The relative stiffness of a cell’s environment is known to have a large effect on that cell’s behavior, including how well the cell can stick or move. Now, a new study by University of Pennsylvania researchers demonstrates the role timing plays in how cells perceive this stiffness.
Previous modeling studies have treated the extracellular matrix (ECM) as an elastic solid, but in reality, the ECM is partly viscous. Like mayonnaise or toothpaste, it has a mix of solid and liquid traits and is therefore viscoelastic. Most importantly, the stiffness of a viscous material changes when it is pushed or pulled on, and that change depends on the speed at which those deformations are applied. And just as different viscous materials have different intrinsic rates of relaxation, different cell types exert forces at different speeds.
The Penn team’s study shows that the closer those two timescales match, the more the cell is able to spread out on a surface. This kind of spreading is what allows cells to exert force in the first place, so it is a key quality for determining their role in a variety of diseases, such as cancer.
