Zebra Fish, Chickens and Hearing Loss – Promising Research Into Inner Ear Hair Cell Regeneration
Many of the problems that cause hearing problems for our patients cannot be reversed which can be frustrating for our hearing professionals. One of the main causes of hearing loss, for example, is damage to the tiny hair cells in our inner ears that vibrate in response to sound waves. Our sense of hearing is the result of these vibrations being converted into electrical impulses and sent to the brain for decoding.
These hair cell structures have to be very small and sensitive to do their jobs correctly. It is precisely because they are small and sensitive that they are also readily damaged. This damage may occur as the result of aging, infections, medications, and by prolonged exposure to high-volume noises, resulting in noise-induced hearing loss, or NIHL. The hair cells in human ears can’t be regenerated or “fixed” once they have become damaged or destroyed. As a result, hearing specialists and audiologists have to treat hearing loss technologically, using hearing aids or cochlear implants.
If humans were more like chickens or fish, we would have other options. That may sound like a peculiar statement, however it is true, because – unlike humans – some birds and fish can regenerate the hair cells in their inner ears, and thus regain their hearing once it has become lost. Chickens and zebra fish are just 2 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 crucial to mention 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 from the innovative Hearing Restoration Project (HRP). This research, financed by the non-profit Hearing Health Foundation, is currently taking place at 14 laboratories in Canada and the United States. Researchers involved in the HRP are trying to isolate the molecules that allow the inner ear hair cells in some animals to replicate themselves, with the eventual goal of discovering some way to enable human hair cells to do the same.
The work is painstaking and difficult, because so many different compounds either contribute to replication or prevent hair cells from replicating. But their hope is that if they can identify the compounds that stimulate this regeneration process to happen in fish and avian cochlea, they can find a way to enable it to happen in human cochlea. Some of the HRP researchers 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 absolutely nothing would delight us more than being able to completely cure our clients’ hearing loss.