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Presentations at the IFSCC International Congress

The R&D Center of the POLA Chemical Industries, Inc. presented five academic papers at the 26th IFSCC International Congress in Buenos Aires.

The R&D Center of the POLA Chemical Industries, Inc. presented the following five academic papers at the 26th IFSCC International Congress in Buenos Aires (September 20–23, 2010).

The five articles presented at the congress by the POLA Chemical Industries, Inc. included three oral and two poster presentations. Only papers that passed a rigorous screening were allowed to be presented as an oral presentation. Here are the five presentations.

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1. A Novel Cross-Section Analysis Method and Its Application in Designing Ideal Cosmetic Films (Oral Presentation)

It was very hard to prepare accurate cross-sections of cosmetic films by using a conventional microtome.
Because a microtome processes a cross-section by physical force, the structure of cosmetic films is broken during the preparation of a cross-section of the film.
In order to avoid the collapse of the structure, we newly introduced a cross-section polishing (CP) method into the conventional preparation of cross-sections of cosmetic films.
The CP method did not cause the structural collapse of cosmetic films and was demonstrated to be a highly effective and valuable process for the preparation of cross-sections of cosmetic films.
We then applied the CP method to sunscreen development.
We selected fatty acid or silica-treated TiO2 as conventional general-purpose inorganic ultraviolet (UV) filters, prepared a cross section using the CP method, and then analyzed the cross section using SEM/EDS.
The accurate cross-section analysis using the CP method revealed that the TiO2 of the conventional TiO2 UV filters did not disperse uniformly in the cosmetic film.
In order to maximize the UV-protection effect, it is essential to improve the dispersion state, that is, to make UV filters disperse uniformly in sunscreen films.
Therefore, we developed sodium polyacrylate-treated TiO2 (P-TiO2), a new inorganic UV filer, which remains in a more uniform dispersion state in a cosmetic film.
The cross-section of P-TiO2 was prepared by the CP method and then analyzed by SEM/EDS. The results showed that the TiO2 was uniformly dispersed from the upper to lower layers of the cosmetic film.
It was also revealed that the distribution of carbon, the polyacrylic acid backbone, was larger in the superficial layer of the cosmetic film.
This shows that the cosmetic films after drying are hydrophobic, though P-TiO2 is a water-dispersing element.
Finally, we made a preparation containing P-TiO2 and evaluated its SPF in vivo.
Our results revealed that the preparation had a high UV-protection effect (UV-protection effect was maximized) and that it was highly water resistant despite its oil-in-water state.

 

Makeup Products R&D Department
Yoshito Hongo

2. Thermo-Sensitive Barrier: Importance of Transient Receptor Potential Vanilloid 4 (TRPV4) in Epidermal Barrier Function (Oral Presentation)

The human body’s core temperature is constant, while skin temperature significantly changes due to the effects of ambient temperature. However, the mechanism, by which such temperature changes directly affect skin physiology, has been poorly understood. The present study has revealed the mechanism by which temperature acts directly on skin physiology by the temperature-sensitive ion channel TRPV4 present in the epidermal cells. It has been found that TRPV4 detects warm temperature to promote calcium influx into the cells, is involved in the formation of a cell-to-cell adhesion structure (adherens junction and tight junction) by the activation of Rho, and regulates the skin barrier function. We are convinced that these findings will allow us to open a new field, “temperature,” and encourage the development of new skin-care materials based on skin temperature and the functions of temperature-sensitive ion channels.

 

Cutaneous Drug Research Department
Naoko Kida

3. Development of Make-up Products which Reproduce the Radiance from the Inside of Skin (Oral Presentation)

Pearl shells and some other seashells beautifully shine from within because of their layered structure. Based on the mechanism of shells’ radiance, we decided to instantaneously reproduce skin radiance from within by using makeup cosmetics. We examined the relationship between skin radiance from within and stratum corneum structure, focusing on the layered structure of skin (the stratum corneum). First, we performed sensory analysis of radiance, measured the ratio of scattered light—proportion of the amount of scattering light inside the skin to the total amount of reflected light, and observed the state of the stratum corneum for evaluating skin radiance from within. We found that there was a significant correlation among the regularity of the stratum corneum, results of the sensory analysis of skin radiance from within, and the scattered light ratio. Then, the ratio of scattered light of existing makeup powder was measured, revealing that the ratio was 49.2–82.2%, which is comparable to or less than that for irregular conditions of the stratum corneum. Therefore, we set out to develop a new powder capable of reproducing radiance from the inside of the skin. The design concept was based on a regular layered structure. The new powder we produced has alternating layers of nylon and polyester with the refractive index of 1.53 and 1.58, respectively. The ratio of scattered light of the new powder was higher (90.16%) in comparison to that of the regular stratum corneum. We finally produced a makeup cosmetic material containing the new powder and evaluated its efficacy in vivo. The ratio of scattered light was 84.9% on subjects’ bare skin without cosmetics and up to 91% after application of the new makeup cosmetics, with higher radiance observed in the finished makeup. The present study demonstrates that innate skin radiance from within could be improved through developing makeup cosmetics containing the new powder capable of reproducing skin radiance from within and improving the stratum corneum structure.

 

Makeup Products R&D Department
Masae Iida

4. Improving for Dry Skin through Lamellar Structure Reconstruction in the Lower Stratum Corneum (Poster Presentation)

There are many possible causes of dry skin, and to date, various approaches have been proposed to improve dry skin. The findings from recent skin histological studies have suggested that the intercellular lipid layer of the stratum corneum of dry skin is more disordered than that of normal skin. We therefore assumed that reconstructing an intercellular lipid lamellar structure in the lower stratum corneum could deal with dry skin more effectively compared with the conventional improvement approaches focusing on obstruction of the stratum corneum surface. To prove the hypothesis, we used vesicles constructed using amphiphiles. Vesicles have higher stratum corneum permeability, and depending on the environment, are capable of undergoing phase transition to planar lamellae, which are similar to an intercellular lipid lamellar structure. Using these vesicle properties, we aimed to prepare vesicles capable of undergoing phase transition to planar lamellae under the moisture environment of the stratum corneum region (40 wt%). In a high-moisture environment with a moisture content of 40 wt%, conventional amphiphiles do not form vesicles undergoing phase transition to planar lamellae. In the present study, we designed vesicles based on the amphiphiles derived from microorganisms to control the physicochemical properties of vesicles and then generated the desired product. The prepared vesicles were applied to a model of dry skin and were observed using a transmission electron microscope. The results demonstrated that a planar lamella structure had been reconstructed in the lower stratum corneum region, showing a phase transition of vesicles, which we intended to produce. Finally, the lotion containing these vesicles was continuously applied to subjects with dry skin for two weeks to evaluate its efficacy. The results revealed that dry skin was improved in a shorter time compared to the conventional approaches for improving dry skin. This means that the approach to reconstruction of lamella structure in the lower stratum corneum is effective for improvement of dry skin.

 

Skin Care Products R&D Department
Yuuichiro Takeyama

5. A New Look at Skin Aging: Advanced Glycation End Products (AGEs) in the Stratum Corneum (Poster Presentation)

Skin surface morphology and physical properties deteriorate with aging. Although skin texture can affect the impression of aged skin, the factors related to its morphology have remained unclear. One of the factors possibly related to changes in skin texture would be the mechanical properties of the stratum corneum. Advanced AGEs are known to reduce the elasticity and plasticity of proteins. However, most studies for AGEs in skin have focused on the dermis but not on the stratum corneum. The present study aims to investigate how AGEs in the stratum corneum affect skin surface morphology and physical properties. We measured the asperity of the surface layer of the skin of the cheek (indicator of asperity of texture), isotropy of surface morphology (indicator of texture flow), and plasticity of the surface layer of the skin and detected AGEs in the stratum corneum by immunostaining. The results revealed that asperity of the surface layer of the skin was lower or absent when the plasticity of the surface layer of the skin was lower, isotropy was low, and texture flow occurred. We then found AGEs in the stratum corneum; their amount was positively correlated with reduction in plasticity of the surface layer of the skin and was negatively correlated with asperity of the surface layer of the skin and isotropy. In addition, UVB rapidly promoted the formation of AGEs in the stratum corneum. Taken together with these data, it appears that AGEs in the stratum corneum reduce the plasticity of skin and affect the state of texture and that UVB relates to the formation of AGEs in the stratum corneum. Therefore, AGEs in the stratum corneum is considered to be a cause of the impression of aged skin and taking care of AGEs in the stratum corneum would be important to prevent skin aging.

 

Cutaneous Drug Research Department
Takamasa Gomi

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