Role of the endothelium and blood stasis in the development of varicose veins.

Today, chronic venous insufficiency affects millions of people but the investigation of veins and of venous diseases is still very poor. Additionally, the mechanism of the occurrence of varicose veins is not understood. Blood stasis is often associated with these pathological situations and we propose that resulting ischemic conditions can trigger the endothelium to release inflammatory mediators and growth factors. On one hand, the inflammatory mediators will recruit and activate neutrophils, which then infiltrate the venous wall and damage components of the extracellular matrix. On the other hand, growth factors induce smooth muscle cell migration, proliferation and de-differentiation into the synthetic phenotype, all together leading to the formation of neointima. These processes, being repeated over time, would eventually lead to alterations of the venous wall as observed in varicose veins. Venotropic drugs are used to treat chronic venous insufficiency. They are able to increase venous tone and to decrease vein and capillary permeability but they are also able to protect the endothelial cells against ischemia. Indeed, they target complexes of the mitochondrial respiratory chain and maintain ATP production during hypoxia. Hence, the cells are resistant to ischemia and do not release inflammatory mediators and growth factors. These drugs should thus be able to prevent the alterations of the venous wall induced by blood stasis.