From the Guidelines
Endothelial cells play a crucial role in maintaining vascular health and function by regulating blood flow, controlling blood clotting, and managing the passage of materials between the bloodstream and tissues. They form a single-cell layer called the endothelium, which acts as a barrier between the blood or lymph and the surrounding tissues. According to 1, the vascular endothelium is a large paracrine organ that secretes numerous factors regulating vascular tone, cell growth, platelet and leukocyte interactions, and thrombogenicity. The endothelium senses and responds to internal and external stimuli through complex cell membrane receptors and signal transduction mechanisms, leading to the synthesis and release of various vasoactive, thromboregulatory, and growth factor substances.
Some of the key functions of endothelial cells include:
- Regulating blood flow by producing substances that cause blood vessels to dilate or constrict
- Controlling blood clotting
- Managing the passage of materials between the bloodstream and tissues
- Involvement in inflammation responses, angiogenesis, and immune function As noted in 1, the vascular endothelium plays an important role in the regulation of arterial tone and local platelet aggregation, in part through the release of endothelium-derived relaxing factors such as nitric oxide.
The proper functioning of endothelial cells is essential for overall cardiovascular health, and dysfunction of these cells is associated with various cardiovascular diseases, including atherosclerosis and hypertension. The endothelium's ability to adapt to changing conditions in the body makes it a critical component of the circulatory system's homeostasis.
From the Research
Endothelial Cell Functions
The endothelium plays a critical role in maintaining multiorgan health and homeostasis 2. The key functions of endothelial cells include:
- Dynamic maintenance of vascular tone
- Angiogenesis
- Hemostasis
- Provision of an antioxidant, anti-inflammatory, and antithrombotic interface
- Regulation of blood fluidity and fibrinolysis
- Modulation of monocyte/leukocyte adhesion and platelet aggregation 3
Endothelial Dysfunction
Endothelial dysfunction is characterized by impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion, and hyperpermeability 2, 3. This condition is a hallmark of many diverse human panvascular diseases, including:
- Atherosclerosis
- Hypertension
- Diabetes
- Severe coronavirus disease 2019 2
Mechanisms of Endothelial Dysfunction
The mechanisms underlying endothelial dysfunction involve:
- Disrupted endothelial cell metabolism
- Endothelial-to-mesenchymal transition
- Imbalanced vasodilation and vasoconstriction
- Elevated reactive oxygen species (ROS) and proinflammatory factors
- Deficiency of nitric oxide (NO) bioavailability 2, 3
- Destabilization of intercellular junctions between endothelial cells, leading to increased junctional permeability 4
Protective Effects of Physical Exercise
Physical exercise has been shown to protect against endothelial dysfunction in cardiovascular and metabolic diseases 5. Exercise training-induced protection to endothelial injury has been well documented in clinical trials, and the underlying mechanism has been explored in animal models.