PRP and Skin Barrier

Skin is the largest organ of the human body as well as the first defensive barrier of our body being in contact with the environment (Fig. 3.1). The appearance and function of the human skin change profoundly with the increase of age (intrinsic aging) and the accumulation of external factors (extrinsic aging). Photoaging is the primary cause of extrinsic aging, and some environmental factors could make the skin vulnerable. It is well documented that radiation from solar ultraviolet (UV), infrared, and visible light could produce oxidative stress, photoaging, and photocarcinogenesis [1]. In recent years, research also focused on the assessment of injury that environmental contaminants may cause to the skin. Signs of skin aging include dryness, pigmentation disorders, wrinkles, and sagging skin. Histologically, the characteristics of aging skin are excessive damage of the epidermis, atypical hyperplasia and inflammatory cells of keratinocytes, flattening of the dermis-epidermis junction, atrophy of the dermis, disorder of collagen fiber arrangement, elastic degeneration, a small number of fibroblasts, irregular hyperplasia of accessory glands [2], and so on. In a word, with aging, the skin barrier function is diminished, and cellular replacement in the skin and mechanical protection continually decreases. Therefore, skin health and maintaining or restoring a young appearance is the priority choice in people's life.