only lead to a new rAAV vector to treat hearing lossbut also provide a new rAAV library for the research field PROJECT NARRATIVE The work in this proposal focuses on the development of an rAAV based tool for gene therapy against hearing lossIf successfulthis project will not only lead to a new rAAV vector to treat hearing lossbut also provide a new rAAV library for the research field