High-tech foam offers new tool for developing stem cells

Researchers Yan Li, left, and Changchun Zeng are using auxetic foam to explore ways to better control the fate of stem cells.

Two Florida State University researchers are developing a high-tech material currently used in athletic equipment and prosthetics into a special tool to better develop stem cells. The work could improve drug screening, disease modeling, precision medicine and cell therapy.

FAMU-FSU College of Engineering researchers Yan Li, an associate professor in chemical and biomedical engineering, and Changchun Zeng, an associate professor in industrial and manufacturing engineering, received a $400,000 grant from the National Science Foundation for this research to explore ways to better control the fate of stem cells.

Their project will examine induced pluripotent stem cells, which are stem cells developed from mature cells and changed into a state that allows them to then turn into any tissue in the body. Using a unique, high-tech material developed by Zeng called auxetic foam, they will build three-dimensional scaffolds on which the cells can grow.

Scientists already have created several techniques with varying degrees of success to develop different stem cell lineages, so the hope for this project is that the new scaffolds will be a more effective tool. For example, by creating scaffolds that mimic the same mechanical properties as the brain, researchers hope they will better influence the stem cells to become neural cells.

“When we first tried this idea, it was new, and there was not a lot of data,” Li said. “As we get more and more data exploring this, it looks more likely that it works.”

Li and Zeng are interested in how the scaffolds’ mechanical properties influence the fate of the stem cells they surround. Their goal is to understand how three-dimensional scaffolds that surround growing stem cells influence the extracellular structures and a kind of protein those cells secrete, and therefore, the types of cells they become.

For example, does changing the elasticity of the scaffold influence what happens to the accompanying cell? What if researchers change the way the scaffold deforms when biomechanical force is applied to it?

The auxetic foam scaffolds have an unusual property known as a negative Poisson’s ratio. Unlike a normal piece of foam, which gets thinner when it is stretched, auxetic foam expands in all directions when it is stretched. When the foam is compressed, it gets denser and harder instead of spreading apart.

The foam was developed as part of a two-year project funded by the U.S. Department of Veterans Affairs to create a more comfortable prosthetic sock for amputees. It has also been used in protective athletic equipment, saddles and footwear.

But Li and Zeng thought it might have an unexpected application for scaffolding in cell cultures. Early work showed that scaffolds built with auxetic foam allowed stem cells to better differentiate into neural and vascular cells — the types of cells the researchers were interested in — compared to the scaffolds typically used for growing cell lines.

A three-dimensional scaffold has two important properties: the elastic modulus — or how hard the material is — and how the material deforms in three-dimensional space when a force is applied.

“Most people only studied the first property: the modulus,” Zeng said. “This grant allows us to conduct a comprehensive investigation on the second property. While people have long sought to understand the effect of 3D-deformation characteristics on stem cells, they were unable to because of the lack of materials systems needed for such studies, until now.”