Purchase this article with an account.
Maria Notara, Nasrin Refaian, Gabriele Brown, Philipp Steven, Felix Bock, Claus Cursiefen; Effects of UVB irradiation on limbal stem cell niche and its role in cornea lymphangiogenesis. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5622.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
UVB radiation is linked to various ocular pathologies including photokeratitis and pterygium. However the response mechanisms of the limbal epithelial stem cell (LESC) compartment are unclear. Here, the effect of UVB irradiation on the LESC phenotype and the subsequent role of the LESC niche in cornea (lymph)angiogenesis were investigated.
Primary human limbal epithelial cells (HLE) and fibroblasts (HLF) have been irradiated with 0.02 J/cm2 of UVB. Cell proliferation was tested by using the Alamar Blue assay. The putative LESC phenotype was assessed using the markers P63a, ABCG2, integrin b1 and CK3 (immunophenotyping and QPCR) as well as a colony forming efficiency (CFE) assay. An HLE-HLF co-culture model mimicking the LESC niche was used to compare the ability of irradiated and non-irradiated HLF to support HLE putative LESC phenotype. The levels of angiogenesis-related cytokine and growth factors in conditioned media of irradiated and non-irradiated cells were assessed in a protein array. The effects of the CM on the proliferation, wound healing (scratch wound assay) and tube formation of human lymphatic endothelial cells (LEC) and blood endothelial cells (BEC) were also tested.
UVB caused significant reduction of HLE and HLF proliferation after 24h although no difference was observed at 48h. UVB irradiated HLE assumed a differentiated phenotype, as their coloy forming effect and putative SC marker expression significantly decreased. Interestingly, HLE cells co-cultured with irradiated HLF cells also exhibited a differentiated phenotype. Conditioned media from HLF stimulated LEC and BEC proliferation, wound healing and tube network complexity compared to conditioned media of HLE. This effect diminished after UVB irradiation of HLF. The latter finding correlates with the UVB-induced down-regulation of pro-angiogenic factors (IGFBP3, Amphiregulin, Angiogenin) in HLF.
UVB irradiation seems to induce LESC disruption both by having a direct effect on the stem cell phenotype as well as by impacting on the ability of the accessory niche cells (HLF) to support LESC maintenance. Moreover, while HLF produce soluble mediators that promote hem- and lymphangiogenesis, this action is reversed following UVB irradiation. These data demonstrate the key role of HLF in the LESC niche response to UVB and subsequent (lymph)angiogenic events.
This PDF is available to Subscribers Only