Research finds select proteins that could restore hearing
Most hearing loss is caused by problems with hair cells lining the inside of the ear or damage to the auditory nerves that connect the hair cells to the brain. Unfortunately, as human hair cells cannot regenerate like that of other mammals, damaged hair cells -from loud noises or viral infections- likely causes permanent hearing loss.
An American research team from Johns Hopkins University School of Medicine in Baltimore has since tried to find a way to reverse deafness caused by damaged hair cells.
They studied the intricate patterns of precursor cells along the cochlear spiral of the ear. Of the precursor cells that would later transform into functional hair cells that detect sound, two proteins -Activin A and follistatin- were noted to have opposing behaviour on precursor cells, nonetheless vital to hair cell development.
In an experiment, increased levels of Activin A in the cochleas of normal mice resulted in too-early transformations of precursor cells into hair cells and also caused the hair cells to appear prematurely all along the cochlear spiral. In contrast, mice engineered to either overproduce follistatin or not produce Activin A at all had late-forming hair cells which were scattered across the cochlea.
Angelika Doetzlhofer, associate professor of neuroscience at the university, thus explains the importance of hair cells in hearing loss, “The action of Activin A and follistatin is so precisely coordinated during development that any disturbance can negatively affect the organisation of the whole cochlea – like building a house, if the foundation is not laid correctly, anything built upon it is affected.”
The prompted but yet unrefined division of precursor cells has potential applications – Doetzlhofer notes that this newfound knowledge could guide new and more effective treatment strategies for hearing loss.
