Coronary vessel assembly involves patterned endocardial sprouting and tip-cell-to artery specification

Abstract

The coronary vasculature comprises superficial coronary veins and deeper coronary arteries and capillaries that critically support the high metabolic activity of the beating heart. Understanding how different endothelial progenitor sources jointly shape and remodel the coronary vasculature into its adult pattern has recently attracted great research interest, and spurred much debate. Here, using lineage tracing tools in combination with three-dimensional imaging, live-imaging in explants and single-cell transcriptional profiling, we demonstrate that sprouting angiogenesis drives both sinus venosus and endocardial contribution to coronary plexus. Whereas previous studies limit endocardial contribution to coronary vessels to the interventricular septum and ventral aspect of the heart, our study demonstrates extensive endocardial sprouting angiogenesis in the free ventricular walls. In particular, we identify a distinct subpopulation of endocardial cells that express future coronary markers and reside in both the embryonic and adult ventricular wall endocardium. Most importantly, we provide evidence for sprouting angiogenesis from both endocardium and subepicardial plexus towards the inner myocardial wall to determine pre-arterial specification. Additionally, sprouting from the endocardium leads to the establishment of perfused connections to the advancing coronary plexus, also followed by transitioning to the pre-arterial cell state. Distinct molecular profiles characterize sprouting populations in the intramyocardial and subepicardial layers that shape the prospective coronary arteries and veins, respectively. Harnessing the endocardial progenitors and targeting the distinct sprouting populations may in the future serve to tailor cardiac vascular adaptations for therapeutic purposes.

Mechanosensitive PIEZO2 channels shape coronary artery development

“…2a). Additionally, single cell RNA datasets (scRNA) from FACS-sorted cardiac endothelial fractions (CD31+ alias PECAM1+/CD45alias PTPRC -) from four different stages: E12.5, E15.5, postnatal day (P)2 and adult (8 weeks old) were used to monitor ongoing Piezo2 expression 48 . Unsupervised clustering was performed using the Uniform Manifold Approximation and Projection (UMAP) method and cell type clusters were classified based on the expression profiles of the top differentially expressed genes 48 (Fig.…”

“…At E12.5 Piezo2 expression was mainly found in the coronary endothelial cells (CoEC). At E15.5 Piezo2 expression was mainly found in two sub-clusters of coronary endothelial cells designated CoEC_I and CoEC_II, which are capillary cells 48 . At postnatal day 2, Piezo2 expression was still present in the same capillary cell types (CoEC_I and CoEC_II) and in the proliferating cell cluster however, in adult hearts, no significant Piezo2 expression was found in any of the cell types analyzed (Fig.…”

“…Gene count matrices from single-cell sequencing from E12, E15, P2 and 8-weeks-old C57Bl/6J animals were generated by Cano et al 48 , and deposited on the Gene Expression Omnibus repository with accession number GSE223266. The sequence data were mapped to the mouse reference genome (mm10 pre-build references v 2.1.0).…”

“…The sequence data were mapped to the mouse reference genome (mm10 pre-build references v 2.1.0). Custom code was generated using R to analyze the data and to generate plots as described in Cano et al 48 .…”