Fig. 3

MSC small extracellular vesicles (sEVs) improved survival and attenuated lung injury in LPS-induced ALI mice

(A) Experimental design for the in vivo study. Mice were intratracheally administered with LPS (10 mg/kg) or Saline. PBS or MSC sEVs (40 µg per mouse in 150 µl of PBS) was injected through the tail vein 6 h after LPS administration. Mice were then sacrificed 48 h to evaluate the therapeutic efficacy or observed until 168 h to evaluate the survival rate

(B) Kaplan-Meier survival curves showed that administration of MSC sEVs significantly improved survival at 168 h in LPS-induced ALI mice (n = 20 mice per group, *P < 0.05, compared between the Sham + sEVs and the LPS + PBS group. # P < 0.05, compared between the LPS + PBS and the LPS + MSC sEVs group

(C) Representative images of MSC sEVs incorporation in lung epithelial cells in lung tissues. Scale bar = 50 μm. n = 6 for each group

(D) Quantitative analysis of the Dil-labeled MSC sEVs in lung tissues of mice. The percentages of lung epithelial cells surrounded with Dil-labeled MSC sEVs in CLP + sEVs mice were significantly higher compared with sham + sEVs mice. n = 6 for each group

Statistical analysis: Results are presented as mean ± SD, ** P < 0.01, unpaired two-tailed Student’s t-test

(E) Sections were stained with hematoxylin and eosin and examined histologically. The representative sections are shown at 200 original magnification, and scale bars are 100 μm

(F) Severity scores of lung injury in the four groups of mice (n = 15). Results are represented as mean ± SD

Statistical analysis: one-way ANOVA with a Tukey-Kramer post hoc test. ** P < 0.01, compared between the Sham group and each treated group (LPS + PBS, Sham + MSC-sEVs, LPS + MSC-sEVs). ## P < 0.01, compared between the LPS + PBS and the treated group (Sham + MSC-sEVs, LPS + MSC-sEVs). && P < 0.01, compared between the Sham + MSC-sEVs and the LPS + MSC-sEVs group