Fig. 5

a, b Cell trajectories suggested by pseudotime analysis with Monocle 3. Shown on a UMAP, the starting point of each trajectory was labeled with a number. The pseudotime is shown as a heatmap in a. Red arrows and letters highlight different branches in b. Clusters are labeled in the same number and color as in Fig. 2c. c Schematic of transgenic lines and experimental design to define the origin of aEPCs. 4HT was used at 10 μM. d Section images of 3 dpa hearts carrying the tcf21:Switch; tcf21:CreER^t2; col12a1b^EGFP reporters. 4HT treatment was performed as indicated in c. mCherry and EGFP are shown in magenta and green, respectively in the merged image. Single-channel images are shown in grayscale. Arrows indicate representative EGFP⁺mCherry⁺ cells. White dashed lines indicate the injury sites. Scale bar, 100 μm. e fn1a expression shown on the pseudotime UMAP. The mural cell trajectories are circled with red dashed lines. f Whole-mount images of the ventricular surface showing expression of pdgfrb:EGFP (green) and tcf21:H2R (magenta) in transgenic lines at 7 dpa. The framed regions are enlarged to show details on the right, with single-channel images shown in grayscale. Arrows indicate representative EGFP⁺mCherry⁺ cells. Scale bar, 100 μm. g Schematic of transgenic lines and experimental design to define the fate of aEPCs. 4HT was used at 5 μM. h Whole-mount images of the ventricular surface from hearts carrying the ubi:Switch; ptx3a:CreER^t2 reporters. pdgfrb expression is detected by HCR staining (green). mCherry is shown in magenta, and nuclei were stained with DAPI (blue). Arrows indicate representative pdgfrb⁺mCherry⁺ cells. A maximum projection image is shown on the left. Z-stack images of the numbered frames are shown on the right. Scale bar, 50 μm.