Pulmonary artery smooth muscle cells (PASMCs) and pericytes are NG2+ mural cells that provide structural support to pulmonary arteries and capillaries. In pulmonary arterial hypertension (PAH), both mural cell types contribute to PA muscularization, but whether similar mechanisms are responsible for their behavior is unknown. RNA-seq was used to compare the gene profile of pericytes and PASMCs from PAH and healthy lungs. NG2-Cre-ER mice were used to generate NG2-selective reporter mice (NG2tdT) for cell lineage identification and tamoxifen-inducible mice for NG2-selective SDF1 knockout (SDF1NG2-KO). Hierarchical clustering of RNA-seq data demonstrated that the genetic profile of PAH pericytes and PASMCs is highly similar. Cellular lineage staining studies on NG2tdT mice in chronic hypoxia showed that, similar to PAH, tdT+ cells accumulate in muscularized microvessels and demonstrate significant upregulation of SDF1, a chemokine involved in chemotaxis and angiogenesis. Compared with control mice, SDF1NG2-KO mice in chronic hypoxia had reduced muscularization and lower abundance of NG2+ cells around microvessels. SDF1 stimulation in healthy pericytes induced greater contractility and impaired their capacity to establish endothelial-pericyte communications. In contrast, SDF1 knockdown reduced PAH pericyte contractility and improved their capacity to associate with vascular tubes in coculture. SDF1 is upregulated in NG2+ mural cells and is associated with PA muscularization. Targeting SDF1 could help prevent and/or reverse muscularization in PAH.
Keywords: pericytes; pulmonary arterial hypertension; smooth muscle cells; stromal cell–derived factor-1; vascular remodeling.