In this project, Dr Philippe Vincent at Johns Hopkins University, USA, will build tools that researchers can use to test potential treatments for hearing loss caused by exposure to loud noise.
Project start date: July 2024
Project end date: July 2027
About the project
Very loud sounds can damage hearing by overstimulating the inner hair cells.
These inner hair cells sense sound information and transmit it to the brain via the auditory nerve. They do this by releasing chemical signals called neurotransmitters in the tiny gap that separates them from auditory nerve cells (the spiral ganglion neurons).
Depending on how loud the original sound is, the inner hair cells release more or fewer neurotransmitters into the synapse – fewer for quiet sounds, more for louder sounds. Very loud sounds cause them to release excessive levels of neurotransmitters into the synapses, damaging both inner hair cells and spiral ganglion neurons.
The loss of synapses can cause your hearing to gradually decline over time, but at first, the damage may not be obvious: this is what we call ‘hidden hearing loss.’ Dr Philippe Vincent is developing tools that the hearing research community can use to develop and test potential new drug treatments that can restore the synapses and their function.
How it works
The researchers will study inner hair cells from mice that have been engineered to produce a light-sensitive protein. They will use light to activate these inner hair cells to release neurotransmitters, similar to the way a sound wave would. These cells will be grown in a dish so that they can be observed using a microscope.
The inner hair cells will be grown together with spiral ganglion neurons for several days to allow them to form new synapses. Afterwards, the researchers will assess the activity of the synapses in response to activating the inner hair cells with light. They will also investigate the ability of specific drugs to improve how well these newly-formed synapses work.
How will this research benefit people with hearing loss?
Currently, there are no treatments that can repair the damage to the inner hair cell synapses caused by exposure to loud noise. This research seeks to develop and provide tools that will help the research community to develop drugs that can improve or restore hearing after hearing loss. It could ultimately lead to new treatments that can regenerate inner hair cell synapses.
About the researcher
Dr Philippe Vincent is Assistant Professor at the Johns Hopkins School of Medicine in the US. He was awarded the RNID Discovery Research Grant in 2024.
For years, we’ve underestimated the consequences of hearing loss, especially its correlation to things like social isolation, depression, dementia and cognitive decline. These are major issues that have significant impact on people’s live, and this motivates me to develop treatment approaches for hearing loss.”
