A Harungana madagascariensis extract with retinol-like properties - Gene upregulations and protein expressions in human fibroblasts and skin explants

OBJECTIVE

Because they limit, even reverse, age-induced skin alterations, retinoids became a staple in cosmetology. However, their use can result in undesired secondary effects and there is a demand for natural sources of compounds with retinoid like effects. A preliminary screening identified a Harungana madagascariensis plant extract (HME) as possibly inducing genes stimulated by retinol. We analysed its effect on gene and protein expression, comparing it to retinoids.

METHODS

Gene expression was analysed by real-time qPCR on RNA from isolated fibroblasts subjected to retinol or the plant extract for 6, 48 or 96 hours. Skin markers were quantified in fibroblasts cultured with retinol or extract containing medium, and UV-aged skin explants subjected to topical applications of creams containing retinol, retinaldehyde or HME.

RESULTS

Real-time qPCR show that the extract induced all RARs and RXRs, even RXRγ that was not induced by retinol. Eighty-eight percent of the 25 early retinoid reaction genes induced by a concentration of retinol are induced by the extract. In fibroblasts, only the extract increased collagen III labelling, while collagen I and fibronectin labelling are increased by retinol and the extract, with higher levels for the extract. When topically applied to UV-aged skin explants, only the cream containing the HME led to increased labelling of CRABP1 in the epidermis. CRABP2 and Ki67 are induced by all three creams and no effect was detected on RXRs. In the dermis the extract containing cream increased CRABP2, total collagen, procollagen I and collagen I while creams with retinol or retinaldehyde only affected some of these proteins.

CONCLUSIONS

The HME induces an overall retinol-like gene induction profile in isolated fibroblasts and retinoid-like stimulation of protein synthesis in both isolated fibroblasts and photoaged skin explants.

SpectraCam® : A new polarized hyperspectral imaging system for repeatable and reproducible in vivo skin quantification of melanin, total hemoglobin, and oxygen saturation

BACKGROUND

An accurate way to determine skin pigmentation is to acquire the spectral reflectance of a skin sample and to quantify chromophores by reverse calculation from physical models of light propagation. Therefore, we tested a new hyperspectral imaging device and software suite, the SpectraCam^® system, and evaluated its accuracy to quantify skin chromophores.

METHODS

Validation of the SpectraCam^® system was performed by, firstly, comparing the known and the acquired reflectance spectra of color phantoms. Repeatability and reproducibility were then evaluated by two operators who performed acquisitions at different time points and compared the acquired reflectance spectra. The specificity of the system was tested by quantitative analysis of single chromophore variation models: lentigo and pressure relief. Finally, we tested the ability of the SpectraCam^® system to detect variations in chromophore in the eye region due to the daily application of a new anti-dark circle cosmetic product.

RESULTS

The SpectraCam^® system faithfully acquires the reflectance spectra of color phantoms (r² >0.90). The skin reflectance spectra acquired by different operators at different times are highly repeatable (r² >0.94) and reproducible (r² >0.99). The SpectraCam^® system can also produce qualitative maps that reveal local variations in skin chromophore or underlying structures such as blood vessels. The system is precise enough to detect melanin variation in lentigo or total hemoglobin and oxygen saturation variations upon pressure relief. It is also sensitive enough to detect a decrease in melanin in the eye region due to the application of an anti-dark circle cosmetic product.

CONCLUSION

The SpectraCam^® system proves to be rapid and produces high-resolution data encompassing a large field of view. It is a robust hyperspectral imaging system that quantifies melanin, total hemoglobin, and oxygen saturation and is well adapted to cosmetic research.

Evaluation of the cellulite using a thermal infra-red camera

BACKGROUND

Cellulite is usually related to alterations of the microcirculation. Measuring the skin temperature is a mean to assess the skin microvascular plexus.

OBJECTIVES

A three-step clinical study was performed in order to develop and to validate the use of an infrared thermal camera for measuring cellulite severity.

METHODS

Thermal images of the thigh were recorded and processed to quantify the thermal homogeneity. The proposed protocol was then validated in three steps. Firstly, the parameters which could influence the skin temperature were identified throw a design of experiment. Secondly, the repeatability and reproducibility of the method was estimated (five subjects, four investigators and five experiments). Finally, thermal images and clinical grading of cellulite was performed on 39 women (21-68 years old), and the correlation between these methods was assessed.

RESULTS

All parameters describing the thermal homogeneity were found repeatable and reproducible. The strongest correlation between thermal results and the clinical assessment were observed for Sa (R = 0.53, P < 0.05), Sz (R = 0.53, P < 0.05), Sq (R = 0.54, P < 0.05) and the surface of hot pixels (R = 0.42, P < 0.05).

CONCLUSION

These results show that the thermal camera imaging is a repeatable and reproducible method that can be used to assess the severity of cellulite.

A novel anti-ageing mechanism for retinol: induction of dermal elastin synthesis and elastin fibre formation

Dermal elastic fibres are extracellular matrix protein complexes produced by fibroblasts and involved in skin elasticity. Elastin fibres decrease with age as a result of reduced synthesis and increased degradation, resulting in skin sagging and reduced skin elasticity. In this study, we show that retinol (ROL), known to enhance dermal collagen production, is also enhancing elastin fibre formation. ROL induced elastin gene expression and elastin fibre formation in cultured human dermal fibroblasts. Topical treatment of cultured human skin explants with a low dose (0.04%) of ROL increased mRNA and protein levels of tropoelastin and of fibrillin-1, an elastin accessory protein, as documented by QPCR and immunohistochemistry staining. Luna staining confirmed the increased elastin fibre network in the ROL-treated skin explants, as compared with untreated controls. These data demonstrate that ROL exerts its anti-ageing benefits not only via enhanced epidermal proliferation and increased collagen production, but also through an increase in elastin production and assembly.

Development and validation of a three-dimensional finite element model of the face

A detailed three-dimensional finite element model of the face is presented in this paper. Bones, muscles, skin, fat, and superficial muscoloaponeurotic system were reconstructed from magnetic resonance images and modeled according to anatomical, plastic, and reconstructive surgery literature. The finite element mesh, composed of hexahedron elements, was generated through a semi-automatic procedure with an effective compromise between the detailed representation of anatomical parts and the limitation of the computational time. Nonlinear constitutive equations are implemented in the finite element model. The corresponding model parameters were selected according to previous work with mechanical measurements on soft facial tissue, or based on reasonable assumptions. Model assumptions concerning tissue geometry, interactions, mechanical properties, and the boundary conditions were validated through comparison with experiments. The calculated response of facial tissues to gravity loads, to the application of a pressure inside the oral cavity and to the application of an imposed displacement was shown to be in good agreement with the data from corresponding magnetic resonance images and holographic measurements. As a first application, gravimetric soft tissue descent was calculated from the long time action of gravity on the face in the erect position, with tissue aging leading to a loss of stiffness. Aging predictions are compared with the observations from an "aging database" with frontal photos of volunteers at different age ranges (i.e., 20-40 years and 50-70 years).

Misuse of suncare products: Toward a protocol for sunscreen application

1548

Background: Increasing awareness of the UV-induced skin carcinogenesis has led to a significant demand for improved photo-protection both in UVB and UVA ranges. Sunscreen products are subjected to strict efficacy controls relying on standardized UV protection measurements and are widely recommended by oncologists and dermatologists in order to prevent skin cancers. However, sunscreen effectiveness depends not only on the quality of the product itself but also on the way people use it in real life. Misuse of suncare products might even lead to opposite deleterious effects. We conducted three successive studies in order to validate a sunscreen application protocol. Methods: Three studies were done on healthy volunteers who were asked to apply a sunscreen product as they usually do without any guidance or following a protocol of product application. Spontaneous application was evaluated in the first study (N = 17). Two application protocols were successively tested (N = 31) where both quantity of product and quality of sunscreen spreading were assessed (without and with the protocol) by three independent evaluators using photos taken under UVA light. Results: Spontaneous application of sunscreen resulted in an heterogeneous application of only 27% of the quantity recommended following COLIPA guidelines. Two application protocols giving practical informations concerning the quantity and the way to spread the product on each body anatomical sites were successively evaluated. Use of the application protocols improved both the quantity of suncare product and the homogeneity of product spreading with an highly significant improvement resulting from the use of the final and improved application protocol tested in the third study (p < 0.02). Conclusions: The correct use of sunscreens is a public health issue about which the public still requires considerable education. We propose that, in addition to the usual photoprotection recommendations (i.e., clothing protection and avoidance of middle day exposure), population should be trained to use validated protocols for sunscreen application.

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Influence of facial skin attributes on the perceived age of Caucasian women

BACKGROUND AND OBJECTIVE

The facial appearance of a person does not always reflect the chronological age; some people look younger or older than they really are. Many studies have described the changes in skin properties (colour, wrinkles, sagging, micro relief, etc.) with age, but few of them have analysed their influence on the perceived age. The primary objective of this study was to assess the contribution of individual skin attributes of the face on the perceived age of Caucasian women. Secondary objectives were to assess the influence of age and gender of graders with regard to the age perception.

SUBJECTS AND METHOD

A random sample of 173 subjects of 20 to 74 years of age was taken from a database of more than 5000 healthy Caucasian women. A trained grader performed visual assessment of facial skin attributes (using a visual analogue scale), and a front face photograph was taken from each subject. Photographs were shown to 48 graders (20 men and 28 women, aged 22-64 years) who were asked to estimate the age of the subjects. Graders were classified as young (less than 35 years), middle age (35-50 years) and seniors (older than 50 years). Partial Least Square regression models were built to predict the chronological and the perceived age from the measured facial individual attributes. The contribution of each attribute within the regression model enabled to measure the relevance of this attribute with regards to age prediction.

RESULTS

The eye area and the skin colour uniformity were the main attributes related to perceived age. For age prediction, older graders' estimations were more driven by lips border definition shape and eyes opening, whereas younger graders' (older than 50 years) estimations were more driven by dark circles, nasolabial fold and brown spots. There were statistically significant differences in graders' age perception between gender and among age ranges. Our findings suggest that female graders are more accurate than male, and younger graders (under 35 years) are more accurate than older (over 50 years) to predict Caucasian women age from facial photographs.

CONCLUSIONS

Different skin attributes influence the estimation of age. These attributes have a different weight in the evaluation of the perceived age, depending on the age and of the observer. The most important attributes to estimate age are eyes, lips and skin colour uniformity.