Morris R J, Potten C S
The University of Texas M.D. Anderson Cancer Center, Smithville, USA.
Cell Prolif. 1994 May;27(5):279-89. doi: 10.1111/j.1365-2184.1994.tb01425.x.
Slowly cycling label-retaining epidermal cells were identified by light microscopic autoradiography in the dorsal epidermis and hair follicles of adult mice 8-10 weeks after twice daily injection of [3H]dT on days three through five after birth. Pulse-labelled epidermal cells were identified in the epidermis and hair follicles of 7-8 week old mice 1 h after a single injection of [3H]dT at 8.00 a.m. For mice of both groups, epidermal cells including those from the hair follicles were harvested by trypsinization and were cultured from low density on feeder layers of irradiated Swiss mouse 3T3. On days 2, 4, 5, 7, 10 and 12, the cultures were fixed and processed for light microscopic autoradiography, and the distribution of labelled nuclei was quantified. On day 2 of culture, both label-retaining cells (LRC) and pulse labelled cells (PLC) were found primarily as single cells. After five days, LRC were found as pairs and clusters having silver grain counts consistent with their division. In contrast, PLC remained primarily as single cells. These results suggest that LRC may divide to form colonies (are clonogenic) whereas PLC are rarely clonogenic. The significance of this experiment is that it suggests that the LRC may not only be persistent in the epidermis, but that they may also be cells with relatively greater proliferative potential than the PLC and are thus likely to be stem cells.
在出生后第3至5天，每天两次注射[3H]胸苷，8至10周龄的成年小鼠在出生后8 - 10周，通过光学显微镜放射自显影术在背部表皮和毛囊中鉴定出缓慢循环的标记保留表皮细胞。在上午8点单次注射[3H]胸苷1小时后，在7 - 8周龄小鼠的表皮和毛囊中鉴定出脉冲标记的表皮细胞。对于两组小鼠，通过胰蛋白酶消化收集包括毛囊细胞在内的表皮细胞，并在经辐照的瑞士小鼠3T3饲养层上进行低密度培养。在培养的第2、4、5、7、10和12天，将培养物固定并进行光学显微镜放射自显影处理，对标记细胞核的分布进行定量分析。在培养的第2天，标记保留细胞（LRC）和脉冲标记细胞（PLC）主要以单个细胞形式存在。五天后，发现LRC以成对和簇状形式存在，其银粒计数与其分裂情况一致。相比之下，PLC主要仍为单个细胞。这些结果表明，LRC可能分裂形成集落（具有克隆形成能力），而PLC很少具有克隆形成能力。该实验的意义在于，它表明LRC不仅可能在表皮中持续存在，而且它们可能是比PLC具有相对更大增殖潜力的细胞，因此很可能是干细胞。
