Figure 2. FRDA-iPSCs and - cardiomyocytes retain low levels of FXN and are mainly of ventricular phenotype. (A, B) qPCR and (C) dipstick analysis showing low levels of FXN mRNA (A, B) and protein (C) in undifferentiated cells (A) and their cardiac derivatives (B, C). Significance was assessed by comparing FRDA-iPSCs to undifferentiated H9 controls (A) or FRDA-iPSC derived cardiomyocytes to H9 derived cardiomyocyte controls (B, C). One-way ANOVA followed by Bonferroni’s multiple comparison test, ** p<0.01, **** p< 0.0001. (D) qPCR analysis of cardiomyocytes showing significantly higher expression of MYL2 than MYL7 across all cell lines (p<0.05, paired t-test). (A-D) Data are mean ± SEM of combined clones or 3 individual experiments, normalized to ACTB and relative to undifferentiated cells (A, B, D) or normalized to the control line cardiomyocyte (C). (E-G) Representative images of FA6- cardiomyocytes (E), FA8- cardiomyocytes (F) and FA9- cardiomyocytes (G) for MYL2/MLC2v (green), MYL7/MLC2a (red, weak or absent) and counterstained with DAPI (blue).