Fig. 1.

Schematic of the magnetic microtissue testing (MMT) system and the mechanical parameters associated with the early stage anisotropic compaction of the microtissues (µtissue). (A) Arrays of fibroblast populated 3D microtissues were formed through self-assembly in microwells containing paired microcantilevers. (B) The microtissues’ elastic modulus was measured through magnetically actuated tensile testing on individual microtissues. (C) A homogeneous collagen gel with uniformly distributed cells formed in a microwell after seeding. Collagen, F-actin and Nuclei images are 3D views reconstructed from confocal stacks. (D) Cellular forces drove lateral compaction of the collagen matrix into bands on unconstrained edges by 18 hours. Confocal images in (C) and (D) cover the dashed rectangles in the corresponding phase images. Arrowheads indicate cell nuclei elongated along the contraction direction. The increase of the microtissues’ contraction force (E) and the decrease of the cross-sectional area (F) were accompanied by an increase of the elastic modulus (G) within 24 hours. Scale bar = 100 µm. Sample size for each condition: n = 9, All data are presented as Mean ± S.D.