VCU news

By Dina Weinstein

Caleb Wells, a Virginia Commonwealth University College of Engineering senior, devotes hours to a microscopic project that has a very big application: tissue engineering.

Think of the “Spider-Man” franchise, in which a character’s missing arm is regrown using lizard DNA. Tissue engineering is a somewhat similar concept, and it is used to create vascular grafts for coronary artery bypass surgery. Wells investigates how the tiny scaffolds used in the process degrade.

“We put cells in the scaffold, and the cells build around the scaffold. Just like at the end of a construction project, you tear down the scaffold,” said Wells, a student in the Department of Mechanical and Nuclear Engineering. “This scaffold biodegrades inside the human body. So at some point, the only thing left is the host’s own cells. So there’s no chance of rejection or anything. It’s a perfect replacement.”

Fibers made of a polymer called polycaprolactone form the scaffold, and Wells is focused on the properties of those fibers. To test and establish a baseline measure for the fibers, he uses a scanning electron microscope that magnifies 3,000 times. The minuscule fibers are roughly 1 micrometer in diameter.

To produce the scaffold, a process known as electrospinning distributes the polymer in solution. “You get fibers oriented in every direction on the scaffold, kind of like spinning cotton candy around that cardboard tube,” Wells said. “Which in a way can be beneficial but also, depending on what mechanical properties you’re looking for, not so beneficial.”

Wells works under the guidance of Joao Silva Soares, Ph.D., in his Engineered Tissue Multiscale Mechanics & Modeling (ETM3) Laboratory. It aims to develop highly integrative experimental-computational approaches for cardiovascular tissue engineering.

“The polymer scaffold eventually needs to degrade to be fully replaced by the new tissue that was engineered,” Soares said. “We’re trying to first understand how to engineer the tissue better inside the bioreactor to then be able to achieve better integration inside the body.”

Wells met Soares while taking the professor’s Mechanics of Deformables class in summer 2021, which gave him a window into how materials and shapes bend and deform with their forces.

Wells also is working with device design to do material testing using uniaxial and biaxial mechanical tensile testers. “This helps us determine how those fibers that we looked at on the microscope are affected over time using Young’s Modulus of Elasticity,” he said. “If I’m pulling in every direction, I can look at how each direction’s fibers are being affected. I get to play with programming and electrical design along with operating machines that already exist. I’m now getting to build machines and work on the back end at the same time.”

Here, student and mentor share thoughts on what they learned working together.

Caleb Wells

What attracted you to this project?

What intrigued me was how I can apply mechanical engineering to biomedical work. My family and my friends always told me, based off my personality, I’d go into biomedical stuff because I like to help people. In this lab I’m not directly working on something that is going directly in someone’s body yet. I get to work on the mechanical side of that aspect. Right now I am analyzing the mechanical and material properties of these scaffolds. So I play a part in a bigger project that then plays a part into one solution of one problem in the human body. Being a part of something that can make a difference really excited me.

What did you get out of the experience?

One of the great things about [experimental] research labs is you get to apply what you’re learning in class to the different projects. It was very easy to do that with this lab because I had just taken Mechanics of Deformables and Material Science, which play directly into the work I started doing with material testing. Young’s Modulus of Elasticity was a term I had just learned a semester or two before, so I was applying my theoretical coursework directly to real-world experiences, which really gives a concrete foundation. A lot of things clicked a lot easier after I was able to do that.

What’s one lesson you learned from Dr. Soares?

What I always perceived as bad results or results that didn’t prove my hypothesis would always get me down in the dumps and make me feel like I wasted that entire experiment. But my first summer as an Undergraduate Research Opportunities Program fellow, we did long-term experiments, lasting months at a time. When those results came in, when I felt like they were “bad results” and I’d wasted most of my time — but I learned [there aren’t] “bad results,” according to Dr. Soares. They might not prove your hypothesis and they might not even answer the question that that hypothesis is based off of, but they bring up more questions that help you design more experiments that get you, eventually, to answers you’re looking for. Sometimes you answer completely unrelated questions that are still useful to the general public or useful to research science. So staying motivated when results aren’t what I expected was one of the biggest lessons I learned.

Joao Silva Soares

Why does this research matter?
Understanding how degradable polymers degrade and are absorbed over time is important to design better biodegradable implants. The absorption inside a living body is a very challenging problem to predict, thus a lot of experiments and prototypes are necessary. Doing simpler experiments in the lab under “easier” conditions will provide insight on how to develop theories that describe the behavior of these materials better. We are particularly interested in tissue engineering scaffolds. One would want that the scaffold goes away at the same time that the cells produce the extracellular matrix themselves. In addition, it is important to know how the mechanical environment (i.e., loads and deformations they are subjected to) contributes to the rate of degradation of the scaffold.
How did Caleb help advance the project?
Caleb has single-handedly led this project for the last couple years, continuing the work of Emily Clement (a biomedical engineering undergrad who graduated in spring 2021). He has run several experiments with the degradation chambers that Emily and I have designed and built. Additionally, he has taken big steps in improving our electrospinning setups, led the federal work-study workers in the manufacturing of the scaffolds and also supervises several other undergraduate students performing mechanical testing of the scaffolds.
What’s one lesson you learned from Caleb?
From my undergraduate students like Caleb, I learn the new ways that young people behave nowadays. I’m lucky to be around young people all the time. They have energy. They see the world in new ways that we don’t. Caleb is going to start as a Ph.D. student in the fall, and it’s really nice to have the opportunity to recruit VCU undergraduates as graduate students. He has already learned so much into our specific methods and research and will hit the ground running next fall.