Figure 4. ZLN005 treatment increased expression of Connexin 43 (CX43) and improved electrical activity in hESC-CMs. (A) Representative immunostaining images of CX43 (green) in control and ZLN005-treated hESC-CMs. Hoechst 33342 (blue) and α-ACTININ (red) were also co-stained in the same cells. Scale bar, 20 μm. (B) qRT-PCR analysis of CX43 expression (n=6). (C) Representative Western blot and quantification showed up-regulation of CX43 protein expression with ZLN005 treatment (n=6-9). (D) Representative color map of electrical signal propagation from control and ZLN005-treated hESC-CMs. The color map shows that the electrical signal is initiated at the upper right corner (red) and is propagated to the bottom left corner (blue). The black arrows indicate the direction of the instantaneously local electrical propagation. (E, F) Representative field potential tracings recorded from control (black) and ZLN005-treated (red) hESC-CMs, respectively. (G) Bar graph to compare field potential amplitude (FPA) between control and ZLN005-treated hESC-CMs (n=10). (H) Bar graphs to compare beating rate (left) and coefficient of variation (right) between control and ZLN005-treated hESC-CMs (n=10). (I) Bar graphs to compare inter-spike interval (left) and coefficient of variation (right) between control and ZLN005-treated hESC-CMs (n=10).