Researchers in Boston and Japan have devised a pharmacological method to transform inner ear epithelial cells into working hair cells and have used the method to restore hearing in deaf mice.1 The finding provides proof of concept for treating hearing loss by manipulating developmental pathways in the adult ear, but figuring out the precise pathway to hit in humans will require further work.
Hair cells in the inner ear transmit sound waves into electromechanical signals sensed by the nervous system. The cells can be damaged by chronic exposure to loud noise and die off in aging adults, leading to age-related hearing loss that affects up to 50 million Americans.
The inner ears of adults with the condition are thought to be functional aside from the dead hair cells. Regenerating those cells has been a