P#25   Hair-inducing ability of cultured human dermal papilla cells

Koh-ei Toyoshima1, Hitoshi Kuwamoto2, Mikaru M. Yamao2, Mutsumi Inamatsu1, 2, 3, and Katsutoshi Yoshizato2, 3. 1Institute of Immunology, Co., Ltd, Tokyo, Japan; 2Hiroshima Tissue Regeneration Project, Hiroshima Prefecture Collaboration of Regional Entities for Advancement of Technological Excellence, JST, Japan; 3Dept of Biological Science, Graduate School of Science, Hiroshima University, Japan

The dermal papilla (DP) is a messenchymal component of the hair follicle and can induce ectopic hair follicles when it is implanted into the afollicular skin. We established a serial cultivation method of DP cells by maintaining them in media containing conditioned medium (CM) of rat keratinocytes (J. Invest. Dermatol., 111(5), 767-75, 1998). This method for rat DP cells was applicable to human DP cells. Human DP cells could be serially subcultured until the passage number reached to 10-16. The hair follicle-inducing ability of the human DP cells that had been propagated in culture was assayed by transplanting them to the space between the epidermis and the dermis of rat sole skin, which showed that they retained the hair follicle-inductive ability. However, the growth of hair shafts from the induced follicles was very poor in this assay, which led us to assay the ability by another method, "graft chamber method". The cultured human DP cells (primary or passage number 6) and epidermal cells freshly prepared from newborns of rat were mixed together and transplanted onto the back of nude mice, and the region containing the transplants was covered with a graft chamber. In this assay, we could show that the culture-propagated human papilla cells induced hair follicles from the transplanted rat epidermal cells, and the induced follicles produced hair shafts that came out from the surface of the epidermis. From these results we conclude that human DP cells can be propagated by serial subcultivations without losing their inherent hair-inducing ability.