ANALYTICAL STUDIES OF HAIR GROWTH CYCLE ON THE BASIS OF BEHAVIORS OF FOLLICULAR STEM CELLS.

最近，研究表明，位于隆突部的毛囊干细胞是能够形成毛囊、皮脂腺和表皮的多能细胞，并且它们迁移到毛球成为基质细胞并产生毛发。为了研究毛囊干细胞分化为毛基质细胞的机制，我们将逆转录病毒lac-Z基因导入体外培养的大鼠足跖角朊细胞，获得了lac-Z标记的多层培养上皮细胞。由于标记物存在于所谓的表皮增殖单位中，我们认为表皮干细胞被标记了。将标记的毛乳头上皮细胞移植到毛囊中，观察标记的干细胞如何参与毛囊的诱导过程。到目前为止，由于基底层细胞中lac-Z基因的表达受到抑制，标记物只存在于再生表皮和诱导毛囊的分化细胞中。第二个问题，我们从毛发生长周期的不同阶段的触须毛囊中解剖出毛球，将其移植到同系大鼠的肾囊下。我们从移植物中连续的毛球重建和毛发产生的模式推断了基质祖细胞的迁移过程。这强烈表明，毛囊干细胞在毛发生长周期中不是从隆突到毛球连续招募的，而是在生长期晚期和退化期晚期之间不招募。

Recently, it has been shown that follicular stem cells located in the bulge are multipotent cells capable of forming hair follicles, sebaceous glands and epidermis, and that they migrate to the hair bulb to become matrix cells and produce hairs. However, it has not been clarified how the epidermal stem cells become follicular stem cells and how the latter behave to become hair matrix cells.In order to elucidate the first problem, we introduced retro-viral lac-Z gene into cultured rat sole keratinocytes and got multi-layered, lac-Z-labeled cultured epithelium in vitro. Because the labels were found in so-called epidermal proliferation unit, we thought epidermal stem cells were labeled. Then we transplanted the labeled epithelium with vibrissa dermal papillae and observed how the labeled stem cells participated in the process of hair follicle induction. So far, it was demonstrated that the labels were only found in the differentiated cells of the regenerated epidermis and the induced follicles because of the suppression of lac-Z gene expression in the basal layer cells.We investigated the second problem by dissecting out hair bulbs from vibrissa follicles at different stages of hair growth cycle and transplanting them under the kidney capsules of syngeneic rats. We deduced the process of migration of matrix cell progenitors from the pattern of successive hair bulb reconstruction and hair production in the grafts. It was strongly suggested that follicular stem cells were not continuously recruited from the bulge to the hair bulb during hair growth cycle but they were not recruited between late anagen and late catagen.