ROCKVILLE, MD—Next to being exposed to excessive noise, one of the most common causes of irreversible hearing loss in people of all ages is exposure to chemotherapy for the treatment of cancer. Cisplatin and the aminoglycoside antibiotics, two classes of drugs commonly used with cancer patients, are both toxic to mechanosensory hair cells, the receptor cells of the inner ear.
Unfortunately, unlike exposure to noise, which people can usually minimize, cancer patients who need chemotherapy to survive have no choice but to put their hearing at risk. That’s why scientists have been trying to develop a method to protect the inner ear without inhibiting the therapeutic effectiveness of these cancer-fighting medicines.
SOUND THERAPY TO PROTECT HAIR CELLS
Among those working on this problem are researchers at the National Institute on Deafness and other Communications Disorders (NIDCD), one of the National Institutes of Health (NIH), based in Rockville, MD. In an article published last week in the Journal of Clinical Investigation, Lisa Cunningham, PhD, and co-authors reported some encouraging findings.
Earlier research had discovered that heat shock proteins (HSPs), which are induced in response to cell stress, can protect the hair cells in the inner ear from ototoxic drugs. However, no one had figured out how to deliver HSPs directly to the inner ear where they could reduce the ototoxic effects of chemotherapy.
As they explain in their article, Cunningham et al. “hypothesized that exposure to sound that is titrated to stress the inner ear without causing permanent damage would induce HSPs in the cochlea and inhibit ototoxic drug–induced hearing loss.” They developed a sound exposure protocol to do this, which they tried in conjunction with a newly developed mouse model of cisplatin ototoxicity.
The authors found that “preconditioning mouse inner ears with sound has a robust protective effect against cisplatin-induced hearing loss and hair cell death.” They also said that this sound therapy provided protection against aminoglycoside-induced hearing loss.
The scientists added that the findings from this animal study suggest “that sound therapy holds promise for preventing hearing loss in patients” being treated with cisplatin and aminoglycosides.