Vascular endothelial growth factor affects permeability of brain microvessel endothelial cells in vitro

Vascular endothelial growth factor (VEGF), which stimulates endothelial cell growth and induces hyperpermeability of the microvasculature, plays an important role in normal and tumor-vasculature development and tumor edema generation. In this study, we investigated the effect of VEGF on the permeability of cultured bovine brain microvessel endothelial cells (BMECs), an in vitro blood-brain barrier (BBB) model. We found that addition of purified VEGF to both the apical and basolateral sides of the BMEC monolayers increased the permeability of the monolayer to [14C]sucrose (approximately 3-fold). A more significant increase in permeability was observed when VEGF was applied to the basolateral side of the monolayer (3-fold) than to the apical side (1.5-fold). The permeability-increasing activity of VEGF on the BMEC monolayers is both dose and time dependent. The VEGF-induced permeability increase in BMECs requires a long incubation time with VEGF, and the effect is durable. These results suggest that this cell culture system may be useful for exploring the role of VEGF in regulating the permeability of the BBB, for studying the mechanism of the permeability-increasing effect of VEGF on the endothelial cells, and for evaluating the strategies to regulate the activity of VEGF.