Scientists have coaxed sound-sensing cells in the ear, called “hair cells,” to grow from stem cells. This technique, if perfected with human cells, could help halt or reverse the most common form of hearing loss, according to a new study.
Each human is born with about 15,000 hair cells per ear, these cells detect sound waves and translate them into nerve signals that allow us to hear speech, music and other everyday sounds. Once damaged, these cells cannot regrow. These delicate hair cells can be damaged by excessive noise, ear infections, certain medicines or the natural process of aging. Human hair cells do not naturally regenerate; so as they die, hearing declines.
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.
In a study published online February 21 in Cell Reports (“Clonal Expansion of Lgr5-Positive Cells from Mammalian Cochlea and High-Purity Generation of Sensory Hair Cells”), a research team from Massachusetts Eye and Ear, Brigham and Women’s Hospital (BWH), and Massachusetts Institute of Technology (MIT) has shown that hair cell precursors, LGR5+ cells, can be augmented to a much higher volume and then converted into hair cells. From a single mouse, the team generated more than 11,500 hair cells (compared to less than 200 hair cells generated without efforts to augment).
The drugs could be injected into the middle ear, from which they would diffuse across a membrane into the inner ear.
“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.