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Hyun Jung Lee, J Mario Wolosin, So-Hyang Chung; Effect of Wnt/β-Catenin Signaling Modifiers on Self-Renewal of Human Limbal Epithelial Progenitor Cells Grown from Limbal Biopsy Explants. Invest. Ophthalmol. Vis. Sci. 2017;58(8):959.
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© ARVO (1962-2015); The Authors (2016-present)
Wnt signaling plays an important role in the regulation of self-renewal in stem cells. Here we investigated the effect of modulation of β-catenin, the primary transducer of the Wnt signaling canonical pathway, on the growth and differentiation of the corneal epithelial progenitors that outgrow from limbal biopsy explants.
Explants were made in control medium or medium complemented with IWP2, a Wnt signal blocker, or CHIR99021, an indirect β-catenin activator. We determined outgrowth size from limbal biopsy explants, cell size, protein and mRNA expression of markers for stem/precursor cells for corneal epithelial differentiation, and colony formation efficiency (CFE). Comparative experiments with the two modifying agents were performed in cultures of freshly isolated limbal epithelial cells grown in low calcium medium.
CHIR99021 inhibited limbal explant outgrowth rate and expression of the proliferation marker Ki67. Concurrently, IWP2 increased but CHIR99021 decreased (a) the cell density; b) the expression of the stem/precursor marker p63α; c) the expression of the limbal stem cell marker ABCG2; and d) the CFE from outgrowth cells. CHIR99021 also enhanced the expression of the differentiation marker Krt12. In the isolate limbal epithelial cell cultures the effect of the two Wnt-related agents on ABCG2 expression, function, and CFE were in opposite directions to the effects seen on the limbal explant cultured cells. In spite of the divergence of the effects, measurements of the effect of IWP2 or CHIR99021 on total β-catenin indicated that in both systems IWP2 decreased and CHIR99021 increased total β-catenin, respectively.
This result suggests that activation of the canonical Wnt pathway has a negative impact on stem/precursor cells in outgrowths from limbal explant cultures.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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