hUC-MSC down-regulate bleomycin-induced lung inflammation.

<p>Histology of mouse lungs 8 days (<b>A-D</b>), 14 days (<b>E-H</b>) and 21 days (<b>I-L</b>) after endotracheal injection of sterile saline (saline) or bleomycin (bleomycin), the latter also followed by intravenous infusion of hUC-MSC (bleomycin+hUC-MSC) or sterile saline (bleomycin+saline). Lung sections obtained from C57BL/6 mice (n = 8 per group) were stained with H&E. Controls (<b>A,E,I</b>) demonstrated normal lung architecture. 8 days post bleomycin injury, peribronchial and perivascular inflammatory infiltrates were observed (<b>B</b>). Alveolar and interstitial infiltrates progressively increased from day 8 to 21, with progressive distortion of lung architecture and formation of fibrotic foci (<b>F,J</b>). At each time point, bleomycin-induced alterations were significantly attenuated by hUC-MSC treatment (<b>D,H,L</b>), but not by saline (<b>C,G,K</b>). Representative microscopic images (10× magnification) of three independent experiments are shown. (<b>M</b>) The histopathological inflammatory score of lung sections obtained from C57BL/6 mice (n = 8 per group) that received the aforementioned treatments was calculated. Results are mean ± SD (n = 8 per group) and are representative of three independent experiments. * = P < 0.05 compared to bleomycin treated mice.