Bionic Ear Delivers Gene Therapy

Scientists have designed a cochlear implant that not only improves hearing, but could also deliver genes to enhance long term hearing quality.

AsianScientist (May 2, 2014) – Researchers have for the first time used electrical pulses delivered from a cochlear implant to deliver gene therapy, thereby successfully regrowing auditory nerves.

The research, published in Science Translational Medicine, 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.

“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,” says Professor Gary Housley of the University of New South Wales (UNSW), who is the senior author of the research paper.

“Ultimately, 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, which is particularly important for our sense of the auditory world around us and for music appreciation.”

The work centers on regenerating surviving nerves after age-related or environmental hearing loss, using existing cochlear technology. The cochlear implants are “surprisingly efficient” at localized gene therapy in the animal model, when a few electric pulses are administered during the implant procedure.

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.

However, research has been stalled because safe, localized delivery of the neurotrophins can’t be achieved using drug delivery, nor by viral-based gene therapy.

Housley and his team at UNSW 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.

While the neurotrophin production dropped away after a couple of months, Housley says ultimately the changes in the hearing nerve may be maintained by the ongoing neural activity generated by the cochlear implant.

“We think it’s possible that in the future this gene delivery would only add a few minutes to the implant procedure,” says the paper’s first author, Jeremy Pinyon, whose PhD is based on this work.

“The surgeon who installs the device would inject the DNA solution into the cochlea and then fire electrical impulses to trigger the DNA transfer once the implant is inserted.”

Integration of this technology into other ‘bionic’ devices such as electrode arrays used in deep brain stimulation (for the treatment of Parkinson’s disease and depression, for example) could also afford opportunities for safe, directed gene therapy of complex neurological disorders, the authors say.

The article can be found at: Pinyon et al. (2014) Close-Field Electroporation Gene Delivery Using the Cochlear Implant Electrode Array Enhances the Bionic Ear.

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Source: University of New South Wales.

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