Regeneration of the lung alveolus by an evolutionarily conserved epithelial progenitor [human RNA-seq]

The lung alveolus is the primary site of gas exchange in mammals. Within the alveolus, the alveolar type 2 (AT2) epithelial cell population generates surfactant to maintain alveolar structure and harbors a regenerative capacity to repair the alveolus after injury. We show that a Wnt-responsive alveolar epithelial progenitor (AEP) lineage within the AT2 cell population is critical for regenerating the alveolar niche. AEPs are a stable lineage during alveolar homeostasis but expand rapidly to regenerate a majority of the alveolar epithelium after acute lung injury. AEPs exhibit a distinct transcriptome, epigenome, and functional phenotype with specific responsiveness to Wnt and FGF signaling that modulates differentiation and self-renewal, respectively. Importantly, human AEPs (hAEPs) can be isolated and characterized through a conserved surface marker and are required for human alveolar self-renewal and differentiation using alveolar organoid assays. Together, our findings show that AEPs are an evolutionarily conserved alveolar progenitor lineage essential for regenerating the alveolar niche in the mammalian lung. Overall design: Examination of open chromatin in 2 subtypes of alveolar epithelial cell populations

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Zacharias WJ, Frank DB, Zepp JA, Morley MP, Alkhaleel FA, Kong J, Zhou S, Cantu E, Morrisey EE