Effect Of TMP On Vascular Reconstruction Induced By Ultrasound-targeted Microbubble In An Artery Balloon-injury Rabbit Model

Balloon expansion or stent implantation has become the main methodsto treat congenital vascular malformation and acquired vascular stenosisdiseases. The incidence of Restenosis rate was still10%-15%[1].Numbers factors are involved in Restenosis after PCI， such asendothelial dysfunction, inflammation, thrombosis, smooth muscle cellsphenotype switch, proliferation and migration, extracellular matrixaggregation and vascular remodeling. Neointimal formation and vesselrestenosis were not be inhibited completely with single anti-VSMCproliferation or anti-thrombosis treatment after artery injury. Studies haveshowed that TMP could inhibit VSMC proliferation,prevent plateletaggregation,decrease thrombus formation and protect endothelialcells.Based on the comprehensive treatment of TMP,we explored its effecton vascular reconstruction induced by Ultrasound-Targeted MicrobubbleDestruction and explored its possible mechanisms. OBJECTIVETo explore the effects of different balloon diameter on intimalhyperplasia in rabbit artery after balloon-injury and use the preferredballoon to established rabbits’ iliac artery restenosis model to study theeffect of TMP on vascular reconstruction induced by Ultrasound-TargetedMicrobubble Destruction and to explore its possible mechanisms.METHODS①Lipid was choosed as Microbubbles forming materials, TLM wasprepared by thin-film dispersion method and mechanical vibration.Theappearance,concentration,mean diameter,zeta potential and the entrapmentefficiency of TLM were observed and detected.②Twenty-five New Zealand white rabbits, were randomly dividedinto normal control group (n=5) and operated groups (n=20). Rabbits inoperated groups were averagely divided into group2.5mm,3.0mm,3.5mmand4.0mm, matching to balloon diameters of2.5,3.0,3.5and4.0mm.Stenosis degree was explored with high-frequency ultrasound, and intimalhyperplasia was examined with pathology28days after balloon-injury.③Twenty five New Zealand white male rabbits,weighted (2.2±0.1)kilogram，were divided into five group,five each，A:sham group;B:modelgroup;C:TMP mediated by ultrasound-targeted microbubbles destructioninterference at0day after injury;D:TMP mediated by ultrasound-targetedmicrobubbles destruction interference at1week after injury;E:TMPmediated by ultrasound-targeted microbubbles destruction interference at3 weeks after injury.Intimal hyperplasia and stenosis rate were examined withpathology after artery balloon-injury4weeks.④Thirty New zealand male rabbits,aged(100±5)days，weighted（2.2±0.1）kilogram were included.Angioplasty of the common iliacartery and external iliac artery were performed using a2.5mm ballooncatheter.All animals were averagely divided into six groups,:A,modelgroup;B,TMP group;C,TMP+ultrasound+microbubbles group;D,ultrasoundgroup;E,ultrasound+microbubbles group;F,sham group.They receiveddifferent treatments.The neointimal area,intima/media ratio and the levelof VEGF were measured by HE dyeing and immunohistochemistry dyeingafter4weeks of artery injury.RESULTS①This modified LM had a good shape.The mean diameterwas(516.5±12.6)nm, the concentration of bubble was8.03109/ml, zetapotenital was(-2.6±0.4)mv.②Stenosis ratio of group2.5mm,3.0mm and3.5mm were higherthan that of normal control group and group4.0mm28days afterballoon-injury(P<0.05). Neointimal area and intimal-media ratio increasedin the operated groups compared with normal control group (P<0.01).Positive correlation was noted between the degree of vessel expansion andproliferation index（r2=0.784， P＜0.001） among group2.5mm，3.0mmand3.5mm. The degree of vessel expansion in group4.0mm was the highest, but neointimal area and intimal-media ratio of group4.0mm weresmaller than those of group3.5mm (P<0.05).③Intima-media ratio and stenosis rate of group B1is the largestcompared with group A1(P＜0.01).Intima-media ratio and stenosis rate ofgroup C1and group D1were found lower than group B1（P＜0.05或P＜0.01）.There were the greatest reduction of intimal-media ratio and stenosisrate in group C1compared with group B1with intima-media ratiodecreased by o.99and stenosis rate decreased by39.53%.Althoughintimal-media ratio of group E1was smaller than group B1（P＜0.05）,stenosis rate in this group was similar to model group.④Neointimal area and intima/media ratio of group B,group C,groupD and group E of the external iliac artery were found significantly lowerthan those in group A（P＜0.01or P＜0.05）.There were significantreduction of0.996（t=4.854， P=0.008） of external iliac artery inintima/media ratio in group C compared with group A.The expression ofVEGF in group C decreased obviously compared with other interventiongroups（P＜0.05）.CONCLUSIONSOur study confirmed that:young rabbit artery stenosis model can beestablished feasible by endothelial denudation method,and the degree ofintimal hyperplasia aggravated with the balloon diameter increased fromthe range of1.2-1.8. Rabbit stenosis model could be evaluated by high frequency vascellum ultrasound imaging technology,which was consistentwith pathology testing.TMP mediated by ultrasound-targeted microbubblesdestruction inhibited intimal hyperplasia and vessel stenosis in rabbit siliac artery after balloon-injury,treat earlier will have bettereffect.Ultrasound microbubble method could promote the inhibition ofTMP on intimal proliferation reduce intimal pathological proliferation ofiliac artery after balloon-injury, and decreased expression of VEGF, wouldbe more useful in the prevention and treatment of vascularrestenosis.Ultrasound-mediated drug delivery can be beneficial for theclinical treatment of restenosis after coronary intervention and othercardiovascular diseases.