Many of the conditions that cause hearing problems in our patients can’t be reversed which is quite frustrating for our hearing specialists. For example, one of the extremely common reasons for hearing loss is damage to the tiny, sensitive hair cells that line the inner ear and vibrate in response to sound. Our sense of hearing is the result of these vibrations being translated into electrical impulses and delivered to the brain for interpretation.
The sensitivity of these tiny hair cells allows them to vibrate in such a manner, and thus makes it possible for us to hear, but their very sensitivity makes them extremely fragile, and susceptible to damage. This damage may occur due to aging, certain medications, infections, and by prolonged exposure to loud noises, resulting in noise-induced hearing loss, or NIHL. Once these hair cells are harmed in human ears, science has as yet not found any way to repair or “fix” them. As a result, hearing professionals and audiologists have to treat hearing loss technologically, using hearing aids or cochlear implants.
This wouldn’t be true if humans were more like chickens and fish. In contrast to humans, some fish species and birds have the ability to regenerate their damaged inner ear hair cells and regain their lost hearing. Bizarre, but true. To name a couple such species, chickens and zebra fish have been shown to have the ability to spontaneously replicate and replace inner ear hair cells that have become damaged, and as a result regain their full functional hearing.
While it is crucial to point out at the outset that the following research is in its early stages and that no practical benefits for humans have yet been achieved, considerable breakthroughs in the treatment of hearing loss may come in the future from the groundbreaking Hearing Restoration Project (HRP). This research, funded by the nonprofit Hearing Health Foundation, is currently taking place at 14 labs in Canada and the United States. What the HRP researchers are attempting to do is identify the molecules that allow this replication and regeneration in animals, with the ultimate goal of discovering some way of enabling similar regeneration of hair cells in humans.
The work is painstaking and difficult, because so many distinct molecules either help with replication or prevent inner ear hair cells from replicating. By figuring out which of the compounds regulate this process in avian or fish cochlea, the scientists are hoping to identify which molecules promote hair cell growth. The HRP researchers are taking a divide and conquer approach to attain their joint goal. While some labs pursue gene therapies others focus on approaches using stem cells.
Our entire office extends to them our well wishes and hopes for their success, because nothing would thrill us more than being able to someday completely reverse our clients’ hearing loss.