miR-7704-Enriched Stem Cell-Derived Extracellular Vesicles Attenuate Hyperoxia-Induced Apoptosis and Oxidation in Lung Epithelial Cells.

Bronchopulmonary dysplasia (BPD) is a significant complication of hyperoxia in preterm neonates. Extracellular vesicle (EV)-based therapies derived from mesenchymal stem cells (MSCs) show regenerative potential. We investigated the therapeutic efficacy of EVs derived from human umbilical cord mesenchymal stem cells (HUCMSCs), particularly those engineered to overexpress miR-7704 in a hyperoxia-induced BPD cell model. EVs were isolated from GFP- and miR-7704-transfected HUCMSCs. A549 alveolar epithelial cells were exposed to normoxic or hyperoxic conditions and treated with HUCMSC-EV or miR-7704-HUCMSC-EV. EV uptake was confirmed using fluorescence microscopy. Cell proliferation was evaluated, and apoptosis was assessed by means of Western blot analysis of caspase family proteins and apoptosis-related markers. Both HUCMSC-EV and miR-7704-HUCMSC-EV enhanced A549 cell proliferation under hyperoxic stress, with miR-7704-HUCMSC-EV showing greater efficacy. Protein-level analyses revealed hyperoxia-induced increases in cleaved caspase-3, caspase-7, and FasL, along with decreased Bcl-2. Treatment with miR-7704-HUCMSC-EV significantly reversed these effects, whereas HUCMSC-EVs minimally impacted apoptotic protein expression. Bioinformatic analysis predicted that hsa-miR-7704 targeted the 3' UTR of APOPT1. miR-7704-HUCMSC EVs also enhanced the expression of key antioxidant enzymes, including SOD1, SOD2, and HO-1. miR-7704-enriched HUCMSC-derived EV significantly promoted cell survival and mitigated hyperoxia-induced apoptosis and oxidation in a BPD cell model, suggesting their potential therapeutic role in neonatal lung injury.