Bickenbach J R, Chism E
Department of Anatomy and Cell Biology, The University of Iowa, Iowa City, Iowa, 52242-1109, USA.
Exp Cell Res. 1998 Oct 10;244(1):184-95. doi: 10.1006/excr.1998.4163.
Continuously renewing epithelia contain small undifferentiated stem cells capable of self-renewal and maintenance of the differentiating cell population. In murine epidermis stem cells have been identified as label-retaining cells (LRCs) by long-term retention of tritiated thymidine or BrdU. It has been suggested that epidermal stem cells adhere to basement membranes through differential expression of specific integrins. To determine whether we could use a specific integrin to enrich for murine epidermal stem cells, we tested adherence of LRCs to several substrates. Regardless of the substrate used, approximately 10% of total basal cells and 100% of LRCs adhered in 10 min. In our medium specifically formulated for murine keratinocytes, rapidly adherent stem cells formed large colonies and could be used to form a structurally complete epidermis in organotypic culture. They showed a fivefold greater transient transfection efficiency than total basal cells, and when individual adherent cells were transduced with a retroviral vector, they formed large clones. Although these stem cells grew more slowly than the total basal cell population, they could be subcultured more times. Our results indicate that murine epidermal stem cells can be selected by rapid attachment to a substrate, but not by one specific integrin, and that they can be expanded in culture if the appropriate conditions are maintained.
持续更新的上皮组织含有能够自我更新并维持分化细胞群体的未分化小干细胞。在小鼠表皮中，干细胞已通过氚标记胸腺嘧啶核苷或BrdU的长期保留被鉴定为标记保留细胞（LRCs）。有人提出表皮干细胞通过特定整合素的差异表达附着于基底膜。为了确定我们是否可以使用特定整合素来富集小鼠表皮干细胞，我们测试了LRCs对几种底物的附着情况。无论使用何种底物，在10分钟内，约10%的总基底细胞和100%的LRCs会附着。在我们专门为小鼠角质形成细胞配制的培养基中，快速附着的干细胞形成大菌落，并可用于在器官型培养中形成结构完整的表皮。它们的瞬时转染效率比总基底细胞高五倍，当用逆转录病毒载体转导单个附着细胞时，它们形成大克隆。虽然这些干细胞的生长比总基底细胞群体慢，但它们可以传代培养更多次。我们的结果表明，小鼠表皮干细胞可以通过快速附着于底物来选择，而不是通过一种特定的整合素，并且如果维持适当的条件，它们可以在培养中扩增。
