Spatiotemporal coordination of stem cell behavior following alveolar injury

Abstract

Tissue repair requires a highly coordinated cellular response to ensure the correct balance of replacement cells to lost cells. In the lung, alveolar type 2 (AT2) cells act as stem cells and can replace both themselves and alveolar type 1 cells (AT1); however, the complex orchestration of AT2 stem cell activity following lung injury is poorly understood owing to the inability to track individual stem cells and their dynamic behavior over time. Here, we apply live time lapse imaging to ex vivo mouse precision cut lung slice (PCLS) culture and in vivo mouse lung to track individual GFP-labeled AT2 cells for 72h following intra-tracheal administration of bleomycin. We observe highly dynamic movement of AT2 cells, including migration within and between alveoli, as well as the emergence of at least three distinct morphokinetic AT2 cell states. Small molecule-based inhibition of Rho-associated protein kinase (ROCK) pathway significantly reduced motility of AT2 stem cells following injury and reduced expression of Krt8, a known marker of intermediate progenitor cells. Together, our results uncover motility of alveolar stem cells as a new injury response mechanism in the lung and uncover properties of stem cell motility at high cellular resolution.