Stingl J, Eaves C J, Kuusk U, Emerman J T
Department of Anatomy, University of British Columbia, Vancouver, Canada.
Differentiation. 1998 Aug;63(4):201-13. doi: 10.1111/j.1432-0436.1998.00201.x.
The developmental relationships between the different mammary epithelial cell lineages in the human mammary gland are not well defined. To characterize human breast epithelial cells (HBEC) with progenitor activity, we used flow cytometry and single cell sorting to analyze the distribution of cellular phenotypes in primary cultures of reduction mammoplasties and their associated ability to generate colonies in 2-dimensional (D) and 3-D (collagen gel) culture systems. This approach allowed two distinct types of HBEC progenitor populations to be distinguished on the basis of their differential expression of the MUC-1 glycoprotein, CALLA/CD10 and epithelial-specific antigen (ESA). The first type of progenitor, which is enriched in the MUC-1+/CAL-LA-/ESA+ subpopulation, generated colonies of tightly arranged cells in 2-D cultures and small alveolar-like colonies with a central lumen when cultured in a collagen matrix. The cells produced in the colonies and derived from these MUC-1+/CALLA-/ESA+ progenitors were found to express typical luminal epitopes (keratin 8/18, keratin 19, MUC-1, ESA) and showed low levels of expression of myoepithelial epitopes (keratin 14 and CD44v6). The second type of progenitor, which is present in the MUC-1-to +/-/CALLA +/- to +/ESA+ subpopulation, generated mixed colonies of both luminal and myoepithelial cells when seeded in 2-D and 3-D cultures. In 2-D cultures, the centrally located cells exhibited a luminal morphology and expressed ESA, but were heterogeneous in their expression of MUC-1. Radiating from the periphery of these ESA+ HBEC were highly refractile ESA- teardrop-shaped myoepithelial-like cells. When cultured in a collagen matrix, these bipotent progenitors generated large branched colonies composed of a heterogeneous population of cells, with some of the progeny cells expressing luminal epitopes (keratin 8/18, keratin 19 and MUC-1) and others expressing myoepithelial epitopes (keratin 14 and CD44v6). A third type of progenitor, which became apparent is passaged HBEC cultures and was enriched in the MUC-1-/CALLA+/ESA- subpopulation, was found to generate colonies of cells with an exclusively myoepithelial phenotype. These results provide definitive evidence for the existence of multilineage HBEC progenitors in normal adult human mammary tissue. The phenotypic profile of these cells suggest that these multilineage progenitors are a relatively undifferentiated cell since they express low levels of MUC-1 and that they have a luminal location within the mammary epithelium since they are ESA+. Furthermore, we suggest that the MUC-1+/CALLA-/ESA+ and the MUC-1- to +/-/CALLA +/- to +/ESA+ progenitors we have identified and characterized are candidate in vivo alveolar and ductal progenitors, respectively.
人类乳腺中不同乳腺上皮细胞谱系之间的发育关系尚未明确界定。为了表征具有祖细胞活性的人乳腺上皮细胞（HBEC），我们使用流式细胞术和单细胞分选来分析缩乳术原代培养物中细胞表型的分布，以及它们在二维（2-D）和三维（胶原凝胶）培养系统中形成集落的相关能力。这种方法使得基于MUC-1糖蛋白、CALLA/CD10和上皮特异性抗原（ESA）的差异表达，能够区分出两种不同类型的HBEC祖细胞群体。第一种祖细胞在MUC-1+/CAL-LA-/ESA+亚群中富集，在二维培养中产生紧密排列的细胞集落，而在胶原基质中培养时则产生具有中央管腔的小肺泡样集落。发现这些集落中产生的、源自这些MUC-1+/CALLA-/ESA+祖细胞的细胞表达典型的管腔表位（角蛋白8/18、角蛋白19、MUC-1、ESA），并且肌上皮表位（角蛋白14和CD44v6）的表达水平较低。第二种祖细胞存在于MUC-1-至+/-/CALLA+/-至+/ESA+亚群中，接种到二维和三维培养物中时会产生管腔和肌上皮细胞的混合集落。在二维培养中，位于中央的细胞呈现管腔形态并表达ESA，但MUC-1的表达具有异质性。从这些ESA+ HBEC的周边辐射出高折光性的ESA-泪滴状肌上皮样细胞。当在胶原基质中培养时，这些双能祖细胞产生由异质细胞群体组成的大分支集落，一些子代细胞表达管腔表位（角蛋白8/18、角蛋白19和MUC-1），另一些则表达肌上皮表位（角蛋白14和CD44v6）。第三种祖细胞在传代的HBEC培养物中变得明显，并在MUC-1-/CALLA+/ESA-亚群中富集，被发现能产生仅具有肌上皮表型的细胞集落。这些结果为正常成人乳腺组织中多谱系HBEC祖细胞的存在提供了确凿证据。这些细胞的表型特征表明，这些多谱系祖细胞是相对未分化的细胞，因为它们MUC-1表达水平低，并且由于它们是ESA+，所以在乳腺上皮内具有管腔位置。此外，我们认为我们已鉴定和表征的MUC-1+/CALLA-/ESA+和MUC-1-至+/-/CALLA+/-至+/ESA+祖细胞分别是体内肺泡和导管祖细胞的候选者。
