Figure 2

Motility and mechanics.

(a) Three substrates used to monitor cell motility: 2D collagen-coated glass substrate, 3D collagen matrix and 1D fibronectin-coated microchannels (13 μm wide, 25 μm deep) etched in silicon. Motion tracking based on time-lapse imaging. (i) Schematic. (ii) Tracking data. (iii) Speed (μm/min) and maximum invasion distance (mean ± s.e.m.). (b) TFM quantified traction stresses exerted by cells on 5kPa 2D polyacrylamide substrate mimicking mammary tumor stiffness by measuring displacement of embedded fluorescent polystyrene beads. Phase image followed by fluorescent images of bead field under stressed and unstressed (post-trypsinization) conditions. Bead displacement yields magnitude (|T|) and distribution of traction stresses⁴². (i) Schematic. (ii) Tension maps (Left); phase images (Right); MCF-10A (Top); MDA-MB-231 (Bottom). Scale bars: 50 μm. (iii) Force magnitudes exerted by cells at different surface laminin concentrations (mean ± s.e.m.). (c) Microprinted Covalent HA array. (i) Schematic. (ii) CD44 expressing MCF-10A and MDA-MB-231 cells (red) attached to FL-HA micro-patterned substrates (green) after 24h culture. Scale bars: 50 μm. (iii) Cells attached to HA squares (mean ± s.e.m.). (d) Cells rolling on E-selectin surfaces. (i) Schematic. (ii) Phase images. Scale bars: 50 μm. (iii) Rolling velocities and numbers of MCF-10A cells captured on surface under physiological wall shear stresses (mean ± s.e.m.). (e) (i) SEM reveals distinct ECM structures deposited by MCF-10A (Left; scale bar: 4 μm) compared to MDA-MB-231 (Right; Scale bar: 5 μm). (ii) IF imaging of cells stained with fluorescein-tagged HA demonstrate expression of HA in both MCF-10A and MDA-MB-231. Scale bars: 50 μm. (iii) Flow cytometry shows higher CD44 expression in MDA-MB-231 compared to MCF-10A (left: histogram; right: quantified MFI). (f) AFM probe aligned with confocal fluorescence lifetime microscope scans points of interest over cytoplasm, nuclei and nucleoli. Force-indentation curves used to calculate elastic moduli. (i) Schematic. (ii) Curves (middle) and corresponding images (top, bottom). Scale bars: 10 μm (top); 2 μm (middle, horizontal), 0.2nN (middle, vertical); 4 μm (bottom). (iii) Depth-dependent elastic moduli (mean ± s.e.m.). (g) Fluorescent nanoparticles injected into cells and trajectory monitored over time. (i) Schematic. (ii) Cell monitored in real time. Inset: nanoparticle trajectory. Scale bars: 10 μm (main); 0.2 μm (inset). (iii) MSD values over cumulative time (mean ± s.e.m.). All p-values indicated by Michelin guide scale (p ≤ 0.001:[***]; 0.001 < p ≤ 0.01:[**]; 0.01 < p ≤ 0.05:[*]; 0.05 < p:ns).