Figure 1.

Soft Matrices Promote Cardiac Reprogramming

(A) Solid tissues exhibit a range of stiffness, as measured by the elastic modulus. Conventional PS dishes and dishes with Matrigel-based hydrogels of different elasticities (1–126 kPa) were used for cardiac reprogramming. αMHC-GFP mouse fibroblasts were transduced with pMX-GHMT to generate induced cardiomyocytes (iCMs).

(B) Fibroblasts were seeded on PS and hydrogels of various elasticities and transduced with GHMT. The effect of substrate elasticity on cardiac reprogramming was analyzed by counting spontaneously beating cells after 4 weeks; n = 3 independent triplicate experiments.

(C) Time course of cardiac reprogramming on 126 kPa and 8 kPa hydrogel culture; n = 3 independent triplicate experiments.

(D and E) FACS analysis of cTnT expression after 1 week. Fibroblasts were transduced with GHMT and cultured on PS or 126 kPa and 8 kPa substrates. (E) Quantitative data; n = 3 independent triplicate experiments.

(F–H) Immunocytochemistry of αMHC-GFP, cTnT, and DAPI after 4 weeks. Cells were treated as described in (D). High-magnification views, as insets, show sarcomeric organization.

(G and H) Quantitative data; n = 3 independent triplicate experiments.

All data are presented as the means ± SD. ^∗p < 0.05 versus the relevant control. NS, not significant; ND, not detected; CTRL, control. Scale bars represent 100 μm.