State Key Laboratories for AgroBiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China; College of Basic Medical Sciences, Dalian Medical University, Dalian, PR China.
College of Life Sciences, Peking University, Beijing, PR China.
Exp Cell Res. 2014 Sep 10;327(1):123-34. doi: 10.1016/j.yexcr.2014.06.008. Epub 2014 Jun 19.
The cells with mammary repopulating capability can achieve mammary gland morphogenesis in a suitable cellular microenvironment. Using cell surface markers of CD24, CD29 and CD49f, mouse mammary repopulating unit (MRU) has been identified in adult mammary epithelium and late embryonic mammary bud epithelium. However, embryonic MRU remains to be fully characterized at earlier mammary anlagen stage. Here we isolated discrete populations of E14.5 mouse mammary anlagen cells. Only Lin(-)CD24(med)CD29(+) cell population was predicted as E14.5 MRU by examining their capacities of forming mammosphere and repopulating cleared mammary fat pad in vivo. However, when we characterized gene expressions of this E14.5 cell population by comparing with adult mouse MRU (Lin(-)CD24(+)CD29(hi)), the gene profiling of these two cell populations exhibited great differences. Real-time PCR and immunostaining assays uncovered that E14.5 Lin(-)CD24(med)CD29(+) cell population was a heterogeneous stroma-enriched cell population. Then, limiting dilutions and single-cell assays also confirmed that E14.5 Lin(-)CD24(med)CD29(+) cell population possessed low proportion of stem cells. In summary, heterogeneous Lin(-)CD24(med)CD29(+) cell population exhibited mammary repopulating ability in E14.5 mammary anlagen, implying that only suitable mammary stroma could enable mammary gland morphogenesis, which relied on the interaction between rare stem cells and microenvironment.
具有乳腺重建能力的细胞可以在合适的细胞微环境中实现乳腺形态发生。使用 CD24、CD29 和 CD49f 等细胞表面标志物，已在成年乳腺上皮和晚期胚胎乳腺芽上皮中鉴定出小鼠乳腺重建单位 (MRU)。然而，胚胎 MRU 在更早的乳腺原基阶段仍有待充分表征。在这里，我们分离了离散的 E14.5 小鼠乳腺原基细胞群体。只有 Lin(-)CD24(med)CD29(+)细胞群体通过检查其形成乳腺球体和在体内重建清除的乳腺脂肪垫的能力，被预测为 E14.5 MRU。然而，当我们通过与成年小鼠 MRU（Lin(-)CD24(+)CD29(hi)）比较来表征这个 E14.5 细胞群体的基因表达时，这两个细胞群体的基因谱表现出很大的差异。实时 PCR 和免疫染色分析揭示，E14.5 Lin(-)CD24(med)CD29(+)细胞群体是一种异质的基质丰富的细胞群体。然后，有限稀释和单细胞分析也证实，E14.5 Lin(-)CD24(med)CD29(+)细胞群体具有低比例的干细胞。总之，异质的 Lin(-)CD24(med)CD29(+)细胞群体在 E14.5 乳腺原基中表现出乳腺重建能力，这表明只有合适的乳腺基质才能使乳腺形态发生，这依赖于稀有干细胞与微环境之间的相互作用。
