[Adenovirus-mediated VEGF165 gene transfer has neuroprotective effects in neonatal rats following hypoxic-ischemic brain damage].

OBJECTIVE

To investigate the protective effects of adenovirus-mediated vascular endothelial growth factor (Ad-VEGF)165 gene transfer against hypoxic-ischemic brain damage (HIBD) in neonatal rats.

METHODS

Ad-VEGF recombinant adenovirus was constructed by bacterial homologous recombination technology. Seven-day-old Sprague-Dawley rats were randomly assigned to 4 groups: sham-operated (n=20), HIBD (n=25), buffer-treated (n=20), and Ad-VEGF-treated (n=25). The HIBD model was prepared by permanent occlusion of left common carotid artery, followed by exposure to 8% oxygen for 2 hrs. In the Ad-VEGF-treated and the Buffer-treated groups, 2 microL recombinant adenovirus suspension or buffer was injected into the left sensorimotor cortex of the rat brain 3 days after HIBD. Seven days after transplantation, VEGF165 mRNA expression was detected using RT-PCR. Neuronal apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nickel end labeling (TUNEL). CD34 and VEGF protein were detected using immunohistochemistry. Microvascular density in the cerebral cortex was measured based on CD34 positive cells. A radial arm maze test was performed from 30 postnatal days to evaluate long-term learning and memory functions. At 35 postnatal days, the rats were sacrificed for cerebral histological examinations by hematoxylin and eosin.

RESULTS

The expression of VEGF165 mRNA increased in the Ad-VEGF-treated group more than in the untreated HIBD and the buffer-treated groups (p<0.05). The number of apoptotic neurons was less in the Ad-VEGF-treated group compared with that in the untreated HIBD and the buffer-treated groups (p<0.05). Microvascular density and VEGF positive cells increased in the Ad-VEGF-treated group compared with that in the untreated HIBD and the buffer-treated groups (p<0.05). In the radial arm maze test, the Ad-VEGF-treated group had more improved achievements than the HIBD and the buffer groups (p<0.05). Neuronal degeneration and necrosis were lessened in the Ad-VEGF-treated group compared with the HIBD and the buffer groups.

CONCLUSIONS

Ad-VEGF gene transfer can increase the expression of VEGF mRNA and VEGF protein, decrease neuronal apoptosis, and increase angiopoiesis in the brain. This attenuates brain damage and improves long-term learning and memory functions in neonatal rats after HIBD.