Human skin stem cells, aging, and possible antiaging strategies

Human skin is the largest organ of the body and it provides the first line of the defense system against environmental factors coming in contact by evading our ecosystem. Skin possesses notable regeneration capacity due to the presence of different types of stem cells including epithelial stem cells, melanocyte stem cells, mesenchymal stem-like cells, and progenitor cells. Moreover, the integrity of the skin is mainly maintained by epidermal stem cells. Skin and skin stem cells are more vulnerable toward aging process due to their direct contact with external stimuli including environmental pollutants, infection, and UV irradiation. Aging is a complex and multifactorial process mainly caused by imbalanced redox status, DNA mutation, and telomere shortening. The reactive oxygen species (ROS) overproduction is the major contributor of skin aging as ROS exert oxidative damage to macromolecules and cell organelles, which continuously accumulate and further accelerate aging process. Additionally, UV irradiation induces oxidative stress, overproduction of ROS, and DNA damage which collectively cause photoaging of the skin. This chapter summarizes the overall effects of oxidative stress on skin aging, and several antiaging strategies such as supplementation of nutritional antioxidants and autophagy modulation are also described to slow down the aging process of skin as well as skin diseases.