Bulge cells of human hair follicles: segregation, cultivation and properties.

The bulge region of hair follicle has been reported as a putative reservoir of hair follicle stem cell (HFSC) for years; however, few studies were done about the characteristics of bulge-originated cells in vitro up to now. In this experiment, the bulge cells isolated from human hair follicles by enzymatic digestion and microdissection were cultured and passaged, and the morphological and biological features of cultured bulge cells were investigated by microscopy and immunocytochemistry. The result showed that new-proliferated cells could be observed on the second day after inoculation, and the quantity of the cells with a greater proliferation potential, reached a peak at the 6th day and maintained this higher level for several days. The mitotic figures of bulge cells were seen and these cells showed undifferentiated morphologic features. The bulge cells strongly expressed K19 and beta1-integrin, which are the markers of HFSC, in a descensive way with the culture time. The result indicates that the cultured bulge cell from human hair follicle possesses the properties of primitive cells and supports the hypothesis that HFSC resides in the bulge area.