Virally Mediated Gene Therapy for Genetic Hearing Loss

描述（由申请人提供）：大约每1000个儿童中有1.5个在出生时受到耳聋的影响，其中1/2可归因于遗传原因。对这些遗传性耳聋的治疗非常有限，包括轻度至重度听力损失的听力放大和重度至重度听力损失的人工耳蜗植入。基因疗法被认为是遗传性听力损失的一种潜在治疗方法，但在这一领域的成功仍然是难以捉摸的。利用病毒介导的基因传递在毛细胞再生方面取得了重要进展；然而，细胞再生的突破可能不会使那些遗传性耳聋患者受益，因为潜在的遗传背景不会改变。然而，由于手术途径的进步和耳蜗骨结构对液体空间的限制，内耳仍然是基因治疗的一个有吸引力的目标。我们一直在研究一种转基因小鼠，该小鼠在缺失水疱性谷氨酸转运蛋白-3 （VGLUT3）基因后会导致深度失聪，该基因与人类非综合征性耳聋的DFNA25基因相同。我们最近的工作已经通过使用腺相关病毒载体（AAV-VGLUT3）的局部单基因治疗成功地恢复了出生后小鼠的听力。这一新颖的初步发现为研究这种疗法是否可以优化和推广到其他形式的遗传性耳聋提供了强大的动力。本研究的总体目标是优化VGLUT3敲除（KO）小鼠耳蜗恢复听力的病毒-基因传递方法，验证恢复正常的突触生理，并确定该技术是否可以推广到另一种遗传性耳聋小鼠模型——otoferlin敲除小鼠，即人类遗传性耳聋DFNB9模型。这些研究的结果可能为将来在某些形式的遗传性耳聋患者中进行临床试验提供基础。

DESCRIPTION (provided by applicant): Approximately 1.5 in 1000 children are affected by deafness at birth, 1/2 of which can be attributed to a genetic cause. Treatment for these inherited forms of deafness is quite limited, and consists of hearing amplification for mild to severe hearing loss, and cochlear implantation for severe to profound hearing loss. Gene therapy has been suggested as a potential treatment for genetic hearing loss, but success in this area has remained elusive. Important advances have been made towards hair cell regeneration using virally-mediated gene delivery; however breakthroughs in cellular regeneration likely would not benefit those with genetic deafness because the underlying genetic background would be unchanged. Yet the inner ear remains an attractive target for gene therapy due to advances in surgical access and confinement of fluid space by the bony structure of the cochlea. We have been studying a transgenic mouse that is profoundly deaf after deletion of the vesicular glutamate transporter-3 (VGLUT3) gene, the same gene responsible for the human non-syndromic deafness DFNA25. Our recent work has led to successful restoration of hearing in postnatal mice by local monogenic therapy using an adeno- associated viral vector (AAV-VGLUT3). This novel initial finding provides a powerful incentive to investigation if this therapy can be optimized and generalized to other forms of genetic deafness. The overall goals of this proposal are to optimize the viral-gene delivery method to the cochlea for hearing restoration in the VGLUT3 knockout (KO) mouse, verify that normal synaptic physiology is restored, and determine whether this technique can be generalized to another mouse model of genetic deafness, the otoferlin knockout mouse, a model for the human genetic deafness DFNB9. Results from these studies may provide the foundation for future clinical trials in humans with some forms of genetic deafness.