Reconstruction of the alveolar-capillary barrier in vitro based on a photo-responsive stretchable Janus membrane.

The lung is the respiratory organ of the human body, and the alveoli are the most basic functional units of the lung. Herein, a photo-responsive stretchable Janus membrane was proposed for the reconstruction of the alveolar-capillary barrier in vitro. This Janus membrane was fabricated by photocrosslinking methylacrylamide gelatin (Gelma) hydrogel and N-isoacrylamide (NIPAM) hydrogel mixed with graphene oxide (GO). The Gelma hydrogel containing large amounts of collagen provides a natural extracellular matrix environment for cell growth, while the temperature-sensitive NIPAM hydrogel combined with GO gives the membrane a light-controlled stretching property. Based on this Janus membrane, an open polydimethylsiloxane chip was established to coculture alveolar epithelial cells and vascular endothelial cells at the air-liquid interface. It was demonstrated that the alveolar epithelial cells cultured on the upper side of the Janus membrane could express epithelial cell marker protein E-cadherin and secrete alveolar surfactant. In addition, VE-cadherin, an endothelium-specific protein located at the junction between endothelial cells, was also detected in vascular endothelial cells cultured on the underside of Janus membrane. The constructed lung tissue model with the dynamically stretchable Janus membrane is well-suited for COVID-19 infection studies and drug testing.