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Objective To develop a vulnerable plaque targeting ultrasound contrast agent (UCA) and to evaluate its affinity and imaging performance in vitro.Methods E-selectin receptor-targeting UCA,which conjugated with monoclonal antibody of E-selectin,was prepared with filming-rehydration method and biotin-avidin linkage.The size and distribution of UCA were measured with particle size analyzer,the connectivity condition of microbubbles with E-selectin antibody was also detected with fluorescence analysis.The cytotoxicity from microbubble and ultrasound irradiation was evaluated through cell counting kit-8 (CCK8) assay.The adhesion effect of UCA was assessed after co-incubated with activated mouse endothelial cells (bEnd.3) and compared with that of free antibody intervention group and control group.The imaging performance of UCA at different time points was observed on an ultrasound equipment with a high-frequency transducer.Two-sample t test and one-way analysis of variance were performed to analyze the data.Results E-selectin receptor-targeting UCA was successfully prepared.The cytotoxicity result with CCK8 assay demonstrated the favorable biocompatibility of UCA.The connection amount of UCA on activated bEnd.3 cells ((6.23 ± 0.45) bubbles/cell) was significantly higher than that of the free antibody intervention group ((1.57±0.34) bubbles/cell) and control group ((0.07±0.03) bubbles/cell;F=291.43,P＜0.01).The performance of in vitro ultrasonography at the same time points showed no obvious difference between targeting UCA and control UCA (all t＜0.51,all P＞0.05).Conclusions The prepared E-selectin receptor-targeting UCA has favorable targeting and imaging capabilities.It might be a potentially ultrasound molecular imaging agent for early detection and prognosis evaluation of vulnerable plaque.
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Objective To evaluate the effectiveness of treating glioma in combination with drugs multiply by comparing the size of tumor and the survival time of different groups in rat glioma after targeted blood-brain barrier (BBB ) disruption by MRI-guided focused ultrasound.Methods The stereotaxis instruments and the 10 μl gas-tight syringes were used to inject gliosarcoma cells into the targeted area of the brain in 50 male Sprague-Dawley rats.The glioma-bearing rat model was established.Each rat received either:(1 )no treatment (control;n =8);(2)single liposomal doxorubicin (DOX;n = 10);(3)multiple DOX (n =10);(4)single Avastin (AVS)and DOX (n =10);(5)multiple AVS and DOX (n =10).The SonoVue microbubble ultrasonic contrast agent and DOX or AVS were injected into the tail vein respectively on day 12 after implantation.The tumor size was measured by MRI on pre-treatment,immediacy and once a week of post-treatment after targeted BBB disruption by focused ultrasound,and the life span in rat glioma was recorded.Results The mediam survival of different groups in rat glioma(The range of the life span 13-90 d):no treatment (7 d);single DOX (12 d);multiple DOX (1 5 d);single AVS + DOX (22 d), multiple AVS+ DOX (30 d).There was significant difference of the groups on mediam survival comparison (P < 0.01 ).The tumor growth pattern after post-treatment of different groups in rat glioma except control:single DOX was noticeable fast and multiple AVS+DOX was visibly delayed comparable to other groups,and finally the tumor size of multiple AVS + DOX even became small.Conclusions The microbubble blasting enhances the local tissue permeability and promotes the drug delivery of chemotherapy and anti-angiogenesis locally in glioma-bearing rats by MRI-guided focused ultrasound.Especially,the combination with drugs multiply has a synergism efficacy that may enhance the effectiveness of chemotherapy,reduce tumor growth,and even become small of the tumor size,and increase survival time significantly after BBB disruption.
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Objective To prepare urokinase plasminogen activator (uPA)-loaded anionic lipid microbubbles (uPA-MBs) for thrombolysis with low-frequency ultrasound in vitro.Methods Anionic microbubbles composing of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC),1,2-dipalmitoyl-sn-glycero-3-phospho-(l'-rac-glycerol) (DPPG),1,2-distearoyl-sn-glycero-3-phosphoethanol amine-N (succinyl PEG2000) (DSPE-PEG2000) and perfluoropropane (C3F8) were prepared by the mechanical vibration method.Then,the resulting anionic microbubbles were incubated with uPA.uPA-MBs were obtained via electrostatic adsorption.Bubble size and distribution were measured by particle size analyzer.FITC-labeled uPA-MBs were obtained and observed under fluorescence microscope.The surface potential of uPA-MBs and plain microbubbles (P-MBs) were detected by Zeta potential analyzer.Sodium dodecyl sulfonate-polyacrylamide gel electrophoresis (SDS-PAGE) was used for confirming the binding of uPA protein and anionic microbubbles.The encapsulation efficiency of uPA-MBs was determined by bicinchoninic acid (BCA) protein assay kit under three different dosages of uPA (10 000,50 000 and 100 000 U).The thrombolysis efficiency of uPA-MBs combined with low-frequency ultrasound was examined in vitro.Two-sample t test,one-way analysis of variance and Bonferroni test were performed to analyze the data.Results UPA-MBs were successfully obtained with the mean particle size of (1.76±0.29) μm.The surface potential of these bubbles was significantly higher than that of P-MBs:(-36.64±0.21) mV vs (-66.33±2.38) mV (t =21.538,P＜0.05).Fluorescence microscope showed a green shell of FITC-labeled uPA-MBs.The encapsulation efficiency of uPAMBs with the added dosage of 10 000 U was (42.01±2.02) ％,which was significantly higher than those of 50000 and 100 000 U ((33.24±1.95)％ and (33.10±1.65)％ respectively,F=22.340,P＜0.05).The thrombolysis efficiency by saline was (4.09±0.80)％,saline + ultrasound (8.50±1.48)％,MBs + ultrasound (14.27± 1.59) ％,uPA-MBs + ultrasound (35.72±6.31) ％ and uPA (16.87±0.46) ％,respectively (F =48.783,t =-8.613,-7.273,-5.942,-6.908,all P＜0.05).Conclusion Anionic microbubbles can successfully load uPA,and achieve significantly better thrombolysis effect when combined with low-frequency ultrasound.
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Objective To evaluate the effectiveness of treating glioma in combination of two kinds of drugs by comparing the size of tumors and the survival time of different groups in rat glioma after targeted blood‐brain barrier (BBB) disruption by focused ultrasound under MRI‐guide. Methods The stereotaxis instruments and the 10 μl gas‐tight syringes were used to inject gliosarcoma cells into the targeted area of the brain in 40 male Sprague‐Dawley rats. The glioma‐bearing rats models were established. Rats were divided into 4 groups to receive different treatment :(1) no treatment (control, n = 8), (2) IV Avastin (Avastin only, n =10), (3) IV liposomal doxorubicin (DOX only, n =10), (4) IV Avastin and liposomal doxorubicin (Avastin+DOX, n =10). The SonoVue microbubbles and DOX or Avastin were injected into the tail vein respectively on the 12th day after implantation. The tumor size was measured by MRI on immediacy, once a week after targeted BBB disruption by focused ultrasound, and the life span in rat glioma was recorded. Results The average survival time of different groups in rat glioma was as follows :no treatment(17 ± 4)d, Avastin(20 ± 4)d, DOX(25 ± 5)d, DOX+ Avastin(40 ± 5)d. The tumor size after post‐treatment of different groups in rat glioma was as follows :no treatment(5 7.0 ± 4 3.0)mm, Avastin(4 3.0 ± 2 5.0)mm, DOX(4 1.2 ± 3 1.0)mm, DOX + Avastin(2. 20 ± 1. 30)mm. There was significant increased in average survival time and decreased in tumor size after a combination treatment DOX+ Avastin compared with other groups( P < 0 0.1). Conclusions The microbubble blasting by MRI‐guided focused ultrasound enhances the local tissue permeability and promotes the drug delivery of chemotherapy and anti‐angiogenesis locally in glioma‐bearing rats. Especially, the combination of two kinds of drugs has a synergism efficacy that may reduce tumor growth and increase survival time significantly after BBB disruption.
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<p><b>OBJECTIVE</b>Ultrasonic pulse wave Doppler technique for noninvasive blood flow imaging does not provide precise information of complex blood flow field, and observing two-dimensional artery blood flow field distribution provides important clinical information for cardiovascular disease.</p><p><b>METHODS</b>Ultrasonic particle image velocimetry (Echo PIV) was used to measure blood flows on B-mode ultrasonic particle image to assess the whole field velocity of the blood vessels in 5 groups of healthy rats. The reliability of Echo PIV was verified in comparison with ultrasonic Doppler method in 3 cardiac cycles.</p><p><b>RESULTS AND CONCLUSION</b>The results of Echo PIV were similar with the those of ultrasound spectral Doppler. The Echo PIV-measured peak and average velocity within 3 cardiac cycles were about 5%-10% and 2%-8% below the values measured by the ultrasonic spectral Doppler, respectively, but these differences were not statistically significant (P>0.05). As a new technique for monitoring complex blood flow in stenotic arteries, echo PIV can be used to directly and non-invasively assess whole field hemodynamic changes in blood vessels in real time and distinguish different groups of rats by velocity.</p>
Subject(s)
Animals , Rats , Arteries , Diagnostic Imaging , Blood Flow Velocity , Hemodynamics , Reproducibility of Results , Rheology , Ultrasonics , UltrasonographyABSTRACT
The development and progression of atherosclerosis and thrombosis are closely related to changes of hemodynamics parameters. Ultrasonic pulse wave Doppler technique is normally used for noninvasively blood flow imaging. However, this technique only provides one-dimensional velocity and depends on the angle between the ultrasound beam and the local velocity vector. In this study, ultrasonic particle image velocimetry method was used to assess whole field hemodynamic changes in normal blood vessels. By using the polynomial fitting method, we investigated the velocity gradient and assessed the shear in different blood flow velocity of 10 healthy rats. It was found that using four polynomial fitting could result in optimal measurement results. The results obtained by ultrasonic particle image velocimetry accorded with the results obtained using Doppler technique. The statistical average of cyclical vessel wall shear stress was positively related to the locational mean velocity. It is proven that ultrasonic particle image velocimetry method could be used to assess directly the real-time whole field hemodynamic changes in blood vessels and was non-invasively, and should be a good prosperous technique for monitoring complex blood flow in stenotic ar- teries.
Subject(s)
Animals , Rats , Algorithms , Arteries , Diagnostic Imaging , Pathology , Blood Flow Velocity , Echocardiography, Doppler , Hemodynamics , Models, Cardiovascular , Rheology , Stress, Mechanical , UltrasonicsABSTRACT
Purpose To prepare the tranexamic acid liposome with high encapsulation efficiency and stability, through interaction of avidin and biotin, and to prepare its microbubble-liposome compound whose properties are to be assessed. Materials and Methods Thin film hydration technology was used to prepare tranexamic acid liposome. Taking encapsulation efficiency as indication, the microbubble-liposome compound was optimized by the design of orthogonal experiment. The basic properties of the compound were tested and the acoustic characteristic was measured by ultrasound and gray-scale values. Results The optimum formula of tranexamic acid liposome were as follows:molar ratio of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, cholesterol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[biotinyl (polyethylene glycol) 2000] was 85∶10∶5;concentration of tranexamic acid was 5.0%;ultrasonic time was 15 min. The encapsulation efficiency was 62.62%. The size was approximately (104.00±1.84) nm. The Zeta potential was approximately (-50.50±0.56) mV. The liposome was good in stability. The size of the microbubble-liposome compound was approximately (4.56±0.28)μm. Under the microscope, they were round with transparent center, evenly distributed without aggregation. The acoustic characteristic of the compound in vitro showed typical characteristics of microbubble, which was compatible with the results under the microscope. As the concentrations of the compound increased, both ultrasound imaging effect and the gray-scale values enhanced. However, to avoid acoustic shadows, the imaging concentrations were supposed to be at least lower than 1.15×108/ml in vitro. Conclusion The preparation of the tranexamic acid microbubble-liposome compound can be optimized by taking encapsulation efficiency as reference, and it can be effectively traced by ultrasound according to its acoustic characteristics in vitro.
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When insonated with fundamental frequency, the ultrasound contrast microbubbles are able to produce nonlinear scattering and generate nonlinear frequencies. The nonlinear properties of these microbubbles can be used to create nonlinear imaging modality and significantly improve the diagnostic capability of medical ultrasound. This paper was a review about the current research progress of nonlinear properties of ultrasound contrast microbubbles and nonlinear imaging, especially about the nonlinear properties under different frequency, acoustic pressure and the application of nonlinear imaging. A prospect of the future research and application was finally put forward in the paper.