Researchers have discovered a drug combination that can regenerate hair cells in human ears that detect sound waves and translate them into nerve signals enabling us to hear sounds.
Each human being is born with about 15,000 hair cells per ear and once damaged, these cells cannot regrow -- one of the leading causes of hearing loss.
The findings showed that the new combination of drugs expands the population of progenitor cells -- also called supporting cells -- in the ear and induces them to become hair cells, offering a potential new way to treat hearing loss.
"Hearing loss is a real problem as people get older. It's very much of an unmet need, and this is an entirely new approach," said Robert Langer, Professor at Massachusetts Institute of Technology.
The drugs could be injected into the middle ear, from which they would diffuse across a membrane into the inner ear, the researchers said.
For the study, appearing in the journal Cell Reports, the team exposed cells from a mouse cochlea -- the spiral cavity of the inner ear containing the organ of Corti, that produces nerve impulses in response to sound vibrations -- grown in a lab dish, to molecules that stimulate the Wnt pathway, which makes the cells multiply rapidly.
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Once they had a large pool of immature progenitor cells, the researchers added another set of molecules that provoked the cells to differentiate into mature hair cells, which generated about 60 times more mature hair cells than the previously used technique.
"We only need to promote the proliferation of these supporting cells, and then the natural signalling cascade that exists in the body will drive a portion of those cells to become hair cells," said Jeffrey Karp, Associate Professor at Brigham and Women's Hospital (BWH) in Boston.
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