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Stem Cells Allow Deaf Gerbils to Hear

By on September 20, 2012

A new study out of the United Kingdom has found that deafness can be effectively treated using stem cells after researchers were able to restore hearing in gerbils for the first time.

This study, which was published in Nature, found that hearing was improved when nerves were rebuilt using stem cells, which then allowed the nerves to pass sound directly from the ear to the brain.

While it will be many years before this research can be applied to humans, it could mean a great improvement in the ability to hear and allow millions of people to hear well enough to understand a conversation.

Hearing works when sound waves are turned into electric signals that the brain can recognize. This conversion occurs in the inner ear, as vibrations from sound waves move very fine hairs which create electical signals.

About 10% of people, however, suffer from profound hearing loss because the nerve cells that should pick up this signal are somehow damaged and unable to relay the message to the brain.

The team at the University of Sheffield began by replacing these nerves, which are known as spiral ganglion neurons, with brand new ones by using stem cells harvested from human embryos. These stem cells have the unique ability to transform into any type of cell found in the human body, including muscle cells, heart cells, skin cells and even nerve cells. Once these cells were turned into spiral ganglion neurons they were carefully injected into the tiny inner ears of 18 gerbils with deafness. Gerbils were chosen for this study over mice because their range of hearing closely mimics that of humans, whereas mice are able to hear very high-pitched sounds inaudible to humans.

During the 10-week study, the hearing of the animals improved dramatically and around 45% of their range of hearing was restored.

This isn’t a cure for deafness and humans eventually treated with this method would still be unable to hear soft noises like whispers. Still, it could allow many people with profound hearing loss to carry on a normal conversation.

Researchers also note that 30% of the gerbils had amazing reactions to the treatment and got back 90% of their hearing range but another 30% of the animals had barely any response.

This study is definitely encouraging for the millions of individuals who suffer from hearing loss and nerve deafness, which affects nearly every aspect of life. While there would be ethical concerns to address regarding this treatment, it’s definitely a sign of hope.