Since the damage or loss of hair cells, specialized inner-ear cells that transmit sound vibrations via electrical signals to the brain, is responsible for hearing loss, restoring those hair cells could restore hearing. That was simply a logical theory until a team led by Harvard Medical School and Massachusetts Eye and Ear (MEE) recently announced they’re one step closer to regrowing those missing cells.
Their proof-of-concept study, published in Nature Communications, identified a new strategy to induce cell division in the mature inner ear, then reprogram cells there to regenerate into hair cell-like cells in adult mice. Though previous research had found that regeneration can be induced in newborn mice inner ears, the MEE study is the first to demonstrate the same phenomenon in mature inner ears—essential to broad treatment applications for humans.
“Our work revealed that reprogramming is achieved by reactivation of early inner-ear developmental genes so that the mature inner ear regains neonatal properties, which enables them to redivide and regenerate,” explains Zheng-Yi Chen, DPhil, an associate scientist at the Eaton-Peabody Laboratories at MEE. “These findings of renewed proliferation and hair cell generation in a fully mature inner ear lay the foundation for the application of reprogramming and hair cell regeneration.”
Importantly, some of the new cells observed by Dr. Chen and his team developed characteristics of hair cells, including the transduction channels that carry out mechanical-to-electrical conversion, and the ability to form connections with auditory neurons, both of which are essential to hearing. His laboratory is now working to discover druglike molecules that achieve inner-ear cell division in larger animal models, with the hope of eventually informing a treatment option for people with hearing loss.
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