BACKGROUND: Therapeutic angiogenesis has opened up new pathway for the treatment of ischemic cerebrovascular disease in recent years. The exploration of the effect of vascular endothelial growth factor (VEGF) on inducing angiogenesis following ischemia/reperfusion injury can provide better help for the long-term treatment of cerebrovascular disease in clinic.OBJECTIVE: To observe the effect of VEGF on inducing angiogenesis following focal cerebral ischemia/reperfusion injury in rabbits through the angiogenesis of microvessels reflected by the expression of the factors of vascular pseudohemophilia.DESIGN: A randomized controlled animal trial.SETTING: Department of Medical Imaging, Second Hospital of Hebei Medical University.MATERIALS: Sixty-five healthy male New Zealand rabbits of clean degree, weighing (2.6±0.2) kg, aged4.5-5 months, were used. The polyclonal antibody against vascular pseudohemophilia (Beijing Zhongshan Company), recombinant VEGF165 (Peprotech Company, USA), biotinylated second antibody and ABC compound (Wuhan Boster Company) were applied.METHODS: The experiments were carried out in the Laboratory of Neuromolecular Imaging and Neuropathy,Second Hospital of Hebei Medical University from May to August in 2005. ① The rabbits were randomly divided into three groups: sham-operated group (n=15), control group (n=25) and VEGF-treated group(n=25). In the control group and VEGF-treated group, models were established by middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia/reperfusion. In the VEGF-treated group, VEGF165(2.5 mg/L) was stereotactically injected into the surrounding regions of the infarcted sites immediately after the 2-hour ischemia/reperfusion; Saline of the same dosage was injected in the control group. But the rabobserved on the 3rd, 7th, 14th, 28th and 70th days of the experiment respectively, 3 rabbits in the sham-operated group and 5 in the control group and VEGF-treated group were observed at each time point. The brain tissues in the surrounding regions of the infarcted sites were collected. The positive expressions of the factors of vascular pseudohemophilia in vascular endothelial cells were analyzed with immunohistochemical method. The microvessels in unit statistical field were counted with the imaging analytical software.MAIN OUTCOME MEASURES: The changes of microvascular density in the brain tissue and the positive expressions of the factors of vascular pseudohemophilia in the surrounding regions of the infarcted sites were observed on the 3rd 7th, 14th, 28th and 70th days of the experiment.RESULTS: All the 65 New Zealand rabbits were involved in the analysis of results without deletion. ①Changes of the number of microvessels at different time points in each group: There were no obvious changes at different time points in the sham-operated group. The numbers of microvessels at 7 and 14 days were obviously more in the control group than in the sham-operated group [(6.0±1.1), (9.0±0.9) microvessels; (3.0±1.1), (3.0±1.1) microvessels; P＜ 0.05-0.01], and those at 3, 7, 14 and 28 days were obviously more in the VEGF-treated group than in the control group [(8.3±2.0), (13.4±1.4), (15.5±2.3), (6.8±1.0) microvessels; (3.4±0.6), (6.0±1.1), (9.0±0.9), (3.2±0.8) microvessels; P ＜ 0.01]. ② Positive expressions of the factors of vascular pseudohemophilia in the surrounding regions of infarcted sites: There were no obvious changes at different time points in the sham-operated group. In the control group, the changing law of the expressions was the same as that for the number of microvessels that the expression began to mildly increase at 7 days, reached the peak value at 14 days, and began to reduce at 28 days. In the VEGF-treated group, the expression was obviously increased at 3 days, also reached the peak value at 14days, and reduced to the normal level at 70 days, but the expressions were obviously stronger than those in the control group at the same time points.CONCLUSION: Angiogenesis can be obviously induced in rabbits after the focal cerebral ischemia/reperfusion injury is treated with VEGF for 18 days.