Can irreversible hearing loss be countered? Scientific discoveries shed light on potential strategies to regenerate the cells crucial for auditory perception.
In a groundbreaking development, researchers at the University of Rochester Medical Center have discovered a new pathway that could potentially restore hearing in mammals. The study, published in Frontiers in Cellular Neuroscience, focuses on the growth gene ERBB2 and its role in promoting cochlear hair cell regeneration.
The research, led by Dorota Piekna-Przybylska, PhD, a staff scientist in the White Lab, compares cells with an overactive growth gene (ERBB2 signaling) with similar cells that lacked such signaling. The team, which includes additional authors Daxiang Na, Cameron Baker, and John Ashton, PhD, found that when ERBB2 is expressed or activated in cochlear tissues, it can trigger molecular cascades known for promoting cell survival and proliferation.
This regenerative process is significant because cochlear hair cells, which are essential for hearing, typically do not regenerate naturally in adult mammals. The loss of these cells leads to permanent hearing loss when they are damaged.
The potential implications for hearing loss treatment are promising. Activating ERBB2 signaling could enable regrowth of sensory hair cells lost to noise, aging, ototoxic drugs, or genetic conditions. By regenerating hair cells, ERBB2-targeted therapies might reverse sensorineural hearing loss (SNHL) that currently has no cure.
Moreover, ERBB2 or its downstream effectors could serve as molecular targets for drugs or gene therapy aimed at stimulating intrinsic regenerative capacity within the cochlea. Understanding ERBB2’s role may also help develop strategies for other neuro-sensory cells.
However, most evidence for ERBB2's role comes from animal models, particularly neonatal mice, where regenerative capacity is higher. Translation to adult humans will require overcoming challenges such as limited progenitor cell availability and ensuring safe modulation of ERBB2 without oncogenic effects.
The primary cells responsible for detecting sound waves in humans are cochlear hair cells. The loss of these cells is a major cause of progressive hearing loss in humans. Concert goers and those with repeated exposure to loud noises, such as military personnel, construction workers, and musicians, are most at risk for progressive hearing loss.
The research was supported by the U.S. Army Medical Research and Development Command (USAMRDC), the National Institute on Deafness and Other Communication Disorders, UR Ventures, and the Schmitt Program on Integrative Neuroscience. Researchers at the Del Monte Institute for Neuroscience are also working on identifying mechanisms that may promote hair cell regeneration in mammals.
The growth gene ERBB2 promotes stem cell-like development by initiating the expression of multiple proteins, including SPP1. SPP1 is a protein that signals through the CD44 receptor, which is known to be present in cochlear-supporting cells. ERBB2 expression drives the protein expression of SPP1 that is necessary to activate CD44 and grow new hair cells.
The increase in cellular response promoted mitosis in the supporting cells, a key event for regeneration. Previous work has shown that activating the growth gene ERBB2 can trigger the growth of new hair cells in mammals.
This new study explains how this activation is happening, which is a significant advance toward the goal of generating new cochlear hair cells in mammals. The ultimate goal of the research is to determine whether the phenomenon can improve auditory function after damage in mammals. The discovery represents a major step forward in regenerative therapies for hearing loss, which affects millions worldwide.
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