Fig 1.
HiPSC-CMs and measurement of force by TFM.
A. Representative cell, 30 days post-differentiation on a 9.8 kPa substrate. B. Heat map showing magnitudes of deformation strain of the substrate under the representative cell. C. Heat map showing magnitudes of stress of the representative cell calculated from strain of the substrate. D. Total force of a single cell over time with respect to baseline at the point t = 0 seconds, over four contractions paced at 0.5 Hz, fitted with a smoothed spline curve. E. Total force of a single cell over time, average of four contractions, fitted with a smoothed spline curve. F. Histograms showing distribution of cell geometries.
Fig 2.
Effects of single cell d90 hiPSC-CM morphology on force production.
A. Peak force versus cell area, R2 = 0.21, P<0.03, n = 24. B. Peak force versus long axis (axis of contraction). C. Peak force versus short axis (perpendicular to axis of contraction). D. Peak force versus aspect ratio (long axis/short axis).
Fig 3.
Effects of length of hiPSC differentiation on force production.
Data shown as mean ± SEM. A. Representative hiPSC-CMs from day 14, day 30, and day 90 post-differentiation, and representative NRVM on substrate with modulus 9.8 kPa. B. Total force versus length of differentiation (mean = 0.012 ± 0.001 μN, n = 17; 0.083 ± 0.013 μN, n = 15; 0.103 ± 0.011 μN, n = 24; 0.113 ± 0.016 μN, n = 12). C. Cell area versus length of differentiation (mean = 605.7 ± 47.1 μm2, 702.3 ± 63.2 μm2, 898.2 ± 64.4 μm2, 741.9 ± 61.4 μm2). D. Normalized force versus length of differentiation in culture (mean = 2.12 ± 0.23 mN/mm2 x 10−5, 13.0 ± 2.14 mN/mm2 x 10−5, 11.4 ± 1.4 mN/mm2 x 10−5, 15.3 ± 1.5 mN/mm2 x 10−5).
Fig 4.
Effects of substrate stiffness on d30 hiPSC-CM force production.
Data shown as mean ± SEM. A. Total force versus substrate elastic modulus (mean = 0.236 ± 0.02 μN, n = 21; 0.083 ± 0.01 μN, n = 15; 0.075 ± 0.01 μN, n = 22). B. Area versus substrate elastic modulus (mean = 754.9 ± 31.5 μm2, 702.3 ± 63.2 μm2, 851.6 ± 43.7 μm2). C. Normalized force versus substrate elastic modulus (mean = 32.4 ± 3.5 mN/mm2 x 10−5, 13.0 ± 2.1 mN/mm2 x 10−5, 9.1 ± 1.0 mN/mm2 x 10−5). D. Strain energy versus substrate elastic modulus (mean = 29.7 ± 4.3 fJ, 5.5 ± 1.7 fJ, 3.1 ± 0.6 fJ).
Fig 5.
Effects of calcium concentration in growth media on d30 hiPSC-CM force production on a substrate with modulus 9.8 kPa.
Data shown as mean ± SEM. A. Total force versus calcium concentration (mean = 0.083 ± 0.013 μN, n = 15; 0.147 ± 0.02 μN, n = 14). B. Cell area versus calcium concentration (mean = 702.3 ± 63.2 μm2, 1130.3 ± 86.2 μm2). C. Normalized force versus calcium concentration (mean = 13.0 ± 2.14 mN/mm2 x 10−5, 14.0 ± 2.0 mN/mm2 x 10−5). D. Rcan1.4 mRNA fold change (low Ca2+ group mean = 1.00 ± 0.29, n = 8; physiological Ca2+ mean, 1.74 ± 0.29, n = 7)(P = 0.02).