Quantifying Cardiomyocyte Surface Area

Cell size was measured following the method of Jeong et al. (2015) (link) with slight modifications described by Siti et al. (2021) (link). Cells were stained with a primary antibody against α-actinin (1:200 dilution; ab9465, Abcam, Cambridge, MA, United States) followed by an Alexa Fluor 488-conjugated anti-mouse secondary antibody (1:200 dilution; A-11059, Invitrogen, Waltham, MA, United States) and visualized via fluorescence microscopy (Olympus Optical, Tokyo, Japan). A blinded assessor quantified the cardiomyocytes’ surface areas (>60 cells) using ImageJ software (U. S. National Institutes of Health, Bethesda, MD, United States) and compared them to control cells. A minimum of three biological replicates was performed in triplicate (n = 3).