The Expression Of Tenascin-X And CD34 In The Process Of Atherosclerotic Plaque Formation And The Experimental Study Of Tenascin-X In Vivo Imaging In MR-targeted Plaques

Objective1.To detect the dynamic expression of Tenascin-X?TNX?and CD34 in the formation of aortic plaque after high fat feeding in apolipoprotein E knockout(Apo E^-/-)mice and to explore the correlation between them.2.To explore the feasibility of Tenscin-X targeting USPIO molecular probes for MR in vivo imaging in aortic plaques,and to provide further experimental research for the extension of molecular imaging.Materials and methods1.The male model of atherosclerosis?AS?was established in the high-fat male ApoE^-/-mice.The male C57BL/6 mice fed the normal diet were the control group,and the number of the two groups was 25.At the 8th,12th,20th,28th and 36th week of feeding,5 mice were tested for blood lipid levels,then aortic vascular specimens were collected.Oil red O staining and hematoxylin-eosin staining?HE?were used to observe the pathological morphology of aortic plaques and to analyze histomorphology,Tenascin-X?TNX?and CD34 immunohistochemical expression.2.Animals with atherosclerosis?AS?were established in 40 ApoE^-/-mice fed with high-fat diet.7.0 magnetic resonance scans were performed at the 30th week of feeding.They were randomly divided into experimental group and control group before scanning,with 10 mice in each group.Each group of mice underwent the first abdominal aorta scan before the drug was administered.At the end of the scan,the experimental group injected a TNX-targeted magnetic resonance imaging probe?anti-TNX-USPIO?synthesized by chemical coupling method into the tail vein,and the control group injected simple ultrasmall superparamagnetic particles of iron oxide?USPIO?.MR imaging was performed again after 12 h of injection,and the relative relative signal change rate was used to calculate the plaque relative signal change.At the end of imaging,the mouse abdominal aorta specimens were taken for TNX immunohistochemical staining and Prussian blue staining.The expression of TNX and the deposition of iron particles in the plaques were observed and the signal changes of the plaques were analyzed.Results1.The analysis of blood lipid levels showed that the levels of low-density lipoprotein?LDL?and total cholesterol?TC?in the experimental group were higher than in the control group?P<0.05?,while the high-density lipid?HDL?and triglyceride?TG?in the experimental group were higher than the control group only at 28 weeks and 32weeks.With the prolongation of feeding time,the plaque area and?plaque area?/?normal lumen area?ratio of the experimental group increased continuously?plaque area:F=313.914,p<0.001;?plaque area?/?normal lumen area?:F=213.215,P<0.001?.The expression of TNX and CD34 in plaque increased with the increase of feeding time,and both of them were most expressed at 36 weeks?TNX:0.541±0.074vs 0.054±0.006,0.146±0.024,0.213±0.011,0.322±0.029;CD34:0.411±0.032 vs0.150±0.033,0.198±0.013,0.220±0.013,0.387±0.055?,and TNX and CD34-positive microvessels were highly expressed around the fibrous cap and lipid core and positively correlated?r=0.87,P<0.001?.The plaque formation in the control group was not obvious.2.The plaque signal reduction in the experimental group was significantly lower than that in the control group at 12h after injection,and the plaque signal change rate was statistically significant compared with the control group?experimental group 12h:-24.98±13.54%vs control group 12h:-4.88±3.08%,F=23.152,P<0.001?.Immunohistochemical staining showed that the expression of Tenascin-X and Prussian blue iron particles were present in the plaques of the experimental group and the control group,and the Prussian blue-dyed iron particles were significantly higher in the experimental group than in the control group.Conclusion1.The expression levels of Tenascin-X and CD34 increased with plaque progression,and the expression regions of both were similar in plaques.TNX may be closely related to the formation of new blood vessels in the plaque.2.The anti-TNX-USPIO probe can detect the expression of TNX in atherosclerotic plaques in vivo,and the relative signal change rate of plaque provides a quantitative evaluation method for the absorption of TNX in plaques.Further laid the foundation for molecular imaging of atherosclerosis.