Department of Ophthalmology, University of Duisburg-Essen, Essen, Germany.
Curr Eye Res. 2011 Dec;36(12):1086-97. doi: 10.3109/02713683.2011.608238. Epub 2011 Sep 29.
Mechanisms that control ocular surface stem cells (SCs) are unclear. Recent studies have shown that several adult SCs express pluripotency markers. Our objective was to analyze the expression of key molecules of pluripotency in human ocular surface tissues as well as in cultivated limbal epithelium.
Four samples of human corneal, limbal and on amniotic membrane cultivated limbal epithelium (HLEC-AM), as well as bulbar and fornical conjunctiva were analyzed. Human embryonic stem (ES) cells and human umbilical vein endothelial cells served as controls. Expression of corneal epithelial differentiation markers (K3, K12, Cx43), putative limbal SC markers (ABCG2, p63, K15), and molecules associated with pluripotency/multipotency (NANOG, OCT4, SOX2, KLF4, KIT, NESTIN, PAX6, NOTCH1) was examined using real-time polymerase chain reaction (PCR) and immunohistochemical staining.
Limbal epithelium showed a significantly (p < 0.05) higher expression of K15, ABCG2, OCT4, SOX2, NESTIN and NOTCH1, but a lower expression of K3 than corneal epithelium. Besides a higher expression of ABCG2 in fornix, the expression of pluripotency markers was similar in both conjunctival regions, although lower than in limbal epithelium. Expression of pluripotency factors in ES cells was significantly higher than in ocular surface SCs, whereas the expression in limbal epithelium was the closest to ES cells. HLEC-AM in comparison to limbal epithelium showed a lower expression of differentiation markers, a similar expression of ABCG2 but a significantly lower expression of pluripotency factors.
Human ocular surface epithelial cells and especially limbal epithelial cell express genes are important for pluripotency and may have preserved some common mechanisms with pluripotent SCs.
控制眼表面干细胞（SCs）的机制尚不清楚。最近的研究表明，几种成年SCs 表达多能性标记物。我们的目的是分析人眼表面组织以及培养的角膜缘上皮中多能性关键分子的表达。
分析了 4 个人角膜、角膜缘和羊膜培养的角膜缘上皮（HLEC-AM）以及球结膜和穹窿结膜的样本。人胚胎干细胞（ES 细胞）和人脐静脉内皮细胞作为对照。使用实时聚合酶链反应（PCR）和免疫组织化学染色检测角膜上皮分化标记物（K3、K12、Cx43）、潜在的角膜缘 SC 标记物（ABCG2、p63、K15）以及与多能性/多能性相关的分子（NANOG、OCT4、SOX2、KLF4、KIT、NESTIN、PAX6、NOTCH1）的表达。
角膜缘上皮的 K15、ABCG2、OCT4、SOX2、NESTIN 和 NOTCH1 表达显著（p<0.05）高于角膜上皮，而 K3 表达低于角膜上皮。除穹窿结膜中 ABCG2 的表达较高外，两个结膜区域的多能性标记物表达相似，尽管低于角膜缘上皮。ES 细胞中多能性因子的表达明显高于眼表面SCs，而角膜缘上皮的表达与 ES 细胞最为接近。与角膜缘上皮相比，HLEC-AM 表现出分化标记物表达较低、ABCG2 表达相似但多能性因子表达显著较低的特征。
人眼表面上皮细胞，特别是角膜缘上皮细胞，表达与多能性相关的重要基因，可能与多能性SCs 具有一些共同的机制。
