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Stem cells treatment could cure deafness

Profound deafness caused by inner ear nerve damage could be cured with stem cells.

Researchers at the University of Sheffield used human embryonic stem cells to reverse total deafness in gerbils.

The cells were first partially matured in the laboratory to set them on the right development path. They were then injected through a hole drilled into the cochlea, the spiral shaped sensory organ of the inner ear where sounds are converted to nerve messages.



RECOVERY

Of the 18 animals treated, about half showed "substantial" recovery after 10 weeks.

The pioneering research could lead to the first patients being treated within "a few years", scientists said.

Gerbils were used in the experiments because they hear the same range of sounds as humans.

Dr Marcelo Rivolta, who led the research, reported in the journal Nature, said: "Stem cells have been used in animal models of deafness before, mostly the mouse, with different results, but none have shown functional recovery.

"What we have shown here is functional recovery using human stem cells, which is unique. As a proof-of-concept we have shown that human stem cells can be used to repair the ear."

The gerbils were first deafened in one ear using a drug that destroys the auditory nerve carrying sound messages to the brain.

A similar form of nerve damage causes auditory neuropathy, an incurable form of deafness for which cochlea implants are little help.

The implants are designed to replace lost hair cells, which vibrate in response to sounds and stimulate the nerves. Without functioning auditory nerves, the signal pathway to the brain is blocked.

Auditory neuropathy deafness can be caused by faulty genes and be present from birth. Other risk factors include being born with jaundice, noise exposure, and ageing.

Dr Rivolta's team also made progress on producing hair cells from stem cells. If both kinds of cells can be replaced in the cochlea, it could lead to a potential cure for 80-90pc of cases of profound deafness.

hnews@herald.ie


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