Scientist takes Hearing Lessons from Mother Nature


Barald believes zebrafish like these could hold the key to understanding and correcting hearing loss (Credit: Wikimedia Commons).

If you like rock concerts, you should be envious of chickens and zebra fish. Unlike humans, these simple animals can actually regrow cells damaged from the raging music.

“We think we’re finally getting clues as to why this is possible,” says Kate Barald, a cell and developmental biology professor at the University of Michigan. Barald believes that understanding how fish and chickens regrow their cells may have implications for the 26 million Americans suffering from noise-induced hearing loss. This condition is on the rise in children and teens, possibly due to the popularity of loud music and portable ear buds. The identification of factors that trigger inner ear development and regeneration could someday lead to new therapies to correct hearing loss. It could also improve cochlear implants, surgically-implanted devices used to treat profound hearing loss in 219,000 people worldwide.

Barald believes that a cytokine called macrophage migration inhibitory factor could be part of the answer. Cytokines are messengers normally produced by the immune system that help trigger a response to infection. Barald and coworkers discovered that their cytokine–macrophage migration inhibitory factor–plays an additional role: It helps direct the growth of neurons during inner ear development. “We think these cytokines could be the key to regeneration [and] formation of the early developing inner ear,” Barald says. Since adult ear cells still have the ability to interact with the cytokine, there’s a possibility it could be used to help correct nerve damage caused by hearing loss. Barald will further test the cytokine’s therapeutic potential this summer at The Bionic Ear Institute in Melbourne, Australia.

Barald, 68, grew up in Lyndonville, Vermont. She has a personal history with hearing loss. “I lost my hearing in my left ear when an—unfortunately drunk—pediatrician poured nearly boiling temperature oil into my ear at four months of age in an attempt to sooth an ear infection. I’ve been deaf in that ear ever since,” she says.

Kate Barald speaking at a University of Michigan workshop for the NSF Graduate Research Fellowship Program.

Barald speaking at a University of Michigan workshop for the NSF Graduate Research Fellowship Program (Credit: Michael M. Schofield).

Barald received her PhD from University of Wisconsin in Madison. After postdoctoral work at University of California, San Diego, Barald sought additional training in the sciences. She immediately knew she wanted to work for Norman Wessells at Stanford University when she read his book, Tissue Interactions and Development. The book was meant to supplement developmental biology textbooks, but Barald says it read more like a novel. “I can remember my hands literally trembling because the ideas were so powerful, so interesting, and so well expressed,” Barald says. Wessells helped introduce Barald to developmental biology and modeled the mentorship she now provides to her own students.

Barald makes time for family amidst her scientific studies. She met her husband, Douglas Jewett, in a chemistry course at Madison. “He was passing, and I was not. He offered to tutor me… I’ve been grateful for the 45 years we’ve been together,” she says. Their son, Ethan Jewett, is a biology graduate student at Stanford University. “My mom is hugely supportive and encouraging. She has a very busy career, but I always feel like I’m the most important thing to her,” he says. “That being said… she gives the same kind of attention to her students and her work.”

Barald trains students in the sciences and helps them find funding. She hosts an annual workshop for students applying for funding from the National Science Foundation. As Barald took the podium at the this year’s workshop, her greying hair and serious demeanor added wisdom to her 33 years of experience in reviewing grant applications. Every time she spoke, the room was filled with the sounds of furious pencils as more than 30 students jotted down her advice.

Barald also inspires scientists closer to her own generation. Andy Groves, a neuroscience professor at Baylor College of Medicine in Houston, says that Barald was among the first scientists to apply modern techniques to inner ear research. “She’s been one of the people who inspired me to get into this [research] area. I’ll always be very grateful to her for having the courage to get started when most of the rest of us were too scared,” Groves says. Groves recommended one of her articles on macrophage migration inhibitory factor for Faculty of 1000, a service that helps scientists follow new discoveries by highlighting significant articles in different research specialties.

In this study, Barald and coworkers also found that their cytokine’s ability to trigger neuron growth worked on cells found outside the ear. Groves suggested that with a lot more research, this could someday translate to treatments for other types of nerve damage—maybe even those affecting the brain or spinal cord.

Shen YC et. al. (2012) “The cytokine MIF acts as a neurotrophin in the developing inner ear of the zebrafish.” Dev Biol.

Bank LM et. al. (2012) “MIF acts as a neurotrophin in the developing inner ear.” Development