Hear2day

Loss of or damage to the sensory hair cells of the inner ear is the leading cause of both congenital and acquired deafness. Hair cells usually connect to nerve cells that form a pathway (called the ‘spiral ganglion’) into the brain, but if the hair cells degenerate, so does the spiral ganglion. Researchers at the University of California, San Diego, School of Medicine and the National Institutes of Health have found that Sox2, a protein that regulates stem cell formation, is involved in spiral ganglion neuron development.

“These findings may provide the first step toward regenerating spiral ganglion neurons, the nerve cells that send sound representations to the brain,” said Alain Dabdoub, PhD, co-author of the study and Assistant Professor of Surgery with the Division of Otolaryngology at the UC San Diego School of Medicine. “This has significant implications for advances in cochlear implant technology and biological treatments for hearing loss.” Inside the cochlea, hair cells convert sound vibrations into electrical signals that are then sent on to the spiral ganglion cells. If these cells are lost or damaged, hearing loss occurs. Existing therapies for hearing loss are based either on increasing hair cell stimulation with hearing aids or introducing an electronic substitute for the hair cells with cochlear implants. In either case, the presence of working spiral ganglion neurons is required for a successful outcome.

Prior research shows that as few as 10 percent of the typical number of spiral ganglion neurons is sufficient for the success of cochlear implants. Finding out that Sox2 is involved in generating new working cells opens up the possibility of treating hearing loss with therapy that stimulates Sox2 into action. Sox2 is part of the SoxB1 family of proteins, which plays a significant role in neural development in the spinal cord and elsewhere. The study demonstrates a new role for Sox2 in ear development, showing that the protein is critical for the production of auditory neurons and that generating new neurons is possible.
The study was published in the 13th January issue of the Journal of Neuroscience.