A number of the problems that cause hearing loss for our patients can’t be reversed which is quite frustrating for our hearing specialists. One of the principal reasons for hearing loss, for example, is damage to the tiny hair cells in our inner ears that vibrate in reaction to sound waves. What we think of as hearing are the translations of these vibrations into electrical energy, which is then sent to the brain.
The sensitivity of these tiny hair cells enables 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 become damaged as a result of exposure to loud noises (causing noise-induced hearing loss, or NIHL), by specific medications, by infections, and by aging. In humans, once these hair cells have become damaged or destroyed, they can’t be regenerated or “fixed.” Instead, hearing specialists and audiologists must use technologies such as hearing aids or cochlear implants to make up for hearing loss that is essentially irreversible.
If humans were more like chickens or fish, we’d have other options available. In contrast to humans, some bird species and fish actually have the ability to regenerate their damaged inner ear hair cells and regain their lost hearing. Odd, but true. For reasons that are not fully understood, chickens and zebra fish(to name just 2 such species) have the ability to automatically duplicate and replace damaged hair cells, and thus attain full functional recovery 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, significant breakthroughs 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 presently being conducted in 14 unique labs in Canada and the United States.Working to isolate the compounds that allow the replication and regeneration in some animals, HRP researchers hope to find a way to stimulate human inner ear hair cells to do the same.
This research is slow and demanding. Researchers need to sift through the many compounds involved in the regeneration process – some of which facilitate replication while others impede it. Scientists are hoping that what they learn about inner ear hair cell regeneration in avian or fish cochlea can later be applied to humans. The researchers 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 exact same objective.
Our entire staff extends to them our best wishes and hopes for their success, because absolutely nothing would delight us more than being able to someday completely cure our clients’ hearing loss.