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Human stem cells restore hearing

For the first time, scientists have improved hearing in deaf animals by using human embryonic stem cells, an encouraging step for someday treating people with certain hearing disorders.
"It's a dynamite study [and] a significant leap forward," said one expert familiar with the work, Dr. Lawrence Lustig of the University of California, San Francisco.
The experiment involved an uncommon form of deafness, one that affects between 1 percent and 15 percent of hearing-impaired people. And the treatment wouldn't necessarily apply to all cases of that disorder. Scientists hope the approach can be expanded to help with more common forms of deafness. But in any case, it will be years before human patients might benefit.
Results of the work, done in gerbils, were reported online in the journal Nature by a team led by Dr. Marcelo Rivolta of the University of Sheffield in England.
To make the gerbils deaf in one ear, scientists killed nerve cells that transmit information from the ear to the brain. Stem cells were used to make immature nerve cells. Those were then transplanted into the deaf ears of 18 gerbils.
Ten weeks later, the rodents' hearing ability had improved by an average of 46 percent, with recovery ranging from modest to almost complete. How did the researchers know the gerbils could hear in their deafened ears? They measured hearing ability by recording the response of the brain stem to sound.
The gerbils were kept on medication to avoid rejecting the human cells, much like people who get transplants of human organs, Rivolta said.
- Associated Press