(A–E) In vitro assessment. (A) Transepithelial electrical resistance (TEER) with decline of barrier integrity following 0.1% polidocanol (PDOC) exposure and recovery following implantation. (B) Using chamber traces of WT and CFG551D FBECs 4 weeks after injury and GFP⁺ cell implantation. (C) Change in short-circuit current (ΔIsc) after forskolin with CFTR functional rescue in transplanted CF cultures (P = 0.0024). (D) Fluorescent microscopy confirms incorporation of GFP⁺ donor cells into epithelium. Scale bars: 50 μm. (E) Micro-optical coherence tomography (μOCT) shows improvement in mucociliary transport in transplanted CF cultures (P = 0.0005). (F–K) Ex vivo tracheal engraftment. (F) FBEC harvest, expansion, and transplant protocol. (G) H&E staining showing intact ciliation in untreated control (left) compared with ciliary loss and basal cell exposure with injury (middle) and evidence of differentiation after transplant (right). Scale bars: 100 μm. (H) Immunofluorescence microscopy showing GFP⁺ cell engraftment (middle and right, top row) 3 weeks after transplant compared with controls (left, top and bottom row). GFP⁺ FBECs differentiate into ciliated (second image, bottom row, yellow arrows, GFP⁺AT⁺), secretory (third image, bottom row, orange arrow, MUC5B only; last image, bottom row, costained with GFP and MUC5B), and basal cells (last image, bottom row, white arrow, KRT5⁺GFP⁺). (I) Isc responses under chloride secretory gradient conditions and (J) summary data (ΔIsc, n = 4) with recovery of CFTR function in engrafted tissue (P = 0.038). (K) μOCT showing improved ciliary beat frequency in transplanted tissue (P = 0.0049). Data presented as mean ± SD. Statistical significance determined using 1-way ANOVA: *P < 0.05; **P ≤ 0.01; ***P ≤ 0.001.