Kenney Nicholas J., Smith Gilbert H., Lawrence Erin, Barrett J. Carl, Salomon David S.
J Biomed Biotechnol. 2001;1(3):133-143. doi: 10.1155/S1110724301000304.
The mouse mammary gland may undergo cycles of proliferation, terminal differentiation, tissue remodeling, and more importantly malignant transformation.Mammary epithelial stem cells and their progeny participate in these processes.Mammary epithelial stem cells are multipotent, exhibit properties of self renewal (up to 7 divisions)and may exist either as long-lived nondividing cells or as proliferating-differentiating cells. The focus of this study was to locate stem cells by identifying them as long-lived, label-retaining mammary epithelial cells (LRCs)in growth active (developing)or growth static (aged)mammary ducts. Initially, primary epithelial cells were pulse labeled with either fluorescent tracker dye and/or BrdU. Cells were then transplanted into cleared juvenile syngeneic mammary fat pads and held for 5 weeks or 8 weeks. In this study, we demonstrate that LRCs are stem cells and their progeny (transitional cells)are arranged as transitional units (TUs). Additionally, TUs are located every 250 +/- 75 &mgr;m in ducts or in the terminal end bud 200-600 &mgr;m in diameter. Molecules expressed in TUs were Zonula Occludens-1 and alpha-catenin proteins which were significantly detected in 75%-91% (P <0.001)of the LRCs cells that make up the TU. These data suggest that transitional units may be a group of label-retaining stem cells and maybe involved in the developmental or cancer process.
小鼠乳腺可能经历增殖、终末分化、组织重塑等周期，更重要的是会发生恶性转化。乳腺上皮干细胞及其子代细胞参与这些过程。乳腺上皮干细胞具有多能性，表现出自我更新特性（最多可分裂7次），并且可能以长期不分裂细胞或增殖分化细胞的形式存在。本研究的重点是通过将其鉴定为生长活跃（发育中）或生长静止（衰老）乳腺导管中的长期标记保留乳腺上皮细胞（LRCs）来定位干细胞。最初，用荧光追踪染料和/或BrdU对原代上皮细胞进行脉冲标记。然后将细胞移植到清除后的同基因幼年乳腺脂肪垫中，并维持5周或8周。在本研究中，我们证明LRCs是干细胞，其后代（过渡细胞）排列为过渡单元（TUs）。此外，TUs在导管中每隔250±75μm定位，或在直径为200 - 600μm的终末芽中定位。在TUs中表达的分子是紧密连接蛋白-1和α-连环蛋白，在构成TU的LRCs细胞中有75% - ９１%能显著检测到这些分子（P<0.001）。这些数据表明，过渡单元可能是一组标记保留干细胞，可能参与发育或癌症过程。
