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Alveolar organoid model

ABSTRACT: Rationale: Alveolar epithelial type 2 (AT2) cells are stem/progenitor cells in the adult lung and their maintenance and regulation is achieved through their interaction with mesenchymal cells which constitute their niches. However, the precise identity of the niche cells is still elusive. Objectives: To characterize the niche cells capable of supporting the self-renewal of AT2 stem cells in the murine model. Methods: The alveolar organoid model was used to test the efficiency of different subpopulations of mesenchymal cells isolated by FACS from well-established (PdgfraGFP, Axin2LacZ, Fgf10LacZ) reporter mice to support the self-renewal of mature AT2 cells. The reporter-positive cells where pre-sorted based on Cd45neg Cd31neg Epcamneg Sca1pos. Additional selection was achieved using LipidTOX staining for cells containing high level of neutral lipids. Organoid size and colony formation efficiency after 2 weeks in culture were quantified. RNAscope combined with immunofluorescence on adult lungs. qPCR, gene array were used to characterize the niche cells. Measurements and main results: A subset of Sca1+; Fgf10-expressing cells positive for LipidTox staining in the distal mesenchyme is efficient in the self-renewal and differentiation of AT2 stem cells. Co-staining of adult lung by using ISH and IF staining for Fgf10 and Sftpc respectively, indicate that 28% of Fgf10+ cells are located to close to AT2 cells. These cells do not overlap with Fgf7-expressing cells. Gene array comparing MANC (Cd45Neg Cd31Neg EpcamNeg Sca1Pos Axin2LacZ/FDGPos) with Fgf10Pos Lipofibroblasts (Cd45Neg Cd31Neg EpcamNeg Sca1Pos Fgf10LacZ/FDGPos) support that these two cell subsets are different and express differential markers that can be further used for the respective characterization of these cells. Conclusions: We have demonstrated for the first time that Fgf10Pos LIF cells play important role to support AT2 stem cells in terms of self-renewal and differentiation toward the AT1 cell type. These cells appear different from the previously characterized MANC and display a similar activity in eliciting AT2 self-renewal.

ORGANISM(S): Mus musculus

PROVIDER: GSE162859 | GEO | 2021/12/01

REPOSITORIES: GEO

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Project description:Alveoli are thin-walled sacs that serve as the gas exchange units of the lung. They are affected in devastating lung diseases including COPD, Idiopathic Pulmonary Fibrosis, and the major form (adenocarcinoma) of lung cancer, the leading cause of cancer deaths. The alveolar epithelium is composed of two morphologically distinct cell types: alveolar type (AT) 1 cells, exquisitely thin cells across which oxygen diffuses to reach the blood, and AT2 cells, specialized surfactant-secreting cells. Classical studies suggested that AT1 cells arise from AT2 cells during development and following injury, but more recent studies suggest other sources. Here we use histological and marker analysis, lineage tracing, and clonal analysis in mice to identify alveolar progenitor and stem cells and map their locations and potential in vivo. The results show that AT1 and AT2 cells arise independently during development from a bipotential progenitor. After birth, new AT1 cells derive from rare, long-lived, self-renewing AT2 cells, each producing a slowly expanding clonal focus of regenerated alveoli contiguous with the founder AT2 cell. This stem cell function of AT2 cells is broadly activated by diffuse AT1 cell injury, and AT2 self-renewal can be induced in vitro by EGF ligands and permanently activated in vivo by AT2 cell-specific targeting of the oncogenic KrasG12D allele, efficiently transforming AT2 cells into monoclonal adenomatous tumors that rapidly enlarge and prove fatal. Thus, there is a developmental switch in alveolar progenitor cells after birth, when mature AT2 cells function as facultative stem cells that contribute to local alveolar renewal, repair, and cancer. We propose that short-range signals from dying AT1 cells regulate AT2 stem cell activity: a signal transduced by EGFR-KRAS controls AT2 self-renewal and is hijacked during oncogenic transformation, and a separate signal controls reprogramming to AT1 cell fate. To compare expression between ATII and E18 BP populations, RNA was isolated from either population purified by FACS. Two populations are analyzed with 3 biological replicates per population.

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Alveolar organoid model

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