Single-Cell analysis of respiratory epithelial cell differentiation and maturation
Alexandros Sountoulidis1,2,3, Elpidoforos Sakkas1,2,3, Andreas Liontos1,2, Xiaoyan Qian2, Mats Nilsson2, Christos Samakovlis1,2,3,4
1Stockholm University, Molecular Biosciences, The Wenner-Gren Institute (MBW);2Science for Life Laboratory, Stockholm, Sweden; 3Justus-Liebig University of Giessen, Medical Clinic II, Department of Internal Medicine, Excellence Cluster Cardio-Pulmonary System (ECCPS), Giessen, Germany; 4Max Planck Institute for Cardiopulmonary Research, Bad Nauheim, Germany
The lung epithelium extends an immense surface functioning both as a dynamic exchange platform with the environment and as a protective barrier. The mature lung epithelium is composed of morphologically and functionally distinct cell populations along its proximal-distal axis. We utilize a mouse model to characterize the differentiation, maturation and function of respiratory epithelium in development and homeostasis. We have labeled multipotent embryonic epithelial cells by GFP (Scgb1aCreER; RosafGFP) and lineage traced them in order to isolate individual cells and analyze their gene expression profiles at different embryonic and postnatal stages by a single-cell sequencing protocol. Data clustering methods identified seven distinct clusters. Two of these correspond to the mature ciliated and club cells, based on already known expression markers. Additionally, we revealed a new group of mature secretory airway cells and a population of Scgb1a1pos SftpCpos airway cells, which have been previously suggested to be adult progenitor cells of the lung epithelium. The remaining 3 groups correspond to immature differentiating cells. We established the gene expression signatures of each of the cell populations and used immunofluorescence and in situ sequencing to evaluate the results in mature and developing mouse lung tissues. Our work provides a view of unexpected heterogeneity in the airways and establishes a rich resource of candidate regulators, like transcription factors and secreted molecules of airway differentiation and homeostasis.