Figure 1.

Mechanical characterization of the cellular assemblies formed by WI-38 cells on compliant substrates over 5 days. (a) Different cellular assemblies formed when cells were cultured on compliant gels. Nodules represent three-dimensional cellular aggregates. Plaques represent a flattened version of the nodules. And lastly, single cells represent a variety of morphologies demonstrated by non-assembling cells, present at early time points for all substrates and at later time points on substrates with elasticities stiffer than the mechanophenotype of the cell. Average mechanical properties, (b) E_elastic, (c) E_R, (d) E₀, and (e) μ, of single and assembled WI-38 cells over four days across PAAm gels and glass coverslips (CS). In general, cells tested on Day 0, about 30 minutes after seeding, showed the most variation due to substrate stiffness for all four mechanical properties. WI-38 cells maintained their mechanophenotype from Day 1 onwards, regardless of organizational morphology and substrate stiffness. At later time points, cells only formed plaques on the 1.4 kPa gel, which exhibited mechanical properties similar to the nodules formed on other gels and single cells on glass CS. Data shown as mean ± s.d., with statistical significance determined using Kruskal-Wallis ANOVA on ranks within each day, followed by a Dunn’s post-hoc analysis (* p < 0.05). #, Only single cells were present for this condition, instead of nodules/plaques. +, Individual cells in spherical morphologies were tested on Day 0 for all substrates.