Using CK-7 Cre in combination with mTmG-2a-Puro cells enables cardiomyocyte purification.

<p>(<b>A</b>) Flow cytometry for cardiac troponin T (cTnT) indicating the percentage of cardiomyocytes present after mTmG-2a-Puro hESCs were subjected to a directed cardiac differentiation protocol. (<b>B</b>) Mean percentage of cTnT⁺ cells resulting from three independent differentiation runs. (<b>C</b>) The percentage of cells that immunostained for eGFP, tdTomato, and/or the cardiomyocyte marker α-actinin was determined before and after puromycin selection (n = 230–600 cells per condition for three independent differentiation runs). (<b>D</b>) Magnification at 10x (i and ii) and 60x (iii and iv) showing fluorescent photomicrographs of cardiac differentiated mTmG-2a-Puro cells before (i and iii) and after (ii and iv) puromycin selection. Scale bars are 200 µm in (i and ii) and 50 µm in (iii and iv). Error bars represent one standard error of the mean.