Stem Cells Help Deaf Gerbils Hear

(CNN) About 37 million Americans have some level of hearing problem, and science hasnt come up with a perfect solution to restore this valuable sense.

Help may be on the way, at least in theory. A team of researchers reports in the journal Nature that they have used embryonic stem cells to restore some hearing in impaired gerbils. But more investigation is necessary before the technology can move to humans.

Background

Everyone has two main sensory cell types associated with hearing: the hair cell and the auditory neuron. Hair cells take sound and make it into an electrical signal. Neurons pick up the signal and transfer it to the brain, so you know what youre hearing.

Most deafness is caused by a problem in one or both of these cells, said Marcelo Rivolta, senior author of the study and stem cell biologist at the University of Sheffield, United Kingdom. The cells are usually created during the embryonic stage of development.

Adult mammals have lost the ability to replace these cells, Rivolta said. In other words, if these cells are damaged, you cant naturally grow them back.

Cochlear implants are electronic devices designed for people with hearing loss, but they dont work well in people with auditory nerve damage, Rivolta said.

How they did it

Researchers used a drug to chemically damage the auditory nerve in gerbils, creating a condition that would be called auditory neuropathy.

To see if hearing could be brought back, researchers used human embryonic stem cells, and applied biological factors to them that the human body would naturally use in its development. This coaxed them into becoming otic progenitor cells, which can differentiate into cells that function as hair cells and auditory neurons.

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Stem Cells Help Deaf Gerbils Hear