Endothelial cells are a type of cell that lines the interior surface of blood vessels and lymphatic vessels. They act as a barrier between the blood and surrounding tissues, regulating the passage of substances such as nutrients, oxygen, and waste products. Endothelial cells are also involved in the regulation of blood pressure, blood clotting, and inflammation. Research in this area explores the functions of endothelial cells in health and disease, including conditions such as cardiovascular disease, cancer, and diabetes. Recent advancements in understanding endothelial cell biology have led to the development of new therapeutic strategies for various diseases.