Effects of vascular endothelial growth factor on angiogenesis of the endothelial cells isolated from cavernous malformations

Human cerebral cavernous malformation (CM) is a common vascular malformation of the central nervous system. We have investigated the biological characteristics of CM endothelial cells and the cellular and molecular mechanisms of CM angiogenesis to offer new insights into exploring effective measures for treatment of this disease. The endothelial cells were isolated from CM tissue masses dissected during operation and expanded in vitro. Expression of VEGFR-1 and VEGFR-2 was examined with immunocytochemical staining. Proliferation, migration and tube formation of CM endothelial cells were determined using MTT, wounding and transmigration assays, and three-dimensional collagen type I gel respectively. The endothelial cells were successfully isolated from the tissue specimens of 25 CMs dissected without dipolar electrocoagulation. The cells show the general characteristics of the vascular endothelial cells. Expression of VEGFR-1 and VEGFR-2 on the cells is higher than that on the normal cerebral microvascular endothelial cells. After treatment with VEGF, numbers of the proliferated and migrated cells, the maximal distance of cell migration and the length and area of capillary-like structures formed in the three-dimensional collagen gel increase significantly. These results demonstrate that expression of VEGFR-1 and VEGFR-2 on CM endothelial cells is up-regulated. By binding to receptors, VEGF may activate the downstream signaling pathways and promote proliferation, migration and tube formation of CM endothelial cells. VEGF/VEGFR signaling pathways play important regulating roles in CM angiogenesis.