Fig. 2

Human cardiac LECs are associated with coronary arterial and epicardial cells that express VEGFC (A) Dot plots showing PROX1, FLT4, LYVE1, MRC1, PDPN, NRP2, and NRP1. All these markers, except for NRP1, co-exist in cluster 14 and are expressed in a mixed pattern in the other clusters. (B) Violin plots showing the distribution of PROX1, FLT4, LYVE1, MRC1, and PDPN in the dataset. (C) GO analyses of molecular function of cluster 14 identify VEGF activity and hyaluronic acid binding as main functions. (D) Immunostaining of PROX1 on the dorsal side of human heart ventricle showing tubular structure formation. (E) Whole-mount dorsal view of 10PCW human fetal hearts immunostained for PROX1 (green) and KDR (red) (below). Arrowheads indicate a region where PROX1+ cells are enriched in KDR expression (n = 3). (E′) The zoomed-in area (the dashed box) in (E). The dashed box indicates KDR expression in the CA (right) and high expression of KDR in LECs (left). (F) Immunohistochemistry for N1ICD (red), PROX1 (green), and ACTA2 (white) on 11PCW human heart transverse section shows PROX1+ cells surrounding the CA (white arrowheads) (n = 3). (G) Whole-mount dorsal view of 10PCW human fetal hearts immunostained for VEGFC (red) and ACTA2 (blue). (G′) The magnified view indicates a region (dashed box in G) where VEGFC is detected (white arrowheads), in close proximity to CA (n = 2). (H) Pseudobulk of the genome accessibility for the VEGFC locus for selected clusters (from top to bottom: cluster 0 for CM, clusters 1, 4, and 13 for SMC, cluster 10 for vein, cluster 14 for LECs, and cluster 17 for artery) from the snMultiome and the correlation coefficient between the accessibility of the peak and RNA expression of the gene showing positive correlation between the potential enhancers (white arrowheads) and the promoter of the VEGFC gene in artery. (I) FeaturePlots illustrating RNA expression levels from the WNN analysis of VEGFC (left) and CXCR4 (right) are high in arterial endothelium. Scale bars, 100 μm.