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

最近的研究表明，位于毛囊隆起中的毛囊干细胞是一种多能细胞，能够形成毛囊、皮脂腺和表皮，并迁移到毛球成为基质细胞和产生毛发。为了阐明第一个问题，我们将逆转录病毒lac-Z基因导入体外培养的大鼠足底角质形成细胞，获得多层、lac-Z标记的培养上皮细胞。因为这些标记是在所谓的表皮增殖单位中发现的，所以我们认为是标记了表皮干细胞。然后，我们将标记的上皮与触须毛乳头一起移植，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Lac-Z基因在基底层细胞中的表达受到抑制，因此标记只存在于再生表皮和诱导毛囊的分化细胞中。第二个问题是在毛发生长周期的不同阶段，从触须毛囊中分离出毛球，并将其移植到同基因大鼠的肾被膜下。我们从移植物中连续的毛球重建和毛发生成的模式中推断了基质细胞前体细胞的迁移过程。结果表明，毛囊干细胞在毛发生长周期中不是从毛球向毛球连续募集，而是在生长期晚期和退化期晚期之间不断募集。

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.