Changes in the mechanical properties of dermis occur during skin aging or tissue remodeling and affect the activity of resident fibroblasts. With the aim to establish elastic culture substrates that reproduce the variable softness of dermis, we determined Young's elastic modulus E of human dermis at the cell perception level using atomic force microscopy. The E of dermis ranged from 0.1 to 10 kPa, varied depending on body area and dermal layer, and tended to increase with age in 26-55-year-old donors. The activation state of human dermal fibroblasts cultured on "skin-soft" E (5 kPa) silicone culture substrates was compared with stiff plastic culture (GPa), collagen gel cultures (0.1-9 kPa), and fresh human dermal tissue. Fibroblasts cultured on skin-soft silicones displayed low mRNA levels of fibrosis-associated genes and increased expression of the matrix metalloproteinases (MMPs) MMP-1 and MMP-3 as compared with collagen gel and plastic cultures. The activation profile exhibited by fibroblasts on "skin-soft" silicone culture substrates was most comparable with that of human dermis than any other tested culture condition. Hence, providing biomimetic mechanical conditions generates fibroblasts that are more suitable to investigate physiologically relevant cell processes than fibroblasts spontaneously activated by stiff conventional culture surfaces.

Ubiquinone (coenzyme Q10, Q10) represents an endogenously synthesized lipid‐soluble antioxidant which is crucial for cellular energy production but is diminished with age and under the influence of external stress factors in human skin. Here, it is shown that topical Q10 treatment is beneficial with regard to effective Q10 replenishment, augmentation of cellular energy metabolism, and antioxidant effects. Application of Q10‐containing formulas significantly increased the levels of this quinone on the skin surface. In the deeper layers of the epidermis the ubiquinone level was significantly augmented indicating effective supplementation. Concurrent elevation of ubiquinol levels suggested metabolic transformation of ubiquinone resulting from increased energy metabolism. Incubation of cultured human keratinocytes with Q10 concentrations equivalent to treated skin showed a significant augmentation of energy metabolism. Moreover, the results demonstrated that stressed skin benefits from the topical Q10 treatment by reduction of free radicals and an increase in antioxidant capacity. © 2015 BioFactors, 41(6):383–390, 2015

Employing MPLSM, dermal changes occurring in photo-aged human skin were visualized in an unprecedented manner and correlated to a loss of firmness. Treatment of aged skin with a topical formulation containing folic acid and creatine counteracted this age-dependent decline by exerting sustained effects on collagen metabolism. Our results support previous findings on the efficacy of these actives.

In summary, creatine represents a beneficial active ingredient for topical use in the prevention and treatment of human skin aging.

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