Would you like to have a new eardrum?
Soon it might be possible to have an operation done on one’s ears to restore hearing. It will not, however, involve a laser, as with LASIK. The process will involve attempting to regrow the hair cells located in the cochlea’s Corti. Thus far, such regeneration is only common in birds, reptiles, fish, and amphibians. Mammals are incapable of doing this, so when hair cells die from exposure to loud noise, ageing, or the use of antibiotics; we get cochlear implants or similar hearing devices.
The auditory hair cells are important because they convert vibrations into nerve impulses. When these hairs die, sensorineural hearing loss and balance disorders occur. Animals’ new hair cells grow up from a layer of supporting cells underneath the auditory hair cells. These supporting cells divide and sub-divide until the full complement of hairs is reached. Their hearing is restored to what it was like before. To achieve the same results in humans, laboratories are researching which genes can be manipulated to stimulate re-growth. Someday soon, hearing aids and cochlear implants might no longer be needed.
This type of research has been happening since the late ‘80s, when they discovered birds’ damaged hair cells are spontaneously regenerated. This research has been speeding up recently with the first successfully cultured human eardrum cells. These drums, made from human tympanic membrane tissue gathered from an autopsy, were grown over a scaffold of specially formulated silk. These replicated the human eardrum’s fibrous structure and have the same vibrating abilities. With new surgical procedures, these regenerated eardrums could be implanted successfully.
Researchers at various laboratories will soon start with tests to determine whether the scaffold material is compatible with animals. Within a few years, researchers hope to conduct these same tests in humans. If these tests are successful, they could give a new alternative to millions of hard of hearing people, especially those who might be self-conscious about wearing hearing aids.
About 90 per cent of deafness cases involve damage to the hair cells. It is also hoped that within the next ten years this possible new procedure might prevent these hair cells from dying.