Advanced glycation end products induce choroidal endothelial cell proliferation, matrix metalloproteinase-2 and VEGF upregulation in vitro

Background: Advanced glycation end products (AGEs) are considered to be important modulators of angiogenesis and accumulate in choroidal neovascularization (CNV). Their effects regarding cells involved in proliferation of CNV [retinal pigment epithelial (RPE) cells, Muller cells and choroidal endothelial cells (CECs)] were investigated. Furthermore, the effects of AGEs on expression of matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor (VEGF) by CECs were explored. Methods: RPE cells, CECs and Muller cells were exposed to AGEs (10 mug/ml, 50 mug/ml and 100 mug/ml) for a time course of three days in their desired medium and proliferation was estimated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. MMP-2 expression of AGE-stimulated CECs was determined by zymography and reverse-transcription polymerase chain reaction (RT-PCR) after 36 h of exposure. Furthermore, VEGF expression of AGE-stimulated CECs (50 mug/ml and 100 mug/ml) was determined by RT-PCR after an exposure time of 36 h. Results: AGEs in a concentration of 50 mug/ml and 100 mug/ml increased the proliferation of CECs (41% vs 46.1%; P<0.005). No AGE effect on RPE cell and Muller cell proliferation was seen. AGEs in all concentrations used upregulated the VEGF mRNA expression of CECs. Zymography and RT-PCR demonstrated the upregulation of MMP-2 by CECs after AGE exposure. Conclusion: AGEs stimulate CEC proliferation, MMP-2 secretion and VEGF upregulation and may be important promoters of CNV formation in exudative AMD in vivo.