Effect of respiration on primary human alveolar epithelial cells

Abstract

The effect of the mechanical stretch associated with breathing on lung pneumocytes is of great importance in regulating lung functions. Standard in-vitro lung alveolar models do not mimic this dynamic environment. In addition, most of those models use a cancer cell line that further counteracts the human lung in-vivo situation. We recently developed a lung-on-a-chip able to mimic the mechanical stress of the thin alveolar barrier. The goal of this study is to characterize the effects of mechanical stretch on primary human alveolar epithelial cells obtained from five patients. Primary human pulmonary alveolar epithelial cells from patients undergoing lung resections were sorted by FACS and cultured in the lung-on-a-chip, as described previously (Stucki, AO et al. Lab Chip 2015). Cells from a total of 5 patients were grown to confluence for 48h. The cells were then exposed to 3D cyclic, physiological, mechanical stretch (10% linear, 0.2Hz) during 48h. The supernatant was collected daily for analysis of secreted factors such as IL-8 or IL-6. After 48h, RNA was harvested for gene expression analysis. Results showed a significantly increased release of IL-8 after 48h of stretch compared to a static control (9.7±2.6 ng/ml vs. 3.8±1.6 ng/ml, n=3). These findings are in accordance to results obtained in cell lines. We could show that mechanical stretch has an effect on primary human pulmonary alveolar epithelial cells, which may be of importance in regulating lung functions. Genetic analysis and expression profiles of cytokines and cytokine-related genes performed on those cells are currently on-going. Those results are expected to provide a more complete picture of the effect of mechanical stretch on patients9 cells.