Figure 3
Time-lapse OCM imaging reveals collagen degradation by invasive cells and strands of cells. (a) En face plane intersecting the center (i.e., the ‘equator’) of a lean (WT) ASC monoculture spheroid, acquired at time t = 0 h. The spheroid (green, highlighted via temporal speckle contrast) is recently embedded, and has not yet invaded the surrounding collagen (white). (b) The same en face plane as in (a), acquired at time t = 48 h. Invasive protrusions are abundant. Large dark regions surrounding the spheroid and invasive strands correspond to ‘voids’ with low/weak scattering signals, suggesting a lack of either cells or collagen. (c) Time-lapse view of insets 1–3 from (a,b). Red arrows at time t = 48 h indicate newly formed ‘void’ regions where only collagen was initially present. These new ‘voids’ are likely due to degradation of the collagen matrix by invasive strands via matrix metalloproteinase activity. (a,b) span a 750 × 750 μm2 lateral FOV. Time-lapse animation is available in Supplementary Video 3.
