Evaluation of sex-related changes in skin topography and structure using innovative skin testing equipment

Sex- and age-dependent skin mechanics-A detailed look in mice

Skin aging is of immense societal and, thus, scientific interest. Because mechanics play a critical role in skin's function, a plethora of studies have investigated age-induced changes in skin mechanics. Nonetheless, much remains to be learned about the mechanics of aging skin. This is especially true when considering sex as a biological variable. In our work, we set out to answer some of these questions using mice as a model system. Specifically, we combined mechanical testing, histology, collagen assays, and two-photon microscopy to identify age- and sex-dependent changes in skin mechanics and to relate them to structural, microstructural, and compositional factors. Our work revealed that skin stiffness, thickness, and collagen content all decreased with age and were sex dependent. Interestingly, sex differences in stiffness were age induced. We hope our findings not only further our fundamental understanding of skin aging but also highlight both age and sex as important variables when conducting studies on skin mechanics. STATEMENT OF SIGNIFICANCE: Our work addresses the question, "How do sex and age affect the mechanics of skin?" Answering this question is of both scientific and societal importance. We do so in mice as a model system. Thereby, we hope to add clarity to a body of literature that appears divided on the effect of both factors. Our findings have important implications for those studying age and sex differences, especially in mice as a model system.

Evaluation of the effect of several moisturizing creams using the low frequency electrical susceptance approach

Moisturizers are cosmetic compounds designed to increase the moisture content of the skin. There are many types of these products in the market making it difficult for consumers to select the most effective moisturizer according to their age and gender. Hence, the aim of this study was to evaluate the effects of different moisturizers on skin hydration as well as to figure out any dependencies of the effects of these products on age or gender-related differences. We investigated the short-term moisturizing effects of five different skin moisturizers on 60 participants by using a low frequency electrical instrument. Skin surface susceptance was recorded and compared before and after the application of moisturizers. Statistically significant differences were observed in the moisturizing effect among different types of products. However, with respect to gender and age differences, there were insignificant differences in the effects of the moisturizers. Results of this study suggest that some types of moisturizers that exist in the markets are not as effective as required, which calls for a further evaluation of the moisturizers before entering markets and offering them for sale. In addition, findings suggest that gender or age differences are perhaps not important to consider in the application of moisturizers.

Sex differences in the skin microbiome of burn scars

Sex differences are observed in various spectrums of skin diseases, and there are differences in wound healing rate. Herein, sex differences were identified for the newly healed skin microbiome of burn patients. Fifty-two skin samples (26 normal skin, 26 burn scars) were collected from 26 burn patients (12 male, 14 female) and microbiota analysis was performed. The correlation between skin microbiota and biomechanical properties of burn scars was also investigated. There were no significant differences in clinical characteristics between male and female patients. Considering the biomechanical properties of burn scars and normal skin around it performed before sample collection, the mean erythema level of men's normal skin was significantly higher than that of women, whereas the mean levels of melanin, transepidermal water loss and skin hydration showed no significant sex differences. The erythrocyte sedimentation rate was significantly higher in females than that in males. Alpha diversity showed no significant differences between normal skin and burn scars in the male group. However, the scar was significantly higher than that of normal skin in the female group. Microbial network analysis revealed that the male group had more complex microbial network than the female group. Additionally, in the male group, the edge density and clustering coefficient were higher in burn scars when compared to normal skin, than the female group. There were sex differences in the results of microbiome of normal skin and burn scars. Some of the altered microbiota have been correlated with the biomechanical properties of burn scars. In conclusion, sex difference in the burn scar microbiome was confirmed. These results suggest that burn treatment strategies should vary with sex.

Sex- and Age-dependent Skin Mechanics - A Detailed Look in Mice

Skin aging is of immense societal and, thus, scientific interest. Because mechanics play a critical role in skin's function, a plethora of studies have investigated age-induced changes in skin mechanics. Nonetheless, much remains to be learned about the mechanics of aging skin. This is especially true when considering sex as a biological variable. In our work, we set out to answer some of these questions using mice as a model system. Specifically, we combined mechanical testing, histology, collagen assays, and two-photon microscopy to identify age- and sex-dependent changes in skin mechanics and to relate them to structural, microstructural, and compositional factors. Our work revealed that skin stiffness, thickness, and collagen content all decreased with age and were sex dependent. Interestingly, sex differences in stiffness were age induced. We hope our findings not only further our fundamental understanding of skin aging but also highlight both age and sex as important variables when conducting studies on skin mechanics.

A Systematic Review of the Efficacy of Microfocused Ultrasound for Facial Skin Tightening

Objective: to systematically review the efficacy of microfocused ultrasound (MFU) for facial skin tightening. Methods: A systematic search was performed (Pubmed, Embase) to assess the efficacy of single MFU treatments for facial skin tightening. Eligible studies included randomised controlled trials, controlled trials, cohort studies and case series (n ≥ 10). Objective and subjective outcomes were assessed. Results: A total of 693 studies were identified of which 16 studies were eligible. All the studies involved female patients. MFU is capable of tightening the skin, as observed in studies measuring the results of brow lifts (0.47−1.7 mm) and submental lifts (measured as a 26−45 mm2 reduction in the submental area on lateral photographs). Data from the Global Aesthetic Improvement Scale (GAIS) were pooled, and the day 90 pooled subjective investigator reported scores (IGAIS) (n = 337) showed that 92% of the patients demonstrated an improvement in skin tightening and/or in wrinkle reduction which continued up to one year. Longer-term follow-up data are not available. The patient-reported pooled scores (SGAIS) (n = 81) showed that the skin improvements were mild and continued to increase from 42% (90 days) to 53% (360 days) post-treatment. The MFU treatment was moderately painful and caused transient erythema with or without oedema. Other adverse effects were rare (2%), including dysesthesia (numbness or hypersensitivity), bruising and stinging, mandibular burns, striations and contact dermatitis. Various device settings, treatment protocols and energies were applied. Excessive skin laxity and a BMI > 30 were posed as relative contraindications for MFU treatment because positive results declined with an increase in laxity and BMI. Conclusions: MFU treatment is effective in tightening female patients’ mildly to moderately lax facial skin. Future studies should focus on objective treatment outcomes, optimising treatment regimens and male patients.

Exploring the Potential of Nannochloropsis sp. Extract for Cosmeceutical Applications

Recently, there has been emerging interest in various natural products with skin protective effects as they are recognized as safe and efficient. Microalgae have developed chemical defense systems to protect themselves against oxidative stress caused by UV radiation by producing various bioactive compounds including a number of secondary metabolites, which have potential for cosmeceutical applications. In addition, microalgae have various advantages as a sustainable source for bioactive compounds with diverse functions due to their rapid growth rate, high productivity, and use of non-arable land. In this study, we aimed to investigate the cosmeceutical potential of ethanol extract from Nannochloropsis sp. G1-5 (NG15) isolated from the southern West Sea of the Republic of Korea. It contained PUFAs (including EPA), carotenoids (astaxanthin, canthaxanthin, β-carotene, zeaxanthin, violaxanthin), and phenolic compounds, which are known to have various skin protective functions. We confirmed that the NG15 extract showed various skin protective functions with low cytotoxicity, specifically anti-melanogenic, antioxidant, skin-moisturizing, anti-inflammatory, anti-wrinkling, and UV protective function, by measuring tyrosinase inhibition activity; melanin content; DPPH radical scavenging activity; expression of HAS-2, MMP-1, and Col1A1 genes; and elastase inhibition activity as well as cell viability after UV exposure. Our results indicated that the NG15 extract has the potential to be used for the development of natural cosmetics with a broad range of skin protective functions.

Lipid Nanoparticles Loaded with Selected Iridoid Glycosides as Effective Components of Hydrogel Formulations

One possibility of improving active ingredient penetration into deeper skin layers to enhance the cosmetic product effectiveness, is the application of lipid nanoparticles. The aim of the study presented in this paper was to evaluate the potential of hydrogel formulations enriched with iridoid glycosides-loaded lipid nanoparticles. Lipid nanocarriers were produced using an emulsification-ultrasonication method based on multiple emulsions. The encapsulation efficiency was determined at the level of 89% and 77% for aucubin and catalpol, respectively. The next stage was the incorporation of the obtained dispersions of lipid nanoparticles into hydrogel formulations, followed by determination of their physicochemical properties, shelf-life stability, and application properties (in vivo tests). The introduction of lipid nanoparticles increased the stabilization of the consistency of the obtained hydrogel formulations, and was confirmed by viscosity measurements. No effect of lipid nanoparticle incorporation on shelf-life stability of the hydrogels was detected. In vivo studies showed improvements in moisture content of the epidermis, transepidermal water loss, skin topography, and macrorelief parameters. In particular, a synergistic effect of the active ingredients and lipid nanoparticles on the anti-wrinkle effect, moisturizing effect, and regeneration of the protective barrier of the stratum corneum was evidenced. The attractiveness of aucubin and catalpol as cosmetic raw materials in hydrogel formulations was evidenced, especially when the iridoid glycosides were applied in the form of lipid nanoparticles.

Identification of skin aging biomarkers correlated with the biomechanical properties

BACKGROUND

Skin aging can be described as a combination of intrinsic and extrinsic aging. Various parameters for evaluating skin characteristics have been proposed. However, an accurate biomarker for skin aging and the relationship between biomarkers and biomechanical parameters of the skin is yet to be explored.

MATERIALS AND METHODS

This study included 20 subjects by age. Skin aging was measured using non-invasive devices. Skin tissues were acquired through punch biopsy for immunohistochemistry and qRT-PCR of skin aging biomarkers, and analyzed correlation both, validated their use.

RESULTS

Biomechanical properties of skin aging decreased with age. Among the biomarkers previously reported, we found that the expression of Moesin, TXNDC5, RhoGDI, and RSU1 decreased, while that of Vimentin and FABP5 increased with age. Pearson correlation showed that the expression levels of TXNDC5, RhoGDI, RSU1, and Vimentin were significantly correlated with the results of non-invasive measurements. In addition, the expression of TXNDC5, RhoGDI, and RSU1 increased, while that of Vimentin decreased, in skin explants upon treatment with one of the anti-aging compounds, retinoic acid.

CONCLUSION

From this study, we identified practical molecular biomarkers of skin aging, TXNDC5, RhoGDI, RSU1, and Vimentin, which correlated with the skin biomechanical properties of skin aging.

Noninvasive evaluation of the influence of aucubin-containing cosmetic macroemulsion on selected skin parameters

BACKGROUND

Objective evaluation of skin condition on the basis of noninvasive methods has become obligatory and may be a good strategy for verifying the efficiency of new cosmetic active ingredients.

AIM

The aim of this study was to assess the influence of aucubin-containing cosmetic macroemulsion on skin parameters using the skin testing equipment.

PATIENTS/METHODS

The study was carried out on the group of 25 female volunteers of the mean age 27 ± 2 years. The skin parameters were measured using the following devices: Tewameter^® TM 300 (transepidermal water loss, TEWL), Corneometer^® CM 825 (skin hydration), Cutometer^® MPA 580 (skin elasticity), Visioscan^® VC 98 (skin topography), and Visioline^® VL 650 (skin macrorelief). All measurements were performed on the inner part of the left forearm.

RESULTS

The skin parameters measured revealed the beneficial influence of aucubin on TEWL and skin hydration level. The application of aucubin-enriched cream caused more significant improvements of all determined SELS parameters, in comparison with cream without it. An analogous tendency was noticed in the case of skin macrorelief parameters; the addiction of the active ingredient led to a decrease in the value of total wrinkle area and diminished the mean length and depth of single wrinkles.

CONCLUSIONS

Noninvasive methods of skin testing have provided a possibility of objective evaluation of the action of new active ingredients in cosmetic formulations. The study has proved the positive influence of aucubin on effectiveness of cosmetic macroemulsions, diminishing TEWL, increasing skin hydration level, and improving the values of SELS and skin macrorelief parameters.

Reduction of enlarged facial pore using ion-paired amino acid through enhancement in skin permeation and exfoliation: A placebo-controlled in vivo study

BACKGROUND

Serine is a hypoallergenic but inefficient chemical exfoliant. Serine paired with arginine (ion-paired amino acid, IPA) shows enhanced lipophilicity, skin permeation, and exfoliation efficacy.

AIM

This study was conducted to determine whether exfoliation using an emulsion containing IPA could reduce enlarged facial pores and improve the dermis density.

METHODS

IPA formation was validated by spectroscopic analysis. Enhanced permeability and exfoliation efficacy were evaluated ex vivo using porcine skin. In a clinical trial, healthy Korean women aged 20-49 years (mean age ± SD: 35.6 ± 8.6, n = 64) were evaluated, and the right and left sides of the cheeks were randomly chosen. An emulsion containing 4.0% IPA and placebo emulsion were applied to each side for 6 weeks. To evaluate pore sizes following treatment, the number of enlarged facial pores, inner skin structures from the stratum corneum to epidermal-dermal interface, and dermal density on each cheek of the participants were assessed.

RESULTS

IPA showed a significantly increased partition coefficient in n-octanol-water. In porcine skin, permeation of serine after 12 hour was 70% higher for the IPA than for serine alone at the same percent weight concentrations. In the clinical trial, after 6 weeks, the number of enlarged facial pores was changed by -19.317% in the IPA emulsion group (P < .001) and -2.930% in placebo emulsion group (P = .254).

CONCLUSION

Exfoliation with an IPA-containing emulsion reduced enlarged facial pores and increased the dermis density. IPA, effective mild exfoliator, can be used as a major ingredient for the cosmeceutical skincare products in the future.