Pericytes and perivascular fibroblasts contribute to central nervous system fibrosis in a region dependent manner

Fibrotic scar tissue formation is conserved throughout the central nervous system in humans and mice, and impairs tissue regeneration and functional recovery. However, the origin of scar-forming stromal fibroblasts is controversial. Here, we show that stromal fibroblasts found after spinal cord injury derive from two populations of perivascular cells that are anatomically and transcriptionally defined as pericytes and perivascular fibroblasts. We identify two distinct perivascular cell populations, which activate and transcriptionally converge on the generation of stromal myofibroblasts after injury. Our results suggest potential targets to improve tissue regeneration and functional recovery after central nervous system injuries. We crossed GLAST-CreERT2;R26R-tdTomato mice to the Pdgfrb-eGFP reporter line, which drives EGFP expression in all PDGFRb+ perivascular cells (pericytes, vSMCs and fibroblasts). We isolated GLAST-expressing perivascular cells from the uninjured spinal cord and 5 days after spinal cord injury by fluorescence activated cell sorting (FACS) based on tdTomato and EGFP expression. To define the molecular identity and compare GLAST-expressing perivascular cells (tdTomato+EGFP+) to other perivascular cells, we also sorted dTomato-EGFP+ cells. Sorted cells were subjected single cell sequencing using the SmartSeq 2 protocol.