Single-cell RNA sequencing reveals maturation trajectory in human pluripotent stem cell-derived cardiomyocytes in engineered tissues

Cardiac in vitro models have become increasingly easy and affordable with the optimisation of stem cell-based cardiomyocyte (CM) differentiation. However, the CMs obtained are still far from being as mature as their in vivo counterparts. Here we study the cellular phenotype of human pluripotent stem cell-derived CMs by comparing the single-cell level gene expression profiles among different engineered cardiac tissue configurations: human ventricular cardiac anisotropic sheet, human ventricular cardiac tissue strip, and human ventricular cardiac organoid chamber (hvCOC). As a control, the spontaneously formed 3D cardiac spheroid aggregates (CS) were used. Our results suggest that the level of maturation increases with the level of complexity of the engineered tissues with CS being the least mature and hvCOC the most mature tissue. We show that the contractile components are the first function to mature, followed by electrophysiology and oxidative metabolism. Notably, the cellular structures in the 2D constructs show higher organisation while metabolic maturity preferentially increase in the 3D structures. We conclude that more complex tissue engineering models could offer more physiological and reliable in vitro matured cardiac tissue model for drug screening or disease modelling. Overall design: Single-cell RNA-seq profiling for three types of engineered cardiac tissue configurations: human ventricular cardiac anisotropic sheet (hvCAS), human ventricular cardiac tissue strip (hvCTS) and human ventricular cardiac organoid chamber (hvCOC). The spontaneously formed 3D cardiac spheroid aggregates (CS) were used as a controls.