Although hearing impairment is the most prevalent disability in the United States, affecting millions of people across age groups, the treatment options remain few and largely unsophisticated. Deafness occurs when the sensory cells of the inner ear- hair cells- die and are not replaced. This happens progressively over our lives and has been previously thought to be irreversible. However, the cochlea is a somewhat self-contained organ, making it an ideal testing ground for gene therapy and molecular techniques to replace lost hair cells. Some of the most promising approaches involve the re-expression of developmental genes (such as the pro-hair cell gene Atoh1) in the cochlea, which can be achieved by inserting the gene into a benign virus which infects the cells of the inner ear and converts non-sensory cells to new hair cells. Additionally, new fascinating mouse models allow us to selectively “turn off” certain signaling mechanisms in the inner ear which inhibit new hair cells from forming after damage. This frees gene expression and new hair cell regeneration in the ear, which would not naturally occur.
Furthermore, other approaches involve replacing the lost hair cells with stem cells or artificial, engineered cells that integrate into the cochlear epithelium and mimic the function of natural hair cells.
Finally, while cochlear implants (the only successful brain-machine interface!) are certainly clinically helpful in cases of profound deafness, the implants also further destroy the cochlea and do not yield a high-quality level of sound. This may be remedied by completely “switching gears” in the design of cochlear implants, from being reliant on electrical impulses to using light to communicate sound information to the cochlear nerve. In all, many new and exciting studies related to the restoration of hearing are currently underway and I would love to share the innovation and excitement of emerging technology in the field with a broad audience.
I am a Neuroscience graduate student at the University of Michigan as well as a freelance science writer and blogger for ScienceBlogs/SEED Magazine. My PhD thesis is related to cures for deafness including gene therapy and small molecule intervention for cochlear hair cell regeneration, as well as innovating the next generation of cochlear implants.