- Published on 03 August 2015
Researchers from Washington University School of Medicine in St. Louis (USA) have identified two signaling molecules in mice that are required for proper development of the cochlea. The two signaling molecules called FGF9 and FGF20 were found to be necessary for proper inner ear development in mice. Normal signaling of these molecules was activated at about day 11 of the development cycle and stopped by day 14 when the progenitor cells no longer multiplied and began to differentiate to become functional adult sensory cells. Abnormal signaling resulted in a shortened cochlear duct and impaired hearing in the mouse model.
The study’s results were published online in the journal eLife and contribute to understanding of inner ear development, a first step toward the goal of restoring hearing in mammals. This regenerative process has been identified in birds and amphibians but is absent in the more complex mammalian ear.
“To eventually be able to restore hearing, we would like to be able to regenerate the sensory hair cells of the cochlea,” explains David M. Ornitz, PhD, senior author of the study. “If the inner ear in birds and fish is damaged, for example, cells in the inner ear are naturally turned back into progenitor cells that are capable of replacing the sensory cells. But mammals are more complex, with a better sense of hearing over a wider range of sounds. However, it is thought that in exchange for better hearing, we have lost the ability to regenerate sensory hair cells.”