By Rebecca Moragne, Research-Highlights Editor
About one in 1,000 babies are born with hearing impairments, according to the Centers for Disease Control and Prevention. Scientists from Harvard Medical School and the Massachusetts General Hospital are working with gene therapy to restore hearing in those with genetic and acquired deafness.1
Gene therapy is either replacing a mutated gene with the healthy copy of the gene or inactivating the mutated gene.3 The scientists were recently successful in restoring partial hearing and balance to mice with genetic conditions affecting both. This accomplishment was previously unsuccessful because accessing hair cells was extremely difficult with previous gene therapy methods.
Hair cells are the cells in the inner ear that sense sound and head movement and translate them in to neural signals for hearing and balance.1 In humans, 95% of the fibers in the auditory nerve are from the inner hair cells.2 The auditory nerve is the connection between the neural signals produced by the hair cells and the brain.2 From gene therapy newly constructed hair cells in mice, the mice developed “notable gains in hearing and allows mice that would normally be completely deaf to hear the equivalent of a loud conversation.”1 Significant steps are necessary to apply this treatment to humans, but with this achievement, the goal is now one step closer.
If you are interested in reading more, the published findings of the study can be found in the February issue of Molecular Therapy.
1. Harvard Medical School. (2017, January 26). New gene-delivery therapy restores partial hearing, balance in deaf mice. ScienceDaily. Retrieved January 28, 2017 from www.sciencedaily.com/releases/2017/01/170126120504.htm
2. Sinauer Associates, Inc. (2001). Two kinds of hair cells in the cochlea. Neuroscience, 2nd. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK11122/
3. U.S. National Library of Medicine. (2017). What is gene therapy. Genetics Home Reference. Retrieved from https://ghr.nlm.nih.gov/primer/therapy/genetherapy