|Ear hair cell derived from embryonic stem cells | Stefan Heller, Stanford University School of Medicine|
As Gretchen Vogel from ScienceNOW so nicely writes, “All you graying, half-deaf Def Leppard fans, listen up.” She goes on:
“When it comes to hearing, hair cells in the inner ear, so named for their bristlelike appearance, keep the process humming along, converting mechanical vibrations caused by sound waves into nerve impulses. Unfortunately for people, loud noises can overwork and destroy the cells. And once they’re gone, they’re gone: Birds and fish can regenerate the inner ear hair cells, but mammals cannot. Researchers have been looking for ways to reactivate the regenerative potential that other species enjoy.”So, the question is how to get human inner ear stem cells to behave more like those of our avian cousins, allowing once-wild baby boomers to enjoy the dulcet tones of their grandchildren’s voices.
A group at the Massachusetts Eye and Ear Infirmary in Boston worked with inner ear stem cells in the lab, looking for drugs that would prompt those cells to regenerate. This approach of testing drugs using stem cells in the lab is one that a number of scientists in California and elsewhere are using to find better drugs that act directly on the body’s stem cells.
The Boston group applied a drug that had stimulated stem cells to regenerate in the lab directly to the ears of mice with induced hearing damage. The result was mice with more youthful levels of ear hair cells.
Whether those mice could enjoy a Def Leppard concert with youthful abandon remains to be seen. As always, it pays to be skeptical until a potential therapy is tested in humans rather than mice. Also, the mice in this study had hearing damage for just a day. Results could be quite different in those graying music fans who began damaging their inner ear cells decades before.
Mizutari, K., Fujioka, M., Hosoya, M., Bramhall, N., Okano, H., Okano, H., & Edge, A. (2013). Notch Inhibition Induces Cochlear Hair Cell Regeneration and Recovery of Hearing after Acoustic Trauma Neuron, 77 (1), 58-69 DOI: 10.1016/j.neuron.2012.10.032