Laboratory of Biology, School of Medicine, University of Athens, Athens, Greece; Cell and Gene Therapy Laboratory, Center of Basic Research II, and Biotechnology Laboratory, Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece; First Department of Obstetrics and Gynecology, School of Medicine, University of Athens, Athens, Greece.
Stem Cells Transl Med. 2014 Jan;3(1):54-68. doi: 10.5966/sctm.2013-0081. Epub 2013 Dec 4.
MicroRNAs (miRNAs) have recently been shown to act as regulatory signals for maintaining stemness and for determining the fate of adult and fetal stem cells, such as human mesenchymal stem cells (hMSCs). hMSCs constitute a population of multipotent stem cells that can be expanded easily in culture and are able to differentiate into many lineages. We have isolated two subpopulations of fetal mesenchymal stem cells (MSCs) from amniotic fluid (AF) known as spindle-shaped (SS) and round-shaped (RS) cells and characterized them on the basis of their phenotypes, pluripotency, proliferation rates, and differentiation potentials. In this study, we analyzed the miRNA profile of MSCs derived from AF, bone marrow (BM), and umbilical cord blood (UCB). We initially identified 67 different miRNAs that were expressed in all three types of MSCs but at different levels, depending on the source. A more detailed analysis revealed that miR-21 was expressed at higher levels in RS-AF-MSCs and BM-MSCs compared with SS-AF-MSCs. We further demonstrated for the first time a direct interaction between miR-21 and the pluripotency marker Sox2. The induction of miR-21 strongly inhibited Sox2 expression in SS-AF-MSCs, resulting in reduced clonogenic and proliferative potential and cell cycle arrest. Strikingly, the opposite effect was observed upon miR-21 inhibition in RS-AF-MSCs and BM-MSCs, which led to an enhanced proliferation rate. Finally, miR-21 induction accelerated osteogenesis and impaired adipogenesis and chondrogenesis in SS-AF-MSCs. Therefore, these findings suggest that miR-21 might specifically function by regulating Sox2 expression in human MSCs and might also act as a key molecule determining MSC proliferation and differentiation.
微小 RNA（miRNAs）最近被证明可以作为调节信号，维持干细胞的干性，并决定成体和胎儿干细胞（如人骨髓间充质干细胞（hMSCs））的命运。hMSCs 构成了多能干细胞群体，这些细胞可以在培养中很容易地扩增，并能够分化为许多谱系。我们已经从羊水（AF）中分离出两种胎儿间充质干细胞（MSCs）亚群，称为纺锤形（SS）和圆形（RS）细胞，并根据其表型、多能性、增殖率和分化潜能对其进行了特征描述。在这项研究中，我们分析了源自 AF、骨髓（BM）和脐血（UCB）的 MSC 的 miRNA 谱。我们最初鉴定出 67 种不同的 miRNA，它们在所有三种类型的 MSC 中都有表达，但表达水平因来源而异。更详细的分析表明，RS-AF-MSCs 和 BM-MSCs 中的 miR-21 表达水平高于 SS-AF-MSCs。我们首次证明了 miR-21 与多能性标记物 Sox2 之间存在直接相互作用。miR-21 的诱导强烈抑制了 SS-AF-MSCs 中 Sox2 的表达，导致克隆形成和增殖潜力以及细胞周期停滞减少。引人注目的是，在 RS-AF-MSCs 和 BM-MSCs 中抑制 miR-21 会产生相反的效果，导致增殖率增加。最后，miR-21 的诱导加速了 SS-AF-MSCs 的成骨作用，同时损害了其成脂和成软骨作用。因此，这些发现表明，miR-21 可能通过调节 hMSCs 中的 Sox2 表达特异性发挥作用，并且可能也是决定 MSC 增殖和分化的关键分子。
