Alveologenesis is a developmental step involving the expansion of the lung surface area which is essential for gas exchange. The gas exchange process is mediated by alveolar type I (AT1) cells, which are known to be differentiated from alveolar type II (AT2) or bipotent cells. Due to the difficulty of isolating and culturing primary AT1 cells, the mechanism underlying their differentiation is not completely understood. We performed single-cell RNA sequencing (scRNA-seq) of fibroblast-dependent alveolar organoids (FD-AOs), including human induced pluripotent stem cell (hiPSC)-derived epithelial cells and fetal lung fibroblasts, and identified hiPSC-derived AT1 (iAT1) cells. A comparison of the FD-AOs and fibroblast-free alveolar organoids showed that iAT1 cells were mainly present in the FD-AOs. Importantly, the transcriptomes of iAT1 cells were remarkably similar to those of primary AT1 cells. Additionally, XAV-939, a tankyrase inhibitor, increased iAT1 cells in passaged FD-AOs, suggesting that these cells were differentiated from hiPSC-derived AT2 (iAT2) cells through the inhibition of canonical Wnt signaling. Consequently, our scRNA-seq data allowed us to define iAT1 cells and identify FD-AOs as a useful model for investigating the mechanism underlying human AT1 cell differentiation from AT2 cells in vitro.

中文翻译：

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通过 Wnt 信号抑制定向诱导源自多能干细胞的肺泡 I 型细胞

肺泡生成是一个发育步骤，涉及肺表面积的扩大，这是气体交换必不可少的。气体交换过程由肺泡 I 型 (AT1) 细胞介导，已知这些细胞与肺泡 II 型 (AT2) 或双能细胞不同。由于分离和培养原代 AT1 细胞的难度，其分化的机制尚不完全清楚。我们对成纤维细胞依赖性肺泡类器官 (FD-AO) 进行单细胞 RNA 测序 (scRNA-seq)，包括人诱导多能干细胞 (hiPSC) 衍生的上皮细胞和胎儿肺成纤维细胞，并鉴定出 hiPSC 衍生的 AT1 (iAT1 ） 细胞。FD-AOs 和无成纤维细胞的肺泡类器官的比较表明 iAT1 细胞主要存在于 FD-AOs 中。重要的，iAT1 细胞的转录组与原代 AT1 细胞的转录组非常相似。此外，XAV-939 是一种端锚聚合酶抑制剂，可增加传代 FD-AO 中的 iAT1 细胞，表明这些细胞是通过抑制经典 Wnt 信号转导从 hiPSC 衍生的 AT2 (iAT2) 细胞分化而来的。因此，我们的 scRNA-seq 数据使我们能够定义 iAT1 细胞并将 FD-AO 识别为一种有用的模型，用于研究体外人类 AT1 细胞与 AT2 细胞分化的机制。