Fig. 2

hUC MSC secretome treatment reverses altered lung morphology associated with hyperoxia-induced lung injury in the BPD mouse model. a Representative images of lung histology with H&E stain from the five experimental groups, RA (I), BPD (II), BPD + DMEM:F12 (III), BPD + MSC-CM 25 wks (IV), BPD + MSC-CM 30 wks (V). Asterisks depicts the increased alveolar simplification in the BPD and DMEM:F12-injected BPD mice as compared to RA. ×200 magnification, Scale bar: 50 μm. b Representative images of lung histology with H&E stain from the five experimental groups, RA (I), BPD (II), BPD + PBS (III), BPD + MSC-CM EXO 25 wks (IV), BPD + MSC-CM EXO 30 wks (V). Asterisks depict the increased alveolar simplification in the BPD and PBS-injected BPD mice as compared to RA. ×200 magnification, Scale bar: 50 μm. c-g Histogram depicting the mean chord length (c), septal thickness (d), alveolar area (e), number of branches (f), number of junctions (g) in lungs of RA, BPD, DMEM:F12 or PBS-injected, MSC-CM or EXO 25 wks-injected, MSC-CM or EXO 30 wks-injected BPD mice at PN14. All values are expressed as mean ± standard error of the mean (SEM); eight experiments, N = 3–7 mice per group; one-way ANOVA with Tukey’s post hoc correction; *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. BPD bronchopulmonary dysplasia, CM conditioned medium, EXO exosomes, MSC mesenchymal stem cell, PBS phosphate-buffered saline, PN postnatal, RA room air