The vascular endothelium’s functional role is separated into distinct parts: (1) barrier function—highly selective and regulates inflammatory and immune responses, (2) transport function—responsible for cell–cell signaling and pinocytosis (i.e. particles in extracellular fluid enter the cell through invaginations or clefts in the cell membrane), (3) vascular repair function-restores structural and functional normalcy, (4) angiogenesis function-reparative and adaptive to injurious conditions, (5) thromboregulation function- supports physiological blood flow and prevents unwanted (or needed) blood clotting, (6) vasoregulation function—responds to local conditions and signals vasodilation or vasoconstriction, (7) metabolic function—responsible for a highly regulated synthesis of growth factors, adhesion molecules and receptors; and (8) immune function-responds to a variety of immune cells, expresses histocompatibility antigens and regulates antigen presenting cells [6] (Fig. 3).