A synthetic virus was injected into the cochlea of ten adults and children in China who had been deaf or severely hearing impaired since birth.
The virus delivered a functioning variant of an otof gene, which, due to mutations, had caused a lack of the protein otoferlin, which is needed to transfer sound signals from the ear to the brain.
Already after one month, the hearing had improved significantly in all ten, and after six months, the average sound level that the patients could perceive had improved from 106 to 52 decibels, according to the Karolinska Institute in a press release.
Could talk to her mother
The study was conducted in collaboration with several hospitals and universities in China and is published in the journal Nature Medicine.
Maoli Duan, who is a senior physician and lecturer at the Karolinska Institute and one of the study's corresponding authors, says that the breakthrough can change the lives of both children and adults.
It's a revolutionary technique, he says.
The best results were obtained in those between five and eight years old. A seven-year-old girl quickly got almost normal hearing and could have daily conversations with her mother four months after treatment.
Next step
Even adults, who the method was tested on for the first time, got a good effect from the injection. No serious side effects were reported during the study's follow-up period. To see the effect in the long term, the ten patients will continue to be followed.
– The next step is to move on to treat more common genetic hearing impairments in the future, says Maoli Duan.
Sophie Tanha/TT
Fact: "A revolutionary technique"
TT
The study included ten patients with congenital deafness or severe hearing impairment, aged 1 to 24 years, at five hospitals in China. All had a genetic form of hearing impairment caused by mutations in a gene called otof.
In the gene therapy, a synthetic adeno-associated virus (AAV) was used to deliver a functioning version of the otof gene to the inner ear with a single injection. The gene was injected through a membrane on the outside of the cochlea called the round window.
Researchers are now working on other, more common genes that cause deafness, such as GJB2 and TMC1.
These are more complicated to treat, but animal experiments have so far shown positive results.
The study was conducted in close collaboration with, among others, Zhongda Hospital, Southeast University, China, and was funded by several Chinese research programs and Otovia Therapeutics Inc., the company that developed the gene therapy. Several of the researchers who participated in the study are employed by this company.
Source: Karolinska Institute
