Our inner ear contains hair cells that are important for hearing and balance. Unfortunately, the final number of hair cells is determined before we are even born. From then on, loud noise, trauma, infections and aging take their toll, until loss of hair cells impairs hearing and balance.
But a new study on mice at The Rockefeller University in New York could help researchers look at new ways to regrow hair cells and restore lost hearing and balance. By examining mice before and after birth, researchers discovered two genes that could switch on the process of generating hair cells. More than 90 percent of hearing loss occurs when either hair cells or auditory nerve cells are destroyed.
Researchers spotted that two genes that are highly active before birth become silent after birth, and this dramatic reduction in activity coincides with a halt in the development of hair cells in the mice's utricles, an ear structure that is lined with hair cells and detects motion.
Their study revealed that by switching off both genes in the developing mice, the entire inner ear, not just the utricle, developed abnormally. And, when the genes were turned on in older mice with fully mature hair cells, it led to the regeneration of new hair cells inside fully developed utricles.
Researchers say their ultimate goal is to restore hair cells later on in life. It appears possible that these proteins, or perhaps other steps in the same pathway, might be potential targets.