The Rutgers-led study was published in Stem Cell Reports and led by Zhichao Song, a doctoral student in Kwan’s lab. Co-author Azadeh Jadali is a post-doctoral associate in the lab.
Here’s a link to the study: http://www.cell.com/stem-cell-reports/fulltext/S2213-6711(17)30418-6
Here’s a link to a Rutgers Today story with images: https://news.rutgers.edu/research-news/inner-ear-stem-cells-may-someday-restore-hearing/20171102#.WgB9OltSy73
So-called hair cells in the inner ear convert sounds into neural signals that are relayed to the brain by spiral ganglion neurons, the study notes. Hearing loss from overexposure to noise causes hair cell loss, severe damage to neuronal processes and slow degeneration of auditory neurons. The neurons do not regenerate once they are lost.
“Hearing loss impacts about 15 percent of the American population – probably more,” Kwan said. “Over the years, you don’t realize that you’re not hearing well until you get tested. We’re one of the few labs trying to figure out how to address the hearing loss issue.”
In their study, the scientists overexpressed a gene called NEUROG1 to turn inner ear stem cells into auditory neurons.
“But since that leads to increased cell division and NEUROG1 is used in other stem cells to make other types of neurons, scientists in other fields should be aware that when using this factor, they’ll probably also increase cell proliferation,” Kwan said.
The Rutgers scientists also discovered that chromatin – DNA studded with histone proteins – influences how NEUROG1 functions. Changes in chromatin may help reduce unwanted stem cell proliferation and can be achieved by adding drugs to experimental cultures in Petri dishes, Kwan said.
“Ideally, we would change the chromatin state before we start overexpressing NEUROG1 and prevent unwanted stem cell proliferation,” he said.