Fig. 1.

Coupled cell and nuclear morphologies are lost following cyclic tensile strain (CTS). a Relative areas of primary human mesenchymal stem cells (hMSCs) cultured on static substrates (collagen-I coated polyacrylamide hydrogels; 2–50 kPa; n = 6 donors), showing increase with substrate stiffness (p < 0.05). b Cell areas of hMSCs following low-intensity CTS (0–4% strain at 1 or 2 Hz for 1 h; n = 4 donors). Areas increased immediately following strain (1 Hz, p = 0.05; 2 Hz, p = 0.0006 and p = 0.002 at 3 h). c Cell areas of hMSCs following high-intensity CTS (2.6–6.2% strain at 5 Hz for 1 h; n = 4 donors), showing decreased 24 h post strain (p = 0.05). d Relative nuclear areas of hMSCs cultured on static substrates (collagen-I coated PA hydrogels; 2–50 kPa; n = 6 donors). Nuclear areas increased with substrate stiffness (p < 0.05). e Nuclear areas of hMSCs after low-intensity CTS (0–4% strain at 1 or 2 Hz for 1 h; n = 4 donors). f Nuclear areas of hMSCs cultured following high-intensity CTS (2.6–6.2% strain at 5 Hz for 1 h; n = 4 donors). Nuclear areas decreased immediately following strain treatment (p = 0.003). g Nuclear to cytoplasmic area ratio of hMSCs following CTS (1 h; 0–4% strain at 1 or 2 Hz or 2.6–6.2% strain at 5 Hz; n = 4 donors). Area ratios decreased immediately following strain treatment for all CTS frequencies (1 Hz, p = 0.01; 2 Hz, p < 0.0001; 5 Hz, p = 0.01). Only the 5 Hz treatment group showed an increased ratio at 24 h (5 Hz, p = 0.04). All CTS experiments normalized to unstrained controls; data displayed as mean ± s.e.m.; p-values determined from ANOVA. See Supplementary Fig. 1a–c, f for example cell images and donor-to-donor variability; Supplementary Table 1 for sample sizes. h In summary, cell and nuclear areas appeared coupled on increasingly stiff substrates. Low-intensity CTS increased cell area, but did not change nuclear area; high-intensity CTS caused nuclear area to decrease independently of cell area