USC researchers they reversed the hearing damage in mice activating a regenerative capacity they have as newborns and they think it could make it possible to reverse permanent hearing loss in humans too.
Permanent hearing loss is a common side effect of aging – it hits over 60% of people reach retirement age.
Reversing hearing loss could improve the lives of tens of millions of people, allowing them to live independently for longer.
The special “gift” of hearing
The inner ear contains two types of sensory cells. There are “hair cells,” which are hair-like and receive sound vibrations, and there are also supporting cells, which play a role in the structure and function of hearing in the inner ear.
Hair cells are very delicate. They can be damaged, to the point of producing hearing loss, by loud noises, infections, some medications and in general by aging. The death of a single hair cell can severely affect hearing, and when a hair cell is gone, it is gone forever.
Or so we've always thought.
Hearing restoration in mice
For about a week after birth, mice can reverse any damage to the ear and hearing by turning the supporting cells into cells ciliate. A process called “transdifferentiation”.
In a new study, USC researchers determined that a molecule called H3K4me1 it is the key to this regenerative capacity. It keeps the genes for hair cells “primed” within supporting cells, like players on the bench, ready to take the field.
If their hair cells are damaged, nearby support cells transform and replace them. After a week after birth, however, mice lose this molecule and the ability to repair hearing loss.
The researchers gave the mice a drug that extended the presence of H3K4me1, and with it the regeneration capacity of hair cells.
From mice to men
Given the success of the mouse tests, researchers suspect that humans could also reverse hearing loss through transdifferentiation.
Unlike mice, which have this “superpower” within a week of birth, we lose this ability before we are even born.
Of course, if the team's hypothesis is right, it could trigger the growth of new hair cells in our ears and restore hearing ability. But how?
“Our study raises the possibility of using therapeutic drugs, gene editing or other strategies. We could make epigenetic modifications that exploit the latent regenerative capacity of inner ear cells to restore hearing,” he said Neil Segil, USC researcher.
Beyond the sound
Segil also speculated that someday this technique could also be used to regenerate other parts of the body.
“Similar epigenetic modifications may also prove useful in other non-regenerating tissues, such as the retina, kidneys, lungs and heart.”
