Lineage tracing in the adult mouse corneal epithelium supports the limbal epithelial stem cell hypothesis with intermittent periods of stem cell quiescence.
Lineage tracing in the adult mouse corneal epithelium supports the limbal epithelial stem cell hypothesis with intermittent periods of stem cell quiescence.
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DOI：
10.1016/j.scr.2015.10.016
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发表时间：
2015-11
影响因子：
1.2
通讯作者：
West JD
中科院分区：
文献类型：
--
作者：
Dorà NJ;Hill RE;Collinson JM;West JD
角膜缘上皮干细胞(LESC)假说认为，角膜缘中的LESC在正常内稳态和伤口修复过程中维持角膜上皮。另一种角膜上皮干细胞假说认为，LESCs只参与伤口修复，而角膜上皮细胞本身的CESCs在正常的动态平衡中维持角膜上皮细胞。我们使用他莫昔芬诱导的、Creer-loxP谱系追踪来区分这些假说。在成年CAGG-Creer、R26R-LacZ报告基因小鼠体内诱导标记细胞克隆，分析不同追逐时间后标记细胞的分布。来自标记的瞬时扩增细胞的短寿命克隆在追逐期间被剥离，而来自干细胞的长寿命克隆被扩张。在6周时，标记的克隆出现在边缘，向心延伸为放射状条纹，少数在14周时到达中心。条纹数取决于他莫昔芬治疗的年龄。条纹长度不一，有些是不连续的，很少有到达中心的，几乎一半的条纹在边缘有一端。在CAGG-Creer；R26R-mt/mg报告小鼠中，类似的条纹延伸到整个角膜。如果LESC在活动期和静止期之间循环，则标记克隆的分布与CESC假说不一致，并支持LESC假说，每个LESC持续数周。我们使用世系追踪来评估可供选择的角膜上皮干细胞模型。无性系从外围出现，向心延伸为放射状条纹。这意味着活跃的干细胞位于角膜的外围，而不是整个角膜。标记模式表明，干细胞在静止期内循环。通过治疗更年轻的小鼠，可以诱导出更多的标记克隆。
The limbal epithelial stem cell (LESC) hypothesis proposes that LESCs in the corneal limbus maintain the corneal epithelium both during normal homeostasis and wound repair. The alternative corneal epithelial stem cell (CESC) hypothesis proposes that LESCs are only involved in wound repair and CESCs in the corneal epithelium itself maintain the corneal epithelium during normal homeostasis. We used tamoxifen-inducible, CreER-loxP lineage tracing to distinguish between these hypotheses. Clones of labelled cells were induced in adult CAGG-CreER;R26R-LacZ reporter mice and their distributions analysed after different chase periods. Short-lived clones, derived from labelled transient amplifying cells, were shed during the chase period and long-lived clones, derived from stem cells, expanded. At 6 weeks, labelled clones appeared at the periphery, extended centripetally as radial stripes and a few reached the centre by 14 weeks. Stripe numbers depended on the age of tamoxifen treatment. Stripes varied in length, some were discontinuous, few reached the centre and almost half had one end at the limbus. Similar stripes extended across the cornea in CAGG-CreER;R26R-mT/mG reporter mice. The distributions of labelled clones are inconsistent with the CESC hypothesis and support the LESC hypothesis if LESCs cycle between phases of activity and quiescence, each lasting several weeks. We used lineage tracing to evaluate alternative corneal epithelial stem cell models. Clones emerged from the periphery and extended centripetally as radial stripes. This implies that active stem cells are at the periphery, not throughout the cornea. Labelling patterns suggested stem cells cycle through quiescent periods. More labelled clones were induced by treating younger mice.