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Cells get smart to suit environment

SYRACUSE U. (US) — Shape memory polymers are offering new insight into how cells sense and respond to their physical environment.

Applications of the principles could offer potential solutions for current limitations of static substrate research in bioengineering research, such as medical devices and tissue engineering scaffolds.

“Living cells are remarkably complex, dynamic and versatile systems, but the material substrates currently used to culture them are not,” says James Henderson, assistant professor of biomedical and chemical engineering at Syracuse University.

“What motivated our work was the need for cell culture technologies that would allow dynamic control of cell-material interactions. We wanted to give a powerful new tool to biologists and bioengineers.”

Most cell biomechanics research has examined cell behavior on unchanging, flat surfaces. Henderson wanted to develop a temperature-sensitive shape memory polymer substrate that could be programmed to change shape under cell-compatible conditions.

Shape memory polymers (SMPs) are a class of “smart” materials that can switch between two shapes on command, from a fixed (temporary) shape to a pre-determined permanent shape, via a trigger such as a temperature change.

Kevin Davis, a third-year Ph.D. student in Henderson’s lab succeeded in developing a SMP with a transition temperature that worked within the limited range required for cells to live, observing greater than 95 percent cell viability before and after topography and temperature change.

After confirming that cells remained viable on the substrate, he investigated the changes in cell alignment on the surface that results from topography change and programmed a SMP substrate that transitioned from a micron-scale grooved surface to a smooth surface.

When the cells were seeded on the grooved sample at 30ºC, the cells lined up along the grooves of the surface. The substrates were then placed in a 37ºC incubator, which was the transition temperature for the substrate to recover to a smooth surface. Following shape memory recovery, the cells were observed to be randomly oriented on the substrate.

Details of the research, the first demonstration of this type of cell-compatible programmable topography change, is published in the journal Biomaterials.

The project aimed to determine if cells could remain viable with a change in substrate topography and determine whether cells responded to the change. The next phase of this research is to move from a 2D substrate to a 3D substrate and examine cell viability.

Additionally, Henderson’s team will be looking at what is going on inside the cells as a result of topography changes.

Since most scaffolding is made out of polymers, Henderson envisions one day using SMPs to create scaffolds that can expand inside the body, allowing for less invasive surgical procedures.

“For the first time, we’ve shown that this general concept can be used successfully with cells, which suggests that it can be extended to a number of biomaterials that could be used for scaffolds and many other applications,” says Davis.

Researchers from Case Western University contributed to the study.

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