by Neil Bauman, Ph.D.
Hard of hearing people are impatient for hair cell research to bring forth positive results so they can have their hearing restored to normal or near normal. That is their desire, but this reality is still far in the future.
In spite of all the advances that have been made in recent years, hair cell regeneration in humans is still at least 20 years away according to Dr. Douglas A. Cotanche, an Associate Professor in the Departments of Otolaryngology—Head & Neck Surgery, and Anatomy & Neurobiology, at the Boston University School of Medicine in MA.
Dr. Cotanche explains, “We are still in the very early stages of developing techniques for inducing hair cell regeneration in damaged mouse and guinea pig ears. To date, we have not yet perfected a technique that leads to full, or even partial functional recovery in a damaged cochlea. We need to accomplish this before we can think of trying therapies in humans. I would project that a potential therapy will not be available for at least 20 years.”
Before human trials can begin, according to Dr. Cotanche, “We would need to be able to show that the therapy did not somehow cause a reduction in the surviving hair cell population and lead to further hearing loss.”
You see, some unexpected negative results have shown up in the animal research undertaken so far. As Dr. Cotanche explains, “We know that mammal cochlear hair cells will not regenerate on their own when the native hair cells are lost. But experimental models have shown that we can induce some levels of regeneration by stimulating genes that cause cells to divide. So we do see an initial burst of hair cell regeneration, but then the ear somehow senses that these new hair cells are not normal—that this should not happen—and eliminates these cells.”
Dr. Cotanche continues, “Now we need to find a way to keep these newly regenerated hair cells in the mammal ear from dying off, and determining if they can regain function.”
As a result, hair cell regeneration in humans is not just “around the corner”. At present we need to use the hearing aids and cochlear implants that are available to us, and not wait for the possibility of hair cell regeneration to give us better hearing.
Although hair cell regeneration is still a long way in the future, Dr. Cotanche confidently asserts, “We’re getting there slow but sure!”