Figure 1.

Dynamic and static strains both increase cell stiffness yet have different effects on mechanoresponders. Mesenchymal stem cells were seeded in minimal essential medium at a density of 2000 or 10 000 cells/cm² for β-catenin or YAP1 experiments respectively. Twenty-four hours later, application of 2% dynamic (200 cycles over 20 minutes) or static strain (2% and hold tension) was followed by staining with phalloidin (green), anti-β-catenin (yellow), or anti-YAP (red), scale bar = 25 μm (A, D, and E). Nuclear intensity of β-catenin and YAP1 was analyzed by ImageJ program and statistical significance indicated by letter a and b, both of them P < .0001 and ∗ ≠ ∗∗ (D and F). (b) Application of dynamic strain increased the AFM-measured cell modulus by 22% (P < .001, N = 350/grp) compared with non-strained control and while static strain resulted in a 13% increase compared with non-strained control (P < .0001, N = 800/grp). Cell modulus of MSCs treated with dynamic strain were, on average, 11% larger compared with static strain groups (P < .05).