Endothelial cells in the lung

Pulmonary endothelial cells, a key player in lung pathophysiology, have recently become better understood owing to advances in single-cell technology. The lung endothelium is heterogeneous, composed in mice mainly of two molecularly distinct capillary populations: Car4 endothelial cells expressing carbonic anhydrase 4 and Plvap endothelial cells expressing plasmalemma vesicle-associated protein. These cells engage in crosstalk with the other cell types in the lung, making them active members within their niche, and play an important role in developmental pathologies, as well as in the onset and progression of diseases of the adult lung. The recently described lung endothelial cell heterogeneity leads to new questions including the unique contribution of each endothelial cell type to development, homeostasis, disease and regeneration. This chapter will compare endothelial cells across organs, summarise their role as signalling and receiving cells in developing and adult lungs, and discuss the implications in lung diseases. A better understanding of the lung endothelium will not only further our knowledge about normal physiology but will also provide new therapeutic targets and interventions for prevalent lung pathologies.