Improvement of tube formation model of cell: Application for acute hypoxia in in vitro study of angiogenesis

Angiogenesis caused by acute vascular occlusion occurs in various ischemic diseases. The in vitro tube formation assay by endothelial cells is a rapid, quantitative method for drug discovery on angiogenesis. Tube formation assay on Matrigel has been widely used to identify the angiogenesis, however, there are some problems to limit its application. In this study, we found for the first time that sodium dithionite (SD) could induce endothelial cell tube formation without Matrigel under hypoxia condition. To further verify our findings, the angiogenesis related proteins and mRNA at different time points after tube formation were measured both in primary human large-vessel endothelial cell (HUVECs) and murine microvascular endothelial cell line (Bend.3). In conclusion, compared with traditional tube formation on Matrigel, the novel model exhibits the following advantages: (1) Combination oxygen glucose deprivation with sodium dithionite (OGD-SD) model is operated more easily than traditional tube formation. (2) OGD-SD can be used for not only cell imaging, but also immunofluorescence, protein extraction and gene analysis. (3) OGD-SD is more applicable to acute hypoxia model of endothelial cell in vitro. (4) OGD-SD may be more suitable to identify molecular mechanism of compound that intervenes processes of pro-tube formation, tube formation and tube disconnection.