Feb 2017 PRI; Science Daily

Gene therapy delivered by a benign virus enabled deaf lab mice to hear for the first time, offering hope for people with genetic hearing impairments. In the first study, Prof Stankovic and colleagues at Harvard Medical School used a harmless virus to transport — deep into the mouse ear — a gene that can fix a specific form of hereditary deafness. Previous attempts had failed, but this time the viral package was delivered to the right address: the so-called outer hair cells that "tune" the inner ear to sound waves.

In the second study, a team led by Prof Geleoc at Boston Children’s Hospital used the same viral courier to treat mice with a mutated gene responsible for Usher syndrome, a rare childhood genetic disease that causes deafness, loss of balance, and in some cases blindness. The virus carried a  normal version of the same gene to damaged ear hair cells soon after the mice were born.

Hearing in miceThe results far exceeded anything to date: 19 of 25 treated mice heard sounds quieter than 80 decibels. Normal human conversation is about 70 decibels. A few of the mice could hear sounds as soft as 25 to 30 decibels — roughly equivalent to whispering.

The technique bestowed hearing and balance "to a level that's never been achieved before," Geleoc said. "Now you can whisper, and the mice can hear you." 

According to Margaret Kenna, a specialist in genetic hearing loss at Boston Children's Hospital not involved in the studies, "cochlear implants are great, but your own hearing is better.” Another expert not involved in the research welcomed the findings as "very encouraging", but cautioned the technique has yet to be proven safe, and that human trials are likely years away.