Institute for Clinical and Translational Science (ICTS) members Marlan Hansen, MD, associate professor of otolaryngology, and C. Allan Guymon, PhD, professor of chemical and biochemical engineering, are in the early stages of investigating ways they can improve the hearing of people with cochlear implants. Their research of nerve growth and developing polymers with surface patterns may allow nerves to grow from the inner ear into a cochlear implant.
Funded by an ICTS pilot grant, these UI researchers are conducting preliminary studies with the goal of developing grant proposals for external funding. The ICTS is the academic home to the NIH-NCRR funded Clinical and Translational Science award at the University of Iowa and views such pilot grant work as absolutely vital to the transformation of clinical and translational research at the university and throughout the nation.
Cochlear implants are electronic devices that are surgically implanted in deaf individuals who lack cells that normally turn the mechanical energy of sound into electrical impulses. The cochlear implant is a series of electrodes in the inner ear that process sound and then decides where the electrical impulse should be delivered to excite the nerve. Current implant technology is limited because it only offers a small number of channels (only six to eight channels can be used at any given time within a patient).
Thousands of Sounds
"A normal ear would be like a piano with thousands of sounds. A current cochlear implant has eight keys in comparison. Try to compare a piece of music that you can play using thousands of sounds versus a piece you can play using only eight keys," Hansen explained. The brain needs more information to be able to determine what is really happening, so these investigators want to produce a good fidelity signal that replicates auditory reality, "And you need lots of channels to do that," he said.
Inspired by "casual" hallway conversations about their respective interests in neuron growth and photopolymers, the ICTS pilot grant has brought Hansen and Guymon together from opposite sides of the UI campus. These researchers are looking at a wide variety of polymers, similar to the chemical make-up of contact lenses, to determine which ones might successfully interact with the different cells of the inner ear in rats. Guymon's lab is currently using light to form patterns of ridges and valleys in polymers. Hansen then places nerve cells on the polymer and observes how the nerve grows in response to the patterns.
"It turns out that the pattern has a big influence, so we can direct where the nerve regenerates by making it grow across a pattern," Hansen said. If they can successfully control where the nerve ends up, then they can also control what it interacts with, and how the sound is processed. Controlling nerve regeneration in this way could ultimately enhance an individual's ability to distinguish different sounds, especially complex sounds such as music and human speech in background noise.
Broadly Applicable
Joe Clark is a T-32 resident working in Hansen's lab. He looks at the polymers to determine which ones could be most compatible with the neural tissue of the inner ear. Joe recently finished an internship in general surgery and selected this project as his research focus because, "It was so novel. I like the translational aspect of it and it has the appeal of being something that could be broadly applicable," he said.
Bradley Tuft is a graduate student working in Guymon's lab. He designs the polymers using light to create patterns that serve as guidance paths for the nerve growth. "I became interested in coming to the University of Iowa after hearing Dr. Guymon present about polymers," he said.
Guymon added, "The fact that Brad is a Presidential Scholar and selected to work on this project is certainly a testament to these types of collaborations."
The investigators are embarking upon their first paper together. "We want this grant to succeed in terms of translational science and actually be able to improve peoples' hearing," Guymon said. "Both groups are very interested and want to make this a success," Hansen said.
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