Notch inhibitor makes a noise for deaf mice
Normal inner and outer ear hair cells--courtesy of Massachusetts Eye and Ear
After news of cell transplants making blind mice see, U.S. researchers have used an experimental drug to make deaf mice hear. And while it's hard to get a mouse to describe what it can hear, the results are looking promising.
Loud noise, whether it's from headphones or machinery--along with some drug treatments and advancing age--can damage the tiny sensory hairs in the ear, and once they are gone, they are gone. This is known as sensorineural hearing loss. The study used mice that had been deafened by loud noise, destroying virtually all of their hair cells.
Treatment with a drug known as a Notch inhibitor triggered existing cells in the ear to become new hair cells. This restored at least some hearing in the animals, enough to hear traffic or a slamming door, according to BBC News. The results were confirmed with brain scans and are published in Neuron.
Stem cells have made gerbils with nerve damage hear again, and gene therapy has prompted hair-cell regrowth in prepubescent mice, but this is a breakthrough because it is the first time hair cells have been regenerated in an adult mammal, as Albert Edge of Harvard Medical School and the Massachusetts Eye and Ear Infirmary explains.
"We're excited about these results because they are a step forward in the biology of regeneration and prove that mammalian hair cells have the capacity to regenerate," Edge said.
Hearing loss affects nearly 50 million people in the U.S. alone, and as the population ages and lives longer, this will only get worse. Currently, people with hearing loss have to rely on hearing aids or cochlear implants. Research into drugs or stem cells to regenerate hearing is still in early stages, but nevertheless it could point to potential therapeutic applications in the future.
Dave Moore of the Institute of Hearing Research in Nottingham, U.K., sounded a note of caution, though, explaining to BBC News that there have been a number of false starts in the regeneration of hair cells, an active field since the 1980s. He added that, while promising, these results need "to be treated with considerable caution in terms of a human therapy."
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