Scientists regenerate hair cells that enable hearing

For as long as I can remember I've had great difficulty hearing in noisy environments. In my younger years it didn't bother me too much as I was mostly at noisy events to enjoy the music anywhere, and if I wanted to talk we'd move somewhere quieter. If I make a concerted effort I can usually hear someone directly opposite me fine, though in an especially noisy venue like a concert I'm often filling in the blanks with lip reading or other visual cues. If I'm standing by something noisy in the house (range, operating vacuum cleaner, etc.) I can often tell someone is talking to me but usually have no idea what they are saying. All this has been on the "minor inconvenience" end of a personal impact spectrum. Recently I had a minor traffic accident (reversed into a car at very low speed, little damage and no injuries) and I realised that in that moment I had such little awareness of what was around me that it I was concerned. There was a lot of very loud conversation happening around me at the time. No screaming or anything, and I wasn't part of the conversation, but it was enough to completely destroy my focus at the time. I'd had a similar incident a couple of years prior. All this meant I decided I should book in to have my hearing checked.

Fast forward to the results: she said the tympanogram results show a highly compliant middle ear, but far more aggressively responsive than she'd seen before. Usually you'd see little or slow response if there was a problem but I'm the complete opposite of that. For the audiogram results I can hear into negative decibels but with a large enough delta in the results between left and right ear that I'll need to do some follow-up scans. She also ran two separate types of test to check for Auditory Processing Disorder.

Everything game back within range, or at least on the opposite side of what you'd call hearing "loss". Which prompted her to mention "but, at conferences lately they have been talking about a phenomenon that is presenting more frequently and being referred to as 'hidden hearing loss'...". So I've been down a rabbit hole of reading for the past week trying to filter out the things that a pure woo to the stuff that looks like it has some rigour to it. Seems like there's also been a trend for people to label some of these symptoms as "pub deaf".

I'm curious if any others on HN have had similar experiences and/or been down this research path before.

Might be the same thing depending on your full set of symptoms.

> Despite the progress in our approach to achieve HC regeneration in the adult cochlea in vitro and in vivo, major challenges remain before potential clinical applications. First, regenerated HCs need to be terminally differentiated and fully mature, and to be located in the sensory epithelial region such that their stereocilia contact the tectorial membrane to mediate the mechanoelectrical transduction, as well as be able to survive long term. The current regenerated HC-like cells are immature and the time frame we used is not ideal to determine their long-term survival. One potential reason for the lack of terminal differentiation is the continuous Atoh1 expression mediated by adenovirus, which is known to impact HC maturation and is detrimental to HC survival (9, 56). Future studies to express Atoh1 transiently in the reprogrammed SCs could address the issue. Second, the surgical procedure of “cochleostomy” in the adult cochlea severely damages the microenvironment of the cochlea including extensive OHC death around the injection site. Future studies using an alternative delivery vehicle with a minimally invasive surgical procedure such as an AAV with round window injection could significantly improve HC regeneration efficiency without causing trauma to the inner ear. Third, major efforts should be made to identify/create new AAVs or novel delivery vehicles such as nanoparticles capable of targeting adult cochlear SCs for reprogramming. Finally, the restoration of hearing in adult deaf animal models significantly and reliably by HC regeneration will elevate the field of HC regeneration to a clinically relevant stage.

It sounds like the authors have found a more effective way to trigger generation of immature Hair Cells than was already known, but they're several large steps away from "restoration of hearing in adult deaf animal models".

However, the submitted article (from hms.harvard.edu) summarizes the findings as:

> [Authors] reported creating a drug-like cocktail of different molecules that successfully regenerated hair cells in a mouse model by reprogramming a series of genetic pathways within the inner ear.

While it's not outright false, the "successfully regenerated" isn't the way I'd interpret the PNAS paper. Perhaps I misread the paper.

[0] https://www.pnas.org/doi/10.1073/pnas.2215253120