Neuropilin-1 enriched mesenchymal stem cell derived-exosomes alleviate vascular hyperpermeability in acute lung...

Aim: Mesenchymal stem cells (MSCs) have shown therapeutic potential in acute lung injury (ALI); however, the key functional components and their roles in regulating pulmonary vascular endothelial permeability remain unclear. This study aimed to identify functional proteins within MSC-derived exosomes (MSC-Exo) and elucidate their roles in regulating pulmonary vascular endothelial permeability to enhance MSC-Exo-based therapy. Methods: Proteomic analysis identified neuropilin-1 (NRP1) as a candidate functional protein in MSC-Exo. Functional assays, including annexin V flow cytometry for apoptosis, colony formation assays for proliferation, and Transwell migration and wound healing assays, were performed to assess these processes in injured pulmonary microvascular endothelial cells (PMVECs). Immunofluorescence and Western blotting were used to evaluate NRP1 localization, p130Cas phosphorylation and matrix metalloproteinases 1 (MMP1)/9 expression. In ALI rat models, histopathology, Evans blue extravasation, and immunohistochemistry were used to assess lung injury and vascular permeability. Results: NRP1-enriched MSC-Exo reduced apoptosis, enhanced colony formation, and promoted migration in PMVECs. Mechanistically, NRP1 modulated the Bcl-2/Bax ratio, inhibited caspase 3/9 activation, and promoted p130Cas phosphorylation with increased MMP1/9 expression. NRP1 also colocalized with PDGFR-α, suggesting a potential role in PDGF-BB signaling. In vivo, NRP1-overexpressing exosome showed superior efficacy in reducing pulmonary edema, vascular leakage, and restoring tight junction proteins, whereas NRP1 depletion impaired these effects. Conclusion: NRP1 in MSC-Exo enhances endothelial repair by promoting proliferation and migration while inhibiting apoptosis. In vivo, NRP1-enriched MSC-Exo improve vascular barrier function and attenuate lung injury, supporting their therapeutic potential in ALI.