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Birds, Fish and Human Hearing Loss – New Research Into Regenerating Inner Ear Hair Cells

As hearing specialists, one of the sometimes frustrating things we encounter in our practice is that the conditions that have caused hearing problems in our patients cannot be reversed. Damage to the tiny, sensitive hair cells of the inner ear is among the more prevalent reasons for hearing loss. The work 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.

The fact is that, the 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 susceptible to damage. The hair cells of the inner ear can become damaged as a result of exposure to high decibel noises (causing noise-induced hearing loss), by specific drugs, by infections, and by aging. In humans, once these hair cells have become damaged or destroyed, they cannot be regenerated or “fixed.” Since we can’t reverse the damage, hearing professionals and audiologists turn to technology instead. We make up for hearing loss due to inner ear hair cell damage with hearing aids and cochlear implants.

If humans were more like fish or chickens, 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 recover their lost hearing. Odd, but true. To name two such species, zebra fish and chickens have been proven to have the capacity to spontaneously replicate and replace inner ear hair cells that have become damaged, and as a result regain their full functional hearing.

While it is vital 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 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 the U.S. and Canada.Scientists included in the HRP are working to identify the molecules that allow the inner ear hair cells in certain animals to duplicate themselves, with the eventual goal of finding some way to enable human hair cells to do the same.

The work is painstaking and challenging, because so many different molecules either contribute to replication or prevent inner ear hair cells from replicating. But their hope is that if they can identify the compounds that enable this regeneration process to happen in fish and avian cochlea, they can find a way to stimulate it to happen in human cochlea. A few 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.

Although this work is still in it’s early stages, our staff wishes them swift success so that their results can be extended to humans. Nothing would be more thrilling than to be able to offer our hearing loss patients a true cure.

This entry was posted on Thursday, May 30th, 2013 at 10:42 am. Both comments and pings are currently closed.