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. Author manuscript; available in PMC: 2017 Nov 15.
Published in final edited form as: Circulation. 2016 Oct 13;134(20):1557–1567. doi: 10.1161/CIRCULATIONAHA.114.014998

Figure 2.

Figure 2

Characterization of cell alignment and matrix remodeling. A, Constructs exposed to stress conditioning demonstrated significantly increased cell alignment compared to constructs without stress conditioning. Electrical pacing along with stress conditioning did not further promote the cell alignment. n=7 for NS, n=7 for SS, and n=4 for SE. B, The passive stiffness of constructs was measured by stretching constructs incrementally to 125% of slack length. Tensile stiffness was estimated from the slope of passive stress-strain relationship. The tensile stiffness of cell-free collagen matrix is 0.079 ± 0.041 kPa. Addition of cells increased the stiffness ~7-fold, stress conditioning by a further ~20-fold, and electrical pacing by an additional ~2-fold (NS: 0.47±0.22 kPa; SS: 11.13±1.17 kPa; SE: 21.51±4.02 kPa,). n=6 for NS, n=7 for SS, and n=9 for SE. C, Electrical pacing promotes ECM remodeling by increasing the cell volume fraction within the constructs (NS vs SS, p=0.0728, NS vs SE, p=0.0121, SS vs SE, P=0.3)). n=7 for NS, n=7 for SS, and n=4 for SE. D, E, and F, are representative Sirius Red/Fast Green stains of NS, SS and SE, respectively.