The main reasons for these three skin modifications are outlined below. Wrinkles and stretch marks are the result of a lack of skin firmness and elasticity linked to a dramatic alteration of the cells and of the main constituents of the dermis located in the space surrounding the cells. The latter contains macromolecules, polysaccharides, glycosaminoglycans (GAGs), fibrous protein (collagens, elastin), salts and water which together are known as the extra cellular matrix, responsible for tissue cohesion. The main structure proteins are collagens and elastin. The extra cellular matrix components are synthesised and secreted by cells such as the fibroblasts and degraded by enzymes called Matrix MetalloProteinases (MMPs). MMP activity is regulated by various factors including activators like plasminogen, plasmin, tissue plasminogen activator (t-PA) and urokinase plasminogen activator (u-PA), but also by inhibitors like Tissue Inhibitors of Metalloproteinase (TIMPs), anti-plasmin and Plasminogen Activator Inhibitors (PAI 1 and PAI 2).
Angiogenesis is defined as the formation of new blood vessels from preexisting vessels. This excess growth of blood vessels is the cause of unattractive skin problem such as acne rosacea, vascular imperfections and dark circles under the eyes. All these defects are due to the dilation of superficial veins that become visible on the surface of the skin. Vascular imperfections often result in the appearance of unsightly spider veins on the legs. They can become varicose veins due to the stagnation of blood in the lower limbs. Hormone changes (contraception, pregnancy, etc.), constantly standing or sitting, and ageing also contribute to the formation of these small imperfections. Dark circles are due to small veins under the eyes which tend to dilate; blood circulates badly and since the skin is very thin in this site, they rapidly appear. Their appearance is also supported by stress, lack of sleep and pollution.




