|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.