Heenen M, Galand P
Service de Dermatologie, Hôpital Erasme, Université Libre de Bruxelles, Belgique.
Dermatology. 1997;194(4):313-7. doi: 10.1159/000246122.
In human epidermis, germinative cell production is determined by three parameters: the cell cycle time, the loss of cycling cells by programmed cell death and the proportion of keratinocytes actively engaged in the cell cycle or growth fraction. The last parameter is still a subject of debate as the identification of a proliferative cell with certainty is impossible. Two indirect methods (grain count dilution of labelled cells and continuous labelling) suggest that non-proliferative cells may exist in the germinative compartment of human epidermis. Results obtained in vitro demonstrate that keratinocytes can be blocked in certain conditions in a state of quiescence similar to a G0 phase. Increasing evidence suggests that, as in mouse epidermis, the germinative compartment of human epidermis is and is divided into a small proportion of stem cells (10%) with a high proliferative potential, a larger proportion of transit-amplifying cells with a limited proliferative potential (50%) and postmitotic cells committed to undergo terminal differentiation (40%). In this hierarchical arrangement, most of the nonproliferative cells belong to the postmitotic compartment. If this model is correct, the germinative cell population in a quiescent or G0 state is a small proportion of the stem cell compartment and has therefore little influence on the kinetics of normal human epidermis.
在人类表皮中，生发细胞的产生由三个参数决定：细胞周期时间、程序性细胞死亡导致的循环细胞损失以及积极参与细胞周期或生长分数的角质形成细胞比例。由于无法确定地识别增殖细胞，最后一个参数仍是一个有争议的话题。两种间接方法（标记细胞的颗粒计数稀释和连续标记）表明，人类表皮生发区可能存在非增殖细胞。体外实验结果表明，角质形成细胞在某些条件下可被阻滞在类似于G0期的静止状态。越来越多的证据表明，与小鼠表皮一样，人类表皮生发区存在并分为一小部分具有高增殖潜能的干细胞（10%）、一大部分具有有限增殖潜能的过渡放大细胞（50%）和致力于终末分化的有丝分裂后细胞（40%）。在这种分层排列中，大多数非增殖细胞属于有丝分裂后区。如果这个模型是正确的，处于静止或G0状态的生发细胞群体在干细胞区中只占一小部分，因此对正常人类表皮动力学的影响很小。
