Fig. 1. Identification of cardiac fibroblast subpopulation F-Act.

a UMAP clustering of 13441 cardiac interstitial cells (left) and fibroblasts (right) isolated from C57BL/6 J wild-type (WT) mice at 7 and 14 days post-sham and post-MI surgery. Each dot represents a single cell. The expression of known marker genes annotated cell type. b UMAP and violin plots depict Postn, Acta2, and Comp expression in fibroblasts. c Triple IF staining for periostin (green) and αSMA (red) in the peri-infarct zone of the hearts of C57BL/6 J WT mice 0, 7, 14, 21, and 28 days after MI surgery. Nuclei were stained blue. Scale bar = 100 μm. Quantification of the number of periostin⁺αSMA⁺ F-Myo and periostin⁺αSMA^- F-Act in each high-power field (HPF). n = 5 mice at each time point after MI. d Flow cytometry of fibroblasts isolated from hearts of C57BL/6 J WT and Pdgfra-CRE:tdTomato mice. Total cardiac fibroblasts were lineage traced by pdgfrα. F-Myo and F-Act were marked with antibodies against periostin-AF488 and αSMA-AF647. Quantification of the pdgfrα⁺ fibroblast ratio in live cells, periostin⁺ fibroblasts ratio in pdgfrα⁺ fibroblasts, periostin⁺ αSMA⁺ F-Myo ratio in pdgfrα⁺ fibroblasts, and periostin⁺ αSMA^- F-Act ratio in pdgfrα⁺ fibroblasts. n = 5 mice at each time point after MI. e Spatial distribution of the F-Act and F-Myo subpopulation in mouse heart sections from sham and 10 days post-MI conditions, visualized through the integration of scRNA-seq and stereo-seq methodologies. c, d Data are the mean ± SEM and p-values are displayed in the bar charts, one-way ANOVA followed by Tukey’s multiple comparisons tests. Source data are provided as a Source Data file.