Tiepei Zhu

Zhejiang University, Hangzhou, Zhejiang Sheng, China

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Publications (3)3.93 Total impact

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    ABSTRACT: To explore the potential role of vascular endothelial growth factor compared with transforming growth factor-β2 in the regulation of human retinal pigment epithelium cell-mediated collagen gel contraction. The retinal pigment epithelium cell mediated type I collagen gel contraction assay was performed to evaluate and compare the effect of vascular endothelial growth factor and transforming growth factor-β2. The number of viable retinal pigment epithelium cells in the gel and the expression of α-smooth muscle actin were analysed. Both vascular endothelial growth factor and transforming growth factor-β2 caused a time dependent gel contraction, associated with over expression of α-smooth muscle actin in retinal pigment epithelium cells undergoing a fibroblast like transformation. The decrease in volume of the collagen gel and increase in α-smooth muscle actin expression were more significant in the transforming growth factor-β2-treated group than in vascular endothelial growth factor-treated group beginning at day 2, and the growth of retinal pigment epithelium cells was significantly more inhibited in the transforming growth factor-β2-treated group compared with the vascular endothelial growth factor-treated group after day 1 (P < 0.05). Transforming growth factor-β2 stimulation increased both vascular endothelial growth factor mRNA expression and secretion. The α-smooth muscle actin expression and the change in volume of collagen gel were significantly positively correlated in both experimental groups. Both vascular endothelial growth factor and transforming growth factor-β2 can cause induction of retinal pigment epithelium cell-mediated collagen gel contraction in vitro via partial upregulation of α-smooth muscle actin expression.
    Clinical and Experimental Ophthalmology 06/2011; 40(1):e76-86. · 1.96 Impact Factor
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    ABSTRACT: Purpose: To investigate the effect of small interfering RNA (siRNA) targeting VEGF of retinal pigment epithelium (RPE) cells on the growth activity of human retinal vascular endothelial cells (RECs) under a co-culture system. Methods: By applying the vector (pGPU6)-based siRNA plasmid gene silence system, we specifically silenced VEGF expression of RPE cells (ARPE-19) through plasmid (pGPU6-VEGFA-siRNA) transfection. Reverse transcription polymerase chain reaction (RT-PCR) was applied for selecting the most efficient siRNA segment among three pGPU6-VEGF-siRNA groups (siRNA-1, siRNA-2 and siRNA-3). Treated RPE cells were co-cultured with RECs in a co-culture system made up of a 24-well culture plate and transwell inserts assembled inside During 7-day culture period, the growth capacity of RECs were observed and tested in the form of cell counting assay. Three groups were established in this study: RPE cells transfected with pGPU6-VEGF-siRNA and co-cultured with RECs (group A), RPE cells transfected with siRNA null vector and co-cultured with RECs (group B), and RECs cultured alone (group C). Results: After transfection, VEGF expression of RPE cells in three pGPU6-VEGF-siRNA groups (siRNA-1, siRNA-2 and siRNA-3) evaluated by RT-PCR were 2.56±0.45, 1.17±0.38 and 4.39±0.51, respectively (n=10). siRNA-2 was selected as the foremost segment for transfection (P<0.05, SNK-q test). During the 7-day co-culture period, an influence upon the growth of RECs was observed. Growth curve of RECs under co-culture showed a lower growth rate in group A than in group B (P<0.05,dunnett's test), but no significant difference between group A and group C was noted ( P>0.05,dunnett's test). RECs in group A proliferated much faster during the first four days post-transfection . Conclusion: Delivery of siRNA targeting VEGF plays an efficient role in down-regulating VEGF expression in RPE cells, therefore modulating the growth activity of RECs under a co-culture system in vitro. The application of this technique may provide novel evidence for the prevention and treatment of retinal neovascularisation diseases.
    Yan ke xue bao = Eye science / "Yan ke xue bao" bian ji bu 06/2011; 26(2):20-7.
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    ABSTRACT: To evaluate the efficacy of intravitreal injection of bevacizumab as a preventive intervention of vascular endothelial cell proliferation in the retina of diabetic rats. Fifty-four streptozotocin-induced diabetic Wistar rats were injected intravitreally with 3 µL (25 mg/mL) of bevacizumab into left eyes and 3 µL of saline into the right eyes. Immunohistochemistry and enzyme-linked immunosorbent assays for CD34 and VEGF were used to assess retinal angiogenesis, and transmission electron microscopy was used to evaluate the ultrastructure of retinal capillaries. Retinal expression of VEGF was inhibited 1 week and 1 month after injection (P < 0.01, paired t-test), and the expression of CD34 was not obviously inhibited until 2 months after injection (P < 0.05, paired t-test). Using multiple comparisons between the left eyes of bevacizumab-treated rats, the VEGF expression before injection was higher than at 1 week or 1 month after injection (P < 0.05, Dunnett's t-test), and similar to 2 months after injection (P > 0.05, Dunnett's t-test). The amount of VEGF expression was higher 2 months after injection than 1 week or 1 month after injection, and also higher 1 week after injection compared with 1 month after injection (P < 0.05, Student-Newman-Keuls test). CD34 expression decreased more significantly 2 months after injection compared with before injection, 1 week or 1 month after injection (P < 0.05, Dunnett's t-test). A single intraocular injection of bevacizumab may be beneficial as a therapy for preventing retinal vascular endothelial cell growth in the eyes of diabetic rats.
    Clinical and Experimental Ophthalmology 12/2010; 38(9):875-84. · 1.96 Impact Factor