Evaluation of Absorbability of Macromolecular Substances in the Oral Mucosa and Skin using a Three-Dimensional Tissue Culture Model

Introduction: Collagen exists in various connective tissues and helps to provide them mechanical strength and elasticity. The main component of the tendon is properly arranged collagen fibers withstanding very strong forces. The compactly packed collagen fine fibers inside the bone and cartilage increase their elasticity. Collagen also helps skin elasticity and strength. Hyaluronic acid widely exists in extracellular matrix, such as joints and skin. It plays an important role in maintaining cartilage function by making ultra-macromolecular complexes with aggrecan or protein. These collagen and hyaluronic acid decrease with age. Therefore oral supplementation or cosmetics containing them are developed day by day and catch interests of people trackleing anti-aging. The objective of this study was to evaluate and compare the absorbability of macromolecular substances in the oral mucosa and in the skin. Methods: As animal experiments cannot be performed for the evaluation of cosmetics, we used a threedimensional oral mucosa culture model and a three-dimensional epidermis culture model. The absorbability of macromolecular substances with molecular weights from 4,000 to 2,000,000 Da was compared between the oral mucosa model and the skin model. Results: In the skin model, the amount permeated were quite low on all molecular weight. In the oral mucosa model, it absorbed much more compared with that of skin model, though the amount decreased according to the molecular weight. Conclusion: This result was considered due to the absence of the stratum corneum in the oral mucosa. High absorbability through oral mucosa shows the possibility of a new absorption pathway of macromolecular substances.