Small-molecule cocktail could reverse hearing loss

The snail-shell-shaped cochlea of the inner ear contains some 15,000 hair cells that are needed for humans to hear. Audiologist dogma holds that once these cells die off, they never grow back, leading to hearing loss.

But a new study suggests that hair cell death may not be as immutable as it seems. Scientists from Harvard, MIT, Brigham & Women’s Hospital, and Massachusetts Eye & Ear Infirmary have discovered a mixture of molecules that can dramatically reverse hair cell loss in the cochleas of mice (Cell Rep. 2017, DOI: 10.1016/j.celrep.2017.01.066).

Hair cells are surrounded by a population of so-called supporting cells that studies suggest could behave like stem cells, meaning they can multiply and mature into other forms. So Albert S. B. Edge of Massachusetts Eye & Ear Infirmary and colleagues tested mixtures of small molecules on mouse cochlea cells growing in a dish until they found combinations that coaxed the supporting cells to both proliferate and turn into bona fide hair cells.

Edge cautions that the cocktail used in this study is likely too complex for use in humans, but he thinks it will enable researchers to manipulate large numbers of cochlear cells to boost hair cell populations with a single molecule.

“Our ultimate goal is to restore hair cells for hearing loss,” Edge says. “And we are hoping that with this tool, we will be able to get there faster.”