P4.44 COMPARISON OF HAIR-INDUCING ABILITY BETWEEN THE UPPER AND THE LOWER DERMAL PAPILLA

Mikaru Yamao^{1, 2, 3}, Koh-ei Toyoshima^{1, 2, 3}, and Katsutoshi Yoshizato^{3, 4}

Phoenixbio Co., Ltd., Hiroshima, Japan¹, Institute of Immunology Co., Ltd., Tokyo, Japan², Innovation Plaza Hiroshima, JST, Hiroshima, Japan³, Department of Biology Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan⁴

Objectives: Hair matrix (HM) cells are heterogenous in mitotic activity. HM cells in the compartment above Auber’s line are more proliferative than those below the line. Dermal papilla (DP) has the capacity to induce epidermal cells to differentiate into hair follicle. In the present study, we examined whether DP cells are heterogenous in hair-follicle inducing ability above and below the line.

Methods: DPs were isolated from vibrissa follicles of enhanced green fluorescent protein (EGFP)-transgenic rats. Under a dissecting microscope, EGFP-labeled DPs were separated into two parts: the DP above (upper DPs) and below Auber´s line (lower DPs). They were subjected to explant-culture. DP cells migrated from the explants and were proliferated. Proliferated DP cells were mixed with newborn rat epidermal cells and transplanted onto the back of nude mice to assay their hair-inducing ability. The animals were sacrificed at 3 weeks post-transplant and these implants were removed for histological examinations.

Results: The upper and the lower DP cells were quite different in growth potential and hair-inducing ability. The upper DP cells showed a higher proliferative capacity and hair-inducing ability than the lower DP cells until 3 passages in serial subcultures. However, the lower DP cells showed a higher proliferative capacity and hair-inducing ability than the upper DP cells beyond more than 4 passages.

Conclusions: These results suggest that DP cells are heterogenous in growth potential and hair-inducing ability depending on their location above and below Auber´s line. Biological significance of this heterogeneity is discussed in relation to DPcell lineage.