Fig. 5

Pericyte-derived myofibroblasts produce collagen 1 after bleomycin injury. A Schematic illustration of the experimental setup for the induction of lung fibrosis. PDGFRβ-tdTomato reporter mice were injected with tamoxifen (tam) on 5 consecutive days to induce the expression of the fluorescent dye tdTomato under control of the PDGFRβ promotor (PDGFRβ-tom). 50 days later, mice were either sacrificed (= d0) or treated with bleomycin (bleo) and sacrificed after 21 (= d21). B PDGFRβ-tdTomato⁺ lungs (red) were co-stained with an antibody against col1α1 (green). In healthy lung tissue (d0), PDGFRβ-tdTomato⁺ cells are localized in the alveolar wall indicated by col1a1 staining (b1). In fibrotic lung, co-staining of PDGFRβ-tdTomato and col1α1 (yellow) indicates ECM production by pericyte-derived myofibroblasts of the alveolar wall. Overview is shown in b2, single channels are shown in b4–b7. Fibrotic areas of indicated areas are enlarged in b3. Dotted lines indicate areas filled with intra-alveolar myofibroblasts (note their nuclei in b6 and cellular structure in b7). DAPI was used to stain nuclei (blue). DIC/pol illustrates tissue structure