March 2017 newswire, johns hopkins medicine

In a first-of-its-kind study published in Molecular Therapy, researchers from the National Institute on Deafness and Other Communication Disorders (NIDCD) and Johns Hopkins University School of Medicine showed that gene therapy was able to restore balance and hearing in genetically modified mice that mimic Usher Syndrome, a genetic condition in humans characterised by partial or total hearing loss, dizziness, and vision loss that worsens over time. The hearing loss and dizziness is caused by abnormalities of the inner ear. 

StereocilliaThis image shows stereocilia bundles on inner hair cells from whirler mice after whirlin gene therapy. These hair-like protrusions allow sensory hair cells to detect sound and motion. The whirler mutant mouse has very short stereocilia bundles. After whirlin gene therapy, the stereocilia bundles are increased to normal length (red) and whirlin expression is restored (green).

Primary investigator Wade Chien, M.D., a neurootologist and associate professor, who also practices at the Johns Hopkins Healthcare and Surgery Centre, and his team administered gene therapy to the inner ears of genetically modified mice carrying a mutation in a gene which is associated Usher syndrome. These mutant mice are deaf and have significant balance problems from birth. After gene therapy administration, the balance function of the mutant mice was completely restored. In addition, these mutant also had improvement in hearing. This study was one of the first to show that gene therapy can be used to improve hearing and balance functions in a mouse model of hereditary hearing loss. "Inner ear gene therapy offers tremendous potential as a new way to help patients with hearing loss and dizziness," Chien said. While the positive results are striking the researchers caution that the results are preliminary and will require additional research in humans to demonstrate fully their utility in treating humans. However, they are optimistic that their data indicate that inner ear gene therapy hold promise for treating a variety of human inherited vestibular and hearing disorders, including Usher syndrome.