#$%^&*AU2017203769A120170622.pdf#####ABSTRACT A composition and method for replacement and regeneration of hair cells of the inner ear is provided. The composition comprises an active agent in an amount effective to decrease Hes 1 gene expression in a tissue of the inner ear. The active agent can be short interfering RNA (siRNA) molecules encapsulated in a biodegradable nanoparticle. The method involves administering a solution to the inner ear where the solution contains an active agent in an amount effective to decrease Hes 1 gene expression.