A number of the conditions that cause hearing loss in our patients cannot be reversed which is quite frustrating for our hearing specialists. One of the main reasons for hearing loss, for example, is damage to the tiny hair cells in our inner ears that vibrate in reaction to sounds. Our sense of hearing is the result of these vibrations being translated into electrical energy and sent 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 small and sensitive that they are also readily damaged. The hair cells of the inner ear can sustain damage from exposure to loud sounds (causing noise-induced hearing loss), by specific medications, by infections, and by aging. The hair cells in human ears cannot be regenerated or “fixed” once they have become damaged or destroyed. Therefore, hearing professionals and audiologists have to deal with hearing loss technologically, using hearing aids or cochlear implants.
This would not be the case if humans were more like chickens and fish. That may sound like an odd statement, but it’s true, because – unlike humans – some birds and fish can regenerate the hair cells in their inner ears, thereby regaining their hearing after it is lost. To name a couple such species, chickens and zebra fish have been shown 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 beginning stages and that no practical benefits for humans have yet been achieved, sizeable advancements in the treatment of hearing loss may come in the future as the result of the innovative Hearing Restoration Project (HRP). The non-profit organization, Hearing Health Foundation, is currently sponsoring research at laboratories in Canada and the US What the HRP researchers are attempting to do is isolate the compounds that allow this replication and regeneration in animals, with the goal of finding some way of stimulating similar regeneration of hair cells in humans.
The research is painstaking and challenging, because so many different compounds either contribute to replication or hinder inner ear hair cells from replicating. Researchers are hopeful that what they learn about hair cell regeneration in avian or fish cochlea can later be applied to humans. The HRP scientists are taking a divide and conquer approach to achieve their joint goal. While some laboratories work on gene therapies others work on approaches using stem cells.
Although this research is still in it’s early stages, our staff wishes them quick success so that their findings can be extended to humans. Nothing would be more enjoyable than to be able to offer our hearing loss patients a true cure.