As hearing professionals, one of the sometimes frustrating things we experience in our practice is that the conditions that have caused hearing loss in our patients cannot be reversed. Damage to the tiny, very sensitive hair cells of the inner ear is among the more common reasons for hearing loss. The job of these hair cells is to vibrate in response to sounds. Our sense of hearing is the result of these vibrations being converted into electrical impulses and delivered to the brain for decryption.
Unfortunately, the exact same sensitivity of these hair cells that allows them to react to sounds and translate them into electrical impulses that our brains understand as hearing also makes them fragile, and vulnerable to damage. Infections, certain medications, aging or prolonged exposure to high-volume sounds (resulting in noise-induced hearing loss) are all potential sources of damage. In humans, once these hair cells have become damaged or destroyed, they can’t be regenerated or “fixed.” Since we cannot reverse the damage, hearing professionals 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. In contrast to humans, some bird species and fish actually have the ability to regenerate their damaged inner ear hair cells and recover their lost hearing. Bizarre, but true. Chickens and zebra fish are just two examples of species that have the ability to spontaneously replicate and replace their damaged inner ear hair cells, thus permitting them to fully recover from hearing loss.
While it is important 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 advancements in the treatment of hearing loss may come in the future as the result of the groundbreaking Hearing Restoration Project (HRP). Funded by a not for profit organization called the Hearing Health Foundation, this research is currently being carried out in 14 different labs in the U.S. and Canada.Researchers involved in the HRP are trying to isolate the compounds that allow the inner ear hair cells in some animals to replicate themselves, with the future goal of finding some way to enable human inner ear hair cells to do the same.
The research is painstaking and challenging, because so many distinct compounds either contribute to replication or hinder hair cells from replicating. But their hope is that if they can isolate the compounds that stimulate this regeneration process to happen in avian and fish cochlea, they can find a way to stimulate it to happen in human cochlea. The researchers in the various HRP labs 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 a great success, because nothing would thrill us more than being able to someday completely reverse our clients’ hearing loss.