4.3. Immunofluorescence Staining

iPSC-derived cardiomyocytes were cultured on matrigel-coated 15 µ-Slide 8 well culture plates (Ibidi, Gräfelfing, Germany) for 5 days. Cells were fixed with Formaline Solution 10% (Sigma-Aldrich, St. Louis, MO, USA) and stained with the primary antibodies at 4 °C overnight: anti-troponin T (1:200; cTNT, Sigma Aldrich), anti-GATA-4 (1:50; GATA4, Santa Cruz Biotechnology, Dallas, TX, USA), α-smooth muscle actin (1:250; SMA, Sigma Aldrich) and anti-α-actinin (1:200; α-ACT, Sigma Aldrich). Alexa Fluor dye secondary antibodies were used (1:200). Fluorescence images were acquired using a Zeiss Confocal Fluorescence Microscope.