Fig 2: PDGF-C enhances VEGF-C production by meningeal fibroblasts and promotes the recovery of meningeal lymphatic function after TBI. (A) Schematic of the signaling network through which other cell types regulate meningeal fibroblasts. (B) Dot plot showing macrophage-fibroblast interactions through ligand-receptor pairs, quantified by ligand-receptor scores. (C) Pdgfc/Pdgfra signaling network from other cells to fibroblasts. (D) Violin plots showing the expression levels of Pdgfc across cell types. (E) Violin plots showing the expression levels of Pdgfc in macrophage subsets. (F) Immunofluorescence staining showed colocalization of PDGF-C with macrophages (CD206). (G) ELISA analysis showing PDGF-C levels after TBI and macrophage depletion (n = 5). (H) Experimental design for TBI and uninjured mice with subdural injection of PDGF-C or vehicle. (I) Representative flow cytometry plots and quantification of CD45⁻CD31⁻VEGF-C⁺ cells from TBI mice following subdural injection of PDGF-C or vehicle (n = 5). (J) Immunofluorescence showing mLVs (LYVE-1) and VEGF-C⁺ cells in the meninges of TBI mice after subdural injection of PDGF-C or vehicle and quantification of LYVE-1 coverage, and VEGF-C⁺ cell abundance in these two groups (n = 4). (K) Representative images and quantification of fluorescent beads accumulation in hot spots (n = 4). (L) Representative images and quantification of fluorescent beads accumulation in dCLNs (n = 6 for TBI + Vehicle, n = 5 for TBI + PDGF-C). (M) Representative flow cytometry plots and quantification of the proportion of VEGF-C⁺ cells in NIH/3T3 fibroblasts treated with different concentrations of PDGF-C in vitro (n = 5). (N) Representative images and quantification of VEGF-C⁺ cells in NIH/3T3 fibroblasts treated with different concentrations of PDGF-C in vitro (n = 9). (O) Timeline of experimental design illustrating the viral delivery and TBI induction. (P) Representative immunofluorescence images and quantification showing the number of VEGF-C⁺ cells and LYVE-1 coverage in meninges isolated from TBI mice following AAV9 treatment (n = 4).