Endothelial cells (ECs) are a heterogeneous population of cells that line the lumen of the entire vascular system. They play a crucial role in various physiological processes and are actively involved in both innate and adaptive immune responses
Functions of endothelial cells
- Regulation of blood flow and fluidity: ECs actively regulate blood flow and maintain blood fluidity
- Control of transfer between blood and tissue: They control the transfer of water, solutes, and macromolecules between the bloodstream and tissues
- Immune cell recruitment and activation: ECs modulate the recruitment and activation of circulating immune cells
- Participation in immune responses: ECs are among the first cells to detect foreign pathogens and endogenous danger signals in the bloodstream, functioning as sensors and amplifying the immune response by recruiting immune cells
- Angiogenesis: ECs play an active role in the formation of new blood vessels, a process known as angiogenesis
- Maintenance of organ-specific normalcy: ECs adopt structures specific to the needs and functions of each tissue and organ and are subject to tissue-specific signaling inputs
Endothelial cell activation and dysfunction
- Activation: ECs acquire new functions to restore local and systemic homeostasis during critical illness
- Dysfunction: Breakdowns in EC functions contribute to local and systemic pathological responses
- Senescence: ECs are susceptible to pathogenic stimuli that activate tumor suppressor pathways leading to cellular senescence, which contributes to various cardiovascular and metabolic diseases
Endothelial cells in disease
- Sickle cell disease: In sickle cell disease, a mutation in the β-globin gene leads to vascular occlusion and hemolytic anemia, triggering a cascade of pathological events leading to vascular endothelial dysfunction
- Erectile dysfunction: Increased biochemical measures of endothelial cell activation have been associated with erectile dysfunction, suggesting it may be a sentinel of early atherosclerosis
In conclusion, endothelial cells are dynamic and versatile cells that play a crucial role in maintaining vascular homeostasis and participating in immune responses. Their dysfunction can contribute to the pathogenesis of various diseases.