| The First PartEstablishment of atherosclerotic vulnerable plaque model in rabbit abdominal aorta and evaluation value of SWEObjective:2D ultrasound and shear-wave ultrasound elastography(SWE)were combined with pathological examination to evaluate the atherosclerotic vulnerable plaque model in rabbit abdominal aorta prepared by different modeling methods,to explore a relatively ideal method for the model of atherosclerotic vulnerable plaques in rabbit abdominal aorta,and to provide experimental basis for further experimental treatment of the plaque model.Methods:48 4-month-old male New Zealand white rabbits ranging from 2.0-2.5kg were randomly divided into four groups(12 rabbits in each group):Experimental group 1:high-fat diet+abdominal aortic balloon injury;Experimental group 2:high-fat diet+injection of calf serum albumin;Experimental group 3:high-fat diet+abdominal aortic balloon injury+injection of calf serum albumin;Control group:high fat diet.All rabbits were fed on a high fat diet,and at the end of 12th week,the experimental groups were treated with balloon strain and immune injury.Ultrasound observation,SWE evaluation and pathological examination were performed on all rabbits at week 0,week 12,week 16 and week 20 to determine the plaque composition and vulnerability.Results:1.Survival of the model:31 of 48 experimental rabbits survived and 17 died.2.Evaluation of Intima media thickness(IMT)in rabbits by 2D ultrasound:IMT in the same group gradually thickened with the feeding cycles(all P<0.05).At the end of week 16 and week 20,after balloon strain and immune injury,IMT in group 1,2 and 3 was thicker than that in the control group(all P<0.05).3.Evaluation of the types and number of atherosclerotic plaques in rabbit abdominal aorta by 2D ultrasound:76 atherosclerotic plaques were prepared.High-fat feeding+abdominal aortic balloon injury+injection of calf serum albumin produced the maximum number of plaques(P<0.05).After balloon injury and immune injury,type ? and type ? plaques were more likely to form(allP<0.05).4.SWE of atherosclerotic plaque in rabbit abdominal aorta:the Mean,Min and Max of plaques:type ?>type ?>type ?>type ?,the Young's modulus of plaques increased with the type and grade of plaques(all P<0.05).5.The Mean,Min and Max optimal diagnostic thresholds of SWE about four types plaque were calculated by drawing ROC curve with SWE measurements:Mean(29.75kPa?40.4 kPa?54.1 kPa),Min(13.75kPa?23.2kPa?34.1kPa),Max(39.75kPa?61.4kPa?84.7kPa)?6.The results of pathological examination were combined with SWE measurements to draw the ROC curve to obtain the optimal cut-off value:the area under the curve of Mean,Min and Max values was between 0.7 and 0.9,and the optimal cutoff values of Mean,Min and Max for vulnerable and non-vulnerable plaques were 39.45kPa,23.2 kPa and 60.75 kPa.Conclusions:An ideal atherosclerotic plaque model of rabbit abdominal aorta can be prepared by high fat feeding+abdominal aortic balloon injury+injection of calf serum albumin.At the same time,2-D ultrasound combined with SWE can quantitatively,repeatedly and sustainably observe and evaluate the vulnerability of plaques,which provides a good experimental basis for further experimental treatment research on plaque model.The Second PartStudy on the stability of plaque by ultrasound targeted microbubble destruction technique with IL-6 monoclonal antibodyObjective:Shear-wave ultrasound elastography(SWE)combined with ultrasound targeted microbubble destruction(UTMD)to evaluate the role of IL-6 monoclonal antibody targeting contrast agent in increasing the stability of atherosclerotic plaque.Methods:40 male New Zealand white rabbits with atherosclerotic plaques(modeling methods refer to the first part)were divided into 4 groups(10 rabbits in each group):Irradiation group:normal saline was used to replace the contrast agent;Bare microbubble group:bare microbubble was used for contrast;Targeted therapy group:targeted contrast agent carrying IL-6 monoclonal antibody was used for contrast;Blank control group:no treatment.The rabbits were treated with UTMD every two weeks from week 20 to 28.IMT and SWE hardness of atherosclerotic plaques in 40 rabbits were monitored at week 20,24 and 28.Meanwhile,IL-6 and blood lipid(TG,TC,LDL-c,HDL-c)in rabbits'blood were detected during the treatment.In the end,pathological examination confirmed the plaque composition and vulnerability after targeted therapy.Results:1.Parallel plate flow chamber experiment measured the adhesion efficiency of microbubbles:Biotin-avidin bridge can make USphere TM contrast agents and ligand(IL-6 monoclonal antibody)tightly coupled,at shear force 0.2dyn/cm2,the targeted microbubble specific adhesion efficiency was the highest(the number of stationary microbubbles was the highest).2.Evaluation of IMT in rabbits by 2D ultrasound:IMT in the targeted therapy group gradually thinned with the extension of treatment cycle(P<0.05).3.SWE of atherosclerotic plaque in rabbit abdominal aorta:after treatment,the Mean of plaques in the targeted therapy group showed an increasing trend(P<0.05).4.Analysis of IL-6 content in rabbits' serum:after the cessation of high-fat feeding,IL-6 levels in all rabbits' serum gradually decreased(all P<0.05).At week 24 and 28,the levels of IL-6 in the targeted therapy group were significantly lower than those in the blank control group,the irradiation group and the bare microbubble group(all P<0.05).5.Analysis of blood lipid detection results:with the progress of routine feeding,the contents of various blood lipid indexes(TC,TG,LDL-c,HDL-c)in all rabbits gradually decreased(all P<0.05).6.Pathological observation of rabbit abdominal aorta:after targeted therapy,there were significantly fewer foam cells in the abdominal aorta-mesenchymal of the rabbits in the targeted therapy group than in the control group.The targeted therapy group had fewer collagen fibers than the control group.And the thickness of the red stained lipid cells in the targeted therapy group was significantly thinner than that in the control group,and the red stained area was significantly smaller than that in the control group.Conclusions:Biotin-avidin bridge can successfully prepare targeted microbubbles with IL-6 monoclonal antibody,the IL-6 monoclonal antibody binds firmly to the microbubble.Using UTMD mediated targeted therapy with IL-6 monoclonal antibody contrast agent,the concentration of acute inflammatory factor IL-6 in rabbit serum decreased,IMT in rabbit abdominal aorta became thinner,and the hardness of vulnerable plaques increased significantly.Therefore,UTMD is an effective treatment method for atherosclerotic vulnerable plaques in the abdominal aorta of rabbits and is expected to be a new method to improve the stability of plaques. |
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