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Background Fibrosis is a hallmark of heart disease, particularly following myocardial infarction (MI) and in heart failure. We previously identified a key role for extracellular matrix protein (ECM1) in wound healing post-MI but the cellular origin and mechanism of ECM1 remained elusive. Here, we investigate the spatiotemporal cellular origin of ECM1 in healthy and diseased human and mouse hearts, and ECM1 dependent human cardiac fibroblast (HuCFb) signalling mechanisms. Methods ECM1 specific analysis of existing single-cell/-nuclei RNA sequencing data was conducted. ECM1 expression was assessed in non-failing (NF), ischaemic (ICM) and dilated (DCM) failing human heart tissue via immunoblotting (n=8), immunohistochemistry (ICM; n=8, NF; n=4) and mRNA in-situ hybridisation (n=3). HuCFbs were treated with recombinant ECM1 and assessed via phosphoproteomics (n=6), wound healing assay (n=4), MTT assay (n=8), qPCR (n=6). Results ECM1 originates from fibroblasts, macrophages/monocytes (MΦ/Mo), and pericytes/vascular cells in uninjured human and mouse hearts. In mouse hearts post-MI, ECM1 originates predominantly from M1MΦ/Mo at day-3, and myofibroblasts and M2MΦ’s at day-7, and expression correlated with cell-cell communication, collagen organisation, inflammation, adhesion, and migration. Fittingly, ECM1 expression was upregulated in human ICM (p=0.048) and DCM (p=0.027), localised interstitially to fibrotic, inflammatory, and peri-vascular areas. In vitro, ECM1 inhibited HuCFb migration (p=0.044) and CCL2 mRNA expression, and stimulated inflammatory (IL-6, IL-1β), fibrotic (TGF-β1, Col1a2), and non-canonical Wnt5a mRNA expression (p |
