Fig. 3.

Increased lateral convergence of the collagen bands on stiffer micropillars correlated with significant microtissue stiffening. The deflection of micropillars caused by the microtissue contraction is inversely proportional to the pillar spring constant (A, Top view, Side view), indicating that the microtissues generated essentially the same contraction forces for each of the three boundary conditions (B). Decreased microtissues’ cross-sectional area on the stiff pillars (A, Top view, Side view; C) led to increased contraction stress (D). Lateral convergence of the collagen bands increased significantly from soft pillar to stiff pillar (A, Collagen), which corresponded to 190% and 410% increase in microtissue’s elastic modulus for intermediate and stiff pillars, respectively (E). Collagen images are 3D views reconstructed from confocal stack. Sample size for each condition: n > 9. All data are presented as Mean ± S.D.