Expression and Neuroprotection of Vascular Endothelial Growth Factor in an in vitro Ischemia

ABSTRACT

BACKGROUND: Vascular endothelial growth factor (VEGF) is an angiogenic peptide that enhances microvascular perfusion. Recently, VEGF is known to have neurotrophic effect and rescues neurons from cell death induced by serum deprivation. To investigate the serial changes in VEGF expression and neuroprotective properties of VEGF during acute ischemia. METHODS: Human cortical-neuroblastoma hybrid cell line (A1G11), human neuroglioma cell line (H4), and human vascular endothelial cell line (ECV304) were placed in the glucose/serum free media and incubated in the hypoxic chamber (94% N2/5% CO2/1% room air) at 37 degrees C. Cell viability was determined by MTT assay. Western blot analysis was performed to detect VEGF and its receptor (VEGFR) expression. To test the protective effect of VEGF, human recombinant VEGF165 was used. RESULTS: Morphological changes and the decrease of cell viability were observed following 6 hr ischemia. In A1G11 cells, VEGF expression was not noted until 3 hr ischemia, but was induced after 6hr and continued to 12 hr and then diminished. In H4 and ECV304, the change of VEGF expression was not observed. VEGFR-2/Flk-1 expression was induced from 6 hr (peak level) to 12 hr in A1G11, and induced after 3 hr and continued to 12hr in ECV304. Administration of VEGF increased cell viability in A1G11 cells at 6 hr, 12 hr and 18 hr ischemia (p=0.009, p=0.01 p=0.013), but not in H4 or ECV304 cells ( p>0.05). CONCLUSION: Ischemia induces VEGF production in neurons and VEGF may exert a direct neuron-specific protective effect through VEGFR-2/Flk receptors during the acute phase of ischemic neuronal injury.