(509) Evaluating the Therapeutic Benefit of Airway-Basal-Stem-Cell Transplantation to Decreased Lung Inflammation

Introduction: Stem cell therapy represents a promising curative treatment for cystic fibrosis (CF), a monogenic disorder characterized by a chronic, non-resolving inflammatory response in the airway epithelium. Given that this persistent inflammation ultimately leads to respiratory failure, evaluating the therapeutic benefit of airway basal stem cell (ABC) transplantation in the large airway to reduce inflammation is a critical step towards an effective cell therapy.

Methods: Syngeneic tdTomato+ ABC were transplanted in a focal region of the trachea upon local airway mechanically preconditioning, a clinically translatable approach to remove the underlying host epithelium with a brush in wildtype (WT, C57Bl6) or CF-like mice (βENaC-Tg) (N=5/group). At 1-month post-transplantation, tracheal tissue was collected and processed for immunofluorescence analysis to visualize the airway epithelium (KRT5+ basal cells and ACT+ ciliated cells). Lung inflammatory cell response was evaluated by flow cytometry.

Results: At endpoint, histological analysis confirmed robust engraftment of ABC in WT and βENaC-Tg mice, covering up to 60% of the host epithelium. Engrafted ABC reconstituted both basal progenitor pools and differentiated lineages in 100% of samples, revealing endurance of transplanted ABC. Using specific cell surface markers, the frequency of neutrophils showed similar levels among all groups. However, the frequency of lung resident macrophages in ABC-treated βENaC-Tg mice was reduced to 4-fold compared with untreated and mock-treated βENaC-Tg mice (p=0.0017, p=0.0420), dropping to the WT mice level.

Conclusions: These findings demonstrated a potential modulation of local pulmonary immune responses following airway epithelial restoration. Moreover, the impact of ABC treatment on inflammation identifies a broader therapeutic benefit of restoring airway epithelial function.