Expression of tissue factor in venous bypass grafting of rats / 中国组织工程研究

ABSTRACT

BACKGROUND: Previous studies demonstrated that smooth muscle injury or ischemia/reperfusion injury result in tissue factor (TF) increasing. However, few reports concern the expression and mechanism of TF in venous bypass grafting.OBJECTIVE: To examine changes in TF protein expression in response to venous bypass grafting.DESIGN, TIME AND SETTING: The animal observation experiment was performed at the Department of Cardiovascular Surgery, Affiliated Union Hospital of Tongji Medical College, Huazhong University of Science and Technology from May 2006 to May 2008.MATERIALS A total of 30 Sprague-Dawley (SD) rats.METHODS: Rats were underwent interposition bypass grafting of the common carotid artery via the ipsilateral external jugular vein. Namely, the proximal end of external jugular vein was ligated at the joints of external jugular vein and internal jugular vein, and the distal end of external jugular vein was ligated before branches. The proximal and distal ends of common carotid artery were occluded by artery clamp, and a 5 mm artery was removed. The proximal end of artery was anastomosed with distal end of artery, and the frontal wall was sutured with posterior wall. After that, the proximal end of external jugular vein was cut down and coincided with the distal end of common carotid artery.MAIN OUTCOME MEASURES: The expression of TF and proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry. Meantime, TF activity in vessel protein extracts was determined with TF activity assay kit, and the thickness of intima, media were calculated by computer imaging analysis system. The contralateral external jugular veins were served as the control.RESULTS: The adventitia of all vessels showed abundant TF staining. In early vein grafts, TF staining was markedly increased in the intima and media. However, intimal and media TF staining was absent in the contralateral control jugular veins and late vein grafts. The number of PCNA positive cells was increased in the vein grafts at day 3 after grafting, obvious increased at day 7, and reached the peak at day 14. TF activity in whole-vessel protein extracts was similar in control veins and early and late vein grafts. The thickness of neointima of the vein graft increased significantly at days 7, 14, and 28, and the thickness of media increased significantly at days 14 and 28.CONCLUSION: The changes of TF expression at various time points may relate to hyperplasia of neointima.