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Figure 3. Effect of up-regulation of NRP1 level in MSC-Exo on vascular endothelial repair. (A) Western blot analysis confirmed that NRP1 protein levels were significantly increased in plasmid-transfected MSCs compared to controls; (B) Immunofluorescence analysis demonstrated a significant upregulation of NRP1 expression in MSCs transfected with the overexpression plasmid; (C) Annexin V-FITC/PI assay demonstrated that NRP1-enriched MSC-Exo significantly suppressed apoptosis in LPS-injured PMVECs; (D) Wound healing assay demonstrated the pro-migratory effect of NRP1-overexpressing MSC-Exo on injured PMVECs; (E) Transwell migration assay confirms the enhanced pro-migratory effect mediated by NRP1-overexpressing MSC-Exo. Scale bar = 50 μm. All experiments were independently repeated three times. Data are presented as mean ± SD. Statistical analysis for (A and B) was performed using unpaired Student’s t-test, while (C-E) were analyzed using one-way ANOVA followed by Tukey’s multiple comparisons test. ^*P < 0.05; ^**P < 0.01; ^***P < 0.001. NRP1: Neuropilin-1; MSCs: mesenchymal stem cells; MSC-Exo: mesenchymal stem cell-derived exosomes; OE: overexpression; OE-Exo: exosomes derived from NRP1-overexpressing mesenchymal stem cells; Con-Exo: exosomes derived from control mesenchymal stem cells; LPS: lipopolysaccharide; PMVECs: pulmonary microvascular endothelial cells; FITC: fluorescein isothiocyanate; PI: propidium iodide; DAPI: 4’,6-diamidino-2-phenylindole; NC: normal control; SD: standard deviation; ANOVA: analysis of variance.