Biological actions of oligomeric procyanidins: Proliferation of epithelial cells and hair follicle growth

Abstract

Hair is composed of epithelial and mesenchymal cells. Interactions between epithelial and mesenchymal cells are considered to be important both in hair morphogenesis in embryonic skin and in the progress of the hair cycle through the anagen, catagen, and telogen phases in adult skin. 1 Inner root sheath cells, outer root sheath cells, and hair matrix cells are all types of epithelial cell. Dermal papilla cells are a type of mesenchymal cell. 2 These mesenchymal-epithelial interactions are assumed to stimulate stem cells to proliferate, to induce the anagen phase in the hair cycle, and to produce hair. Stem cells are hypothesized to exist in the bulge area in the outer root sheath, 3 in the matrix, 4 or between the bulge and the matrix 5; however, stem cell sites have not been elucidated positively. Hair growth stimulants are expected to prolong the anagen phase or to promote hair epithelial cell proliferation following anagen induction. 6 For in v i t ro evaluation of hair growth stimulants, tissue culture methods 7 and organ culture methods using dissected hair follicles 8 or sectioned skin 9 have been reported. For in v i v o evaluation of hair growth stimulants, methods using murine models such as C3H mouse, l° C57BL mouse, II or nude mousel2; rabbit13; and stump-tailed macaque 14 have been reported.