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Background Stretch marks or striae distensae (SD) are characterized by epidermal atrophy following repeated over-stretching of the skin tissue. The objective of this study was to investigate the skin texture and microstructure of SD lesions compared to those of normal adjacent skin in vivo using non-invasive methods. Methods A population of 26 women and 3 men with SD were examined after giving written informed consent. Following clinical grading, skin replicas were collected, confocal microscopy was performed on SD lesions and healthy neighboring skin. Skin surface texture parameters were calculated using 3D image analysis of the skin replicas and epidermal and dermal microstructure were evaluated by analysis of the confocal images. In a parallel study, histological analysis was performed on 6 skin biopsies taken from abdominal reduction surgeries in areas where skin exhibited SD. Results Analysis of the skin surface texture showed that the SD area was more anisotropic and with higher skin roughness than the adjacent skin in terms of directions of skin microglyphics. Confocal microscopy demonstrated that SD were characterized by shallower dermal papillae ( P < 0.05) and that dermal papillae height inversely correlated to the intensity of collagen alignment on the SD sites ( P < 0.05). The histology findings confirmed the in vivo confocal microscopy findings. Conclusions The skin structure of SD is qualitatively and quantitatively different compared to healthy skin. Altered skin relief reflects structural modifications in the dermis. Flattening of the dermal-epidermal junction maybe functionally related to the observed collagen fiber alignment. Observations by non-invasive methods were in line with the histological findings and therefore relevant in studies assessing the efficacy of SD treatment options. [ABSTRACT FROM AUTHOR]

Synopsis Three studies were performed to investigate the mechanism of action and evaluate the efficacy of a topical cosmetic slimming product combining tetrahydroxypropyl ethylenediamine, caffeine, carnitine, forskolin and retinol. The Ex vivo study on skin explants showed that caffeine and forskolin both stimulated glycerol release and demonstrates for the first time that retinol and carnitine in combination synergistically stimulated keratinocyte proliferation, which leads to an increase epidermal thickness. The double-blind, randomized, placebo-controlled clinical study associating circumference measurements on five selected parts of the body, cutaneous hydration measurements as well as blinded expert grading of skin aspect was conducted on 78 women who applied the product or placebo twice daily for 12 consecutive weeks. After 4 weeks of twice-daily application of the product, significant reductions in circumference of abdomen, hips-buttocks and waist were already observed. Improvements concerned all the measured body parts after 12 weeks. Orange peel and stubborn cellulite decreased significantly from 4 weeks of treatment and tonicity improved from 8 weeks, demonstrating that the product improved skin aspect. At the end of the study, eight parameters of the thirteen evaluated were significantly improved in the active group and compared with placebo. [ABSTRACT FROM AUTHOR]