Poster: 297KRT7-lineage airway glandular ductal stem cells drive regeneration and CFTR function

Z. Hu; L. Yang; Y. Ma; Y. Yi; C. Wang; Z. Yan; X. Sun; X. Liu; J. Engelhardt

doi:10.1016/j.jcf.2026.07.328

Airway submucosal glands (SMGs) are a major source of mucus and play a critical role in maintaining airway surface hydration and host defense. In cystic fibrosis (CF), impaired CFTR-dependent ion transport leads to defective mucus clearance and chronic airway obstruction. Emerging evidence suggests that a subpopulation of glandular duct epithelial cells has been identified as glandular duct stem cells (GDSCs), which function as progenitors and contribute to epithelial repair following airway injury. Keratin 7 (KRT7) is expressed in proliferative epithelial populations and is highly enriched in SMG ducts of adult ferret airways, suggesting that KRT7 may serve as a marker of progenitor cells involved in airway epithelial regeneration in CF. However, the precise identity and functional capacity of KRT7-expressing cells in SMGs—particularly their ability to regenerate CFTR-functional epithelium—remain incompletely understood. Immunofluorescence was performed to characterize KRT7 expression and its co-localization with known ductal progenitor markers in human and ferret airway tissues. A KRT7-CreERT2::ROSA26mTmG transgenic ferret model was generated to enable in vivo lineage tracing of KRT7-positive cells following tamoxifen induction. Airway epithelial injury was induced by intratracheal polidocanol administration to assess regenerative potential. SMG-derived EGFP⁺ KRT7-lineage cells were isolated and cultured as organoids or differentiated under air–liquid interface (ALI) conditions for in vitro validation. CFTR function was evaluated using the forskolin-induced swelling (FIS) assay in organoids to assess proliferation and differentiation capacity, and by Ussing chamber analysis in ALI cultures. KRT7 expression was highly conserved across species and predominantly localized to SMG ductal compartments in adult human and ferret airways. A subset of KRT7⁺ cells co-expressed established ductal progenitor-associated markers, including KRT19 and CD166, supporting their identity as GDSCs in adult ferret airways. In vivo lineage tracing demonstrated that KRT7-expressing cells contribute to SMG morphogenesis and play a critical role in epithelial regeneration following airway injury, with labeled progeny detected in the regenerated surface airway epithelium. In organoid cultures, GFP⁺ KRT7-lineage cells consistently exhibited robust proliferative capacity and multilineage differentiation potential, giving rise to epithelial cell types characteristic of mucociliary proximal airway epithelium. Importantly, organoids derived from KRT7-lineage cells displayed CFTR-dependent functional responses, as demonstrated by the forskolin-induced swelling assay. This study identifies a subpopulation of ductal epithelial cells in adult ferret SMGs that highly express KRT7 and likely represent GDSCs actively involved in airway epithelial regeneration. These cells can generate CFTR-functional epithelium, highlighting their potential as a cellular source and therapeutic target for regenerative and gene-based strategies aimed at restoring epithelial function in cystic fibrosis and other mucus-obstructive airway diseases.

Poster: 297KRT7-lineage airway glandular ductal stem cells drive regeneration and CFTR function

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