Structural and functional variations in human bronchial epithelial cells cultured in air liquid interface using different growth media.

The human bronchial epithelium is an important barrier tissue that is damaged or pathologically altered in various acute and chronic respiratory conditions. In order to represent the epithelial component of respiratory disease it is essential to use a physiologically-relevant model of this tissue. The human bronchial epithelium is a highly organized tissue consisting of a number of specialized cell types. Primary human bronchial epithelial cells (HBEC) can be differentiated into a mucociliated tissue in air-liquid interface (ALI) cultures using appropriately supplemented media under optimized growth conditions. We compared the histology, ciliary length and function, diffusion, and barrier properties of HBEC from donors with no respiratory disease grown in two different media, PneumaCult(TM)-ALI or BEDM. In the former group, the HBEC have a more physiological pseudostratified morphology and mucociliary differentiation, including increased epithelial thickness, intracellular expression of airway-specific mucin protein MUC5AC, and total expression of cilia basal-body protein compared to cells from the same donor grown in the other medium. Baseline expression levels of inflammatory mediators, TSLP, soluble ST2, and eotaxin-3 were lower in PneumaCult(TM)-ALI. In addition, the physiological cilia beat frequency and electrical barrier properties with trans-epithelial electrical resistance were significantly different between the two groups. Our study has shown that these primary cell cultures from the same donor grown in the two media possess variable structural and functional characteristics. Therefore, it is important to objectively validate the primary epithelial cell cultures prior to experimentation to ensure they are appropriate to answer a specific scientific question.