A molecular switch restores hearing with pulses of light

Developed a molecular ‘switch’ which allows you to turn your hearing back on through pulses of light: it’s called TCPfast and it’s a molecule that transforms normal auditory neurons into neurons that are activated with light, without the need to genetically modify them. Successfully tested on cells and laboratory animals, it could open up to a new generation of light-activated cochlear implants which, unlike the electric ones currently in use, would allow deaf or severely hearing impaired people to perceive music correctly. and conversations in noisy environments. The result is published in Journal of the American Chemical Society by an international team led by the Institute of Bioengineering of Catalonia (Ibec) with the contribution of Carlo Matera, a pharmaceutical chemist from Ibec who has been working for two years as a researcher at the Department of Pharmaceutical Sciences of the State University of Milan.

The idea of reactivate auditory neurons with light stimuli and non-electrical had already been tested by one of the authors of the study, Tobias Moser, who at the University of Göttingen had restored hearing in laboratory animals through a genetic modification of cochlear neurons, thus making them capable of transforming the light stimuli received by a special device (the cochlear implant) in an action potential that is transmitted to the brain and perceived as sound. “In order to avoid genetic manipulation – explains Carlo Matera – in this new project we have instead developed an alternative method to couple light to the electrical activity of neurons. We have thus devised a molecule, called TCPfast, capable of binding to a neuronal receptor and functioning as a molecular prosthesis that transforms normal auditory neurons into neurons capable of being activated with light “.

“The main reason why users of cochlear implants are unable to correctly perceive music and conversations in noisy environments is that the cochlea, by its very nature, contains liquids: this causes in some cases the stimuli of an electrical nature propagate inside it excessively ”, explains Antoine Huet, researcher at the University Medical Center of Gottingen. “Since, on the other hand, light can be transmitted in a more defined way through liquids, our technique allows us to stimulate the neurons of the cochlea with far greater precision”.

Experiments conducted on cells and small rodents have shown that when the TCPfast molecule is hit by blue light it is able to induce a signal in the neurons of the cochlea. “This is the first time that such a result has been achieved by adopting a pharmacological rather than genetic strategy,” adds Garrido-Charles, a researcher at Ibec.

“Our computer simulations tell us that listening to light should allow us to recover hearing that is much more similar to the physiological one: the next step – concludes Huet – will be to verify it experimentally”.

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