Protocol for the in vivo tracing of alveolar type I cells from mice using two distinct dual recombinase-mediated genetic approaches.

Revealing the origins of alveolar epithelial stem cells is crucial for preventing and treating lung diseases. Here, we present a protocol for tracing alveolar type I (AT1) cells from mice in vivo using two distinct dual recombinase-mediated systems. We describe steps for model establishment, harvesting tissue, cryosection, immunofluorescence staining, and confocal imaging. We then detail procedures for analysis of image files and quantification. This protocol provides a foundation for elucidating the plasticity of AT1 cell fate during homeostasis and diseases. For complete details on the use and execution of this protocol, please refer to Liu et al.¹.