As hearing professionals, one of the frustrations we experience in our practice is that the issues that have caused hearing problems in our patients can’t 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 sound waves. Our sense of hearing is the result of these vibrations being converted into electrical impulses and delivered to the brain for interpretation.
These hair cell structures must be really small and sensitive to do their jobs correctly. It is precisely because they are very small and sensitive that they are also readily damaged. This damage may occur as the result of aging, infections, medications, and by extended exposure to high-volume sounds, resulting in noise-induced hearing loss, or NIHL. Once these hair cells have been harmed in human ears, science has to date not found any way to repair or “fix” them. Therefore, hearing professionals and audiologists have to treat hearing loss technologically, using hearing aids or cochlear implants.
This wouldn’t be the case if humans were more like fish and chickens. That may seem like an odd statement, however it is true, because – unlike humans – some birds and fish can regenerate the hair cells in their inner ears, thereby regaining their hearing once it has become lost. For reasons that are not fully understood, chickens and zebra fish have the ability to spontaneously replicate and replace damaged hair cells, and thus attain full functional recovery from hearing loss.
While it is vital to state at the outset that the following research is in its early stages and that no practical benefits for humans have yet been achieved, sizeable breakthroughs in the treatment of hearing loss may come in the future as the result of the innovative Hearing Restoration Project (HRP). Funded by a nonprofit organization called the Hearing Health Foundation, this research is currently being conducted in 14 different laboratories in the United States and Canada.Working to identify the molecules that allow the replication and regeneration in some animals, HRP researchers hope to find a way to stimulate human hair cells to do the same.
Because there are so many different molecules mixed up in regeneration process – some that facilitate replication, some that impede it – the researchers’ work is slow-moving and difficult. By pinpointing which of the molecules regulate this process in avian or fish cochlea, the scientists are hoping to pinpoint which molecules promote hair cell growth. Some of the HRP scientists are pursuing gene therapies as a way to stimulate 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 nothing would thrill us more than being able to completely heal our clients’ hearing loss.