The inner ear contains hair cells that are important for hearing and balance, however, the number of hair cells an individual has is reached before we are born. Thereafter, loud noise, trauma, infections and aging will take their toll until loss of hair cells impairs hearing and balance. However, a new mouse study from The Rockefeller University in New York, NY could help researchers look at new ways to regrow hair hair cells and and restore lost hearing and balance. The study took place at Rockefeller and was done by a postdoctoral researcher, Dr. Ksenia Gnedeva. She examined mice before and after birth and found two genes that could switch on the process of generating hair cells.
Dr. Gnedeva began her work by looking for changes in gene expression in the utricle, an inner ear structure. She spotted two genes that are highly active before birth, but become silent after birth, which coincides with a halt in the development of hair cells in the mice's utricles. The two genes code for the transcription factors Sox4 and Sox11, which help shape the destiny of precursor cells into their final cell types by regulating the activity of other genes. Dr. Gnedeva found when the two genes were switched off, the entire ear, not just the utricle, developed abnormally. When she turned on the genes in older mice, she found it led to the regeneration of hair cells inside fully developed utricles. In the picture above, the image on the right happened with the absence of Sox4 and Sox11, which led to severe malformation of the inner ear structures that contain hair cells.
Hearing occurs when sound waves reach the structures inside your ear, where the sound wave vibrations are converted into nerve signals that your brain recognizes as sound. Aging and exposure to loud noise may cause wear and tear on the hair cells in the inner ear. According to the CDC, Centers for Disease Control, around 36 million American adults report some degree of hearing loss. 36 million is a huge number and it is unfathomable to think about. Everyone should be able to hear because life without hearing can be severe. Imagine waking up everyday and not being able to hear. I cannot imagine myself not being able to hear. I hope Dr. Gnedeva does more research with these genes and maybe someday hearing loss will be a thing of the past.
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