With a new five-year, $3.2 million grant from the National Institute on Deafness and Other Communications Disorders, researchers from Case Western Reserve University and Mass Eye and Ear will study what causes acquired hearing loss (AHL) and find new ways to to protect themselves against this.
According to the Centers for Disease Control and Prevention, AHL is one of the most common health problems in older adults. Although hearing aids can help, there is no cure for AHL and in many cases scientists are still unsure of the exact cause.
AHL significantly impacts quality of life, leading to increased social isolation, depression and cognitive decline. Untreated hearing loss is associated with a higher risk of dementia, with even mild, untreated hearing loss doubling the risk.
“We expect that if we are successful, this could point to new strategies to preserve human hearing by regulating mitochondrial calcium levels,” said Ruben Stepanyan, assistant professor in the Department of Otolaryngology at Case Western Reserve School of Medicine.
Understanding hearing loss
An important factor in hearing is the health of the hair cells of the cochlea; sensory cells in the inner ear that detect sound vibrations and send electrical signals to the brain. These cells are packed with mitochondria, or microscopic energy-producing components.
Hearing loss may be the result of damage caused by poorly functioning mitochondria, according to previous peer-reviewed research. The health of hair cells depends on balanced calcium levels that are partly regulated by mitochondria. Loud noises can cause calcium levels to rise too high, putting pressure on the hair cells of the cochlea.
This study will investigate how calcium overload from noise exposure can damage cochlear hair cells and contribute to hearing loss and identify new therapeutic targets to treat it.
Part I
Researchers will use a certain type of mouse models that are more sensitive to calcium overload and premature hearing loss to evaluate how overstimulation by loud sounds affects the structure and function of cochlear hair cells.
They will use advanced three-dimensional imaging technology – along with new machine learning-based approaches to 3D data analysis – to examine the structure of mitochondria in these cells to understand how they change under stress.
Part II
Researchers will next test whether preventing calcium overload in the mitochondria can protect hearing by testing other types of mouse models with reduced mitochondrial calcium to see if they might be more resistant to noise damage.
The ultimate goal is to find ways to prevent hearing loss due to noise exposure and aging, helping millions of people protect their hearing as they age.”
Artur Indzhykulian, assistant scientist at Mass Eye and Ear’s Eaton-Peabody Laboratories and assistant professor of otolaryngology at Harvard Medical School
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