Fig 2: MSC-EVs attenuate pulmonary fibrosis and may cause its resolution.a Schematic design of the treatment of bleomycin-induced pulmonary fibrosis in C57BL/6 mice; Ctrl (DMEM 14 days after bleomycin administration), n = 11; EV_t (MSC extracellular vesicles 14 days after bleomycin administration), n = 9; SF_t (MSC soluble factors 14 days after bleomycin administration), n = 6; n = biologically independent animals per group. b Quantification of dynamic changes in the lung tissue density measured via MRI. c–e Representative image of c hematoxylin–eosin (H&E), d Masson trichrome, and e Picrosirius Red (PSR) staining. Scale bar = 100 µm. f Quantification of pulmonary fibrosis severity using the Ashcroft scale. The assessment was performed by two independent blinded experts. g Quantification of ECM deposition on the PSR staining image. h Quantification of immune cell types in BAL fluid smears. The assessment was performed by two independent blinded experts. i Quantification of the major hematopoietic cell lineages in the BAL fluid via flow cytometry. j Quantification of IL-6 in the BAL fluid using ELISAs. k Percentage of animals with a detected rate of MCP-1 in the BAL fluid using ELISAs. l Representative images of pulmonary tissue immunocytochemical analysis for CD163. Scale bar = 100 µm. m Quantification of CD163-positive cells in pulmonary tissue. n Representative images of pulmonary tissue immunocytochemical analysis for aSMA, FAPa, and CD90. Scale bar = 100 µm. o Quantification of FAPa-positive cells or CD90+ and aSMA+ areas in pulmonary tissue. The green line indicates the median for the intact group.

Fig 3: MSC secretome components do not prevent pulmonary fibrosis development when applied during the acute injury period.a Schematic design of the prevention of bleomycin-induced pulmonary fibrosis in C57BL/6 mice; Ctrl (DMEM 1 day after bleomycin administration), n = 11; EV_p (MSC extracellular vesicles 1 day after bleomycin administration), n = 9; SF_p (MSC soluble factors 1 day after bleomycin administration), n = 6, n = biologically independent animals per group. b Quantification of dynamic changes in the lung tissue density measured via MRI. c–e Representative image of c hematoxylin–eosin (H&E), d Masson trichrome, and e Picrosirius Red (PSR) staining. Scale bar = 100 µm. f Quantification of pulmonary fibrosis severity using the Ashcroft scale. The assessment was conducted by two independent blinded experts. g Quantification of ECM deposition on PSR staining images. h Quantification of immune cell types in BAL smears. The assessment was performed by two independent blinded experts. i Quantification of the major hematopoietic cell lineages in the BAL fluid via flow cytometry. j Quantification of IL-6 in the BAL using ELISAs. k Percentage of animals with a detected rate of MCP-1 in the BAL via ELISAs. l Representative images of pulmonary tissue immunocytochemical analysis for CD163. Scale bar = 100 µm. m Quantification of CD163-positive cells in pulmonary tissue. n Representative images of pulmonary tissue immunocytochemical analysis for CD90 (top panel), aSMA (green), and fibroblast activation protein A (FAPa, red) (bottom panel) expression. Scale bar = 100 µm. o–q Quantification of CD90- (o), aSMA- (p), and FAPa- (q) positive cells measured by average cell area (c, d) or number of cells (e) in the pulmonary tissue sections, n = 4, n = biological independent animals per group. The number of analyzed fields of view per sample = 5–9. The green line indicates the median for the intact group.