A Human Embryonic Stem Cell Reporter Line for Studying Cardiomyocyte Biology

Human embryonic stem cells (hESCs) can be used to generate scalable numbers of cardiomyocytes for studying cardiac biology, disease modeling, drug screens, and potentially for regenerative therapies. Directed differentiation protocols for cardiomyocytes using hESCs are well established, but methods to isolate highly pure population of cardiomyocytes are limited. Reporter cell lines can be valuable for purification and visualization of cells for such applications. We used CRISPR/Cas9 in hESCs to place an mCherry reporter gene into the MYH6 locus, facilitating a simple method to purify cardiomyocytes. MYH6:mCherry positive cells express atrial and ventricular markers and display a range of cardiomyocyte action potential morphologies. At 20 days of differentiation, MYH6:mCherry+ cells show features characteristic of human cardiomyocytes and can be used successfully to monitor drug-induced cardiotoxicity and oleic acid-induced cardiomyocyte arrhythmia. The MYH6:mCherry hESC reporter line should serve as a useful tool for disease modeling and drug development relevant to cardiomyocyte biology. Total RNA was isolated using the Qiagen RNeasy mini kit according to manufacturer’s instructions. The quality of RNA samples was examined by Agilent bioanalyzer (Agilent). cDNA libraries were generated using TruSeq RNA Sample Preparation kits (Illumina). Each library was sequenced using single-end reads in HiSeq4000 (Illumina). Gene expression levels were analyzed with TopHat and Cufflinks by the Weill Cornell Genomic Core facility.