Mom used to say, “Turn that music down or you’ll lose your hearing!” And for good reason. Humans are born with 30,000 sound-sensing hair cells, which die off over time due to loud noises, medications, and natural aging. The problem is, these cells don’t grow back. We only really get one chance to protect our hearing.
But a few years ago researchers from Massachusetts Eye and Ear managed to restore partial hearing in mice by converting a small number of inner ear cells into hair cells.
Now, a team of researchers from Mass. Eye and Ear, Brigham and Women’s Hospital, and the Massachusetts Institute of Technology (MIT) have demonstrated that this technique can scale by increasing the number of regenerated hair cells from 200 to 11,500. The research shows promise for restoring hearing for those of us who ignored the adolescent warnings of our mothers. They published their findings this week in the journal Cell Reports.
“Acquired hearing loss occurs when hair cells are damaged or destroyed by loud noise or exposure to toxic chemicals,” Will McLean, first author of the study, told Digital Trends. “However, even after hair cells die, progenitor cells are still present in the tissue. From our work, we believe small molecules could be delivered directly to the inner ear to activate these native progenitor cells to divide and regenerate new sensory hair cells, restoring healthy tissue to the inner ear and ultimately restore hearing.”
In 2012, researchers discovered that some inner ear cells had properties similar to cells found in the intestines — namely, they both contain Lgr5, a protein that lets intestinal cells regenerate and replace the intestinal lining every eight days. They were able to transform these Lgr5 cells into new hair cells in mice, but only in small numbers.
In the recent study, researchers extracted the Lgr5 cells from the inner ears of mice, placed them in a petri dish, used drugs and growth factors to make them multiply, and then converted the Lgr5 cells into hair cells.
Having identified the cells of interest, the researchers now aim to develop specific drugs to treat acquired hearing loss. They plan to begin clinical trials within the next 18 months.
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