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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]

Costa C, Soares R, Schmitt F. Angiogenesis: now and then. APMIS 2004;112:402–12.Angiogenesis or new blood vessel formation plays an essential role during embryogenesis, adult vascular remodeling and in several pathological disorders, as in tumor development. Although sprouting of blood vessels is the principal angiogenic mechanism, additional ones, such as the recruitment of bone marrow-derived cells, have recently been described. These processes are controlled by several molecules, although members of the VEGF family of angiogenic factors and its receptors seem to be the main mediators. Initially, VEGF receptors were described as endothelial specific; however, further studies have reported their presence in several types of cells of non-endothelial origin, such as tumor cells. This VEGF receptor altered expression has suggested an angiogenesis-independent growth advantage mechanism on certain types of cancers by the generation of autocrine loops. A possible role in tumorigenesis and a potential novel target in cancer therapy have been hypothesized. Detection of other receptors and molecules considered to be angiogenic players has also been observed on tumor cells. Currently, their clinical significance as well as their potential as therapeutic targets for the treatment of certain cancers is being evaluated, having in mind the future development of promising mechanism-based therapies. The aspects mentioned above are the main focus of this review, which aims to throw light on recent findings respecting angiogenesis and novel therapeutic approaches. [ABSTRACT FROM AUTHOR]