Genes Identified Could Help Restore Hearing

A majority of the time, hearing loss occurs due to damage to hair cells or auditory nerve cells located in the inner ear. The hair cells are named due to their hair-like extensions, and they are formally called stereocilia. These cells convert vibrations into electrical signals and the auditory nerve carries them to the brain, producing sound. Stereocilia can be damaged through various means such as aging, medication, trauma, or loud noises. These hair cells grow during fetal development, but this growth stops after birth, which also prevents regeneration later on.

A new study has identified two genes that are responsible for the growth of these hairs. Dr. Ksenia Gnedeva observed the gene expression in an inner ear structure called the utricle. The utricle is lined with these hair cells, as is the cochlea. Gnedeva identified the Sox4 and Sox11 transcription factors. They are highly active during development, but they become dormant after birth. The study was done with mice. The mice that were developing had their genes turned off to observe the results. The inner ear as a whole did not develop normally. The mice that were already developed had their genes switched on and were able to regenerate the stereocilia. 

The overall goal of this study is to turn these genes back on in animals to allow them to regenerate their hair cells in the inner ear. If this is successful, it could potentially mean that humans who suffer from hearing loss could regain it eventually. One issue with this therapy could be if the hearing loss is caused by auditory nerve cell damage. This would only help people affected with hair cell damage. If there is a mix of the two, it is possible for the person to regain some of their hearing but not all. There is still work to be done before use as a therapy for hearing loss.