The renewal of lung epithelial cells is normally slow unless the lung is injured. The resident epithelial stem cells rapidly proliferate and differentiate to maintain lung structure and function when the lung is damaged. The alveolar epithelium is characterized by alveolar type 1 (AT1) and alveolar type 2 (AT2) cells. AT2 cells are the stem cells for alveoli, as they can both self-renew and generate AT1 cells. Abnormal proliferation and regulation of AT2 cells will lead to serious lung diseases including cancers. In this review, we focused on the alveolar stem/progenitor cells, the key physiological function of AT2 cells in lung homeostasis and the complicated regulation of AT2 cells in the repairing processes after lung injury.
Keywords: alveolar type 2 cells; lung diseases; lung stem/progenitor cells; regeneration.
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