Controlling Vascular Permeability: How Does It Work and What Is the Impact on Normal and Pathological Angiogenesis

The permeability of the vasculature is a property of the capillary wall to obstruct movement of fluid or solutes driven by physiological force. The vasculature is essential for the health of normal tissues, hemostasis, lipid transport, and immune surveillance and is also an influential characteristic of many diseases in which it is greatly increased. The control mechanism of vascular permeability is a complex process that needs to be tightly regulated in order to preserve not only the vascular homeostasis but also its integrity. Here, transcellular and paracellular pathways play an important role as well as direct and indirect influence of the vascular permeability by molecules or blood pressure. In pathologies the vasculature is often affected by the disease process. This may result in neoangiogenesis, where an excessive formation of new, unstable, and hyperpermeable vessels with poor blood flow takes place. In this scenario the vascular endothelial growth factor (VEGF) plays a key role.