Current views on non-invasive in vivo determination of physiological parameters of the stratum corneum using confocal Raman microspectroscopy

Confocal Raman microspectroscopy is widely used in dermatology and cosmetology for analysis of the concentration of skin components (lipids, natural moisturizing factor molecules, water) and the penetration depth of cosmetic/medical formulations in the human stratum corneum (SC) in vivo. In recent years, it was shown that confocal Raman microspectroscopy can also be used for non-invasive in vivo depth-dependent determination of the physiological parameters of the SC, such as lamellar and lateral organization of intercellular lipids, folding properties of keratin, water mobility and hydrogen bonding states. The results showed that the strongest skin barrier function, which is primarily manifested by the orthorhombic organization of intercellular lipids, is provided at ≈20–40% SC depth, which is related to the maximal bonding state of water with surrounding components in the SC. The secondary and tertiary structures of keratin determine water binding in the SC, which is depth-dependent. This paper shows the technical possibility and advantage of confocal Raman microspectroscopy in non-invasive investigation of the skin and summarizes recent results on in vivo investigation of the human SC.

Metformin Promotes the Hair-Inductive Activity of Three-Dimensional Aggregates of Epidermal and Dermal Cells Self-Assembled In Vitro

Introduction: Although it has been reported that the anti-diabetic drug metformin has multiple extra-hypoglycemic activities, such as anti-oxidation, anti-aging and even anti-tumor, topical metformin also can induce hair regeneration, but the precise mechanism involved in that process is still unclear. Objectives: To assess the effect of metformin on hair growth in a mouse hair follicle reconstitution model generated by in vitro self-assembled three-dimensional aggregates of epidermal and dermal cells (3D aggregates). Methods: Epidermal cells and dermal cells were isolated and cultured from the mouse skin of fifty C57BL/6 mouse pups (1-day-old). For tracing the distribution of dermal cells during the self-assembly process of 3D aggregates, the dermal cells were labeled with Vybrant Dil cell-labelling solution and mixed with epidermal cells at 1:1 ratio. Formed 3D aggregates were treated with 10 mM metformin and then were grafted into recipient BALB/c nude mice. The biomarkers (HGF, CD133, ALP, β-catenin and SOX2) associated with the hair-inductive activity of dermal cells were detected in the grafted skin tissues and in cultured 3D aggregates treated with metformin using immunofluorescent staining, quantitative real-time RT-PCR (qRT-PCR), and western blotting. Furthermore, the expression levels of CD133 were also examined in dermal cells with different passage numbers using qRT-PCR and western blotting. Results: Metformin directly stimulates the activity of alkaline phosphatase (ALP) of cultured 3D aggregates, upregulates both the protein and mRNA expression levels of molecular markers (HGF, CD133, ALP, β-catenin and SOX2) and improves the survival rate of reconstituted hair follicles. Moreover, we also found that metformin increases the expression of CD133 in dermal cells thus maintaining their trichogenic capacity that would normally be lost by serial subculture. Conclusions: These results suggest that metformin can promote hair follicle regeneration in vitro through up-regulation of the hair inductive capability of dermal cells, warranting further evaluation in the clinical treatment of male or female pattern hair loss.

Melanogenesis markers expression in premature graying of hair- a cross-sectional study

Background: Studies on mice and aging human hair follicles provide compelling evidence that graying of hair results from premature differentiation of Melanocyte stem cells (MeSC) in the niche/bulge. Objective: To analyze whether differentiation of melanocyte stem cells is responsible for premature graying of hair (PGH). Methods: Twenty- five patients of PGH (n=25) attending dermatology department were recruited. Five unpigmented and five pigmented hairs were obtained per patient by separating individual follicles by 1 mm punch biopsies. The hairs were dissected at a distance of 2 mm from the bulb to separate the stem cells (upper segment) (US) from the melanocytes (lower segment) (LS). RNA was extracted from hair follicle segments US and LS, and expression of GP100, Tyrosinase (TYR) and Tyrosinase related protein-1 (TYRP1) genes was quantified using Qiagen one-step RT-PCR kit. Results: We found melanogenesis gene expression in both temporary (US) and permanent (LS) segments of unpigmented and pigmented hair follicles. When compared between the US and LS of white hair, the expression of TYR and GP100 was much higher in US than LS, suggestive of melanogenesis in the bulge. Similarly, when compared between white and black US, the expression of all three genes was higher in white US than black US, although not statistically significant. Limitations: Low samples size and lack of data pertaining to the expression of genes at protein level are the limitations of current study. Conclusion: Even though this pilot study data yielded key information about the expression of GP100, TYR and TYRP-1 at mRNA level, further studies quantifying the expression of these genes at protein level are needed to provide additional clues to further address the results in detail.

Use of Cosmetic Products in Real Life by Women with Facial Sensitive Skin: Results from an Exposure Study and Comparison with Controls

Triggering factors of sensitive skin are supposed to be physical, chemical (cosmetics, water, and pollutants), and occasionally psychological (stress). A recent meta-analysis showed that the most important triggering factor declared by subjects is the use of cosmetics. This study was designed to compare the consumption of cosmetic products in women with sensitive skin and controls. After a dermatological examination, women between the ages of 18 and 65 years with or without sensitive skin were recruited. They completed different questionnaires about the presence of sensitive skin and use of 28 cosmetics that could be applied on the face. The amount per application was recorded for all products used at least once a week on the face. In total, 160 women were included, with a mean age of 41 ± 13 years. Two groups of 40 women were created based on the sensitive scale (SS-10 score), with the lowest SS-10 scores (nonsensitive skin group) and the highest SS-10 score (sensitive skin group). The number of products used daily was similar in the 2 groups. Women with sensitive skin were significantly more frequent users of liquid soap/soap-free gel cleansers than those without sensitive skin (70 vs. 43%). There was no difference concerning the frequency of use of products in the 2 groups. Concerning the amount of product used by application, women with sensitive skin used twice as much cream per application compared with the women without sensitive skin: 511 ± 438 μg versus 290 ± 203 μg (<i>p</i> = 0.039). Concerning the composition of the cosmetic products used, the only difference concerned phenoxyethanol, which was more often present in the moisturizer of women without sensitive skin (66.7%) than in those with sensitive skin (32.4%) (<i>p</i> = 0.007). Women with sensitive skin were more likely to buy products recommended for sensitive skin by manufacturers. The relationship of causality between the use of cosmetics and sensitive skin cannot be established. Women with sensitive skin used different cosmetic products than women without sensitive skin. Women with sensitive skin used a higher amount of moisturizer, used products recommended for sensitive skin, and bought more cosmetic products at pharmacies than supermarkets. We hypothesized that subjects with sensitive skin are looking for products that improve the sensation of skin sensitivity.

The Response and Tolerability of a Novel Cold Atmospheric Plasma Wound Dressing for the Healing of Split Skin Graft Donor Sites: A Controlled Pilot Study

<b><i>Introduction:</i></b> Cold atmospheric plasma (CAP) has positive effects on wound healing and antimicrobial properties. However, an ongoing challenge is the development of specific modes of application for different clinical indications. <b><i>Objectives:</i></b> We investigated in a prospective pilot study the response and tolerability of a newly developed CAP wound dressing for the acute healing of split skin graft donor sites compared to conventional therapy. <b><i>Methods:</i></b> We applied both treatments to each patient (<i>n</i> = 10) for 7 days and measured 4 parameters of wound healing every other day (i.e., 1,440 measurements) using a hyperspectral imaging camera. Additionally, we evaluated the clinical appearance and pain levels reported by the patients. <b><i>Results:</i></b> The CAP wound dressing was superior to the control (<i>p</i> &#x3c; 0.001) in the improvement of 3 wound parameters, that is, deep tissue oxygen saturation, hemoglobin distribution, and tissue water distribution. CAP was well tolerated, and pain levels were lower in CAP-treated wound areas. <b><i>Conclusion:</i></b> CAP wound dressing is a promising new tool for acute wound healing.