New discovery could restore aging-associated hearing loss

May 23, 2022
New discovery could restore aging-associated hearing loss

Northwestern Medicine scientists have figured out how to program ear hair cells to form either outer or inner ones, rendering the problem of irreversible hearing loss due to aging, obsolete. At present, scientists can produce an artificial ear hair cell, but it is unable to differentiate into an inner or outer cell, which provide different essential functions to produce hearing: the discovery of a master gene, which, when expressed or suppressed (blocked), is able to produce specialised cells for hearing.

About 8.5% of adults aged 55 to 64 in the US have disabling hearing loss – the figure more than doubles as age progresses, according to the Centers for Disease Control. The death of outer hair cells made by the cochlea are most often the cause of deafness and hearing loss, as the cells develop in the embryo and do not reproduce.

As for how they work. the outer hair cells expand and contract in response to the pressure of sound waves and amplify sound for the inner hair cells; the inner cells transmit those vibrations to the neurons to create the sounds we hear – much like the precise motions of a ballet performance.

“Our finding gives us the us the first clear cell switch to make one type versus the other,” Dr. Jaime Garcia-Anoveros, Professor of Anesthesia, Neurology and Neuroscience at Northwestern University Feinberg School of Medicine (Northwestern Medicine). “It will provide a previously unavailable tool to make an inner or outer hair cell.”

The master gene switch Northwestern Medicine scientists discovered is known as TBX2. When the gene is expressed in an ear hair cell, it becomes an inner hair cell; and when the gene is blocked, the cell becomes an outer hair cell. The ability to produce one of these cells will require a gene cocktail (to make a cochlear hair cell from a non-hair cell) and to reprogram supporting cells, Dr. Garcia-Anoveros said.

[The TBX2 could then be accordingly turned on or off to produce the needed inner or outer hair cell.]

“We can now figure out how to make specifically inner or outer hair cells and identify why the later are more prone to dying and cause deafness,” Dr. Garcia-Anoveros said, stressing that this research was still in the experimental stages.

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