Identification of putative bovine mammary epithelial stem cells by their retention of labeled DNA strands
Identification of putative bovine mammary epithelial stem cells by their retention of labeled DNA strands
复制标题
DOI：
10.3181/0703-rm-58
复制
发表时间：
2007-11-01
影响因子：
3.2
通讯作者：
Capuco, Anthony V.
中科院分区：
文献类型：
--
作者：
Capuco, Anthony V.
干细胞似乎可以较长时间地保留标记的DNA，因为它们在有丝分裂期间选择性地分离模板DNA链。在这项研究中，每天五次注射5-溴-2-脱氧尿苷(BrdU)标记青春期前牛乳腺中的增殖细胞。5周后，BrdU标记的乳腺上皮细胞仍清晰可见。BrdU标记的上皮细胞在乳腺下部靠近腺池的部位所占比例最大，向导管侵犯乳腺脂肪垫的实质周边方向逐渐减少。腺体基底区BrdU标记的上皮细胞数量增加可能是该区域增殖率下降和细胞周期停滞增加的结果。在乳腺实质的外围区域，重标记的上皮细胞的百分比平均为0.24%，这一数字与小鼠乳腺中干细胞频率的估计一致。上皮标记保留细胞似乎代表了缓慢增殖的细胞群，因为5.4%的重度标记细胞对核增殖抗原Ki67呈阳性。由于上皮标记保留细胞含有雌激素受体(ER)阴性和ER阳性细胞，它们显然构成了一个混合群体，我认为这是由ER阴性干细胞和ER阳性祖细胞组成的。继续的研究将解决这项技术在鉴定牛乳腺干细胞和促进干细胞生物学研究方面的有用性。
Stem cells appear to retain labeled DNA for extended periods because of their selective segregation of template DNA strands during mitosis. In this study, proliferating cells in the prepubertal bovine mammary gland were labeled using five daily injections of 5-bromo-2-deoxyuridine (BrdU). Five weeks later, BrdU-Iabeled mammary epithelial cells were still evident. The percentage of BrdU-Iabeled epithelial cells was greatest in the lower region of the mammary gland, near the gland cistern, and was decreased toward the periphery of the parenchymal region, where the ducts were invading the mammary fat pad. Increased numbers of BrdU-Iabeled epithelial cells in basal regions of the gland are likely a consequence of decreased proliferation rates and increased cell cycle arrest in this area. In peripheral regions of mammary parenchyma, the percentage of heavily labeled epithelial cells averaged 0.24%, a number that is consistent with estimates of the frequency of stem cells in the mouse mammary gland. Epithelial label-retaining cells seemingly represent a slowly proliferating population of cells, as 5.4% of heavily labeled cells were positive for the nuclear proliferation antigen Ki67. Because epithelial label-retaining cells contain estrogen receptor (ER)-negative and ER-positive cells, they apparently comprise a mixed population, which I suggest is composed of ER-negative stem cells and ER-positive progenitors. Continuing studies will address the usefulness of this technique to identify bovine mammary stem cells and to facilitate studies of stem cell biology.