Fig. 5.

Coculture experiment showing that hPSC-derived ventricular cardiomyocytes electrically coupled with surrounding NRVMs. a Representative bright field phase contrast microscopic images (BF) and immunofluorescence staining of NRVM cultures (left panels) and NN-co-cultures, containing NRVMs and G418 selected MYL2^Neo/w-CMs (right panels) in a 3:1 ratio. Cells were stained for cardiac troponin T (cTnT), human nuclear antigen (HNA), gap-junction protein connexin 43 (CX43), and DAPI. G418 selected MYL2^Neo/w-CM nuclei were distinguished from rat nuclei by their positive staining for HNA. Scale bars, 50 μm. b Typical rhythmic spontaneous field potential recordings in NRVM cultures, NN-co-cultures, and NE-co-cultures (NRVMs and EGFP-positive MYL2^EGFP/w-CMs). Quantification of (c) the beating frequency and (d) the percentage of irregular beats. NRVM neonatal rat ventricular myocyte, NN-co-culture MYL2^Neo/w cardiomyocyte, NE-co-culture MYL2^EGFP/w cardiomyocyte, ns not significant