Zaragosi Laure-Emmanuelle, Ailhaud Gérard, Dani Christian
Institut de Recherche, Signalisation, Biologie du Développement et Cander, UMR6543 Centre National de la Recerche Scientifique, Centre de Biochimie, Faculté des Sciences, Université Nice Sophia-Antiplis, Nice, France.
Stem Cells. 2006 Nov;24(11):2412-9. doi: 10.1634/stemcells.2006-0006. Epub 2006 Jul 13.
Adipose tissue-derived stem cells offer tremendous potential for regenerative medicine. However, characterization of their self-renewal ability has not been performed yet, although it is a crucial feature for in vitro expansion of undifferentiated cells and in vivo maintenance of stem cell pools. We have undertaken the identification of molecular events that are involved in in vitro self-renewal of human multipotent adipose-derived stem (hMADS) cells from young donors, by assessing their proliferation rate, their ability to grow at the single-cell level (clonogenicity), and their differentiation potential. As hMADS cells are propagated in culture, cell morphology changes dramatically, concomitantly to a progressive decrease in proliferation, clonogenicity, and differentiation potential. This decrease is associated with a decrease in fibroblast growth factor 2 (FGF2) expression and can be circumvented by chronic treatment with exogenous FGF2. Moreover, analysis of FGF2 secretion revealed that it is exported to hMADS cell surface without being released into the culture medium, suggesting a strictly autocrine loop. Indeed, treatment of FGF2-expressing hMADS cells with PD173074, a specific FGF receptor inhibitor, decreases dramatically their clonogenicity and differentiation potential. Thus, hMADS cells express a functional autocrine FGF loop that allows maintenance of their self-renewal ability in vitro. Finally, inhibition of mitogen-activated protein kinase kinase 1 reduces the clonogenic potential of hMADS cells but does not affect their differentiation potential, indicating that the extracellular signal-related kinases 1/2 signaling pathway is partly involved in FGF2-mediated self-renewal. Together, our data clearly identify the key function of FGF2 in the maintenance of self-renewal of adipose tissue-derived stem cells.
脂肪组织来源的干细胞在再生医学领域具有巨大潜力。然而，尽管自我更新能力是未分化细胞体外扩增及干细胞库体内维持的关键特性，但目前尚未对其进行表征。我们通过评估人多能脂肪来源干细胞（hMADS细胞）的增殖率、单细胞水平生长能力（克隆形成能力）及其分化潜能，对年轻供体的hMADS细胞体外自我更新所涉及的分子事件进行了鉴定。随着hMADS细胞在培养中传代，细胞形态发生显著变化，同时增殖、克隆形成能力及分化潜能逐渐降低。这种降低与成纤维细胞生长因子2（FGF2）表达的减少相关，并且可以通过外源性FGF2的长期处理来规避。此外，对FGF2分泌的分析表明，它被转运至hMADS细胞表面而不释放到培养基中，提示存在严格的自分泌环路。事实上，用特异性FGF受体抑制剂PD173074处理表达FGF2的hMADS细胞，会显著降低其克隆形成能力和分化潜能。因此，hMADS细胞表达功能性自分泌FGF环路，使其在体外维持自我更新能力。最后，抑制丝裂原活化蛋白激酶激酶1可降低hMADS细胞的克隆形成潜能，但不影响其分化潜能，表明细胞外信号调节激酶1/2信号通路部分参与FGF2介导的自我更新。总之，我们的数据明确了FGF2在维持脂肪组织来源干细胞自我更新中的关键作用。
