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Hiroto Terasaki, Makoto Shirasawa, Noboru Arimura, Shozo Sonoda, Taiji Sakamoto; Secretion Of VEGF From Polarized RPE By Tnf-a Or Thrombin. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6552.
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Retinal pigment epithelial cells (RPEs) secrete vascular endothelial growth factor (VEGF) in a polarized fashion (apical side < basal side). Although the previous studies showed various factors to affect secretion of VEGF by RPEs, most of them used non-polarized RPEs, which might not exactly reflect an in vivo condition. This study was conducted to investigate factors affecting secretion of VEGF from polarized RPEs.
Porcine polarized RPE was established in Boyden chamber by our previous report (Sonoda S, et al. Nat Protoc, 2009). Polarized or non-polarized RPEs were treated with tumor necrosis factor alpha (TNF-α) or thrombin in various conditions. VEGF concentration of upper chamber or lower chamber was measured by enzyme-linked immunosorbent assay.
In polarized RPEs, thrombin (1-20 U/ml) increased the amount of VEGF (both upper chamber and lower chamber together) 1.63-3.42 times of control in a dose or a time dependent manner. The amount of VEGF in lower chamber was 2.5 times greater than that of upper chamber. The similar results were obtained in non-polarized RPEs. While, TNF-α increased the amount of VEGF in non-polarized RPEs (1.15 times of controls); however, it decreased that of VEGF in polarized RPEs both in upper chamber and lower chamber.
Although thrombin enhanced VEGF secretion in polarized RPEs similarly non-polarized RPEs, TNF-a affected it differently dependent upon its polarization status. In a physiological condition, polarized RPEs would work not only as a mechanical barrier but also as a functional barrier against insults such as TNF-α. Polarized RPE might be more suitable than for non-polarized RPEs for analyzing the actual functions.
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