Epidermal and dermal changes in response to various skin rejuvenation methods.

During the last years, a number of new devices have been developed to improve the dermal and epidermal signs of photo- and chronological skin ageing. There are well-established ablative and non-ablative skin resurfacing options using different lasers and light sources, but side effects have been observed frequently. A recently developed photorejuvenation method using non-thermal stimulation of skin cells with low energy and narrow band light has been termed photomodulation. Light emitting diodes are the ideal source of this kind of light that stimulate mitochondrial cell organelles leading to up-regulation of cytochrome electron transport pathway leading to mitochondrial DNA gene modulation. This paper reviews the most current knowledge of intrinsic and extrinsic changes of ageing and summarizes different systems for skin rejuvenation with focus on non-thermal non-ablative skin rejuvenation modalities.