Scientists at Harvard Medical School and Boston Children’s Hospital said they have successfully restored hearing in mice that are genetically deaf (born deaf). They have done this by applying genes via injection to the cochlea’s outer ear cells. They use a “virus”/vector named Anc80 in order to “infect” the ear and cause gene changes. They said their genetically deaf mice were able to hear down to 25 decibels (a whisper).
Check out this image of the treatment — on the left side, you can see normal ear hair cells — labelled “control.” In the middle is the mutant — gene mutations (I didn’t know I was a mutant). On the right, you can see the treated ear cells. You can see the “triangular” shapes on the treated cells that the middle didn’t have and they look almost similar to the control cells.
The scientists also tested a mouse with Usher Syndrome (a gene that causes deaf-blindness) with a different vector — Ush1c — and they actually reversed the mouse’s genes, noticing that its inner and outer hair cells started to function normally and was able to hear soft sounds.
The mice were treated shortly after birth, they were previously completely deaf but after treatment, could respond to very soft, light sounds. The mice also showed improvements in balance.
But if the gene therapy was delayed for 10-12 days after the mice were born, their ear cells were not able to be restored — showing that successful treatment depends on immediate “intervention” after birth.
The scientists said they hope the methods used in this study can be used to test larger mammals, and that it could be three years before it is tested on humans. Scientists say it would be a better alternative to cochlear implants. Links below for more information.