Mesenchymal Stromal Cell-Derived Extracellular Vesicles Mitigate Inflammation-Associated Epithelial Senescence in ARDS Through Mitochondrial Transfer

Cellular senescence is a state of cell cycle arrest associated with a pro-inflammatory secretory phenotype and mitochondrial dysfunction. In Acute Respiratory Distress Syndrome (ARDS), signaling cascades may induce premature senescence, but its role in pathophysiology remains unclear. The aim of our work was to determine if the ARDS inflammatory environment induces premature epithelial senescence and whether mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) can mitigate this process via mitochondrial transfer. To test this hypothesis, human small airway epithelial cells (SAECs) and precision-cut lung slices (PCLSs) were co-cultured with EVs (or mitochondria-depleted EVs) in the presence of LPS or ARDS plasma. Senescence markers (β-galactosidase, p21, 53bp1) and senescence-associated secretory phenotype (SASP) were assessed by immunofluorescence and ELISA. Mitochondrial respiration and glycolysis were measured using Seahorse assays, while epithelial barrier function was evaluated via xCELLigence. LPS and ARDS plasma induced p21, 53bp1, and β-galactosidase expression in SAECs and PCLSs, promoting a metabolic shift to glycolysis and SASP secretion (IL-1β, TNF-α, IL-8, IL-6). SASP persisted post-stimulus, and senescent SAECs transferred senescence to naïve cells. EVs restored mitochondrial respiration, reduced senescence markers, and improved SAEC barrier integrity, while mitochondria-depleted EVs were ineffective. The ARDS inflammatory environment induces premature epithelial senescence. MSC-derived EVs alleviate senescence and restore lung epithelial barrier function via mitochondrial transfer.