Recent research indicates hearing loss is expected to nearly double in 40 years. This figure includes individuals who suffer from the condition of “hidden hearing loss,” which is generally defined to be damage to the inner ear that leads to difficulty hearing soft voices in the presence of background noise, but an audiogram within the range of normal hearing sensitivity.
New research, however, hopes to shed light on how hearing loss and its impact of quality of life can be avoided. Researchers at USC and Harvard have developed a new approach to repair cells deep inside the ear — a potential remedy that could restore hearing for millions of elderly people and others who suffer hearing loss.
The lab study demonstrates a novel way for a drug to zero in on damaged nerves and cells inside the ear. It’s a potential remedy for adventitious hearing loss – a condition that afflicts two-thirds of people over 70 years and nearly 20% of all adults in the United States.
“What’s new here is we figured out how to deliver a drug into the inner ear so it actually stays put and does what it’s supposed to do, and that’s novel,” said Charles E. McKenna, a corresponding author for the study and chemistry professor at the USC Dornsife College of Letters, Arts and Sciences. “Inside this part of the ear, there’s fluid constantly flowing that would sweep dissolved drugs away, but our new approach addresses that problem. This is a first for hearing loss and the ear. It’s also important because it may be adaptable for other drugs that need to be applied within the inner ear.”
The paper was published April 4 in the journal Bioconjugate Chemistry. McKenna co-authored it with David Jung of Harvard Medical School, and others. It is the latest achievement in USC’s priority program to advance biomedicine, including the recent launching of the USC Michelson Center for Convergent Bioscience. The Michelson Center unites USC experts across disciplines to solve some of the most intractable research challenges related to health at the molecular level. The facility will house the new USC Center of Excellence in Drug Discovery, with McKenna as its director.
Caveats for the Hearing Loss fix
The public and hearing care professionals who work with adults with hearing loss should remain cautious about this research. The research was conducted on animal tissues in a petri dish, not on human subjects or other living animals. The researchers, however, remain hopeful given the similarities of cells and mechanisms involved. McKenna says since the technique works in the laboratory, the findings provide “strong preliminary evidence” it could work in living creatures. McKenna and colleagues are already planning the next phase involving animals and hearing loss.
According to USC News report, this study breaks new ground because researchers developed a novel drug-delivery method, specifically targeting the cochlea. The researchers designed a molecule combining 7,8-dihydroxyflavone, which mimics a protein critical for development and function of the nervous system, and bisphosphonate, a type of drug that sticks to bones. The pairing of the two apparently delivered the breakthrough solution, as auditory neurons responded to the molecule, regenerating synapses in mouse ear tissue that led to repair of the hair cells and neurons, which are essential to hearing.
“We’re not saying it’s a cure for hearing loss,” McKenna said. “It’s a proof of principle for a new approach that’s extremely promising. It’s an important step that offers a lot of hope.”
Source: Gary Polakovic, USC News; featured image courtesy FDA