The pH of the healthy skin is 5.5 and maintained by many regulatory mechanisms. The pH of the skin care product we use on a daily basis can have an influence on the skin properties. To investigate how the physical properties of skin change after the alkaline or acidic pH of the skin care products are applied on the skin for a long term, we adjusted the pH of the skin care products to 3, 5 and 8 (A, B, C), with glycolic acid and triethanolamine. For 5 weeks the skin care products were applied on 20 healthy subjects' ventral forearm and the skin physical properties were measured. After 5 weeks, skin responses to the external stress of 1% (w/v) SLS (sodium lauryl sulphate) irritation and erythema by UV were measured. Skin colour and skin UV response were not altered by the pH. However, on the C-applied site (pH 8) the transepidermal water loss of stratum corneum (SC) increased significantly, the water content increased and desquamation decreased, respectively, and the SLS significantly impaired the skin barrier in comparison with other sites. The alkaline skin care product impaired the skin barrier after repeated application over 5-week period and the skin barrier was disrupted severely by 1% SLS exposure because SC was already impaired by alkaline pH and sensitive to external stress. This suggests that the pH of daily skin care products is very important for skin barrier homeostasis.

Our observations indicate that skin sensitivity differs considerably between women from different parts of China and South Korea. We recommend that these differences be considered during the development of cosmetic products in these countries.

Striae distensae are skin lesions which occur in rapid tissue expansion such as pregnancy, puberty, obesity as well as in medical use of corticosteroids. They appear as parallel inflammatory streaks aligned perpendicular to the direction of skin tension. In early stage, striae distensae are raised and erythematous (rubra), but they develop into chronic phase of hypopigmented, atrophic scars (alba). Measurements of striae distensae are essential to research the aetiological mechanism or to evaluate the clinical efficacy of treatments. The objective of this study was to investigate skin biophysical properties of striae distensae in vivo. Volunteers with striae rubra or alba on different locations of the body participated. Noninvasive measurements including skin surface structure, skin lightness, and hydration were conducted on striae distensae and compared to adjacent normal skin. As a result, striae alba had a wrinkled, atrophied structure, and the wrinkle depth and depressed volume were higher than normal skin. Striae rubra were slightly raised, and the volume of elevation could be measured quantitatively. As for the blob pattern of skin surface, striae distensae were more anisotropic and directional, and showed more irregular polygonal pattern of each segmented unit than normal skin. The average area of each blob was higher and the number of blob per unit area was less than normal skin. In addition, striae alba showed increased lightness (L*) and decreased redness (a*), whereas striae rubra had decreased L* and increased a* when compared to normal skin. Difference in skin hydration was not detected between striae distensae and adjacent skin. In conclusion, we measured the various skin biophysical properties of striae distensae including rubra and alba, and found out significant differences in skin color and various surface structures when compared to the adjacent normal skin. These features were proved to be reliable evaluation parameters for striae distensae severity. 1341 CXCL12 enhances migration of Multilineage-differentiating stress enduring cells and induces Wnt3a to maintains cell plasticity of fibroblasts

Ginsenosides, the major active ingredient of ginseng, show a variety of biomedical efficacies such as anti‐aging, anti‐oxidation and anti‐inflammatory activities. To understand the effects of 20‐O‐β‐D‐glucopyranosyl‐20 (S)‐protopanaxadiol (compound K), one of the major metabolites of ginsenosides on the skin, we assessed the expression level of approximately 100 transcripts in compound K‐treated HaCaT cells using cDNA microarray analysis. Compound K treatment induced differential expression of 40 genes, which have been reported to be involved in the organization of the structure of the extracellular matrix as well as defense responses in human skin cells. One of the most interesting findings is a two‐fold increase in hyaluronan synthase2 (HAS2) gene expression by compound K. We found that change in expression of HAS2 gene represents a specific response of HaCaT cells to compound K because hyaluronan synthase 1,3 was not changed by treatment with compound K. We also demonstrated that the compound K effectively induced hyaluronan synthesis in human skin cells and hairless mouse skin. A human clinical study indicated that topical application of compound K containing oil‐in‐water emulsion showed improvement of xerosis, wrinkle and fine lines in the aged skin. We concluded that compound K has anti‐aging effects by the induction of HAS2 gene expression and following hyaluronan synthase.

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