Non-invasive methods for assessment of dermal UV damage

Repeated exposure to UV radiation can induce cutaneous damage leading to permanent structural degeneration of the dermal extracellular matrix and formation of visible wrinkles. It is not so easy to efface severely UV-damaged skin, because the degenerated abnormal structure of that skin is usually fixed by tight cross-linkings. So, we think that one of the important approaches to the anti-wrinkle skin care is the treatment of photodamaged skin in the early stage. However, it is difficult for most cosmetic users to perceive their dermal UV damage. In the present study, we investigated the possibilities of two non-invasive measurements of skin mechanical properties as convenient biomarkers of degeneration of the extracellular matrix. The condition of the three-dimensional structures of dermal collagen fibres, which depends on the degree of UV damage, correlated with a mechanical parameter measured by the Resiliometer we developed. Accumulation of denatured elastic fibres (elastosis) induced by photoaging correlated with certain mechanical parameters measured by the Cutometer. These findings suggest that dermal structural changes associated with photoaging can be assessed non-invasively using these devices.