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Hannah Larson, a PhD student in the Paul M. Rady Department of Mechanical Engineering, is a 2023 recipient of the T32 for Interdisciplinary Training in Musculoskeletal Research.

The program provides research and training opportunities for the next generation of musculoskeletal investigators who intend to pursue careers in biomedical and clinical research.

The musculoskeletal system is the study of muscles, tendons, bones, and cartilage and how they interact in the human body.

At first glance, it may seem strange that a student in mechanical engineering is conducting research on the human body.

But a key aspect of mechanical engineering is the study of materials and their behavior. Materials like steel, concrete and aluminum undergo tests that analyze characteristics including strength and the rate at which they experience wear and tear, which is called “material fatigue.” Engineers like Larson bridge those investigation techniques to the human body.

“I’m applying those exact same principles of mechanics to the study of tendons,” said Larson, who works in the  with Professor Sarah Calve. “You do similar tests. It’s just totally different material behavior.”

Larson’s journey to biomechanics was a circuitous one.

As an undergraduate in mechanical engineering, she took a senior elective class called Biologically Inspired Design, which studied how nature finds solutions to engineering and design problems. She did a project on how the material structure of the Namibian beetle shell can passively collect water in the desert.

It was intriguing work, but Larson stuck to a more traditional engineering path after graduation, landing a job as a research assistant in the Massachusetts Institute of Technology Lincoln Laboratory. There she helped develop solid-state, fiber, and diode laser technologies for the scientific and defense communities. Although the job was a good experience, Larson noticed that she didn’t think about her work during off-hours.

When it came time to apply to graduate school, she recalled her senior elective and how fascinating she found biological systems like the human body.

“I like the big picture of trying to help people with their health,” Larson said. “For me, being active is essential. If I tore my Achilles heel and could never run again, that would be devasting.”

A motivator to Larson’s research is the fact that tendons don’t heal well on their own.

She is investigating a subclass of macromolecules called proteoglycans and glycosaminoglycans, whose mechanical functions in tendons are little understood. Her lab work involves dissecting tendon samples and stretching them with a force sensor. She then incubates the tendon in a fluorescent solution that sticks to parts that have been damaged, allowing the amount of damage to be studied in detail.

Larson wants to know if having more, or less, of the proteoglycans and glycosaminoglycans in tissues will help mitigate the material fatigue of tendons.

She hopes that her research can help the medical community better understand how people develop tendinopathy, which is a tendon disorder that results in pain, swelling, and impaired function and is not easily treatable.

NIH has hopes for Larson’s research, too. The T32 grant will provide additional funding to Larson’s graduate research, including money to buy new lab equipment and travel to academic conferences.

After she finishes her PhD program, Larson wants to continue using her engineering skills in a biomedical career.

“Whether it’s developing biomedical devices, tissue constructs or synthetic tendons,” Larson said, “I know this kind of work is for me.”