Cells in the body are constantly moving, squeezing past neighboring cells and exchanging nutrients and signals. But many materials used to study them in the lab hold them unnaturally flat or still. 

As a result, bioengineers have worked to transform the traditional gels used to grow cells in the laboratory into something that more closely resembles a cell’s more dynamic surroundings in the body. At first, they used water-rich hydrogels, which resemble Jello, said Emilie Dressaire, an assistant professor of mechanical engineering. “But there are limitations to these types of environments, including the fact that they dramatically limit transport of fluids, molecules, nutrients, and oxygen between cells.” 

To do this, researchers started breaking up solid hydrogels into collections of soft, slippery particles. These microgels allow cells to move, organize, and divide, making them good candidates for studying cancer cells and, potentially, testing new treatments in the lab.  

Now Dressaire has received a $500,000 CAREER award from the National Science Foundation (NSF) — the agency’s most prestigious grant for early-career faculty and a stepping stone to tenure — to investigate how microgels allow fluids to move and transport molecules.

“I was really hoping to get funding to do the fundamental research so we could understand the system, which is a step that we’ve been missing,” Dressaire said. If all goes well, she said, “we’ll be able to then build a platform for bioengineering applications, which will put us in a really good position to help cancer biologists and bioengineers.”

Fluid Questions

Dressaire has spent much of her career looking at fluid flows and transport, often in porous rocks and sediment. The microgels that she will study with this award are a different kind of porous material, this one made of tiny, Jello-like particles instead of sediment — similar to the antibacterial hand sanitizer gel made popular during COVID.

“It’s like a ball pit made of soft particles,” she said. “If you imagine kids moving through a ball pit, the cells can do the same thing.”

For Dressaire, this fluid environment brings the opportunity to ask new questions. “Here, the particles are soft because they’re made out of gel, and they’re also porous — you can have diffusion inside them,” she said. Inside the microgel, cells can exchange oxygen, nutrients, and other molecules. “It’s a whole new type of porous material for us to think about.”

With her NSF award, Dressaire will look at the fundamental mechanisms of transport within microgels — questions such as what molecules or compounds are going around the particles in the gel, what molecules can go through the particle itself, and how researchers can design microgels to allow for more transport through the particles. 

Collaboration in Motion

Dressaire’s team will work with associate professor of materials Angela Pitenis and her group on developing microgels with varying properties, including the size, shape, and stiffness of particles.

Tailoring microgels toward specific applications would allow researchers to grow mini-tumors, or tumoroids, from a patient’s cancer cells in the lab. “If you can prepare a bunch of those, you could test all sorts of drugs and therapeutic tools, and then see what that tumor responds well to,” Dressaire said. “That’s really the hope down the line.”

The longer-term vision is already beginning to intersect with cancer research at UCSB. PhD student Ella Evensen, who is jointly advised by Dressaire and bioengineering and mechanical engineering assistant professor Ryan Stowers, is already introducing breast cancer cells to the microgel environment. In research funded by the California Breast Cancer Research Program, Evensen is 3D printing channels that can be added to the microgel. These channels would allow the researchers to deliver molecules or compounds to the cells in the gel, then observe how the cells respond.

Dressaire sees those collaborations as central to where the research could lead. Her work brings together experts in fluid mechanics, materials science, bioengineering, and cancer research, reflecting a culture at UCSB in which researchers cross disciplinary boundaries to tackle problems that no single field can solve alone. 

That approach is already taking shape through partnerships with Pitenis, Stowers, and others across the university. For Dressaire, the goal is not simply to improve transport through this new material, but to establish the fundamental knowledge that could help many researchers use microgels more effectively. “I’m grateful for this award, which shows that people in the fluids community are seeing the value of this type of work in emerging technology,” she said. “I hope this work will provide some basic knowledge and guidelines to support the use of these systems.”
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