Temporal differentiation of bovine airway epithelial cells grown at an air-liquid interface

The respiratory epithelium is exposed to assault by toxins and pathogens through the process of inhalation, which has numerous implications on both human and animal health. As such, there is a need to develop and characterise an in vitro model of the airway epithelium to study respiratory pathologies during infection or toxicology experiments. This has been achieved by growing airway epithelial cells at an air-liquid interface (ALI). Characterisation of ALI models are not well-defined for airway epithelial cells derived from non-human species. In this study we have fully characterised a bovine airway epithelial cell models (AECM) grown at an ALI in relation to ex vivo tissue. The morphology of the model was monitored at three day intervals, to identify the time-period at which the culture was optimally differentiated. The model was shown to be fully-differentiated by day 21 post-ALI. The culture formed a stereotypical pseudostratified, columnar epithelium containing the major cell types of the bronchial epithelium (ciliated-, goblet- and basal cells). Once fully differentiated the bovine AECM displayed both barrier function, through the formation of tight-junctions, and active mucociliary clearance, important properties of the mucosal barrier. The bovine bronchial epithelial cells remained stable for three weeks, with no evidence of deterioration or dedifferentiation. The window in which the model displayed full differentiation was determined to be between day 21-42 post-ALI. Through comparison with ex vivo tissue derived from donor animals, our bovine AECM was shown to be highly representative of the in vivo bovine bronchial epithelium and can be utilised in the study of respiratory pathologies.