Many fish, frogs, and birds possess special regeneration capacities that allow them to fully recover from hearing impairments and balance dysfunctions caused by lost hair cells.
Humans and other mammals, however, do NOT have this ability.
Sadly, our mammalian ears are vulnerable to permanent hearing loss and balance deficits.
But that could soon change…
Because new research from Jeff T. Corwin at the University of Virginia appears to have uncovered the reason for the permanent nature of hair cell loss in humans. The findings identify why certain creatures can recover from hearing damage and why humans cannot.
The most exciting part?
The team behind the research, part of Corwin’s Laboratory of Inner Ear Sensory Hair Cell Regeneration, has discovered a pharmacological treatment that could “wake up” the special supporting cells that can allow lost hair cells to regenerate in humans.
To learn more about how it works, here is a link to the study itself — which was published on February 20, 2020 in the Journal of Neuroscience.
Here is the abstract:
J Neurosci. 2020 Feb 19;:
Authors: Kozlowski MM, Rudolf MA, Corwin JT
Sensory hair cell losses underlie the vast majority of permanent hearing and balance deficits in humans, but many non-mammalian vertebrates can fully recover from hearing impairments and balance dysfunctions, because supporting cells (SCs) in their ears retain lifelong regenerative capacities that depend on proliferation and differentiation as replacement hair cells. Most SCs in vertebrate ears stop dividing during embryogenesis, and soon after birth vestibular SCs in mammals transition to lasting quiescence as they develop massively thickened circumferential F-actin bands at their E-cadherin-rich adherens junctions.
Here, we report that treatment with EGF and a GSK3 inhibitor thinned the circumferential F-actin bands throughout the sensory epithelium of cultured utricles that were isolated from adult mice of either sex. That treatment also caused decreases in E-cadherin, β-catenin, and YAP in the striola, and stimulated robust proliferation of mature, normally quiescent striolar SCs. The findings suggest that E-cadherin-rich junctions, which are not present in the SCs of the fish, amphibians, and birds which readily regenerate hair cells, are responsible in part for the mammalian ear’s vulnerability to permanent balance and hearing deficits.
Millions of people are affected by hearing and balance deficits that arise when loud sounds, ototoxic drugs, infections, and aging cause hair cell losses. Such deficits are permanent for humans and other mammals, but non-mammals can recover hearing and balance after supporting cells regenerate replacement hair cells. Mammalian supporting cells lose the capacity to proliferate around the time they develop unique, exceptionally reinforced, E-cadherin-rich intercellular junctions. Here, we report the discovery of a pharmacological treatment that thins F-actin bands, depletes E-cadherin, and stimulates proliferation in long-quiescent supporting cells within a balance epithelium from adult mice. The findings suggest that high E-cadherin in those supporting cell junctions may be responsible, in part, for the permanence of hair cell loss in mammals.
PMID: 32079647 [PubMed – as supplied by publisher]
Additional research shows that there is a U.S. Provisional Patent Application related to the research posted here is currently pending. The application number is 62/951,996 and it was filed on December 20, 2019. The patent applicant is Jeffrey T. Corwin, and the other inventors listed include Mark Rudolf and Mikolaj Kozlowski.
Hearing Loss Treatment Report will continue to keep an eye on this promising new (potential) hearing loss treatment, which involves treatment with an EGF and a GSK3 inhibitor, and is currently being tested in mice. But considering the patent filing and strong evidence, human trials will surely follow.
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