A COUP-TFII human embryonic stem cell reporter line to identify and purify atrial cardiomyocytes

Here, we targeted mCherry to the COUP-TFII genomic locus in NKX2.5eGFP/+ hPSCs. Upon differentiation to atrial and ventricular cardiomyocytes (CMs) this dual atrial COUP-TFIImCherry/+-NKX2.5eGFP/+ reporter line allowed identification and selection of GFP+ (G+)/mCherry+ (M+) CMs following cardiac differentiation. These cells exhibited transcriptional and functional properties of atrial CMs, whereas G+/M- CMs displayed ventricular characteristics. Via CRISPR/Cas9-mediated knockout, we demonstrated that COUP-TFII is not required atrial specification in hPSCs. In total we analyzed 12 samples. 5 G+/M+ hPSC-derived atrial CMs plus 5 G+/M- ventricular samples (sample 1-10) and 2 replicates of G-/M+ non-CMs (sample 11-12). Samples with different COUP-TFII genotype were analyzed: Wildtype COUP-TFII (sample 5 and 6), heterozygotes (samples 7-12) and complete knockout (samples 1-4). Samples 1 and 2 or 3 and 4 originate from two independent hPSC lines. Samples 7 and 10, 8 and 11, as well as 11 and 12 are replicates.