Gene therapy to restore hearing

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Published on 22 December 2015

Researchers at the University of Kansas Hospital, Kansas City (USA) are trying to regenerate hair cells in the inner ear as a method of restoring lost hearing, reports the Kansas City Star.

A large number of clinical trials using drug and gene therapies are currently underway to try to prevent hearing loss or restore hearing once inner ear damage has taken place. One example is the study currently being conducted at Kansas University by a team of researchers led by Dr Hinrich Staecker.

The trial, sponsored by Swiss pharma company Novartis, is testing the injection of treatment using a viral vector to deliver a gene known as atonal bHLH transcription factor 1 (Atoh1), which is known to cause hair cells to grow in mammals during the early stages of development before birth. Once hair cells have developed, however, the gene is no longer expressed in humans.

“We artificially direct it to be on again,” explains Staecker. “The idea is to kick-start the process that turns a supporting cell into a hair cell, and then stop.” The administration technique involves making an incision to open the eardrum and then uses a laser to drill a minute hole into a bone located against the inner ear. This makes it possible to inject a very small amount of product directly into the inner ear.

The complexity of the study has meant that only 8 patients have been treated to date. Results are still pending and many questions remain open. “We don’t really clearly understand how many hair cells you need to get X number of decibels of hearing,” Staecker says. “We don’t even know in animals.” Researchers warn that further long-term studies will be needed before gene therapy can hope to restore hearing in humans.

Kansas City Star