Figure 5. S100A4 is necessary for MPCs to worsen fibrosis in vivo.

(A–I) Immune-compromised mice were administered intratracheal bleomycin (1.25 U/kg) to establish lung fibrosis. Two weeks later, IPF MPCs (1 × 10⁶ cells) were infected with a lentiviral vector containing S100A4 shRNA or scrambled shRNA and injected via tail vein into the mice (n = 5/group). Four weeks after administration of cells, the lungs were harvested. (A) Collagen content in left lungs quantified by Sircol assay. Data are expressed as mean ± SEM. P < 0.03 determined by 2-tailed Student’s t test. (B–I). Serial 4-μm sections of right-lung tissue from mice receiving IPF MPCs treated with scrambled shRNA (B–E; scale bar: 200 μm) and S100A4 shRNA (F–I; scale bar: 100 μm). (B, C, F, and G) Shown are representative H&E and trichrome stains to assess fibrosis and collagen distribution in right-lung tissue. (D and H) IHC was performed using an antibody that recognizes human procollagen to identify human cells and assess collagen synthesis. (E and I) IHC was also performed using an S100A4 antibody to assess distribution of S100A4 expression with human procollagen expression.