Identification of endocardial fibroblasts.a, Clone-independent transitions (for example 50%, top) showed similar transition rates across clones, leading to a strong correlation between yellow and blue cell types. Clone-dependent transition rates (for example 30% and 80%, bottom) caused yellow and blue cell types to lose correlation, requiring a different approach for lineage analysis. b, Conditional cell type probabilities could pinpoint lineage origins despite clone-dependent transitions. c, Conditional probabilities reproduced the epicardial lineage origin of col12a1a fibroblasts. d, Endocardial cell types were present in more than 80% of all nodes containing nppc, spock3 and valve fibroblasts. Asterisks in c and d indicate the queried cell type. e, Cre–lox lineage tracing confirmed the endocardial origin of nppc-expressing fibroblasts in cryoinjured hearts at 7 d.p.i. Sections were stained for GFP (green) and nppc (magenta). Arrowheads point to nppc and EGFP colocalization. Asterisks point to nppc-positive delaminating cells. Scale bar, 100 μm. f, Trajectory analysis revealed a potential transition from endocardial cells to nppc fibroblasts. g, Venn diagram of upregulated genes in nppc fibroblasts compared with activated endocardium (7 d.p.i.). Source data
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