Macro- and micro-heterogeneity of lung endothelial cells: they may not be smooth, but they got the moves:

摘要

It has long been recognized that there is tremendous heterogeneity in endothelial cells (ECs) from different vascular beds1 and that organ-specific differences in EC phenotype have important physiological and pathophysiological implications. It has also been suggested that within the vasculature, there are “niches” of highly proliferative, progenitor-like ECs that likely play an important role in vascular repair and regeneration.2 The lung vascular bed is particularly intriguing because of its many unique features. It has the largest endothelial surface area of any organ and is the only vascular bed that needs to accommodate the entire cardiac output. Moreover, it can do this at rest using only a fraction of the available microvasculature area, at arterial pressures that are little more than venous. As cardiac output increases, the lung can recruit additional unused microvascular area to maintain low arterial pressure. Also, there is a paucity of smooth muscle and other supportive mural cells in its small arterioles, possibly because they operate at such low pressures, which makes these structures particularly fragile.