Fig. 6.

Maturation medium leads to further maturation of the MLC-2v-positive ventricular-like cardiomyocytes. a Basal medium (control) and maturation medium (MM)-treated MYL2^Neo/w-hiPSC-derived cardiomyocytes stained with α-actinin (green) and DAPI (blue). Scale bars, 50 μm. Right panels show enlarged views of the boxed areas in the left merged images, which show detailed α-actinin (green) staining patterns. Compared to MYL2^Neo/w-hiPSC-derived cardiomyocytes cultured in basal medium (control), MM-treated MYL2^Neo/w-hiPSC-derived cardiomyocytes show significant changes in cell size (b), sarcomere length (c), and number of multinuclear cells (d). n > 100 per condition. e Quantitative PCR showing higher transcriptional expression of the functional and mature genes in MM-treated MYL2^Neo/w-CMs compared with control. Gene expressions shown normalized to GAPDH. Data shown as the mean ± SEM of three independent experiments. *P < 0.05; **P < 0.01; ***P <0.001 by two-tailed Student’s t test. f MYL2^Neo/w-CMs show larger calcium transient amplitudes, faster upstroke, and faster decay velocities after culture with MM. n > 45 per condition