An Ex Vivo Acid Injury and Repair (AIR) Model Using Precision-Cut Lung Slices to Understand Lung Injury and Repair.

Recent advances in cell culture models like air-liquid interface culture and ex vivo models such as organoids have advanced studies of lung biology; however, gaps exist between these models and tools that represent the complexity of the three-dimensional environment of the lung. Precision-cut lung slices (PCLS) mimic the in vivo environment and bridge the gap between in vitro and in vivo models. We have established the acid injury and repair (AIR) model where a spatially restricted area of tissue is injured using drops of HCl combined with Pluronic gel. Injury and repair are assessed by immunofluorescence using robust markers, including Ki67 for cell proliferation and prosurfactant protein C for alveolar type 2/progenitor cells. Importantly, the AIR model enables the study of injury and repair in mouse lung tissue without the need for an initial in vivo injury, and the results are highly reproducible. Here, we present detailed protocols for the generation of PCLS and the AIR model. We also describe methods to analyze and quantify injury in AIR-PCLS by immunostaining with established early repair markers and fluorescence imaging. This novel ex vivo model is a versatile tool for studying lung cell biology in acute lung injury and for semi-high-throughput screening of potential therapeutics. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Generation of precision-cut lung slices Basic Protocol 2: The acid injury and repair model Basic Protocol 3: Analysis of AIR-PCLS: Immunostaining and imaging.