A Gel Coated Air-Liquid-Interface Culture System with Tunable Substrate Stiffness Matching Healthy and Diseased Lung Tissues

Since its invention in late 1980s, air-liquid-interface (ALI) culture system has been the golden standard in vitro model for studying human airway biology and pulmonary diseases. In a conventional ALI system, however, cells are cultured on a plastic membrane, which is much stiffer than that of human airway tissue. Here, we develop a gel-coated ALI culture system that enables matching the stiffnesses of healthy and fibrotic airway tissues. We determine the optimum gel thickness that does not impair the transport of nutrients and biomolecules essential to cell growth. Similar to the conventional ALI system, the gel-ALI system allows human bronchial epithelial cells to proliferate and differentiate to a pseudostratified epithelium, capturing the essential biological features in vivo. We discover that hydrogels of different stiffnesses result in significant changes in morphology and migration of cells, highlighting the importance of the mechanical environment to human airway remodeling. The developed technology should benefit the field of human airway biology and pulmonary diseases.