TGFB1 and chronic obstructive pulmonary disease: The present study was therefore designed to directly assess bronchial epithelial cell differentiation both in lung tissue and bronchial epithelial cultures differentiated upon ALI, to address the hypothesis that ciliated cell numbers are reduced in conducting airways from COPD and that this feature reflects an epithelial dysregulation that could persist ex vivo as a result of an aberrant reprogramming through TGF-β1.