Endothelial cells are thin cells that make up the blood vessels and play an important role in the circulatory and lymphatic systems.
Endothelial cells create a lining, the endothelium, inside heart and blood/ lymphatic vessel walls. This special vessel lining improves the ability of blood components to be pumped farther and more efficiently throughout the body.
Endothelial cells are involved in a number of key functions including:
- Vessel constriction and dilation
- Growth of new blood vessels (angiogenesis)
- Clotting
- Thickening of vessel walls
- Exchanges of gases and nutrients
In certain kinds of vascular anomalies such as hemangiomas, extra blood vessels are formed by a process called angiogenesis. These endothelial cells grow at a very fast rate over several months, termed the proliferative phase. The growth rate then stabilizes, and eventually the vascular mass spontaneously improves. This phase is called the involution stage.