Structural and functional characterizations of hCiCMs.

a. Immunofluorescence analyses of CM markers, n=3. Scale bars, 50 µm.b. Transmission electron microscopy images of hCiCMs derived from hUCs at day 60, n=3. MF, myofibrils; Z, Z-bands; Mit, mitochondria.c. RT-qPCR analysis of mRNA levels of genes related to pluripotency markers, cardiac structure, ion channels and mitochondrial functions of hCiCMs derived from hUCs on day 60, n=3.d. Representative action potentials (AP) of hCiCMs derived from hUCs on day 60, n=15. Em, membrane potential in millivolts.e. AP parameters of hCiCMs including AP frenquency, AP amplitude (APA), minimum diastolic potential (MDP), AP durations (APDs) at the level of 30% (APD30), AP durations (APDs) at the level of 50% (APD50) and 90% repolarization (APD90) , n=15. Data are means ± SD.f. Calcium flux in hCiCMs derived from hUCs at day 60 of the induction, n=6.g. Measurement of the maximum calcium transient amplitude, maximum upstroke velocities, and maximum decay velocities of calcium transients in hCiCMs derived from hUCs on day 60 of induction (n = 6). Data are presented as means ± SD.