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Meet the Researcher
Meet the Researcher
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Bradley Walters, Ph.D., St. Jude Children's Research Hospital
Walters received his Ph.D. in integrative biology at Lehigh University in Pennsylvania. Now a postdoctoral research fellow in the Department of Neurobiology at St. Jude Children’s Research Hospital, Walters is a 2012 Hearing Health Foundation grant recipient.
Millions of people suffer from hearing loss, and most of these cases result from the death of cells in the inner ear called hair cells. These cells can die as a result of many different things, most notably noise, side effects from certain medications, and even simple aging. Once these cells die, they are never regenerated, which is why hearing loss is almost always permanent.
It is my hope that by figuring out how to regenerate these cells in the inner ear we may be able to offer people who have lost their hearing the option to regain this vital sense. To try and achieve this goal, I am looking to other animals who have figured out a way to regenerate their hair cells. By learning how they are able to do this, I hope to be able to find a way to make it happen in our own ears.
My current project involves a largely overlooked species in the study of hair cell regeneration: opossums. Opossums are marsupials, like kangaroos and wallabies, but they are much smaller and easier to handle. They have very sensitive hearing and can hear sounds at frequencies much higher than we can.
More importantly, however, opossums differ from most other mammals in that they can continue adding new sensory cells in their inner ear even after they are able to hear. While this isn’t exactly regeneration, it is something that our human ears do not do, and it is exactly the type of process that we will need to re-create if we want to make regeneration happen.
My goal is to figure out what genes may be regulating this addition of new cells, and then to see if we can turn those genes on or off in the ears of other mammals, like mice, who lose their hearing in the same ways that we humans do.
In the short term, I am hoping that my work with the opossums will help me to identify the genes that are important for regeneration in the mammalian ear. If we are successful, then we should be able to manipulate the genes we identify to achieve regeneration in the inner ear of a mouse. If this is successful, then our future work will be in finding or designing treatments that might be suitable for human use.
For example, we may be able to design gene therapies to target those genes that we identify as being important. Or we may be able to find or create drugs that affect those same genes in the ways that are needed. Ultimately, it is my hope that this work will lead to treatments that will be able to reverse hearing loss caused by the loss of auditory hair cells.
This project is relatively new and something that we are obviously very excited about. I would say that I have been thinking about investigating the ears of marsupial species for some time, but was really only able to start with any of the experiments in 2011. That was when I first saw that the cells within the opossum ear behave quite differently from those of most other mammals, including humans. Once I saw that, I knew it was a project that was really worth pursuing.
I was born in 1979 in Wilmington, Del., which is the home of tax-free shopping, credit card companies, and Vice President Joe Biden. I went to Penn State as an undergraduate where I studied pre-medicine and got my Ph.D. in integrative biology/ neuroscience at Lehigh University in Bethlehem, Penn.
I typically go home once (maybe twice) a year, usually for the winter holidays and then maybe again in the spring or summer. Now that I live in Memphis, I would have to say the thing I miss most about home is being close to the ocean, though the barbecue is definitely better in Memphis.
I had a great uncle who used to work for ICI Pharmaceuticals. After he retired he started his own lab and hired me to help process samples for a couple of summers when I was in high school. I remember thinking at the time that the work was so repetitive I could never see myself actually becoming a scientist. I hated it, but I’m grateful that my uncle pushed me to stick with it. The funny thing is now, I can’t imagine doing anything else. I’ve really grown to enjoy it.

I have always been interested in science, and biology in particular. In summer camp once, I was voted most likely to become a marine biologist because I used to love studying the tadpoles and the fish whenever we would go play in the streams and lakes.
Once I had made up my mind to pursue a Ph.D., I applied to several programs, but they were all in evolutionary biology, and I spent a semester studying evolution and ecology in freshwater fish. Those kids in camp almost got it right!
But, halfway through my first year I met a professor in my department who was studying stroke and brain injury and ways to try and protect and regenerate damaged brain tissue. I found it all so fascinating! I immediately switched labs. Apparently it was a good move because I was able to find out some interesting things about why cells die after a traumatic brain injury and how we may be able to minimize much of the damage and even regenerate some of the cells.
As a result, I was invited to present my research at the St. Jude Children’s Research Hospital and while here, I met Dr. Jian Zuo who was (and still is) working on regenerating hair cells in the cochlea of the inner ear. I realized that a lot of the ideas that I had, and a lot of the things I had been working on in the brain, could be applied to the ear. So I moved to Memphis to join the Zuo lab. Since then, I have been working on cochlear regeneration and have no intention of going back to study fish—unless it’s to look at their hair cells.
Both of my grandfathers had moderate hearing loss as they got older. In the case of my mom’s dad, I really believe that it contributed to his cognitive decline later in life. I didn’t really notice it at the time, but looking back, it’s pretty obvious that as he lost his ability to hear, he became less engaged with friends, family, and the world around him, and I think that made it hard for him to keep his mind sharp. I think this is something that we are all familiar with and will have to deal with a lot more in the near future as medical advances continue to increase our lifespan.
On a day-to-day basis, I would say that I most often unwind by cooking or watching TV with my wife, and reading. The funny thing is that even though I do enjoy reading a lot of fiction, most nights I find myself reading scientific papers. I just can’t seem to turn it off.
I love visiting new places, but don’t get to as much as I would like. Still, I have been to many places throughout North America, Central America, the Caribbean, Europe, and Asia. Among the places I have visited, my favorite trip so far would have to be to France, where we traveled along the Riviera, gambled in Monte Carlo, and then met up with some friends in Paris. Taiwan was also great: It was a unique cultural experience and had some pretty great surfing and snorkeling to boot.
While I love working in a research hospital and being able to interact with patients on a personal level, I will most certainly continue working as a scientist rather than a clinician. However, I hope I will always have the same opportunities that I do now to see bench science being translated into therapies for patients.
—Andrea Delbanco, Senior Editor, Hearing Health Magazine
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