Visualization of Water Distribution in the Facial Epidermal Layers of Skin Using High-Sensitivity Near-Infrared (NIR) Imaging.

Skin moisturization is an important function of cosmetics in dermatology, and acquisition of two-dimensional information about the water content of facial skin is of great interest. Near-infrared (NIR) imaging using the water OH band centered near 1460 nm has been applied to the evaluation of water in skin. However, detection of small changes in the water content of skin water is difficult using this band because of the low absorption coefficient of water at that wavelength and inadequate optical units. We developed a high-sensitivity water imaging system using strong water bands centered near 1920 nm. This system can be used for the entire face. With the water imaging system, time-dependent changes in the water content of moisturizer-treated skin and hair were visualized with high sensitivity. In this study, we performed a water distribution analysis, with the aim of understanding the water distribution in facial skin under different environmental conditions. The water imaging system combines a diffuse illumination unit and an extended-range indium-gallium arsenide NIR camera with a detection range of 1100-2200 nm. The skin water distributions for multiple subjects with different facial shapes and sizes were compared using averaged NIR image data and a mesh partition analysis using a developed algorithm. Changes in the facial skin water content with season and humidity were visualized by the algorithm. The water content decreased in autumn, especially near the eyes and upper-cheek. Compared to other areas on the face, the water content around the eyes decreased more during an 85 min stay in a room at 10% relative humidity. The proposed method for water distribution analysis provides a powerful tool for facial skin hydration research in dermatological and cosmetics fields.

Comprehension of terminal differentiation and dedifferentiation of chondrocytes during passage cultures.

A high density collagen type I coated substrate (CL substrate) was used to evaluate the chondrocyte phenotypes in passaged cultures. With increasing age of cell population (population doubling (PD)=0-14.5), the frequency of non-dividing spindle shaped cells without ALP activity increased, accompanied with an increase in gene expression of collagen type I, meaning the senescence of dedifferentiated cells. At the middle age of cell population (PD=5.1 and 6.6), the high frequency of polygonal shaped cells with ALP activity existed on the CL substrate together with up-regulated expressions of collagen types II and X, indicating the terminal differentiation of chondrocytes. When the chondrocytes passaged up to the middle age were embedded in collagen gel, the high frequency of single hypertrophic cells with collagen type II formation was recognized, which supports the thought that the high gene expression of collagen type II was attributed to terminal differentiation rather than redifferentiation. These results show that the CL substrate can draw out the potential of terminal differentiation in chondrocytes, which is unattainable by a polystyrene surface, and that the CL substrate can be a tool to evaluate cell quality in three-dimensional culture with the collagen gel.

Cardiomyogenic induction of human mesenchymal stem cells by altered Rho family GTPase expression on dendrimer-immobilized surface with D-glucose display.

The commitment of stem cells to different lineages is regulated by many cues in the intercellular signals from the microenvironment system. In the present study, we found that alterations in Rho family GTPase activities derived from cytoskeletal formation can lead to guidance of cardiomyogenic differentiation of human mesenchymal stem cells (hMSCs) during in vitro culture. To regulate the cytoskeletal formation of hMSCs, we employed a dendrimer-immobilized substrate that displayed D-glucose. With an increase in the dendrimer generation number, the cells exhibited active migration, accompanied by cell morphological changes of stretching and contracting. Fluorescence microscopy for F-actin, vinculin and glucose transporter1 (GLUT1) clarified the localization of integrin-mediated and GLUT-mediated anchoring, introducing the idea that the morphological changes of the cells were responsive to variations in the generation number of the dendrimer with d-glucose display. On the 5th-generation dendrimer surface, in particular, the cells exhibited RhoA down-regulation and Rac1 up-regulation during the culture, associated with alterations in the cellular morphology and migratory behaviors. It was found that cell aggregation was promoted on this surface, supporting the notion that an increase in N-cadherin-mediated cell-cell contacts and Wnt signaling regulate hMSC differentiation into cardiomyocyte-like cells.

Morphological evaluation of chondrogenic potency in passaged cell populations.

The present study describes the morphological assessment of chondrogenic potency during a cell expanding process through serial subculturing of rabbit chondrocytes at different levels of population doublings (PD) in a T-flask with a conventional polystyrene surface. The passaged populations were seeded on a high-density collagen surface (CL surface) and in a collagen gel (CL gel) scaffold to evaluate the planar and spatial morphologies of the chondrocytes, respectively, as well as the gene expressions of mRNA for collagen types I and II. The planar morphological estimation was based on roundness (R(c)) of chondrocyte cells at different PD values after 1 day incubation on the CL surface. The frequency of round-shaped cells with R(c)>0.9 (f(R)) decreased with increasing PD values, accompanied by an increase in collagen type I mRNA level. At PD=17.8, the frequency reached f(R)=0.12, which was less than one-sixth of that at PD=0. A similar trend was found with respect to the passaged chondrocytes embedded in the CL gels by estimating the spatial morphology in terms of sphericity (S(c)) determined 4 days after seeding. With an increase in PD value, the frequency in spherical-shaped cells with S(c)>0.9 (f(S)) decreased and the mRNA expression of collagen type I increased, giving f(S)=0.28 at PD=17.8 which was less than a quarter of that at PD=0. From these results, the cell morphologies on the CL surface and in the CL gel were proposed as indicators for understanding chondrogenic potentials concerning the phenotypes and differentiated states in the population during cell expansion, ultimately leading to quality control of tissue-engineered cartilage.