Abstract
Chronic cigarette smoke (CS) disrupts epithelial homeostasis, fuels persistent inflammation, and impairs alveolar repair-hallmarks of COPD with few disease-modifying options. Extracellular vesicles (EVs) from human umbilical cord mesenchymal stem cells (hUC-MSCs) are emerging as cell-free modulators of regeneration, yet their impact on the CS-injured alveolus and alveolar type-2 (AT2) stem/progenitor programs remains unclear. We used a preclinical model of chronic CS exposure coupled with organoid-guided analyses to test whether hUC-MSC-derived EVs can restore epithelial regeneration while tempering injury-associated inflammation and remodeling. Following CS injury, animals received vehicle, hUC-MSCs, or purified hUC-MSC EVs; lungs were evaluated histologically (airway/parenchymal inflammation, emphysema-like change), by Masson's trichrome (collagen deposition), and functionally using ex vivo epithelial organoids (organoid number/size, architecture, and AT2/AT1 marker balance). Transcriptomic profiling of organoid-derived RNA mapped pathway-level changes. CS induced robust immune-cell infiltration, increased collagen, and abnormal organoid phenotypes consistent with dysregulated progenitor activity. Post-injury EV treatment reduced inflammatory infiltrates and collagen, normalized organoid number and size, and restored AT2/AT1 lineage balance toward naïve patterns. At the molecular level, EVs dampened injury-upregulated circuits (including IL-17, PI3K-AKT-mTOR, MAPK, oxidative-stress and matrix-remodeling signatures) and enriched pathways associated with epithelial homeostasis and barrier integrity. Together, these data position hUC-MSC EVs as precision modulators of the injured alveolar niche that rebalance inflammation and re-engage endogenous regenerative programs. The organoid-guided, multi-scale readouts provide mechanistic insight and a translational rationale for EV-based regenerative therapeutics in smoke-induced lung injury and, by extension, COPD.