Fig. 1: Molecular and functional assessment of atrial-like hiPSC-CM at 30 days of differentiation.
a K+ channel KCNA5 and KCNJ3 mRNA relative expression in RA vs Std protocols (n = 9 technical replicates from 4 independent differentiations). b The percentage of atrial- vs ventricular-like cardiomyocytes (CM) was evaluated by immunofluorescence for the specific isoform of myosin light chain 2 (MLC2v, ventricular and MLC2a, atrial in red). Cells were counterstained for cardiac troponin T (TnT, in green) cells (n = 4 independent differentiations) scale bars = 200 μm. c Electrical (MEA, cI) and mechanical (MUSCLEMOTION,cII) recordings of RA-treated clusters of CMs compared to Std one. Higher beating rate and shorter FPDc was quantified from MEA (n = 10 and n = 17 clusters of Std and RA respectively, from 6 independent differentiations). Shorter contraction duration in mechanical RA events were analysed in MUSCLEMOTION recordings (n = 7 clusters of Std and RA, from 6 independent differentiations). d Overlapped recordings highlight different kinetic properties of excitation-contraction (EC) coupling in both conditions. Red dashed line showed electromechanical coupling in Std compared to RA cluster (e) Examples of ACh-elicited current recordings and analysis of peak steady-state, in single Std- (black) and RA-treated (red) CMs (n = 10 and n = 21, respectively from 2 independent differentiations). Percentage of ACh-responsive (yes) and not-responsive CMs (no) are quantified using both differentiation protocols. (Std standard protocol, RA retinoic acid, FPDc corrected field potential duration, Contr. ACh acetylcholine, IKACh ACh-activated current). Data shown are mean ± SEM (*p < 0.05 paired t-test RA vs Std).
