Fig. 7

Effect of MSC-EV administration on microscopic lung lesions in pigs infected with SwIV. Eight-week-old pigs were mock infected or infected with swine/MN/08; H1N1 (SwIV). After 12 h, pigs were administered with Dulbecco’s modified Eagle’s medium (DMEM) or MSC extracellular vesicles (EVs). Three days after EV administration, pigs were euthanized and microscopic lung lesions and levels of total protein in bronchoalveolar lavage (BAL) were examined. a Control uninfected lung, showing normal alveolar walls, clear air space, and absence of exudation into the alveolar space. b SwIV induced exudative interstitial pneumonia characterized by thickened alveolar walls, collapsed alveolar spaces, and infiltration of inflammatory cells, whereas c lungs of pigs inoculated with MSC-EVs 12 h after SwIV infection show mild infiltration of inflammatory cells. Hematoxylin and eosin stain. Magnification × 200. d,e Histopathological scores. Lung tissue slides were examined for bronchiolar epithelial changes, peribronchiolar inflammation, and interstitial pneumonia, and lesions were scored from 0–3 (d). Values in each bar indicate mean microscopic lung lesions of three pigs ± SD. e MSC-EV administration decreased the levels of total protein in the BAL of SwIV + EV administered pigs as compared with SwIV + DMEM inoculated pigs. Data are expressed as mean levels of total protein in BAL of three pigs ± SD