Among the sometimes bothersome things about being a hearing care specialist
is that a lot of the conditions we deal with which have caused our patients to lose their hearing can’t be reversed. For example, one of the most common causes of hearing loss is damage to the very small, sensitive hair cells that line the inner ear and vibrate in response to sound. What we think of as hearing are the translations of these vibrations into electrical impulses which are sent to and interpreted in the brain.
These hair cell structures have to be very small and sensitive to do their jobs correctly. It is precisely because they are very small and sensitive that they are also easily damaged. The hair cells of the inner ear can become damaged as a result of exposure to loud sounds (causing noise-induced hearing loss, or NIHL), by certain medications, by infections, and by aging. In humans, once these hair cells have become damaged or destroyed, they can’t be regenerated or “fixed.” As a result, hearing professionals and audiologists have to treat hearing loss technologically, using hearing aids or cochlear implants.
Things would be a lot less complicated if we humans were more like fish and chickens. That may seem like an odd statement, but it’s true, because – unlike humans – some fish and birds can regenerate the hair cells in their inner ears, and thus regain their hearing once it has become lost. For reasons that are not fully understood, zebra fish and chickens(to name just two such species) have the ability to spontaneously replicate and replace damaged hair cells, and thus attain full functional recovery from hearing loss.
Bearing in mind that this research is preliminary and has as yet produced no proven benefits for humans, some hope for the treatment of hearing loss comes from research called the Hearing Restoration Project (HRP). The non-profit organization, Hearing Health Foundation, is currently conducting research at laboratories in the United States and Canada What the HRP scientists are attempting to do is isolate the compounds that allow this replication and regeneration in animals, with the ultimate goal of discovering some way of stimulating similar regeneration of hair cells in humans.
Because there are so many distinct compounds mixed up in regeneration process – some that assist in replication, some that impede it – the scientists’ work is slow and challenging. But their hope is that if they can isolate the compounds that enable this regeneration process to happen in avian and fish cochlea, they can find a way to stimulate it to happen in human cochlea. The scientists in the various HRP laboratories are following different approaches to the problem, some pursuing gene therapies, others working on the use of stem cells, yet all share the same goal.
Our entire team extends to them our best wishes and hopes for their success, because absolutely nothing would thrill us more than being able to completely heal our clients’ hearing loss.