Normal development of an ear(left) and abnormal ear due to loss of hair cells(right) |
Our inner ears all contain hair cells which are important
for hearing and balance. The final number of hair cells we have in our inner
ear are reached before we are even born. Over time loud noises, trauma,
infections, and aging cause us to lose these hair cells which impair our
hearing and balance. Around 90% of hearing loss occurs when hair cells or
auditory nerves are destroyed. Around 36 million adults in the U.S. have
reported some degree of hearing loss. A new study from Rockefeller University
has found that two genes responsible for inner ear development can be switched
on to generate more hair cells in the ear and reverse the loss of hearing and balance.
The study look place at the sensory neuroscience lab at Rockefeller University,
headed by post-doctoral researcher Dr. Ksenia Gnedeva. Dr. Gnedeva began her
study by looking for changes in gene expression in the utricle (an inner ear
structure) of mice before and after birth. She discovered that two genes were
highly active before birth but later became silent after birth. The silencing
of these two genes after birth is what causes hair cells to stop developing. When
both of these genes were switched off in the mice, the entire ear developed
abnormally. However, when Dr. Gnedeva switched on the two genes in elder mice,
she found that new hair cells began to generate inside the utricles of the
inner ear. Dr.Gnedeva says that she hopes her findings will allow us to generate
new hair cells later on in life in order to repair the loss of hearing and
balance as we age.
I was surprised to learn that 36 million people in the U.S.
suffer from some sort of hearing loss. It was interesting to learn that
switching on two genes in the inner ear have the possibility to restore hearing
and balance later on in life. It will be interesting to see if the same results
seen in the mice will also be seen in humans.
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