Transdermal delivery systems have been intensively studied over the past 2 decades, with the focus on overcoming the skin barrier for more effective application of pharmaceutical and cosmetic products. Although the cosmeceutical industry has made a substantial progress in the development and incorporation of new and effective actives in their products, the barrier function of the skin remains a limiting factor in the penetration and absorption of these actives. Enhancement via modification of the stratum corneum by hydration, acting of chemical enhancers on the structure of stratum corneum lipids, and partitioning and solubility effects are described. This review summarizes the advances in the development and mechanisms of action of chemical components that act as permeation enhancers, as well as the advances in appropriate vehicles, such as gels, emulsions, and vesicular delivery systems, that can be used for effective transdermal delivery.

Background: Recently, investigators have been trying to apply the by-products as well as stem cells themselves to various fields such as pharmaceuticals, medical devices, quasi-drug, cosmetis, etc. We aimed to comfirm the anti-senescence effect of 3D cultured adipose tissue-derived mesenchymal stem cell–conditioned medium (3D cultured ADMSCs-CM) and develop them as cosmetic raw materials for anti-aging purposes. Methods: We investigated the effect of 3D cultured ADMSCs-CM on collagen production and performed efficacy tests to evaluate the effect of a cream-based cosmetic product containing the medium using various methods, such as dermal density, skin moisture retention, and so on. Results: Analysis of the effect of ADMSCs-CM on skin regeneration and production of collagen showed 1.5-fold (2D cultured ADMSCs-CM) and 2.5-fold (3D cultured ADMSCs-CM) increase in expressions of procollagen and 4-fold (2D cultured ADMSCs-CM) and 5-fold (3D cultured ADMSCs-CM) increase in the expression of collagen compared with control. In addition, related gene expression was also increased. We conducted a human skin test using a cream-based product containing 3D cultured ADMSCs-CM. In skin texture assessment, skin roughness decreased by 11.94% at the application site and 3.74% at the non-application site after 3 weeks of use. Compared with before cream use, after 2 and 4 weeks of substance use, the skin elasticity analysis showed an increase in the elasticity value by 5.97% and 9.34%, respectively, and the improvement of small wrinkles was 5.01% and 6.23%, respectively. After 2 and 4 weeks of test substance use, dermal density analysis showed 6.97% and 12.53% increase, respectively. Skin moisture retention analysis showed skin moisture maintained at 543.60% and 452.38%, respectively, immediately after one-time use and after 20 min of cool breeze exposure compared with before application of the test substance. Conclusions: As raw material for cosmetic products, 3D cultured ADMSCs-CM prevented skin aging by promoting collagen production, restoring damaged skin, and increasing dermal density. Therefore, 3D cultured ADMSCs-CM can be widely applied to maintain and improve skin condition.

Glucose metabolism is a key metabolic pathway that orchestrates cellular homeostasis by generating ATP, nucleotides, and amino acids. Abnormal glucose signaling has been found in many diseases including cancers and inflammatory diseases. According to recent report, glycolysis contributes to pathogenesis of psoriasis and ablation of Glut1 attenuates animal models of psoriasis. While we were screening a molecular target for atopic dermatitis, we found the levels of glucose transporters including Glut1 (SLC2a1) and Glut3 (SLC2a3) are highly expressed in skin biopsies of dermatitis patients from multiple datasets. We demonstrated that administration of 2-deoxy-d-glucose (2DG) ameliorates animal models of 12-o-tetradecanoylphorbol-13-acetate (TPA) and oxazolone induced dermatitis using morphological and histological analysis. These results suggest that inhibition of glucose metabolism ameliorates dermatitis in animal models.

Cellular metabolism is one of the crucial factors to regulate epigenetic landscape in various cells including immune cells, embryonic stem cells and hair follicle stem cells. Dermal papilla cells (DP) interact with epithelial stem cells to orchestrate hair formation. Here we show that active DP exhibit robust aerobic glycolysis. We observed decrease of signature genes associated with hair induction by DP in presence of low glucose (2 mM) and glycolysis inhibitors. Moreover, hair shaft elongation was attenuated by glycolysis inhibitors. Interestingly, excessive glucose is able to increase the expression of hair inductive genes and elongation of hair shaft. We also observed glycolysis-mediated histone acetylation is increased and chemical inhibition of acetyltransferase reduces expression of the signature genes associated with hair induction in active DP. These results suggest that glucose metabolism is required for expression of signature genes associated with hair induction. This finding may be beneficial for establishing and maintaining of active DP to generate hair follicle in vitro.

6-Shogaol is a constituent of ginger that imparts the pungent flavor and a hydrolysis product of gingerols. This study aimed to investigate the potential of 6-shogaol as a natural cosmetic raw material by examining its anti-apoptotic, antioxidant, and anti-aging effects in human dermal fibroblasts (HDFs). Cell cycle analysis, ApoAlert caspase-3 colorimetric assay, and qRT-PCR analysis to assess the anti-apoptotic effects and qRT-PCR to measure the expression of SOD, CAT, and NRF2 to assess the antioxidant effects of 6-shogaol were performed; dichlorofluorescein diacetate was used to measure reactive oxygen species (ROS). Anti-aging effects were examined using qRT-PCR analysis to measure the expression of COL1A1 and MMP1 as well as using an SA-beta Gal assay. 6-Shogaol showed no toxicity in HDFs at concentrations 5, 10, and 20 μM, and increased cell viability in a dose-dependent manner. qRT-PCR analysis showed that 6-shogaol pre-treatment downregulated the expression of BAX, caspase 3, and caspase 9 in a dose-dependent manner. Sub-G1 cells, which are rarely found in the normal cell cycle, decreased in a concentration-dependent manner after 6-shogaol pre-treatment, and treatment ameliorated the ROS increase observed upon UVA (10 J/cm²) irradiation of HDFs and the expression of NRF2 increased in a dose-dependent manner. In addition, the expression of SOD and CAT, which are typical cellular antioxidant enzymes, increased. 6-Shogaol also increased the expression of COL1A1, the gene type 1 collagen in HDFs, and decreased the expression of MMP1, which codes for an enzyme that degrades type 1 collagen, thus promoting collagen formation. These results suggest that 6-shogaol can be used as a cosmetic material for preventing skin aging because of the cytoprotective, anti-apoptotic, and antioxidant effects in the HDFs identified in this study.