One of the most intrinsic components of aging is hearing loss. Over time, damage to your ears results in the loss of inner ear hair cells in a region called the cochlea. This can happen because of genetics, loud noises, and natural aging processes (1). Particularly since the development of headphones, a lifetime's worth of rock and roll has been found to have its consequences on your ears. This loss of these hair cells results in a failure to sufficiently transduce auditory vibrations into electrical signals for the auditory nerve to process.
In broad strokes, 90% of adult hearing loss is classified as sensorineural hearing loss (SNL), meaning it is caused by damage to the cochlea and auditory nerve (1). This damage can lead to the inability to effectively communicate with loved ones. According to hearing loss professionals, the primary goal of hearing loss treatment is to improve speech perception (2). In the past, this has most commonly been accomplished through hearing aids. However, what if it were possible to regenerate the hair cells that we have seen lost with aging?
Cartoon by Pixabay
There is a novel hearing loss drug that has shown promise at regenerating hair cells within the cochlea. This drug, called FX-322 recently completed Phase 1b of clinical trials- meaning it was tested on a small portion of the human population to determine the safety and pharmacological effects. This drug successfully was able to improve speech perception in a group of 23 patients with SNL (3).
How does it work? Well, FX-322 is a molecule that targets progenitor cells within the inner ear (3). Progenitor cells are descendants of stem cells, which means that in this case they can specifically differentiate into hair cells in the cochlea. FX-322 has been shown to regenerate these mammalian hair cells ex vivo (3). The question remained- would it work in vivo with human participants?
During the study, fluid from the inner ear called perilymph was collected from humans to see if the active components in FX-322 reached the inner ear, despite physical barriers in place that are associated with hearing loss. It was also tested to see if the concentration of the active ingredients was equivalent to the concentration required to produce hair cell regeneration ex vivo. It was found that the active components of FX-322 did reach the target area and target concentrations in the brain, suggesting successful regeneration of hair cells in vivo.
These results were reinforced by improved speech perception in 4/6 patients who received FX-322. The control group saw no improvements in speech perception. These statistically significant results suggests that a single dose of FX-322 was capable of regenerating hair cells and reversing some of the hearing loss associated with SNL. Despite more clinical trials being required before FX-322 can be approved, this drug has huge promise in aiding the hardships associated with the natural process of aging. Any treatment to do with stem cells is absolutely fascinating- and over time who knows what scientific breakthroughs we will achieve by using stem cells to alter the natural process of aging.
Written by Jessica
Sources
Tyagi, B. P. S., & Rout, M. (2019). Platelet rich plasma (PRP): a revolutionary treatment of sensorineural hearing loss. Acta Scientific Otolaryngology (ASOL) Volume, 1(4).
Winn, Z. (2022). Mit Scientists Develop New Regenerative Drug That Reverses Hearing Loss. SciTech Daily.
McLean, W. J., Hinton, A. S., Herby, J. T., Salt, A. N., Hartsock, J. J., Wilson, S., ... & LeBel, C. (2021). Improved speech intelligibility in subjects with stable sensorineural hearing loss following intratympanic dosing of FX-322 in a phase 1b study. Otology & Neurotology, 42(7), e849.