Identification and characterization of Bronchioalveolar stem cells

Objective: The evidence that bronchioalveolar stem cells (BASCs) serve as a real stem cell type for the distal lung has been challenged recently. It is currently unclear what their function is and how their pool and progeny is regulated during lung regeneration and repair. The aim of this study is to identify and characterize BASCs from adult mouse lung by improved detection methods to analyse changes introduced selectively by genetic targeting.

Results: We identified by immunohistochemistry the proposed BASC cell population coexpressing SP-C, a marker for alveolar type 2 cells, and CCSP, a marker for bronchial epithelial clara cells, that resides at the bronchioalveolar duct junction (BADJ). We currently establish a protocol for 100–200 micron thick sections to generate Z-stacks and better describe the BASC cell niche. BASCs were then identified by flow cytometry based on an adjusted McQualter protocol for their expression of EpCAM and CD24 and the absence of CD31 and CD45. Also, lung mesenchymal stromal cells that have EpCAM(-)/Sca-1(+) phenotype required for the differentiation of BASCs were isolated.

Conclusion/Outlook: We further aim to establish in vitro colony formation assays and in vivo differentiation assays for alveolar stem cells to address changes in stemness and proliferative activity during experimental lung diseases and lung regeneration.