title: Thrombosis and neointima formation in vein grafts are inhibited by locally applied aspirin through endothelial protection.
abstract: Vein graft failure within the first month after bypass surgery is largely because of thrombosis. However, systemic study of thrombus formation in vein grafts is still lacking, and few effective techniques are available to prevent this event. Herein, we analyzed the kinetics of thrombosis and tested the effectiveness of locally applied aspirin on prevention of the disease in a mouse model. En face analysis of vein grafts revealed that 67+/-12% and 54+/-17% of the surface areas were covered by microthrombi at 1 and 3 days, respectively. Thrombus generation was also identified by labeling of platelets and fibrin, which occurred in 35 grafts examined at 1 and 3 days and 1, 2, 4, and 8 weeks. In a fifth of grafts, the thrombus occluded the vessel lumen by > or =1/4. Furthermore, a significant loss of endothelial cells was evidenced by beta-gal staining for vein grafts in transgenic mice expressing LacZ gene controlled by TIE2-endothelial specific gene promoter. Following thrombosis, neointimal lesions were significantly increased by 4-fold 2 weeks after the operation. When vein grafts were treated locally with aspirin in pluronic gel-127, the thrombus area was significantly reduced (P<0.005) at 1, 4, and 8 weeks. Interestingly, neointimal lesions were markedly reduced in the local, but not oral, aspirin-treated group at 4 and 8 weeks by 50% to 70% (P<0.005). The mechanism of reduced lesions by locally applied aspirin involved the protection of vein graft endothelium. Thus, we provide strong evidence that thrombus formation occurs before the development of neointimal lesions in vein grafts and that local aspirin treatment successfully reduces vein graft arteriosclerosis through endothelial protection, resulting in reduction of thrombosis.
authors.affiliation: Department of Cardiac and Vascular Sciences, St George's Hospital Medical School, London, UK.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Torsney
authors.forename: Ursula
authors.initials: U
authors.lastname: Mayr
authors.forename: Yiping
authors.initials: Y
authors.lastname: Zou
authors.forename: W Douglas
authors.initials: WD
authors.lastname: Thompson
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Hu
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Xu
mesh_terms: D000818:Animals; D001161:Arteriosclerosis / Q000209:etiology / Q000517:prevention & control*; D001241:Aspirin / Q000494:pharmacology / Q000627:therapeutic use*; D019917:Blood Vessel Prosthesis Implantation; D002339:Carotid Arteries / Q000187:drug effects* / Q000473:pathology / Q000601:surgery; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects*; D005343:Fibrinolytic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D006083:Graft Occlusion, Vascular / Q000209:etiology / Q000517:prevention & control*; D006965:Hyperplasia; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control*; D042787:Receptor, TIE-2 / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D013927:Thrombosis / Q000209:etiology / Q000517:prevention & control*; D013929:Thromboxane B2 / Q000097:blood; D017539:Tunica Intima / Q000187:drug effects / Q000473:pathology*; D014684:Venae Cavae / Q000187:drug effects* / Q000473:pathology / Q000601:surgery
chemical_list: D005343:Fibrinolytic Agents; D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; D042787:Receptor, TIE-2; D001241:Aspirin