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For decades, lab-grown cells have been studied in materials that don’t reflect the softness and flexibility of human tissue.��

Bruce Kirkpatrick

Researchers at the University of Colorado Boulder have developed a water-rich, Jell-O-like material that more closely mimics how real tissues move, stretch and relax and whose liquid or solid state can be precisely controlled by light.

The�� in the journal��Matter��and was directed by Distinguished Professor��Kristi Anseth.��

These new hydrogels will help scientists understand how mechanical cues from tissues affect cells, said Bruce Kirkpatrick, PhD, the paper’s first author and a third-year medical student. These insights could help improve our understanding of disease and how cells respond to drugs. It could also shed light on cell development—how stem cells mature into specialized cell types.

“The convention of growing cells on plastic for drug testing is problematic because plastic is stiff, while human tissue is flexible,” Kirkpatrick said. “Unless you're studying bone or other cells adapted to rigid environments, it’s not an appropriate mechanical setting for studying how cells respond to drugs.”

Kirkpatrick added that a key advantage of the hydrogel-based cell culture platform is its three-dimensional structure, which better reflects the environment cells experience in the body.

“The material we developed will help researchers better understand how mechanical environments influence cell behavior, not just the biochemical cues cells receive through surrounding liquid and nearby cells,” he said.

Shaped by light

Lea Hibbard

Most hydrogels form spontaneously when two liquids are mixed, but these gels provide less control and precision than the newly developed materials, Kirkpatrick said. In addition, researchers traditionally have shaped hydrogels using extrusion printing, a process similar to squeezing Play-Doh through a tube.

Instead, Kirkpatrick and the research team combined the new hydrogel’s dynamic properties with photopolymerization, using light to transform liquids into solids and encapsulate cells during three-dimensional printing. The new approach is faster and provides precise control over shape and material properties, Kirkpatrick said.

“With photopolymerization, we can control exactly how much light is applied, where it goes and when the hydrogel forms,” Kirkpatrick added. “The amount of light determines how much the material gels and its resulting mechanical properties. It gives researchers control over the shape, timing of cell encapsulation and spatial variation in properties.”

For example, if cells are encapsulated in a droplet and one side is exposed to light for only a few seconds while the other receives a longer or stronger dose, researchers can study what happens at the boundary between those regions, observing how cells migrate between them and how differences in mechanical properties influence their behavior.

Abhishek Dhand

The researchers also studied intestinal organoids—tiny lab-grown versions of the intestine—to see how they behaved in different environments. In the body, these cells exist in a soft, viscoelastic environment, where tissues stretch or deform under stress.��

When the team placed the organoids in a hydrogel with similar properties, the cells took on natural shapes and expressed the right proteins. In other words, they behaved like they do inside the body.

“These findings suggest that viscoelasticity is essential for proper cell function and organization,” Kirkpatrick said.

Next steps

The researchers’ long-term goal is to use three-dimensional printing to produce large, cell-laden arrays of the new material for drug testing or disease modeling. This approach allows them to quickly create identical samples with high quality control and study how cells respond to gene mutations—such as removing a disease-linked gene—or to varying drug concentrations in the hydrogel environment.

The material could also help scientists study fundamental processes, such as how embryos organize cells to form correctly shaped organs, and investigate diseases like fibrosis, in which the body overproduces scar tissue in response to injury or chronic inflammation.

Co-first authors��,��PhD, (BioMedEngr’25), and PhD student��Lea Hibbard contributed equally to this study.�� 91��ý faculty involved in the project included Professor��Jason Burdick, Distinguished Professor��Christopher Bowman and Professor��Tim White.