Locally Applied Paeonol Preventsrestenosis In A Rabbit Vein Graft Model

Background and Objective:Withthe improvement of living standards,many researches find thatAtherosclerosis is a general disease associated with high rates of morbidity and mortality in our country。Coronary artery bypass surgery is a important way to cure multivessel atherosclerosis. Although artery is a better choice during CABG, The use of autologous saphenous vein grafts in coronary artery bypass surgery remains the preferred treatment for patients with multivessel atherosclerosis. However, graft failure is a serious problem.Paeonol is the active compound of Cortex Moutan radix, a Chinese herbal remedy widely used to reduce body heat, promote blood flow, eliminate stasis, relieve pain, suppress cough, and alleviate edema. Accumulating evidence suggests paeonol has therapeutic effects on the cardiovascular system, such as inhibiting VSMC proliferation induced by high glucose levels, preventing tumor necrosis factor (TNF)-a-induced monocyte adhesion to rat aortic endothelial cells, suppressing oxidized low density lipoprotein-induced endothelial cell apoptosis, and dilating blood vessels.This was investigated in the present study by applying a one-time topical dose of paeonol to grafted veins in a rabbit model. Find a new way to improve CABG.Methods:1. Thirty-six male New Zealand white rabbits (weight,2-2.5kg) were randomly separated into the control group (CONT, n= 18) and the paeonol group(PAE, n=18). The control rabbits and paeonol rabbits were randomly divided into three groups respectively:0 week (CONT-OW group, n=6),2 weeks (CONT-2W group, n=6),3 weeks (CONT-3W group, n=6) of CONT group, and 0 week (PAE-OW group, n=6),2 weeks (PAE-2W group, n=6),3 weeks (PAE-3W group, n=6) of PAE group. After one week of breeding, the external jugular veins of all rabbits were transplanted to the carotid artery using the improved "Cuff Sleeve Technique". After operation,Paeonol (National Institutes for Food and Dug Control 0.4mg) was dissolved in 300 μl dimethylsulfoxide (DMSO) and resuspended in 10ml 30% pluronic-F127 gel, which was used to coat grafted veins of rabbits in the paeonol treatment group; DMSO in pluronic-F127 gel was applied to control rabbits. Vein grafts were harvested 0,2, and 3weeks after surgery by cutting implanted segments from native vessels at the cuff end. Veins were immediately fixed in 4% paraformaldehyde for analyses. Animals were sacrificed by sodium pentobarbital over dose at the end of the experiment. Expression of PCNA, ICAM-1 and VCAM-1 were detected by immunohistochemical. Apoptosis of scular endothelial cell were tested by TUNEL assay.Results:1,All rabbits survived the surgical procedure, and grafts were confirmed as patent at the time of harvest by cutting open the distal end. The neointima was almost imperceptible at 0 weeks in both paeonol and control groups.neointimal thickening was reduced in paeonol-treated rabbits at 2 and 3 weeks by 42% and 46%, respectively, relative to controls (week 2, 70.27±1.50μm vs.39.32±1.60 μm,P<0.01,n=6; week 3,101.43±1.37μm vs.59.81±1.38μm,P<0.01, n=6). the thickness of the medial tissue at these time points was reduced by 18% and 22%, respectively, in the paeonol as compared to the control group(week 2,120.24±1.70vs.98.66±1.27μm, P<0.01, n= 6; week 3, 140.56±1.68vs.109.65±1.50 μm, P<0.01, n= 6). The intima-to-media ratio in the paeonol as compared to the control group was 0.40±0.02 vs.0.58±0.03 at 2 weeks(P<0.01, n=6) and 0.54±0.01 vs.0.72±0.02 at 3 weeks(P<0.01, n=6). PCNA expression was decreased in the paeonol as compared to the control group at 2 and 3 weeks (week 2,0.02±0.01 vs.0.13±0.01, P< 0.01, n=6;week 3,0.20±0.02 vs.0.42±0.03,P< 0.01, n= 6). we find VCAM-1 expression was decreased in the paeonol as compared to the control group at 2 and 3 weeks(week 2,0.45±0.15 vs 0.26±0.09, P< 0.01, n=6; week 3,0.88±0.06 vs.0.41±0.04, P< 0.01, n=6) (Figs.4B and 6C), however, there was no difference in ICAM-1 expression between groups at 2 and 3 weeks. Paeonol treatment decreased the percentage of TUNEL-positive cells relative to control animals(week 2,0.09±0.04 vs 0.15±0.03, P< 0.01, n=6; week 3,0.18±0.04 vs.0.24±0.03,P< 0.01, n=6).Conclusions:The present study demonstrated that locally administered paeonol can suppress intimal hyperplasia in a rabbit model of autologous vein grafts via inhibition of VSMC proliferation, VCAM-1 expression and VEC apoptosis. These findings indicate that paeonol can be used to prevent occlusion of vein grafts in coronary artery bypass surgery, there by decreasing the rate of graft failure.