In a breakthrough that will likely accelerate research aimed at cures for hearing loss, tinnitus, and balance problems, scientists have perfected a laboratory culturing technique that provides a reliable new source of cells critical to understanding certain inner-ear disorders.
The cells, known as hair cells, are the essential sound and balance detectors in the inner ear. Damage to these cells is a key factor in hearing and balance loss, and while birds, fishes, and amphibians can quickly regrow damaged hair cells, humans cannot. Until now, scientists seeking clues to this problem have been hampered by difficult procedures required to gather these cells for their research.
MBL Whitman Investigators Zhengqing Hu and Jeffrey Corwin, both of the University of Virginia School of Medicine, developed a new technique for isolating cells from the inner ears of chicken embryos and growing them in their laboratory. The scientists achieved these results by inducing avian cells to differentiate into hair cells via a process known as mesenchymal-to-epithelial transition.
Hu and Corwin were able to freeze and thaw the cultured cells, then grow new cells from the thawed cultures - a discovery that will make hair cells accessible to more researchers.
The study of hair cells is crucial to understanding hearing loss because hair cells are a precious commodity in humans. We are born with a limited number of these sound detectors in each ear, which can be easily damaged by age, certain illnesses, loud noises, and adverse reactions to medications. Once damaged, the cells do not grow back, causing hearing and balance problems.
"Until now, scientists working to understand many inner ear disorders had to resort to difficult microdissections to gather even small numbers of these cells, which limited the types of research that could be pursued and slowed the pace of discoveries," says Corwin.
The availability of vials of frozen cells that can be induced to form hair cells should remove a significant barrier to progress toward the development of treatments for the more than 20 million Americans who suffer from hearing loss and balance problems.
The research is published in the September 24-28 early edition of the Proceedings of the National Academy of Sciences.
Dr. Corwin, a professor of neuroscience at the University of Virginia School of Medicine, is a co-director of the MBL's Biology of the Inner Ear course.
The research was supported by two grants from the National Institutes of Health and by the Grass Foundation.
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