超声微泡介导GFP转染C57810及mdx小鼠骨骼肌细胞的实验研究

目的 探讨细胞膜孔开放及含氟烷气体白蛋白外膜在超声微泡介导GFP转染C57810及mdx小鼠骨骼肌细胞中的机制.方法 以肌细胞膜缺损为主要病理改变的mdx小鼠与正常C57810小鼠为研究对象,目的基因GFP与Optison或SonoVue混合注入小鼠胫前肌,一侧胫前肌经超声辐照,另一侧胫前肌不经超声辐照.C57810小鼠作为正常对照,实验分组如下:①C57810小鼠生理盐水组(4条左胫前肌);②C57810小鼠生理盐水+超声组(4条右胫前肌);③C57810小鼠Optison组(4条左胫前肌);④C57810小鼠Oprison+超声组(4条右胫前肌);⑤C57810小鼠SonoVue组(4条左胫前肌);⑥C57810小鼠SonoVue+超声组(4条右胫前肌).mdx肌营养不良小鼠实验分组如下:①mdx小鼠生理盐水组(4条左胫前肌);②mdx小鼠生理盐水+超声组(4条右胫前肌);③mdx小鼠+Optison组(4条左胫前肌);④mdx小鼠Optison+超声组(4条右胫前肌);⑤mdx小鼠SonoVue组(4条左胫前肌);⑥mdx小鼠SonoVue+超声组(4条右胫前肌).1周后处死小鼠,荧光显微镜观察发出绿色荧光者为GFP阳性肌纤维细胞,计数最大GFP阳性肌纤维细胞数,作为GFP基因转染效率指标.结果 正常C57810小鼠:①无超声作用时,与阴性对照组比较,Optison微泡显著提高GFP基因转染水平(P<0.01),SonoVue微泡不提高GFP基因转染水平;②有超声作用时,与阴性对照组比较,Optison微泡显著提高GFP基因转染水平(P<0.01);③有超声作用时,与阴性对照组比较,SonoVue微泡显著提高GFP基因转染水平(P<0.01).mdx小鼠:①与正常C57810小鼠比较,GFP单独(生理盐水组)显著提高GFP基因转染水平(P<0.01),Optison微泡显著提高GFP基因转染水平(P<0.01),SonoVue微泡显著提高GFP基因转染水平(P<0.01);②与阴性对照组比较,Optison微泡显著提高GFP基因转染水平(P<0.01),SonoVue微泡显著提高GFP基因转染水平(P<0.01).结论 细胞膜孔开放是微泡提高基因转染水平的重要因素,含氟烷气体白蛋白外膜是Optison微泡提高GFP转染水平的主要成分.

Abstract：

Objective To investigate the role of sonoporation and the deblic of microbubbles with perfluoropropane gas and albumin in the mechanisms of microbubble-mediated gene enhancement by experimenting in skeletal muscle in C57B10/mdx mice. Methods Plasmid DNA (10 μg) encoding green fluorescent protein (GFP) was mixed with Optison or SonoVue dissolved in saline and injected into the tibialis anterior (TA) muscle of /C57B10/mdx mice with and without adjunct ultrasound. The efficiencies of GFP transgene expression were determined under different experimental conditions. C57B10 mice as normal control:①C57B10 mice + saline (4 left TAs);②C57B10 mice + saline + ultrasound (4 right TAs) ;③C57B10 mice + Optison(4 left TAs);④C57B10 mice+ Optison + ultrasound(4 right TAs);⑤ C57B10 mice + SonoVue(4 left TAs) ;⑥C57B10 mice + SonoVue + ultrasound(4 right TAs). Mdx mice groups:① mdx mice + saline(4 left TAs) ;② mdx mice + saline + ultrasound(4 right TAs);③ mdx mice + Optison (4 left TAs) ; ④ mdx mice + Optison + ultrasound (4 right TAs); ⑤mdx mice + SonoVue(4 left TAs) ;⑥mdx mice + SonoVue + ultrasound(4 right TAs). Mice were sacrificed 1 week after plasmid DNA injection. Fibres with fluorescence green signals were determined as GFP-positive fibres by fluorescence microscopy. Readout was performed on the section with the maximum number of transfected fibers. Results C57B10 mice: ?Optison without ultrasound had significantly increased gene expression compared with negative control ( P <0. 01). SonoVue without ultrasound did not enhance gene expression. ?Optison with ultrasound had significantly increased gene expression compared with negative control (P < 0.01). ?SonoVue with ultrasound had significantly increased gene expression compared with negative control ( P<0. 01).Mdx mice:? Compared with C57B10 mice, GFP alone demonstrated significant GFP expression in mdx mice ( P <0. 01) , Optison demonstrated significant GFP expression in mdx mice ( P <0.01), and SonoVue demonstrated significant GFP expression in mdx mice ( P <0. 01). ?Microbubble groups (Optison and SonoVue) had significantly increased gene expression compared with negative control (P <0. 01). Conclusions In the mechanisms of microbubble-mediated gene enhancement, sonoporation is the key step. The deblic of microbubbles with perfluoropropane gas and albumin is the main constituent in the mechanisms of Optison-mediated gene enhancement. fibers.Results C5781 0 mice:①Optison without ultrasound had significantly increased gene expressioncompared with negative control(P<0.01).SonoVue without ultrasound did not enhance gene expression.②Optison with ultrasound had significantly increased gene expression compared with negative control(P<0.01).③SonoVue with ultrasound had significantly increased gene expression compared with negativecontr01(P相似文献   

Microbubble ultrasound improves the efficiency of gene transduction in skeletal muscle in vivo with reduced tissue damage

Intramuscular injection of naked plasmid DNA is a safe approach to the systemic delivery of therapeutic gene products, but with limited efficiency. We have investigated the use of microbubble ultrasound to augment naked plasmid DNA delivery by direct injection into mouse skeletal muscle in vivo, in both young (4 weeks) and older (6 months) mice. We observed that the albumin-coated microbubble, Optison (licensed for echocardiography in patients), significantly improves the transfection efficiency even in the absence of ultrasound. The increase in transgene expression is age related as Optison improves transgene expression less efficiently in older mice than in younger mice. More importantly, Optison markedly reduces muscle damage associated with naked plasmid DNA and the presence of cationic polymer PEI 25000. Ultrasound at moderate power (3 W/cm2 1 MHz, 60 s exposure, duty cycle 20%), combined with Optison, increases transfection efficiency in older, but not in young, mice. The safe clinical use of microbubbles and therapeutic ultrasound and, particularly, the protective effect of the microbubbles against tissue damage provide a highly promising approach for gene delivery in muscle in vivo.     

超声辐照和SonoVue微泡在介导hAng-1基因体外转染时的作用和量效关系探讨

目的 探讨超声辐照和SonoVue微泡分别使用和联用在介导hAng-1基因体外转染过程中的作用以及辐照强度和微泡浓度对转染效率和细胞活性的影响.方法 实验分四组A组:单纯超声辐照+质粒组;B组:微泡+质粒组;C组:超声辐照+微泡+质粒组和空白对照组D组. C组内转染参数分别设置为超声照射强度0.5、1.0 、1.5和2.0 W/cm~2,微泡浓度5%、10%、20%、30%和40%.将连接有eGFP-C_3-hAng-1质粒的SonoVue微泡对293T细胞进行转染,48 h后检测各组基因转染效率和细胞存活率. 结果转染48 h后C组转染效率最高,荧光阳性细胞数最多,强度最大;A组转染效率很低,见少量荧光表达;B、D组无明显基因转染发生.随着超声照射强度和微泡浓度的增加,基因转染效率会逐步升高,具有统计学意义.微泡浓度大于20%、超声照射强度超过1.5 W/cm~2后基因转染效率不再升高甚至降低,细胞死亡率显著增高(P<0.01).结论 SonoVue微泡介导外源基因转染必须联合超声辐照才能获得较好的转染效率.对于hAng-1基因和SonoVue微泡,选择声强1.5 W/cm~2,微泡浓度20%是相对最佳转染条件.     

Ultrasound-mediated microbubble destruction enhances gene transfection in pancreatic cancer cells

INTRODUCTION: The purpose of this study was to determine whether ultrasound exposure combined with microbubble destruction could be used to enhance non-viral gene delivery in human pancreatic carcinoma cells (PANC-1). METHODS: The study was performed with four experimental groups: Group P, plasmid alone; Group P+M, plasmid and microbubbles; Group P+U, plasmid and ultrasound; Group P+U+M, plasmid with ultrasound and microbubbles. Plasmid DNA encoding enhanced green fluorescent protein (pEGFP) was gently mixed with commercially available ultrasound microbubble contrast agents (SonoVue(R); Bracco Diagnostics Inc, Milan, Italy) in Group P+M and Group P+U+M. The different combinations of DNA and DNA plus microbubbles were added to cultured PANC-1 cells under different conditions. Transfection efficiency and cell viability were assessed by FACS analysis (Becton Dickinson, San Jose, CA, USA), confocal laser scanning microscopy, and trypan blue staining. RESULTS: The results demonstrated that microbubbles with ultrasound exposure could significantly enhance the reporter gene expression as compared with other groups (Group P+U+M, 21.4%+/-3.16%; Group P, 2.9%+/-0.45%; Group P+M, 3.1%+/-0.51%; Group P+U, 6.1%+/-1.27%; P<0.01). No statistically significant difference was observed in the PANC-1 cell viability between Group P+U+M and other groups (P>0.05). CONCLUSION: Our in-vitro findings suggest that ultrasound-mediated microbubble destruction has the potential to promote efficient gene transfer into PANC-1 cells without significant cell death. This non-invasive gene transfer method may be a useful tool for safe clinical gene therapy of pancreatic cancer in the future.     

Optimizing Sensitivity of Ultrasound Contrast-Enhanced Super-Resolution Imaging by Tailoring Size Distribution of Microbubble Contrast Agent

Ultrasound contrast-enhanced super-resolution imaging has recently attracted attention because of its extraordinary ability to image vascular features much smaller than the ultrasound diffraction limit. This method requires sensitive detection of separable microbubble events despite a noisy tissue background to indicate the microvasculature, and any approach that could improve the sensitivity of the ultrasound system to individual microbubbles would be highly beneficial. In this study, we evaluated the effect of varying microbubble size on super-resolution imaging sensitivity. Microbubble preparations were size sorted into different mean diameters and then were imaged at equal concentrations. Commercially manufactured Definity and Optison were also imaged for comparison. Both in vitro experiments in phantom vessels and in vivo experiments imaging rat tumors revealed that the sensitivity of contrast-enhanced super-resolution imaging can be improved by using microbubbles with a larger diameter.     

Assessment of the Superharmonic Response of Microbubble Contrast Agents for Acoustic Angiography as a Function of Microbubble Parameters

Acoustic angiography is a superharmonic contrast-enhanced ultrasound imaging technique that enables 3-D high-resolution microvascular visualization. This technique utilizes a dual-frequency imaging strategy, transmitting at a low frequency and receiving at a higher frequency, to detect high-frequency contrast agent signatures and separate them from tissue background. Prior studies have illustrated differences in microbubble scatter dependent on microbubble size and composition; however, most previously reported data have utilized a relatively narrow frequency bandwidth centered around the excitation frequency. To date, a comprehensive study of isolated microbubble superharmonic responses with a broadband dual-frequency system has not been performed. Here, the superharmonic signal production of 14 contrast agents with various gas cores, shell compositions, and bubble diameters at mechanical indices of 0.2 to 1.2 was evaluated using a transmit 4 MHz, receive 25 MHz configuration. Results indicate that perfluorocarbon cores or lipid shells with 18- or 20-carbon acyl chains produce more superharmonic signal than sulfur hexafluoride cores or lipid shells with 16-carbon acyl chains, respectively. As microbubble diameter increases from 1 to 4 µm, superharmonic generation decreases. In a comparison of two clinical agents, Definity and Optison, and one preclinical agent, Micromarker, Optison produced the least superharmonic signal. Overall, this work suggests that microbubbles around 1 μm in diameter with perfluorocarbon cores and longer-chained lipid shells perform best for superharmonic imaging at 4 MHz. Studies have found that microbubble superharmonic response follows trends different from those described in prior studies using a narrower frequency bandwidth centered around the excitation frequency. Future work will apply these results in vivo to optimize the sensitivity of acoustic angiography.     

Effect of Microbubble Size on Fundamental Mode High Frequency Ultrasound Imaging in Mice

High-frequency ultrasound imaging using microbubble (MB) contrast agents is becoming increasingly popular in pre-clinical and small animal studies of anatomy, flow and vascular expression of molecular epitopes. Currently, in vivo imaging studies rely on highly polydisperse microbubble suspensions, which may provide a complex and varied acoustic response. To study the effect of individual microbubble size populations, microbubbles of 1–2 μm, 4–5 μm and 6–8 μm diameter were isolated using the technique of differential centrifugation. Size-selected microbubbles were imaged in the mouse kidney over a range of concentrations using a Visualsonics Vevo 770 ultrasound imaging system (Visualsonics, Toronto, Ontario, Canada) with a 40-MHz probe in fundamental mode. Results demonstrate that contrast enhancement and circulation persistence are strongly dependent on microbubble size and concentration. Large microbubbles (4–5 and 6–8 μm) strongly enhanced the ultrasound image with positive contrast, while 1–2 μm microbubbles showed little enhancement. For example, the total integrated contrast enhancement, measured by the area under the time-intensity curve (AUC), increased 16-fold for 6–8 μm diameter microbubbles at 5 × 10⁷ MB/bolus compared with 4–5 μm microbubbles at the same concentration. Interestingly, 1–2 μm diameter microbubbles, at any concentration, did not measurably enhance the integrated ultrasound signal at tissue depth, but did noticeably attenuate the signal, indicating that they had a low scattering-to-attenuation ratio. When concentration matched, larger microbubbles were more persistent in circulation. However, when volume matched, all microbubble sizes had a similar circulation half-life. These results indicated that dissolution of the gas core plays a larger role in contrast elimination than filtering by the lungs and spleen. The results of this study show that microbubbles can be tailored for optimal contrast enhancement in fundamental mode imaging. (E-mail: mb2910@columbia.edu)     

超声介导SonoVue微泡破裂对hAng-1基因完整性和表达效率的影响

目的 探讨超声联合SonoVue微泡介导hAng-1基因转染293T细胞的转染效率及基因完整性和表达状况.方法 构建eGFP-C3-hAn-1质粒,根据不同实验组的设计,应用相应的微泡联合超声辐照条件进行293T细胞的eGFP-C3-hAng-1基因转染,转染后48 h,以荧光显微镜观察到绿色荧光为转染成功标志;流式细胞术检测基因转染阳性细胞率,台盼蓝染色检测细胞生存率;RT-PCR和Western blot技术检测hAng-1基因的mRNA和蛋白表达;琼脂糖凝胶电泳检测经超声辐射后质粒的完整性.结果 ①微泡浓度为20%,DNA浓度为15 mg/L时进行基因转染可获较好转染效率和细胞生存率;②转染体系中血清的存在并不影响转染效率和细胞生存率;③最适转染条件下的超声辐照剂量不会影响DNA的完整性,且转染后的基因可正常表达mRNA并翻译目的蛋白.结论 微泡联合超声辐照能够介导体外细胞治疗性基因的转染,血清的存在并不影响基因的转染,转染后的基因能顺利地表达并具有正常功能.     

Microbubble-Enhanced Heating: Exploring the Effect of Microbubble Concentration and Pressure Amplitude on High-Intensity Focused Ultrasound Treatments

High-intensity focused ultrasound (HIFU) is a non-invasive tool that can be used for targeted thermal ablation treatments. Currently, HIFU is clinically approved for treatment of uterine fibroids, various cancers, and certain brain applications. However, for brain applications such as essential tremors, HIFU can only be used to treat limited areas confined to the center of the brain because of geometrical limitations (shape of the transducer and skull). A major obstacle to advancing this technology is the inability to treat non-central brain locations without causing damage to the skin and/or skull. Previous research has indicated that cavitation-induced bubbles or microbubble contrast agents can be used to enhance HIFU treatments by increasing ablation regions and shortening acoustic exposures at lower acoustic pressures. However, little research has been done to explore the interplay between microbubble concentration and pressure amplitude on HIFU treatments. We developed an in vitro experimental setup to study lesion formation at three different acoustic pressures and three microbubble concentrations. Real-time ultrasound imaging was integrated to monitor initial microbubble concentration and subsequent behavior during the HIFU treatments. Depending on the pressure used for the HIFU treatment, there was an optimal concentration of microbubbles that led to enhanced heating in the focal area. If the concentration of microbubbles was too high, the treatment was detrimentally affected because of non-linear attenuation by the pre-focal microbubbles. Additionally, the real-time ultrasound imaging provided a reliable method to monitor microbubble activity during the HIFU treatments, which is important for translation to in vivo HIFU applications with microbubbles.     

Three Decades of Ultrasound Contrast Agents: A Review of the Past,Present and Future Improvements

Initial reports from the 1960s describing the observations of ultrasound contrast enhancement by tiny gaseous bubbles during echocardiographic examinations prompted the development of the first ultrasound contrast agent in the 1980s. Current commercial contrast agents for echography, such as Definity, Optison, Sonazoid and SonoVue, have proven to be successful in a variety of on- and off-label clinical indications. Whereas contrast-specific technology has seen dramatic progress after the introduction of the first approved agents in the 1990s, successful clinical translation of new developments has been limited during the same period, while understanding of microbubble physical, chemical and biologic behavior has improved substantially. It is expected that for a successful development of future opportunities, such as ultrasound molecular imaging and therapeutic applications using microbubbles, new creative developments in microbubble engineering and production dedicated to further optimizing microbubble performance are required, and that they cannot rely on bubble technology developed more than 3 decades ago.     

超声微泡造影剂对心肌组织的生物学效应及介导VEGF基因转染大鼠心肌的实验研究

目的 探讨超声微泡造影剂对心肌组织的生物学效应及其介导VEGF基因转染大鼠心肌的有效性。方法 18只健康雄性Wistar大鼠，取3只采用超声波在鼠胸壁破坏微泡造影剂，观察对心肌组织显微结构的影响。将另15只急性心肌梗死3天后的雄性Wistar大鼠分为3组，每组5只。第一组采用超声破坏微泡造影剂的方式，将pcDzVEGFm基因转染大鼠心肌至造影剂不再显影(约6min)；第二组尾静脉输入同等剂量携pcD。VEGF。基因的造影剂；第三组为对照。2周后，取缺血心肌组织行VEGF免疫组织化学染色，观察心肌组织血管内皮生长因子(VEGF)蛋白表达情况。结果超声波破坏微泡造影剂能使心肌组织充血，产生大量空泡，并有部分心肌细胞坏死。采用超声微泡造影剂介导的VEGF基因转染，能明显增强大鼠心肌组织VEGF蛋白的表达。结论 超声微泡造影剂能明显增强对组织的空化效应，其介导的VEGF基因治疗是一种无创、新型、高效的基因转移方法。     

共聚物P85和微泡造影剂对小鼠骨骼肌超声介导基因转染的影响

目的 探讨共聚物P85、微泡造影剂和超声在质粒DNA对小鼠骨骼肌基因转染中的影响.方法 应用共聚物P85、微泡造影剂Optison与DNA混合后直接小鼠胫前肌(TA)注射,并辐照超声.1周后取出胫前肌并快速冰冻切片,荧光显微镜计数表达GFP转染的肌纤维数,HE染色评价肌肉损伤情况.结果 共聚物P85和微泡造影剂Optison均可促进质粒DNA的基因转染(P<0.01,P<0.05).辐照超声可使P85介导的基因转染效率显著提高(P<0.01),但对微泡造影剂介导的基因转染却无显著提高(P>0.05),并且P85所介导的基因转染效率高于微泡造影剂介导的基因转染效率(P<0.01).微泡造影剂和P85耦合并辐照超声可使质粒的基因转染效率显著提高,与所有各组的差异有统计学意义(P<0.01).同时辐照超声显著增加含微泡造影剂组骨骼肌的损伤面积(P<0.01).结论 共聚物P85和微泡造影剂可介导质粒DNA的基因转染,辐照超声对其有促进作用,三者联合应用具有协同作用.     

Microbubble Type and Distribution Dependence of Focused Ultrasound-Induced Blood–Brain Barrier Opening

Focused ultrasound, in the presence of microbubbles, has been used non-invasively to induce reversible blood–brain barrier (BBB) opening in both rodents and non-human primates. This study was aimed at identifying the dependence of BBB opening properties on polydisperse microbubble (all clinically approved microbubbles are polydisperse) type and distribution by using a clinically approved ultrasound contrast agent (Definity microbubbles) and in-house prepared polydisperse (IHP) microbubbles in mice. A total of 18 C57 BL/6 mice (n = 3) were used in this study, and each mouse was injected with either Definity or IHP microbubbles via the tail vein. The concentration and size distribution of activated Definity and IHP microbubbles were measured, and the microbubbles were diluted to 6 × 10⁸/mL before injection. Immediately after microbubble administration, mice were subjected to focused ultrasound with the following parameters: frequency = 1.5 MHz, pulse repetition frequency = 10 Hz, 1000 cycles, in situ peak rarefactional acoustic pressures = 0.3, 0.45 and 0.6 MPa for a sonication duration of 60 s. Contrast-enhanced magnetic resonance imaging was used to confirm BBB opening and allowed for image-based analysis. Permeability of the treated region and volume of BBB opening did not significantly differ between the two types of microbubbles (p > 0.05) at peak rarefractional acoustic pressures of 0.45 and 0.6 MPa, whereas IHP microbubbles had significantly higher permeability and opening volume (p < 0.05) at the relatively lower pressure of 0.3 MPa. The results from this study indicate that microbubble type and distribution could have significant effects on focused ultrasound-induced BBB opening at lower pressures, but less important effects at higher pressures, possibly because of the stable cavitation that governs the former. This difference may have become less significant at higher pressures, where inertial cavitation typically occurs.     

Monodisperse versus Polydisperse Ultrasound Contrast Agents: In Vivo Sensitivity and safety in Rat and Pig

Recent advances in the field of monodisperse microbubble synthesis by flow focusing allow for the production of foam-free, highly concentrated and monodisperse lipid-coated microbubble suspensions. It has been found that in vitro, such monodisperse ultrasound contrast agents (UCAs) improve the sensitivity of contrast-enhanced ultrasound imaging. Here, we present the first in vivo study in the left ventricle of rat and pig with this new monodisperse bubble agent. We systematically characterize the acoustic sensitivity and safety of the agent at an imaging frequency of 2.5 MHz as compared with three commercial polydisperse UCAs (SonoVue/Lumason, Definity/Luminity and Optison) and one research-grade polydisperse agent with the same shell composition as the monodisperse bubbles. The monodisperse microbubbles, which had a diameter of 4.2 μm, crossed the pulmonary vasculature, and their echo signal could be measured at least as long as that of the polydisperse UCAs, indicating that microfluidically formed monodisperse microbubbles are stable in vivo. Furthermore, it was found that the sensitivity of the monodisperse agent, expressed as the mean echo power per injected bubble, was at least 10 times higher than that of the polydisperse UCAs. Finally, the safety profile of the monodisperse microbubble suspension was evaluated by injecting 400 and 2000 times the imaging dose, and neither physiologic nor pathologic changes were found, which is a first indication that monodisperse lipid-coated microbubbles formed by flow focusing are safe for in vivo use. The more uniform acoustic response and corresponding increased imaging sensitivity of the monodisperse agent may boost emerging applications of microbubbles and ultrasound such as molecular imaging and therapy.     

Microbubble Formulations: Synthesis,Stability, Modeling and Biomedical Applications

Microbubbles are increasingly being used in biomedical applications such as ultrasonic imaging and targeted drug delivery. Microbubbles typically range from 0.1 to 10 µm in size and consist of a protective shell made of lipids or proteins. The shell encapsulates a gaseous core containing gases such as oxygen, sulfur hexafluoride or perfluorocarbons. This review is a consolidated account of information available in the literature on research related to microbubbles. Efforts have been made to present an overview of microbubble synthesis techniques; microbubble stability; microbubbles as contrast agents in ultrasonic imaging and drug delivery vehicles; and side effects related to microbubble administration in humans. Developments related to the modeling of microbubble dissolution and stability are also discussed.     

Phagocytosis of ultrasound contrast agent microbubbles by Kupffer cells

Delayed parenchymal phase images of the liver more than 5 min after IV injection of ultrasound contrast agents are thought to be related to the phagocytosis of contrast agent microbubbles by macrophages. In this study, we examined whether liver-specific macrophages, Kupffer cells, phagocytosed the microbubbles and whether their elimination affected the delayed parenchymal images of the liver. Phase-contrast microscope observations showed that Kupffer cells phagocytosed various contrast agents in vitro. Among the contrast agents used, 99% of Sonazoid and Optison, and 47% of Levovist were phagocytosed, whereas only 7.3% of SonoVue and 0% of Imavist were phagocytosed. Elimination of Kupffer cells in vivo by gadolinium chloride (GdCl(3)) resulted in decreased intensity of the delayed parenchymal images with Sonazoid and Levovist, while SonoVue showed no changes compared with control. Our findings suggested that Kupffer cells phagocytosed contrast agents and they were responsible for the delayed images of contrast ultrasound in the liver.     

Spatial Distribution of Ultrasound Targeted Microbubble Destruction Increases Cardiac Transgene Expression But Not Capillary Permeability

Ultrasound targeted microbubble destruction (UTMD) has evolved as a promising tool for organ specific gene and drug delivery. Using DNA-loaded microbubbles, cardiac transfection has been shown to be feasible. However, two-dimensional properties of the ultrasound beam limit cardiac transgene expression to the focal zone, thus, reducing its potential therapeutic effect. The aim of this study was to test if spatial distribution of ultrasound targeted microbubble destruction in the heart could lead to augmented transgene expression or increased capillary permeability. Lipid microbubbles containing plasmids with a luciferase transgene were used to target rat hearts. The diagnostic ultrasound probe was fixed in a mid-short axis view with a gel stand-off between the chest and probe. Ultrasound (1.3 MHz) with a mechanical index of 1.6 was intermittently applied to rats during microbubble infusion. Rats were randomized to either stay in that position or move horizontally in a cranio-caudal direction (3 mm sweep) relative to the ultrasound probe during UTMD. After 4 days, organs were harvested and analyzed for reporter gene expression. Another group of rats received Evans Blue, followed by UTMD with unloaded microbubbles. Again, rats were randomized into a static or moving group. Hearts were harvested to evaluate extravasation of Evans Blue. Moving rats in a cranio-caudal direction significantly increased transgene expression by 19-fold in the anterior heart, by sixfold in the posterior heart and by 32-fold in the apex. Interestingly, Evans Blue extravasation was not augmented in the moving group. Spatial distribution of UTMD may increase transgene expression due to sonication of larger areas in the heart. In contrast, capillary permeability does not increase, indicating less capillary damage. (E-mail: raffi.bekeredjian@med.uni-heidelberg.de)     

医学超声微泡造影剂空化效应的研究进展

近年来,随着新型超声微泡造影剂的研究和应用,超声微泡介导靶向治疗可增强基因转染效率,提高特定组织的基因表达水平和药物浓度,是一种安全、简便、高效的靶向性基因转染及药物治疗的新方法。本文就超声空化效应和超声微泡的治疗机制和应用做一简要综述。     

六氟化硫微泡介导人脂联素基因兔主动脉内转染及表达

背景:超声微泡载基因传输技术是一种新兴起的定向传输基因技术。目的:构建含人脂联素基因脂联素的真核表达载体,采用六氟化硫微泡介导脂联素基因进行兔主动脉转染及表达,为脂联素用于体内干预动脉粥样硬化的研究奠定基础。方法:人心外膜脂肪组织提取总RNA构建pcDNA3.1-脂联素重组体,通过瞬时转染人脐静脉内皮细胞验证载体构建是否成功。21只大白兔随机分成对照组(n=6)和脂联素转基因组(n=15),脂联素转基因组经兔耳缘静脉注射pcDNA3.1-脂联素与六氟化硫微泡的混合物,诊断超声仪照射兔胸腹主动脉区域,于照射后2,7,14d取兔主动脉血管及血清,检测主动脉血管壁中脂联素基因的表达及血清中脂联素蛋白水平。结果与结论:pcDNA3.1-脂联素瞬时转染入人脐静脉内皮细胞可有效表达。六氟化硫微泡传输脂联素基因2d后即可检测到兔主动脉血管壁脂联素基因高表达,持续至14d,且兔血清脂联素蛋白水平显著增加(P<0.01)。说明pcDNA3.1-脂联素重组体构建成功,六氟化硫微泡可在快速血流状态下,安全、高效传输脂联素基因入兔主动脉血管壁并有效表达与分泌至血浆。