Department of Ophthalmology and Visual Science, Catholic Institute of Visual Science, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, Seoul, Republic of Korea.
Department of Ophthalmology, Eye and Vison Research Institute and Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America.
Sci Rep. 2017 Nov 10;7(1):15241. doi: 10.1038/s41598-017-15454-x.
Wnt signaling plays an important role in the regulation of self-renewal in stem cells. Here we investigated the effect of CHIR99021, the primary transducer of the Wnt signaling canonical pathway, and IWP2, a wide action Wnt signal blocker, on the growth and differentiation of the limbal epithelial progenitor cells when these cells are cultured in two different, common culture approaches, outgrowth from limbal biopsy explants and isolated cell seeded in low calcium medium. Consistent with their expected effects, irrespective of the culture system, IWP2 decreased total β-catenin while CHIR99021 increased it in nuclear localization. However, IWP2 increased stem/progenitor cell marker (p63α and ABCG2) content and clonogenic capacity in the explants but had opposite effects on isolated cells. CHIR99021 reduced the growth rate, stem/progenitor cell marker content and clonogenic capacity in the explants but also had the opposite effect on the isolated cells. These results show that the outcome of Wnt/β-catenin signaling modification is dependent on the culture systems. Transplantation of limbal epithelial sheets from explant cultures is one of the standard treatments of limbal stem cell deficiency. Our study shows that Wnt-associated activity has a strong negative impact on stem/progenitor cell preservation in limbal explant cultures.
Wnt 信号通路在干细胞自我更新的调控中起着重要作用。在这里，我们研究了 CHIR99021（Wnt 信号经典途径的主要转导子）和 IWP2（一种广谱 Wnt 信号阻断剂）对培养在两种不同的常用培养方法中的角膜缘上皮祖细胞的生长和分化的影响，这两种方法分别为角膜缘活检外植体的生长和低钙培养基中分离细胞的接种。与预期效果一致，无论培养系统如何，IWP2 降低了总β-连环蛋白，而 CHIR99021 增加了其核定位。然而，IWP2 增加了外植体中的干细胞/祖细胞标志物（p63α 和 ABCG2）含量和克隆形成能力，但对分离细胞有相反的影响。CHIR99021 降低了外植体中的生长速度、干细胞/祖细胞标志物含量和克隆形成能力，但对分离细胞也有相反的影响。这些结果表明，Wnt/β-连环蛋白信号转导修饰的结果取决于培养系统。从外植体培养物中移植角膜缘上皮片是治疗角膜缘干细胞缺乏症的标准方法之一。我们的研究表明，Wnt 相关活性对角膜缘外植体培养中干细胞/祖细胞的保存有很强的负面影响。
