Fig. 4.

mMSCs modulate secreted cytokines in response to substrate stiffness. (A) Heatmap representing results of cytokine antibody array performed on conditioned media from mMSCs cultured in hydrogels from days 2–3 of culture. Values were normalized to internal positive controls and the maximum signal for each cytokine across the four materials. Cytokines were hierarchically clustered using a Euclidean distance metric and complete linkage. (B) Schematic of MSC–HSPC coculture set-up. Fast-relaxing hydrogels were used for all experiments. Soft corresponded to 3 kPa and stiff corresponded to 18 kPa. (C) Viable cell number as counted by flow cytometry of cells seeded on Transwell membrane after 1 wk of coculture. Error bars represent SD (one-way ANOVA, Tukey post hoc test, *P < 0.05, **P < 0.01). (D) Number and percentage of CD45⁺/lin⁻ cells from Transwell membrane after 1 wk of coculture as analyzed by flow cytometry. Error bars represent SD (one-way ANOVA, Tukey post hoc test, *P < 0.05, **P < 0.01).