Abstract Rationale Aberrant repair after tracheal injury often culminates in fibrotic airway stenosis, severely impairing respiratory function, and there are currently no effective curative therapies. Correcting maladaptive repair while restoring normal epithelial regeneration remains a major unmet need. SMG (Submucosal glands) harbor myoepithelial cells with stem-like properties that can migrate to the luminal epithelium and contribute to regeneration. In our preliminary clinical observations, we detected a marked increase of SMG-EVs (SMG-derived extracellular vesicles) in the BALF (bronchoalveolar lavage fluid) of patients with tracheal injury. We therefore hypothesize that SMG-EVs function as key regenerative niche components that regulate myoepithelial cell migration and differentiation, thereby promoting normal repair and correcting aberrant remodeling.AimsThis study aimed to validate the regulatory role of SMG-EVs as key microenvironmental components in epithelial regeneration following tracheal injury. In addition, it sought to identify the critical signaling mediators involved in myoepithelial cell-driven repair. Methods Normal- and aberrant-repair mouse models of tracheal injury were established to simulate epithelial regeneration and fibrotic stenosis, respectively. SMG-EVs were administered intratracheally, and epithelial reconstruction and fibrosis were evaluated by HR26-tdTomato mice was performed to visualize myoepithelial cell migration and differentiation, thereby defining the role of SMG-EVs in myoepithelial-driven regeneration. Results Across both normal- and aberrant-repair models, SMG-EVs markedly promoted epithelial regeneration and luminal reconstruction while reducing fibrosis. scRNA-seq showed significant upregulation of myoepithelial migration pathways with an increased proportion of ciliated lineages after SMG-EV treatment. Proteomics identified enrichment of ITGA4 (integrin α4) within SMG-EVs; ITGA4 pairs with ITGB1 (integrin β1) to form α4β1, which binds FN (fibronectin) and its EDA (extra domain A) on the basement membrane. Functional assays demonstrated that blocking ITGA4 signaling impaired myoepithelial migration and epithelial repair, whereas ITGA4 activation enhanced these effects, indicating that SMG-EVs promote tracheal epithelial regeneration through ITGA4-mediated matrix adhesion. Conclusion This study, for the first time, identifies the pivotal niche-regulatory role of SMG-EVs in tracheal injury repair. SMG-EVs promote myoepithelial cell migration and differentiation through ITGA4-mediated signaling, thereby orchestrating epithelial regeneration. This work uncovers a previously unrecognized endogenous regulatory pathway of epithelial repair, providing new biological insight for the intervention of aberrant repair and the development of functional regenerative therapies for tracheal injury. This abstract is funded by: None
Chen et al. (2026) studied this question.