New Discoveries In Hair Cell Growth
Kathy Peck
Of the 28 million cases of deafness or hearing impairment reported in
the United States today, some 80% are examples of sensorineural deafness
nerve deafness most often due to the malfunctioning of the hair cells
of the inner ear. These hair cells, which line the snail-shaped cochlea,
convert sound waves into electrical impulses that are passed on to the
brain. Until now, even the most advanced medical technology didn't hold
much hope for the hearing loss that results when hair cells die from aging,
infection, or noise damage: Hair cells weren't thought to regenerate,
and anyone with nerve deafness was condemned to a life of silence. But
new results, based on studies of fish, birds, and mice, suggest that the
ear's cells may indeed be capable of regeneration suggesting that this
process is regulated by chemicals in the cell's environment.
The regeneration starts when the supporting cells directly below the
damaged hair cells, responding to some unknown cue, reenter the cycle
of cell division and begin to proliferate. Although researchers caution
that the possibility of relieving deafness remains remote, what has been
discovered recently is impressive. Even if mammals can regenerate hair
cells, that might not be enough for recovery of hearing. Researchers point
out that hearing loss often involves additional damage to structures around
the hair cells that would also have to be repaired. And any new hair cells
would have to develop functional connections to the brain. If they can
make that key step (and many in the field believe this is a real possibility)
many deaf people might have a chance at regaining the world of sound.
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