In a first, scientists regrow auditory nerves in lab

In a major breakthrough for the hearing-impaired, scientists have re-grown auditory nerves to restore hearing quality in an animal model with 'bionic ear technology' used for gene therapy.

Researchers at University of New South Wales (UNSW) in Australia used electrical pulses delivered from a cochlear implant to deliver gene therapy, thereby successfully regrowing auditory nerves.

"People with cochlear implants do well with understanding speech but their perception of pitch can be poor, so they often miss out on the joy of music," said professor Gary Housley, who is the senior author of the paper.

The work centres on regenerating surviving nerves after age-related or environmental hearing loss, using existing cochlear technology.

The cochlear implants are "surprisingly efficient" at localised gene therapy in the animal model, when a few electric pulses are administered during the implant procedure.

"We hope that after further research, people who depend on cochlear implant devices will be able to enjoy a broader dynamic and tonal range of sound," explained professor Housley, director of the translational neuroscience facility at UNSW.

It has long been established that the auditory nerve endings regenerate if neurotrophins - a naturally occurring family of proteins crucial for the development, function and survival of neurons - are delivered to the auditory portion of the inner ear, the cochlea.

But until now, research has stalled because safe, localised delivery of the neurotrophins can not be achieved using drug delivery, nor by viral-based gene therapy.

Housley and his team developed a way of using electrical pulses delivered from the cochlear implant to deliver the DNA to the cells close to the array of implanted electrodes.

These cells then produce neurotrophins.

"No-one had tried to use the cochlear implant itself for gene therapy. With our technique, the cochlear implant can be very effective," Housley noted.

The research also heralds a possible new way of treating a range of neurological disorders, including Parkinson's disease, and psychiatric conditions such as depression through this novel way of delivering gene therapy.

The research was published in the journal Science Translational Medicine.