Fig. 2

Morphological characterization of iPSC-derived cardiomyocytes carrying the DES^E439K mutation. A Schematic overview of the cardiac differentiation protocol from iPSC. After detachment or freezing at day 19, the cardiomyocytes are cultured for 4, 7 or 21 more days and analyzed. B Cardiac troponin T (Green) and Desmin (Red) immunostaining of cardiomyocytes cultured on gelatin micro-patterns (20 µm-wide lines) for 21 days after thawing. Nuclei were counterstained with Hoechst (blue). Note the marked disorganization of the sarcomeres and the accumulation of desmin in the cytoplasm of mutant cardiomyocytes. C, E Cardiomyocyte length-to-width ratio (C), cardiomyocyte volume (D, troponin T staining) and nuclei volume (E, Hoechst staining) were measured on cardiomyocytes after 21 days of culture on gelatin micro-patterns using ImageJ software. Values are given as means ± SEM. ***, p < 0.001. F Schematic representation of the production of a cardiac spheroid model used for electron microscopy analysis. G-I Bright-Field microscopy images of Toluidine blue-stained semithin sections and representative field emission scanning electron microscopy (FE-SEM) images from the full mapping of ultrathin sections of cardiac spheroids. White arrows indicate Z-lines; L, lipid droplets