The first method to regenerate sound-sensing hair cells and thus restore hearing in animals was reported by Dr. Albert Edge of Harvard Medical School and Massachusetts Eye and Ear Infirmary and colleagues in the Feb. 20, 2014, edition of the journal Stem Cell Reports.
The researchers found that blocking the major cell signaling pathway (Notch) in the ear produced an excitation of neighboring cells. The neighboring cells produced hair cells. Hair cells are necessary for hearing. The study was conducted in mice.
The only cells that were induced to produce hair cells were those cells that express a protein called Lgr5 (leucine-rich repeat-containing G-protein coupled receptor 5). More cells containing Lgr5 can be induced to produce hair cells by the inhibition of the notch protein.
The majority of hearing loss in humans is the result of hair cell loss due to noise damage.
This is the first research that documents that hair cells in the ear that are responsible for initiating the vibrations that result in hearing can be replaced both naturally at low levels and at much higher rates through chemical manipulation.
The researchers plan further tests with humans to develop a method of hearing restoration that is simple and makes use of naturally occurring chemistry in the ear.