Maturation of embryonic stem cell-derived cardiomyocytes by defined physical signals

Despite therapeutic advances, cardiovascular disease remains a leading cause of mortality and morbidity worldwide. Embryonic stem cells (ESCs) may offer significant advances in creating in vitro cardiac tissue models for disease modelling, drug testing and development; however, the induction of ESCs to a more adult-like cardiomyocyte (CM) phenotype still remains challenging. In this study, we employed defined physical signals to induce cardiac differentiation and maturation of mouse and human ESC-derived CMs (ESC-CMs). We demonstrate that combining a cyclic surface strain (5%) with continuous medium flow (1.48 ml per minute) induces differentiation and facilitates ESC-CM maturation. Murine and human ESC-CMs showed an altered morphology, increased cardiac gene and protein expression, and calcium handling properties when exposed to the dynamic culture for either 18 or 20 days. Raman microspectroscopy was employed to detect ESC-CM maturation states by previously identified lipid and protein band intensities in the Raman spectra. Our findings show that physical cues are crucial for the maturation of mouse and human ESC-CMs, and offer exciting new opportunities for bioreactor-based pre-clinical human in vitro models, to study cardiovascular diseases and investigate potential drug candidates.