A nasal airway-on-chip model to evaluate airflow pre-conditioning during epithelial cell maturation at the air-liquid interface.

The function of a well-differentiated nasal epithelium is largely affected by airflow-induced wall shear stress, yet few in vitro models recapitulate this dynamic condition. Models which do expose cells to airflow exclusively initiate flow after the differentiation process has occurred. In vivo , basal cells are constantly replenishing the epithelium under airflow conditions, indicating that airflow may affect the development and function of the differentiated epithelium. To address this gap in the field, we developed a physiologically relevant microphysiological model of the human nasal epithelium and investigated the effects of exposing cells to airflow during epithelial maturation at the air-liquid interface. The nasal airway-on-chip platform was engineered to mimic bi-directional physiological airflow during normal breathing. Primary human nasal epithelial cells were seeded on chips and subjected to either: (1) no flow, (2) single flow (0.5 dyne cm -2 flow on Day 21 of ALI only), or (3) pre-conditioning flow (0.05 dyne cm -2 on Days 14-20 and 0.5 dyne cm -2 flow on Day 21) treatments. Cells exposed to pre-conditioning showed decreased morphological changes and mucus secretions, as well as decreased inflammation, compared to unconditioned cells. Our results indicate that flow exposure only post-differentiation may impose acute stress on cells, while pre-conditioning may potentiate a properly functioning epithelium in vitro .