Figure 3. Aging MSC-EVs failed to alleviate LPS-induced lung injury. Mice were divided into 4 groups: control, LPS, LPS + young MSC-EVs (100 μg), LPS + aging MSCs-EVs (100 μg). MSC-EVs were administered intravenously 30 min after intratracheal LPS treatment. (A) Lung tissue was harvested at 48 h after LPS treatment, stained with H&E, and visualized at x200 magnification (scale bar: 50 μm). (B and C) Protein level, total cell count, and neutrophil count in the BAL were examined at 48 h after LPS treatment to evaluate inflammatory response. Data are presented as mean ± SEM, n = 8. *p < 0.05, **p < 0.01, *** p < 0.001. (D) Cytokine levels (IL-1β and IL-10) in the BAL at 48 h after LPS treatment were assayed via ELISA. Data are presented as mean ± SEM, n = 4-5. *p < 0.05, **p < 0.01, *** p < 0.001.