ABSTRACT
The lung is a complex organ that has multiple functions essential to sustain life. One of the most important main functions of the mammalian lung is gas exchange, which involves the delivery of oxygen to and the removal of carbon dioxide from blood, providing adequate oxygen to tissues. Gas exchange occurs in the alveoli, which are tiny air sacs at the end of the bronchioles, surrounded by capillaries. Damage to the alveoli is induced by bacterial or viral pneumonia and air pollutants. The lung was previously viewed as a non-regenerating organ because of its slow turnover rate of epithelial cells during adult homeostasis. However, studies in the past decade have shown that the lung can be actively repaired upon injury. Indeed, we learned from the COVID-19 pandemic that many patients recover from viral pneumonia without significant radiographic or functional sequelae. In this chapter, we provide an overview of different epithelial cell populations during lung development and repair upon injury, specifically focusing on those with stem/progenitor cell properties. We discuss the current evidence of how the lung repairs after injury and how aberrant repair occurs resulting in lung disease, such as pulmonary fibrosis. We highlight some of the opportunities and challenges in manipulation of these cells to promote lung repair as a therapeutic strategy for lung disease.
