Single cell RNA sequencing of Hic1 and PDGFRa-labeled cells in the heart

The cardiac stroma contains multipotent mesenchymal progenitors. However, lineage relationships within cardiac stromal cells are poorly defined. Here, we identify heart-resident PDGFRa+ SCA-1+ cells as cardiac Fibro/Adipogenic Progenitors (cFAPs) and show that they respond to ischemic damage by generating SCA-1- fibrogenic cells. Pharmacological blockade of this differentiation step with an anti-fibrotic tyrosine kinase inhibitor decreases post-myocardial infarction (MI) remodeling and leads to improvement in heart function. To understand the heterogeneity of cardiac mesenchymal progenitors in the heart, hearts were digested and cell suspensions of Hic1 CreERT2 tdTomato+, Hic1-citrine+ and PDGFRa H2BGFP+ cells were subjected to single cell RNA sequencing. Hic1 CreERT2 tdTomato+ and PDGFRa H2BGFP+ cells were collected from undamaged mice as well as 7 days after left anterior descending (LAD) coronary artery ligation. Hic1 citrine+ cells were only collected from undamaged mice. For the Hic1 CreERT2 tdTomato samples (for each time point), 3 mice hearts were pooled together in one sample. For the PDGFRa H2BGFP mice 4 mice hearts were hashed with anti-MHC I antibodies and pooled (2 undamaged and 2 7 days after LAD ligation). For the Hic1 citrine, cells from 3 undamaged hearts were hashed and pooled together and sequenced as 1 sample.