Australasian Science: Australia's authority on science since 1938

Deaf Mice Follow Their Noses

By Stephen Luntz

Mice with hearing loss have experienced a partial recovery after being treated with nasal stem cells.

While the potential is obvious, Dr Sharon Oleskevich of the Hearing Research Group at the University of NSW says: “The surgery was non-trivial so we are working on refining it before we can think about applying it to humans”.

The mice in question have sensorineural hearing loss caused by the destruction of neurons in the cochlea. In humans this often begins in infancy, sometimes from genetic causes.

“One of the challenges in tackling this condition is that the regenerative ability of the human cochlea is severely limited,” Oleskevich says.

In work published in Stem Cells, Oleskevich obtained nasal adult neuronal stem cells from Prof Alan Mackay-Sim at the National Adult Stem Cell Centre and injected them into the cochleas of sensorineural mice. The treated mice were able to hear sounds at 75 dB, while a control group could hear nothing softer than 85 dB.

This is far from restoration of normal hearing, as many mice can hear sounds fainter than 40 dB. Nevertheless, similar progress in humans could make a major difference to people’s lives.

The transplanted cells did not integrate into the cochlea, instead producing growth factors that appeared to keep existing cells alive. Oleskevich says this was not expected, but nor was it a surprise as many stem cells operate by producing growth factors rather than turning into other cells themselves.

The benefits remained 2–3 weeks after injection, but Oleskevich is unsure how frequently treatments would be required.

An alternative process may be to have the stem cells produce growth factors externally and inject these into the ear, but while Oleskevich says this “would be fabulous” she cautions that we know so little about what the growth factors are that such a procedure is at least 10 years away.