Courtesy of Karl Lewis

Karl Lewis, biomedical engineering, joined Cornell in 2020 — continuing a career of offering a unique set of expertise to the study of the human body's cells.

September 25, 2020

Bringing Mechanical Engineering to Biology; The Story of Cornell BME’s Newest Professor

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Karl Lewis, who joined Cornell’s biomedical engineering faculty in July 2020,  epitomizes Cornell Engineering’s motto “break the rules.”. Though a typical engineer may specialize in just one area, Lewis’s career has driven him to bridge gaps between two historically isolated specialties: biology and mechanics.

As an undergraduate studying mechanical engineering, Lewis was interested in anything with an engine —   his friends described him as a “gearhead.” But Lewis also found that within the realm of mechanical engineering, the number of unasked questions seemed limited compared to those in biology.

Lewis soon joined a biomedical engineering lab with a group that studied the different properties — like toughness and elasticity — of cartilage, a cushiony connective tissue that coats bones and joints, and offsets weight loading. Cartilage may degrade with mechanical stress or age, leading to problems down the road such as osteoarthritis, and Lewis’s work looked at cartilage characteristics as they degraded.

“It was an opportunity to use the analytics and material understanding from my mechanical engineering to look at and interrogate a biological question,” Lewis said.

Fascinated by the concept of using mechanical tools to study biological phenomena, Lewis continued on as a Ph.D. student in the biomedical engineering department at the City College of New York. There, he worked with a diverse group of people that each came from a different specialization, with input from physiologists, nutritionists and cell biologists.

Together, they studied calcium signaling in bone cells, called osteocytes. As the most common cell in bone tissue, with over 40 billion of them in the human body, osteocytes are connected to each other and exchange nutrients within the bony matrix. Bones store the body’s calcium reserves, and when overall calcium levels are low, osteocytes break down bone to obtain more calcium for the body so it can properly mobilize muscles and nerves. Osteocytes also signal to each other using calcium in response to a mechanical load, which was what Lewis’s work focused on.

“It didn’t have to be that everyone was a cell biologist in order to study osteocytes,” Lewis said. “As a mechanical engineer, I brought a unique perspective to the way that those cells work, and working with someone that understood cell biology meant that we could really do something exciting.”

With this group, Lewis built a mechanical loading device in-vivo — inside a living organism — to study calcium signaling in response to mechanical stimuli. Continuing on as a postdoctoral researcher at Indiana University School of Medicine, Lewis’s aim was to create genetically modified mice to further develop ways to study bones.

“If I was going to be a professor, I wanted to be able to study bone cells from in-vitro cell models all the way up through organ models, looking at specific bones under loading, to full systemic models, looking at longitudinal studies of genetically modified mice,” Lewis said.

As a professor, Lewis views his work as a continuation of his past lab experience, reinforcing the concept that mechanical cues are inherently biological. As Lewis explained, cells are constantly subject to mechanical input. Cardiac cells pumping blood, for instance, receive electrical signals that stimulate contraction. Cells also contain proteins that sense mechanical loading — the contraction in this case — and turn the signal into a biological one.

“We typically separate mechanical force from biology, and look at them as different. But mechanical cues are in fact the same as biological cues,” Lewis said.

Embracing this mantra, Lewis and some of his friends from graduate school in New York recognized this discrepancy between Harlem students and engagement in STEM subjects, and formed a community outreach association with the Harlem Children’s Zone, a charter school.The goal was to make STEM accessible by leading science projects with high school juniors and seniors.

“We’d go in wearing normal clothing…and we were going in explicitly as scientists to show these students that it was accessible,” Lewis said.

This experience sparked Lewis’s initial interest in Cornell. Through his community outreach he had the chance to connect with Cornell faculty and took an interest in the University’s “any person, any study” motto, appreciating the “commitment to student curiosity.”

Lewis said he strongly believes in the importance of teaching and remaining mindful of the inequalities that may prevent some from receiving a good education, something he felt that Cornell students are particularly attentive to.

“I feel like it’s a responsibility of mine to give back to the community with the gifts that I’ve been given through education,” he said.

Though he won’t teach until next semester, Lewis has spent his first weeks in Ithaca exploring the natural beauty through running and hiking. As a certified yoga instructor, he is also excited to continue his practice in Ithaca.