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Purpose: This study aimed to elucidate the precise effects of bevacizumab in all steps in the neovascularization process in endothelial cells. Methods: Human umbilical vein endothelial cells (HUVECs) were incubated with bevacizumab at concentrations within the clinically established range or with identical amounts of excipient. Cell cytotoxicity (evaluated by MTT assay), proliferation (by BrdU incorporation assay), apoptosis (by TUNEL assay), migration (by double-chamber assay) and vessel assembly in matrigel-coated plates were assessed in vitro. Mouse plug matrigel assays were performed to confirm in vitro results. Results: Incubation of HUVECs with bevacizumab did not present cytotoxicity. Concentrations comparable with those after intravitreal doses of bevacizumab significantly reduced proliferation and migration capacity, and increased apoptotic rates in these cells. In addition, bevacizumab led to a significant decrease in the assembly of capillary-like structures on matrigel assay in comparison with excipient-treated cells. Further substantiating these in vitro findings, bevacizumab also inhibited angiogenesis in a mouse plug matrigel assay, as evaluated by haemoglobin content levels. Conclusions: These results demonstrate that clinical doses of bevacizumab are able to prevent several steps of the angiogenic process. Bevacizumab is thus currently recommended for treating disorders that present augmented angiogenesis. [ABSTRACT FROM AUTHOR]

Abstract: Anti-VEGF therapy proved to be useful against several ocular pathological situations, including choroidal neovascularization and proliferative retinopathies. Ranibizumab (Ran), Pegaptanib (Peg) and Bevacizumab (Bev) are the pharmacological agents more frequently used in clinical practice by intravitreal injection. However, their exact effects on the angiogenic process have not been accurately established in a comparative study. The aim of the present study was to elucidate the precise effects of Ran, Peg and Bev on the multiple steps of the angiogenic process. Human umbilical vein endothelial cells (HUVEC) were incubated with each agent within the clinically established concentration range, or identical amounts of the excipients; cell cytotoxicity, proliferation, apoptosis, migration and vessel assembly were assessed. No cytotoxic effects were found for any of the agents studied at any concentration tested. At the clinical dose, cell proliferation was significantly reduced by Bev and Ran, whereas no difference was observed after Peg treatment. In addition, HUVEC apoptosis was effectively increased by Bev and Ran. Cell migration was reduced after incubation with every agent analyzed, though only reaching statistical significance upon Ran intravitreal dose. At clinical doses, capillary assembly was only affected by Bev. In agreement with these data, the active form of VEGF receptor-2 expression was decreased after incubation with Bev (to 66% of control values), Ran (78%) and Peg (86%) relative to controls. These findings indicate that these three agents display distinct effects on endothelial cells. [Copyright &y& Elsevier]