Gene therapy restores hearing and balance in mice
February 06, 2017 Source: Technology Daily
Window._bd_share_config={ "common":{ "bdSnsKey":{ },"bdText":"","bdMini":"2","bdMiniList":false,"bdPic":"","bdStyle":" 0","bdSize":"16"},"share":{ }};with(document)0[(getElementsByTagName('head')[0]||body).appendChild(createElement('script')) .src='http://bdimg.share.baidu.com/static/api/js/share.js?v=89860593.js?cdnversion='+~(-new Date()/36e5)];Researchers at Harvard Medical School and Massachusetts General Hospital used new gene therapies to restore partial hearing and balance in mice with impaired hearing and balance. Fully deaf mice were able to hear loud speech. The findings were published in the recently published journal Molecular Therapy.
The key to treating various hearing loss disorders is to find a gene delivery mechanism that can be applied to all types of hair cells. Previous gene therapy was only slightly effective for inner hair cells, but it was useless for outer hair cells. To achieve this, the researchers used a common adeno-associated virus (AAV). The virus has been used as a gene vector for the treatment of retinal diseases, but it has not been able to effectively penetrate into hair cells.
The researchers did not change or directly modify the virus, but instead provided the virus with a "vehicle" that arrived at the inner ear - encapsulating the adeno-associated virus in the vesicle. These small vesicles are composed of cell membranes whose surface is covered with a protein that binds to cellular receptors. When transplanted into cells, the cells can naturally detach small vesicles carrying viruses. The researchers believe that this may be the main reason why adeno-associated viruses encapsulated by vesicles are more likely to bind to the surface of hair cells and penetrate effectively.
Experiments show that the new method can successfully infiltrate 50%-60% of hair cells in the culture dish, while the simple adeno-associated virus can only penetrate about 20% of hair cells. In the animal in vivo test, the researchers injected the adeno-associated virus into the inner ear of young rats whose key hair cell function was missing, and 30%-70% of the inner and outer hair cells were effectively infiltrated. After one month of treatment, 9 of the 12 mice recovered to a certain degree, showing that the mice would be shocked when they clapped their hands loudly, and 4 of them could hear 70 to 80 decibels.
Because hair cells are also important for balance, mice with damaged hair cells have abnormally balanced performance. After treatment, the balance ability has been significantly improved. Compared with the untreated, the symptoms of head tremor and in-situ rotation (representing instability or disorientation) are greatly alleviated.
Currently, the research team is improving its gene delivery technology to increase the proportion of genes delivered to hair cells. Although this method has not been applied to humans at present, it is already a gospel for deaf patients. (Reporter He Wei)
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