Fig 2: Action potential features in a cardiomyocyte group (atrial cell morphology), b TBX3 group (pacemaker morphology), c SM group (pacemaker morphology), d TBX3 + SM (pacemaker morphology)

Fig 3: Effect of treatments with TBX3, SM, and the combination of both on the protein levels of Cx30 and TBX3 using ELISA analysis. Data showed overexpression of Cx30 and TBX3 protein in groups of treatments with TBX3, SM and TBX3 + SM as compared to cardiomyocytes group (p < 0.001). (TBX3: group that transfected with pcDNA TBX3, SM: group that added with small molecule SB431542, TBX3 + SM: Group that transfected with pcDNA TBX3 and added with with small molecule SB431542)

Fig 4: Morphology of the cells observed using invereted microscope at 40 × magnification. a Cells exhibit the characteristics of MSCs; they are elongated and pointed like fibroblast cells. b Cells gathered at one point and formed a new body, leaving empty places around it. c Cells morphology was also different from in the two previous groups, in this group, many black clusters of cells were found, which are a group of cells that formed black irregular circle body. These clusters of cells were also found in the TBX3 + SM group (e), and were not found in the SM group (d). (TBX3: group that transfected with pcDNA TBX3, SM: group that added with small molecule SB431542, TBX3 + SM: Group that transfected with pcDNA TBX3 and added with small molecule SB431542.)

Fig 5: Result of immunofluorescence. It showed the green glow for the appearance of the TBX3 protein, and red glow for the appearance of Cx30 protein. Expression of TBX3 and Cx30 proteins showed in TBX3, SM, and TBX3 + SM group. The AD-MSCs and cardiomyocyte group did not show a positive glow. (TBX3: group that transfected with pcDNA TBX3, SM: group that added with small molecule SB431542, TBX3 + SM: Group that transfected with pcDNA TBX3 and added with with small molecule SB431542.)