Scientists Use Gene Therapy to Restore Hair Cells in Deaf Guinea Pigs

Researchers supported by the National Institute on Deafness and Other Communication Disorders successfully used gene therapy to grow new hair cells and restore hearing in deaf guinea pigs. This is the first time researchers have been able to restore structural and functional levels to auditory hair cells in live adult mammals. Scientists at the University of Michigan's Medical School inserted a gene called Atoh1, a key regulator of hair cell development into non-sensory epithelial cells that were in the inner ears of adult guinea pigs whose original hair cells were destroyed by exposure to ototoxic drugs. An adenoviral vector was used to deliver the Atoh1 gene into the left ears of ten guinea pigs whose hair cells had been destroyed; deaf guinea pigs that were not administered the gene served as matched controls, and the animals right ears served as an additional control. Eight weeks after treatment they found new hair cells in the ears treated with Atoh, and auditory testing confirmed that the generation of hair cells coincided with restoration of auditory threshold levels. The researchers caution that restoring auditory threshold levels is not the same as restoring normal hearing and it will be several years before Atoh1 gene therapy will be ready to test in humans. This study is an important advance in hearing research, and the findings bring scientists one step further in the search for new ways to treat hearing loss that affects approximately 28 million Americans. For more information see Nature Medicine's Advance Online Publication page.

Electron microscopy image of a guinea pig's inner ear after it received ototoxic drugs to destroy all its auditory hair cells. The double-head arrows indicate the areas where hair cells used to be located. Photo credit: Yehoash Raphael, University of Michigan Medical School. View Larger Image.

Electron microscopy image of a guinea pig's inner ear after treatment with the Atoh1 gene therapy. New inner and outer hair cells are labeled with arrows. Photo credit: Yehoash Raphael, University of Michigan Medical School. View Larger Image.