Effect of flow shear stress on endothelial cell proliferation and c-myc expression in cerebral arteriovenous malformation / 中国组织工程研究

ABSTRACT

BACKGROUND:Shear stress can directly mediate the expression of endothelial cells, especially some cytokine genes whose codes are related to angiogenesis. Otherwise, flow shear stress of blood plays an importantly biological role in regulating vascular structure and function.OBJECTIVE: To observe the effects of laminar flow shear stress on the proliferation of vascular endothelial cells and the expression of protooncogene c-myc in human cerebral arteriovenous malformation.DESIGN: Randomized controlled study.SETTING: Department of Neurosurgery, Shenyang General Hospital of Military Area Command of Chinese PLA.MATERIALS The experiment was carried out in the Neuromedical Institute, General Hospital of Shenyang Military Area Command of Chinese PLA from November 2006 to February 2007. Fresh samples of human cerebral arteriovenous malformation were derived from 20 patients who were of grade Spetzler Ⅱ -Ⅲ and received resection of human cerebral arteriovenous malformation in the Department of Neurosurgery, General Hospital of Shenyang Military Area Command of Chinese PLA in 2006. All cases were diagnosed with whole-brain angiography before operation. The main reagents and equipments were detailed as follows M199 culture media (Gilbco BRL), quality fetal bovine serum (HyClone), endothelial cell growth supplement (ECGS; Sigma, USA), CO2 incubator (Forma Scientific, USA), flow cytometry analysis of cell cycle kit (BD Company), flow cytometer (FACS Calibur, BD Company), rat-anti-human c-myc monoclonal antibody (Santa Cruz Company, USA), and reverse transcription polymerase chain reaction (RT-PCR) kit (Promega).METHODS: Tissue explants adherent method was used to culture vascular endothelial cells of human cerebral arteriovenous malformation, and then the cells were classified into 4 groups based on degree of shear stress, including control group, low shear stress group, moderate shear stress group and high shear stress group. Cultured endothelial cells of human cerebral arteriovenous malformation were put in a parallel plate flow chamber. In addition, cells in the low,moderate and high shear stress groups were stressed by low, moderate and high shear stress for 8 hours, respectively.However, shear stress in the control group was 0 Pa. Flow cytometry was used to measure proliferation index, and the expression of c-myc protein and c-myc mRNA were determined by immnocytochemistry and RT-PCR analysis respectively.MAIN OUTCOME MEASURES: Expressions of c-myc protein and c-myc mRNA and proliferation index in endothelial cells under various degrees of shear stress.RESULTS: ① Proliferation index Proliferation index was higher in the moderate and high shear stress groups than that in the control group (P ＜ 0.05, 0.01). ② Expression of c-myc protein Immuneposjtjve expression of c-myc protein was gradually increased with the increase of shear stress and there were significant differences in the three shear stress groups as compared with control group (P ＜ 0.05-0.01). ③ Expression of c-myc mRNA Proliferation index of endothelial cells was higher in the low and moderate shear stress groups than that in the control group (P ＜ 0.05).CONCLUSION: Flow shear stress can induce expression of c-myc and activate expression of c-myc gene based on gene transcription so as to promote the proliferation of vascular endothelial cells in human cerebral arteriovenous malformation