This Phase II project involves the delivery of genes and reagents that could regulate hair cell regeneration into the embryonic inner ear of mice. Two approaches will be taken. In the first, transcription-factor genes that activate pathways that may be involved in regeneration will be delivered, and their ability to trigger hair cell regeneration after those cells are killed will be assessed. In the second, CRISPR/Cas9 reagents will be used to turn off genes that might be preventing hair cell regeneration. While these are experimental and not therapeutic approaches, the project will allow us to determine whether any specific molecules are capable of triggering hair cell regeneration in the mouse.