A Severance Hospital research team has confirmed that gene-editing therapy can treat progressive hearing loss.


A Severance Hospital and Yonsei University research team has proved gene-correction therapy can treat age-related hearing loss. They are, from left, Professors Choi Jae-young, Jung Jin-se, Kim Hyong-bom, and Gee Heon-yung.
According to the hospital, hearing loss is a common sensory disease that affects about 5 percent of the world's population and is steadily increasing.

Notably, deafness due to hearing loss increases with age, but there is currently no treatment. While hospitals currently use cochlear implant surgery as a treatment method, it is closer to the concept of rehabilitation than a complete cure as it cannot hear physiological and natural sounds.

Researchers have found that damage to outer hair cells, synapses, basement membranes, and blood vessels causes age-related hearing loss. Among them, KCNQ4, a potassium ion channel, plays an important role in maintaining the function of outer hair cells.

Therefore, mutations in KCNQ4 can increase the risk of age-related hearing loss.

Also, people with severe mutations in KCNQ4 may develop hereditary hearing loss, which progresses to deafness at a young age.

To resolve this issue, the team, led by Professors Choi Jae-young and Jung Jin-se of the department of otorhinolaryngology, produced a mouse model with a KCNQ4 mutation commonly found in DFNA2 patients through genetic base alteration. Professors Kim Hyong-bom and Gee Heon-yung of the department of pharmacology at Yonsei University College of Medicine also participated in the study.

Afterward, the research team created a gene-removed assembly that removed the mutant KCNQ4 protein using CRISPR gene-editing technology and used the Adeno-associated virus (AAV) to inject it into the mouse's ear.

As a result, after seven weeks, AAV-injected mice showed an average hearing improvement of 20 dB in the entire frequency range (6-30 kHz).

The team stressed that a hearing improvement effect of 20 dB is equivalent to hearing a sound 10 times louder. This means that the level improved from a level where a person can barely hear the noise of the subway passing to a level where they can hear everyday conversations without difficulty.

The team also confirmed that the gene-editing also improved the damaged outer hair cells in the mice whose hearing improved.

"Although the number of patients with age-related hearing loss is increasing, it is an incurable disease with no suitable treatment," Professor Choi said. "By suggesting the possibility of treating progressive hearing loss through gene-editing technology, the research will provide a foothold for future hearing loss treatment."

The study was published in the latest issue of Theranostics.

?? : KBR(http://www.koreabiomed.com)