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2023.6.29

KOSÉ and Niigata University Develop a Three-dimensional
Epithelial Model that Reproduces the Human Lip Area
To be Used for Evaluating the Efficacy and Safety of Cosmetic Ingredients and Products
KOSÉ Corporation (Headquarters: Chuo-ku, Tokyo; President: Kazutoshi Kobayashi) has developedin collaborative research with Professor Kenji Izumi and his colleagues at Niigata University Graduate
School of Medical and Dental Sciences (Faculty of Dentistry) a three-dimensional epithelial model that
reproduces the human lip area from the oral mucosa to the lips and surrounding skin, using cell culture.
This will make it possible to the verify efficacy and safety evaluations of cosmetic ingredients andproducts on a structure more similar to the actual lip area, which has been limited until now toverification using standard skin and oral mucosa in vitro models. The results of this research have been
published online in the scientific journal Histochemistry and Cell Biology in June 2023.

Fig. 1: Tissue staining images of the three-dimensional lip area model developedBackground
The lips are one of the most important elements that determine the impressions of the face, and they
are also an area where many people suffer from problems, such as chapped lips in winter. The lip areais the transition area between the facial skin and the oral mucosa, and has a unique structure andproperties that differ from both of them, such as the stratum corneum being thinner and more delicate
than in skin. However, until now, there has been no evaluation system using lip area models, and it hasbeen necessary to use skin and oral mucosa in vitro models to evaluate the usefulness and safety of
new ingredients. Therefore, the development of lip area models that reproduce its unique structure,and their use for functional analysis of the lip area and evaluation of formulations and ingredients, is a
useful tool to promote better formulation development.
The research group developed a lip area model with the aim of enabling it to be used in cosmetics
research. They used only cells derived from the epidermis and oral mucosal epithelium to develop athree-dimensional model with characteristics similar to those of the human lip area.

Development of a three-dimensional epithelial model reproducing the lips partFig. 2: Outline of method for creating the three-dimensional lip area model
To reproduce the lips part, a technique was used in which cells derived from skin and oral mucosa
coexist. First, cells derived from skin and oral mucosa were seeded on both sides of a divider, and thedivider was then removed to allow spontaneous migration (movement to another position) of the cells
from both sides to the area where the divider was. Subsequently, the lip area-equivalent part was
prepared by culturing the cells in air (Fig. 2). Tissue staining of the constructed lip area model revealed
that the cells have structures and features similar to actual skin, lip areas, and oral mucosa,respectively (Fig. 1).
Confirmation that the model has a mode of differentiation similar to that of human lip area tissue

Fig. 3: Comparison of differentiation modes of the developed lip area model and human lip area tissue

Since it is known that the mechanism of cell differentiation (mode of differentiation), which is theprocess of cell maturation, differs between the skin, lips, and oral mucosa, the mode of differentiation
was confirmed in the lip area model created. The lip area model was stained for keratin 2e (KRT2) andsmall proline-rich protein 3 (SPRR3), proteins representing differing modes of differentiation in cells
derived from skin and oral mucosa, respectively. The results were that KRT2 was more abundant on
the skin side, decreased in the lip area-equivalent part, and disappeared on the oral mucosa side (Fig.
3, red). On the other hand, SPRR3 was found to be more abundant on the oral mucosa side, anddecreased toward the lip area-equivalent part and skin side (Fig. 3, green). This differentiation modeis similar to that of actual human lip area tissue, confirming that the lip area model developed has asimilar differentiation mode to that of the human lip area.
From the above, it is concluded that the lip area model developed in this research has a similar
structure and differentiation mode to that of actual human lip area tissue, and it is expected to be used
for evaluation of the effects of cosmetic ingredients on the lip area and other purposes.

Future outlook
The lip area model developed in this research will be used for basic research on the lips, which has
only been possible until now with alternative methods using skin and oral mucosa, and for future
development of lip care products and ingredients. We will continue our research and development toenable us to provide evidence-based solutions to customers’ lip area problems, such as clarifying themechanisms of chapped lips and developing useful ingredients.