Breathing on chip: Dynamic flow and stretch accelerate mucociliary maturation of airway epithelium in vitro

Human lung function is intricately linked to blood flow and breathing cycles, but it remains unknown how these dynamic cues shape human airway epithelial biology. Here we report a state-of-the-art protocol for studying the effects of dynamic medium and airflow as well as stretch on human primary airway epithelial cell differentiation and maturation, including mucociliary clearance, using an organ-on-chip device. Perfused epithelial cell cultures displayed accelerated maturation and polarization of mucociliary clearance, and changes in specific cell-types when compared to traditional (static) culture methods. Additional application of airflow and stretch to the airway chip resulted in an increase in polarization of mucociliary clearance towards the applied flow, reduced baseline secretion of interleukin-8 and other inflammatory proteins, and reduced gene expression of matrix metalloproteinase (MMP) 9, fibronectin, and other extracellular matrix factors. These results indicate that breathing-like mechanical stimuli are important modulators of airway epithelial cell differentiation and maturation and that their fine-tuned application could generate models of specific epithelial pathologies, including mucociliary (dys)function.

Automated summary

We develop an advanced organ-on-chip device to study the influence of dynamic cues, such as medium and airflow, on human airway epithelial cell differentiation and maturation. By applying airflow and stretch to the airway chip, we observe increased polarization of mucociliary clearance, reduced inflammatory protein secretion, and decreased gene expression of matrix metalloproteinase (MMP) 9 and other extracellular matrix factors. These findings highlight the importance of breathing-like mechanical stimuli in airway epithelial biology and suggest the potential use of this model for studying specific epithelial pathologies.