Fig. 1

Myofibroblasts (`MFs) generate far reaching deformations in fibrillar collagen extracellular matrix (ECM). a Schematic of the experimental set-up. b Confocal reflection and fluorescence microscopy of the experimental set-up. Single MFs (F-actin, red) were attached to the top of fibrillar collagen ECM provided with surface marker beads (green) and allowed to remodel the ECM (reflection, black) for 3 h. Side view z-scanning (bottom) demonstrate the position of beads and MFs on the collagen surface. c MF contraction of ECM was quantified by analyzing position changes of marker beads over time, here shown in overlay before contraction (yellow) and after 8 h of ECM remodeling (blue) by MFs (position indicated by arrowhead). d Marker displacements were used to calculate MF-induced deformation fields using particle image velocimetry, displayed as vectors with color-coded magnitudes as indicated (red—high displacement). Deformation field boundaries were defined by displacement vector amplitudes ≤1 µm (dotted lines). e Breakdown of the deformation field into rings, sections, and sectors allowed computation of average vector magnitudes as a function of distance and direction from the contractile MF. f Such averages were used to align obtained deformation fields along their long axis and generating the overall average after 6 h remodeling (11 macrophages, 11 experiments) with color-coded magnitudes. g The radii of all MF-induced deformation fields were measured over time and medians are shown as center lines of box (25th to 75th percentiles) and whisker (minimum to maximum) plots; black circles and continuous are averages with exponential fit. All scale bars: 100 µm