Experimental Study In The Correlation Among Expression Changes Of VEGF And Brain Edema And Vascular Cell Proliferation After SAH

PartⅠClinical research in the alterations of serum VEGF in patients with aneurismal subarachniod hemorrhageObjective: To explore the relation between dynamic content changes of serum VEGF in patients with aneurismal subarachniod hemorrhage and the progress of the symptom caused by CVS.Methods: Twenty seven cases of aneurysmal SAH were studied as the experimental group and the control group included ten 10 healthy people. About 3 milliliters venous blood were obtained from ulnar vein in SAH patients at the day of 1st,3rd,5th,7th,10th,15th after onset. Blood was centrifuged after coagulation and the serum was stored in a refrigerator at -20℃. The severity of symptom was evaluated according to Hunt and Hess grade and the volume of clot in subarachnoid space was assessed by Fisher CT grade. The position of intracranial aneurysm was identified by DSA or CTA, the incidence and severity of CVS were determined by TCD. All 27 aneurismal SAH patients were received aneurysm clipping operation or endovascular treatment within four days after onset. The volume of cerebral infarction was confirmed by CT after aneurysm treatment. The serum of control group was collected the same as SAH patients.Results: The serum VEGF levels of SAH patients were significantly higher than healthy people and were elevated at the first day after onset. The elevated serum VEGF levels were mainly attributed to additional VEGF expression caused by CVS as the serum VEGF content didn't increase in SAH patients without CVS. The serum VEGF levels of SAH patients who were complicated with mild CVS had no statistical difference from those patients with moderate CVS at day 1,3,5,7 and were gradually decreased since day 10 after onset while the Serum VEGF levels in SAH patients with moderate and severe CVS were increasing continuously and maintained to 15th day after onset. The serum VEGF levels in those patients who were complicated with severe CVS were significantly higher than those patients with mild and moderate CVS at all time point. The serum VEGF levels in SAH patients who evolved cerebral infarction were significantly higher than those patients without cerebral infarction and were increasing continuously since day 5 and maintained to 15th day after onset while the serum VEGF levels in patients who didn't evolve cerebral infarction fluctuated in a smooth state.Conclusion: The serum VEGF levels were significantly increasing in SAH patients with CVS and in SAH patients who evolved cerebral infarction, which suggest that it could reflect the severity of CVS and also could reflect the time course of attenuation of CVS after onset. It suggests that the serum VEGF levels in SAH patients might predict the incidence and severity of CVS and could be used as a molecular marker that to some extent prognose the occurrence of CVS after SAH.PartⅡExperimental research in the correlation among expression changes of VEGF and brain edema and vascular cell proliferation in SAH model ratsObjective: To explore the dynamic changes of serum VEGF in SAH model rats, and to reveal the relations among VEGF and brain edema and vascular cell proliferation in SAH model rats. Then to observe the effect of blockage of VEGF to detect whether it can relieve brain edema and interrupt vascular cell proliferation in order to provide experimental evidence for clinical treatment of SAH.Methods: 72 Sprague-Dawley rats were randomly divided into three groups, sham operation rats were injected normal saline into the cisterna magna, and the SAH model rats were performed by use of the double hemorrhage model, and the intervention group was injected anti-VEGF polyclonal antibody into cisterna magna before autologous arterial blood was injected into cisterna magna. Animals were sacrificed by euthanasia. About three milliliters venous blood were obtained from right ventricle at day 1,3,5,7 after the second injection of blood or normal saline, blood was centrifuged after coagulation and the serum was stored in a refrigerator at -80°C, the brain stem (including basilar artery) and the brain (at position of the hippocampus ) were obtained in order to do hematoxylin and eosin stain and immunohistochemistry stain of VEGF and PCNA, the remnant brain tissue was used to assay water content of the brain by means of wet and dry weight ratio. The dynamic changes of serum VEGF level and brain water content of three groups were measured and compared, and the correlation of the serum VEGF concentration and brain water content was analyzed. The morphological changes of basilar arteries of three groups were observed, and the changes of expression of PCNA in the basilar artery wall and VEGF in the cerebral cortex were compared.Results: The SAH model was produced successfully in this study by use of double hemorrhage model. The basilar arteries showed apparent vasospasm in SAH model rats at day 1 after the second injection of blood, and reached the peak at day 3 and 5, and gradually attenuated at day 7. The serum VEGF levels in SAH model rats were increasing at day 1, reached the peak at day 3, and gradually decreased at day 5, and were significantly higher than the rats in sham operation at time point of day 1,3,5. The water content of brain in SAH model rats was increasing at day 1, reached the peak at day 3, and gradually decreased at day 5, and was significantly higher than the sham operation rats at all time point. There was correlation between the serum VEGF concentration and the water content of brain, the correlation coefficient was 0.564 (P = 0.01). The expression of PCNA in basilar artery wall in SAH model rats was increasing at the first day, peaked at day 3 and 5, and gradually decreased at day 7, while there was no expression of PCNA in sham operation group. The expression of PCNA in basilar atery wall in anti-VEGF polyclonal antibody intervention rats was obviously at lower levels and consistent with attenuation of CVS. The expression of VEGF in cerebral cortex increased at the first day, peaked at day 3 and 5, and gradually decreased at day 7, while there was no expression of VEGF in sham operation group. Injection of anti-VEGF polyclonal antibody into cisterna magna before injection of autologous arterial blood didn't influence the levels of serum VEGF and the expression of VEGF in the cerebral cortex, but could relieve brain edema and block cerebral vascular cell proliferation in intima and could reduce cerebral vascular wall thicking which was the important component of CVS caused by SAH. Conclusion: VEGF may play an important role in brain edema and may be an important factor that can increase permeability of the blood-brain barrier after SAH. VEGF-mediated cerebral vascular cell proliferation in intima and cerebral vascular wall thicking may play a promoting role in occurrence and progress of CVS after SAH. Treatment early with the VEGF antagonist may reduce early brain edema and also can relieve CVS caused by SAH.