To purify cardiomyocytes, a variant of RPMI 1640 without D-glucose (11879, Life Technologies) was used in the medium formula. RPMI without D-glucose was supplemented with 213 µg/mL L-ascorbic acid 2-phosphate (Sigma-Aldrich), 500 µg/mL Oryza sativa-derived recombinant human albumin (Sigma-Aldrich), and 5 mM sodium DL-lactate (L4263, Sigma-Aldrich) and used in place of CDM3 on differentiation days 10–20.