Review of Major Theories of Skin Aging

Here we aim to describe each factor that leads to skin aging and describe their mechanisms. A PubMed database searches (from January 2004 to March 2014) using aging and skin as searched terms. There are substantial evidences showing that aging is associated with damage from free radicals represented by various reactive oxygen species (ROS). Mitochondria are producers and also targets of oxidative stress. The cycle of mitochondrial dysfunction can trigger the aging process. In the cellular senescence and telomeres theory, the diploid cells exhibit a limited proliferation potential. After a finite number of divisions, they enter a state of senescence with a stop replication in cell proliferation. It is suggested that aging is associated mainly with hyper-regulation of apoptosis. Obesity presumably accelerates the process of aging, which is aggravated by smoking. And the influence of the environment, called solar UV irradiation is of considerable importance to skin aging. There are several mechanisms that trigger the natural aging process and contribute to age-related changes, including oxidative stress theory of free radicals, the mitochondrial dysfunction, telomere shortening, UV radiation and other mechanisms that taken together or alone may or not accelerate the change in skin.

Clinical Use of Growth Factors in the Improvement of Skin Wound Healing

To discuss the normal mechanism of wound healing (WH), the role of growth factors (GF) in prec-linical and clinical studies and its importance in the healing of abnormal wound therapy. For search, we used the PUBMED and LILACS database, and the following descriptors: skin, wound healing, growth factor and clinical trials. We also prioritized the analysis of the Clinical Trials in the previous 10 years. Although there are many studies being conducted in the pre-clinical phase, we see that there are few studies in the clinical phase. 274 studies were identified, and 58 were selected. After tissue injury, repair occurs through coordinated biological actions that are healing. The importance of the study of healing in the skin is not only because of its anatomical location, easy access and exposure, but also because of its vital function. There is accumulating evidence that the process of healing after injury may be mediated by several GF. However, may this class of molecules even act effectively on the clinical response of this pathological condition? Many preclinical studies (in vitro and in vivo) reinforce the importance and efficacy of GF in the regeneration of damaged skin. Furthermore, recent studies have reported the use in adjuvant or not, of GF in clinical treatment to improve WH in humans. Therefore, we conclude that it seems to be effective by the use of GF in adjuvant or not in WH. However, it still seems to be necessary to carry out more clinical trials in phase I and II.