Fig. 2

Compressed Collagen Assay provides a stiffer, more structured growth environment. A compressed collagen assay provides a stiffer, more structured growth environment for cell culture facilitating a greater range of cell morphology in colonizing cells. a and b show the collagen matrix in more detail via reflectance microscopy, a showing uncompressed collagen at 2 mg/ml and b compressed collagen derived from 2 mg/ml gel. (Image was taken using Leica TCS SP2 using 488 argon laser and Leica HCX PlanApo lbd.BL × 63 NA 1.4 oil immersion lens, at room temperature, scale bars = 20 μm). Cells seeded on compressed collagen (CC) set into a non-compressed collagen matrix (LC) colonized the compressed collagen in preference to migrating away from it. c and d show MDA-MB-231 cells colonizing the compressed collagen set into a lower density 1 mg/ml collagen gel. Few MDA-MB-231 cells emerged at the border zones (B) (scale bars = 100 μm). e and f show a few cells with a mainly rounded morphology which have escaped (yellow arrows) and moved away from the densely colonized compressed collagen into the lower density collagen (scale bars = 20 μm). In f emerging cells followed the contours of the compressed collagen disk (green arrows) while in e they appeared to form chains moving away from it (green arrows). Images b, c, e, f, were generated using a Nikon TiE phase contrast microscope, moveable stage, environmental chamber at 37 °C with a continuous CO₂/O₂ supply, DS-Fi2 camera, lenses: Plan × 10/0.25 Ph1 DL, Plan Fluor EL WD × 20/0.45 Ph1 DM ∞/0.2 WD 7.4. g and h show live GFP+ HT1080 cells colonizing the compressed collagen matrix. Cells had a diverse range of morphologies including rounded (yellow arrows) and elongated shapes (red arrows). Images were taken using a Zeiss Axio Vert.A1, DS-Fi2 camera, a Zeiss LDA Plan × 20/0.35 Ph1 ∞/1.0 (PS) lens at room temperature, scale bars = 100 μm