Modeling early human heart development using an iPSC-based 3D bioprinted model of embryonic heart tube

Human heart development is a precisely coordinated process involving dynamic transcriptional and morphological changes. Due to limited access to the developing human heart in utero and lack of accurate experimental models, the cell-microenvironmental interactions underlying human heart development remain elusive. Advances in 3D bioprinting and stem cell technologies have enabled the fabrication of in vitro analogues of cardiac tissues with complex structures, while incorporating cell intrinsic (genetic) and microenvironment factors. Here we present a perfusable 3D bioprinted model of human embryonic heart tube (eHT), composed of distinct layers of myocardium, cardiac jelly, and endocardium. Human induced pluripotent stem cell-derived cardiomyocytes and endothelial cells were cocultured in the engineered eHTs under dynamic flow. This system demonstrated robust cell viability and cardiac function, including full lumen endothelialization, progressive myocardial compaction, and global tissue contraction. A promoting effect of dynamic flow on cardiac maturation and cell lineage commitment was revealed by single-cell RNA sequencing. The established eHT model offers a novel research-enabling platform to study human heart development, various (congenital) heart disease, and therapeutic interventions. Overall design: scRNA-seq: hiPSC-CMs and HUVECs cocultured in 3D bioprinted heart tube models were harvested after (1) 7 days of 3D static coculture and (2) 7 days of 3D static coculture + 5 days perfusion coculture. Cell subpopulations and phenotypical gene expression related to 3D coculture and flow-regulated cardiac development were analyzed in this study.