As hearing professionals, one of the frustrations we encounter in our practice is that the conditions that have caused hearing loss in our patients cannot be reversed. One of the primary causes of hearing loss, for example, is damage to the tiny hair cells in our inner ears that vibrate in reaction to sounds. These vibrations are then translated by the brain into what we think of as hearing.
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 very fragile, and prone to damage. The hair cells of the inner ear can sustain damage from exposure to loud noises (causing noise-induced hearing loss, or NIHL), by certain medications, by infections, and by aging. Once these hair cells are damaged in human ears, science has to date not found any way to repair or “fix” them. Since we can’t reverse the damage, hearing specialists and audiologists look to technology instead. We compensate for hearing loss due to inner ear hair cell damage with hearing aids and cochlear implants.
Things would be a lot simpler if we humans were more like chickens and fish. That may seem like a peculiar statement, but it’s true, because – unlike humans – some fish and birds can regenerate the hair cells in their inner ears, thereby regaining their hearing once it has become lost. Chickens and zebra fish are just 2 examples of species that have the capacity to spontaneously replicate and replace their damaged inner ear hair cells, thus permitting them to fully recover from hearing loss
While it is vital to state at the outset that the following research is in its beginning stages and that no practical benefits for humans have yet been achieved, sizeable advancements in the treatment of hearing loss may come in the future as the result of the innovative Hearing Restoration Project (HRP). Funded by a not-for-profit organization called the Hearing Health Foundation, this research is presently being conducted in 14 different labs in Canada and the United States.Working to isolate the molecules that allow the replication and regeneration in some animals, HRP researchers hope to find some way to enable human inner ear hair cells to do the same.
This research is painstaking and challenging. Researchers need to sift through the many molecules involved in the regeneration process – some of which facilitate replication while others inhibit it. Researchers are hoping that what they learn about hair cell regeneration in fish or avian cochlea can later be applied to humans. Some of the HRP researchers are pursuing gene therapies as a way to promote such regrowth, while others are working on using stem cells to accomplish the same goal.
Our entire staff extends to them our well wishes and hopes for their success, because absolutely nothing would thrill us more than being able to someday completely cure our clients’ hearing loss.