New research from the U-M Kresge Hearing Research Institute shows that harnessing the power of a category of cells in the ear called supporting cells may lead to new strategies to combat many causes of deafness.
A group of cells in the ear must work together to allow an individual to hear. Hair cells have long been known to play a crucial role in carrying sound signals to the brain. But the key to restoring lost hearing may be the lesser-known supporting cells. The research shows that damage to the supporting cells in the ears of mature mice results in the loss of hair cells and profound deafness. The big surprise of the study was that if supporting cells are lost in a newborn mouse, the ear rapidly regenerates new supporting cells – resulting in complete preservation of hearing. This remarkable regeneration results from cells from an adjacent structure moving in and transforming into full-fledged supporting cells.
The study not only shows that deafness can result from loss of supporting cells, but it also reveals a previously unknown ability to regenerate supporting cells present for only a few days after birth in the mice. If scientists can learn more about what transpires inside these cells, they may be able to harness it to develop new ways to regenerate auditory cells and restore hearing in humans of all ages.
Findings from the animal study, conducted by researchers from U-M, St. Jude Children’s Research Hospital and other colleagues were published online in November by the Proceedings of the National Academy of Sciences. The study’s senior author is U-M Kresge Hearing Research Institute director Gabriel Corfas, Ph.D.
As Corfas explains, “We had known that losing hair cells results in deafness, and there has been an effort to find a way to regenerate these specialized cells. One idea has been to induce supporting cells to become hair cells. Now we discover that losing supporting cells kills hair cells as well.”
“Now we’ve found that there’s an intrinsic regenerative potential in the very early days of life that we could harness as we work to cure deafness,” says Corfas. “This is relevant to many forms of inherited and congenital deafness, and hearing loss due to age and noise exposure. If we can identify the molecules that are responsible for this regeneration, we may be able to turn back the clock inside these ears and regenerate lost cells.”
Hair cell loss can be a consequence of supporting cell dysfunction or loss, suggesting that in many cases deafness could be primarily a supporting cell disease. Corfas and his colleagues continue to study the phenomenon, and hope to find drugs that can trigger the same regenerative powers that they saw in the newborn mice. “Understanding the mechanisms that underlie these processes should help in the development of regenerative medicine strategies to treat deafness and vestibular disorders,” he says.
Making sure that the inner ear has enough supporting cells, which can transform into hair cells, will be a critical upstream step of any regenerative medicine approaches.
To learn more about the exciting developments taking place at the U-M Kresge Hearing Research Institute, visit www.khri.med.umich.edu.