A number of the problems that cause hearing problems for our patients cannot be reversed which is frustrating for our hearing specialists. Damage to the very tiny, sensitive hair cells of the inner ear is one of the more common reasons for hearing loss. The job of these hair cells is to vibrate in response to sound waves. These vibrations are interpreted by the brain into what we call hearing.
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 at risk of damage. This damage may occur as the result of aging, infections, medications, and by prolonged exposure to high-volume sounds, resulting in noise-induced hearing loss, or NIHL. The hair cells in human ears can’t be regenerated or “fixed” after they are damaged or destroyed. Consequently, hearing specialists and audiologists must use technological innovations such as hearing aids or cochlear implants to compensate for hearing loss that is in essence irreversible.
If humans were more like chickens or fish, we’d have other options available. Unlike humans, some bird species and fish actually have the ability to regenerate their damaged inner ear hair cells and recover their lost hearing. Strange, but true. Chickens and zebra fish are just 2 examples of species that have the capacity to spontaneously replicate and replace their damaged inner ear hair cells, thus allowing them to fully recover from hearing loss.
Keeping 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 nonprofit organization, Hearing Health Foundation, is currently conducting research at laboratories in the U.S. and Canada Working to isolate the compounds that allow the replication and regeneration in some animals, HRP researchers hope to find some way to enable 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 and challenging. Researchers are hoping that what they learn about inner ear hair cell regeneration in avian or fish cochlea can later be applied to humans. Some of the HRP researchers are working on gene therapies as a way to promote such regrowth, while others are working on stem cell-based approaches.
Although this research is still in the preliminary stages, our staff wishes them speedy success so that their results can be extended to humans. Absolutely nothing would be more enjoyable than to be able to provide our hearing loss patients a true cure.