Over time, loud noise, medications and old age combine to kill these cells — and their microscopic hairs called stereocilia — which leads to hearing loss.
"The biology is there, we just need to awaken it," said Jeffrey Karp, associate professor at Brigham and Women's Hospital, Harvard Medical School and an author on the new study appearing Tuesday in the journal Cell Reports.
"For some reason there are brakes that we need to release for a short period of time to allow new hair cells to be produced." Karp and colleagues were able to regrow the hair cells by activating a stem cell in the cochlea called Lgr5 with a small molecule drug treatment.
A similar stem cell is found in the human intestine and allows the body to regrow the exterior lining of the organ every five days.
"I don't see any obvious negative indications right now." Hearing loss can lead to big problems as we age, including the onset of Alzheimer's disease, falls and social isolation, according to Larry Medwetsky, chairman of our Department of Hearing, Speech and Language Sciences at Gallaudet University.