Figure 2: Mechanical strain generates reproducible fiber architecture and supports mechanosensing cell behavior.

A) Alexa-488 collagen gels were strained to create fiber alignment in the central region of the gel, between the cantilevers, while the remainder of the gel had random fiber architecture. The inserted key denotes the orientation of parallel and perpendicular directions with respect to collagen fiber alignment. B) Quantification of the fiber alignment in random (unstrained) matrices (n=27), aligned (strained) matrices with the straining device inserted (n=12), and aligned (strained) matrices where the device was removed after straining (n=14). (*** p < 0.001) C) Windrose plots describe the distance and direction of GFP-LifeAct-MDA-MB-231 cell migration in aligned and random collagen architectures from four independent experiments. In aligned regions of the gel cell migration occurs +/− 30° from the axis of fiber alignment (n=20 cells). In random collagen architecture the direction of cell migration is arbitrary (n=19 cells). D) Quantification of total protrusions per cell in aligned vs random fiber architectures with the strain device inserted (n = 20 and 19, respectively). (* p < 0.05). For the coefficient of alignment, means are reported with standard deviation, and significance was determined by Kruskal Wallis test with Dunn’s correction. For total protrusions, medians and interquartile ranges were reported and significance was determined by Wilcoxon rank sum.