携Sialyl Lewis~X与携抗P-选择素单抗靶向超声微泡粘附性的对比研究

目的对比评价携sialylLewis。与携抗P-选择素单抗靶向超声微泡粘附特性。方法采用“亲和素-生物素”桥接法构建携Sialyl Lewis、（MB-S）、携抗P-选择素单抗靶向超声微泡（MB-P）及携同型抗体微泡（MB-C）。MB-S、MB-P及MB-C以相同流速通过相应小鼠P-选择素Fc段包被培养皿时,利用平行板流动腔在不同时间点测定相应的MB-S、MB-P及MB-C（对照组）的结合数目、滚动数目以及解离时达到半数解离的剪切应力。结果MB-S结合数量前3min快速增加,其后随时间增加无明显变化,而MB-P结合数量与时间呈正相关（P〈0．05）,且MB-S结合数目是MB-P的2～4倍;对照组MB-C未见明显结合（P〈0．05）。MB-S滚动数目大于MB-P（P〈0．05）;MB-S半数解离时剪切力小于MB-P（P〈0．05）。结论靶向超声微泡MB-S表现为早期、快速、不稳定的结合及滚动,MB-P表现为缓慢牢固结合。     

携Sialyl Lewis~X和抗小鼠P-选择素单抗靶向超声微泡评价心肌缺血再灌注损伤对比研究

目的探讨携Sialyl Lewis~X靶向超声微泡结合对比超声分子成像评价心肌缺血再灌注损伤可行性并与携抗小鼠P-选择素单抗靶向超声微泡对比分析。方法采用"亲和素-生物素"桥接法构建携Sialyl Lewis~X和抗小鼠P选择素单抗靶向超声微泡(MB_(slex)、MBp),并应用平行板流动腔技术在体外模拟的生理血流条件下评价MBp和MB_(slex)与小鼠P-选择素Fc段的靶向黏附效能。然后,20只心肌缺血再灌注(IR)小鼠随机经静脉注入MB_(slex)和MBp,分别于注入5min后行心肌对比超声心动图(MCE)检查,测量心肌缺血区和非缺血区的声强度(VI)。结果平行板流动腔实验显示:在第6分钟时,MB_(slex)与小鼠P-选择素Fc段结合数目为MBp的1.7倍。对比超声图像显示MB_(slex)组和MBp组缺血区心肌均见显著造影增强,声强度(VI)值分别为(23.52±1.08)U、(25.98±6.23)U,两者相比无显著差异(P0.05)。但无论是MBp组还是MB_(slex)组的缺血区心肌VI值均明显高于非缺血区心肌VI值[(6.53±0.95)U,(7.13±0.91)U,(P0.05)]。结论 MB_(slex)对炎症组织靶向检出能力与MBp相似,它和对比超声结合可有效评价心肌缺血再灌注损伤。     

超声分子成像对小鼠肾脏急性微血管炎症的可视性评价

目的 应用超声分子成像技术可视性评价小鼠肾脏急性微血管炎症.方法 缺血再灌注处理制备小鼠肾急性微血管炎症模型 (IR组,6只)及肾假手术处理模型(SH组,6只),所有实验小鼠均经静脉随机(间隔30 min)弹丸注射携带抗小鼠P-选择素单抗靶向超声微泡(MBp)、同型对照抗体超声微泡(MBc)及普通脂质超声微泡(MB),10 min后行肾对比超声(CEU)检查,测量肾脏显影的声强度(VI).并采用平行板流动腔技术在微血管生理血流条件下体外评价MBp的靶向黏附效能.结果 在缺血再灌注肾,MBp呈显著的超声显影,而MBc和MB呈轻度的超声显影;3种超声微泡在假手术肾均无明显的超声显影.MBp的VI值在缺血再灌注肾较假手术肾明显增大(P<0.05),同时较MBc和MB在缺血再灌注肾的VI值也都明显增大(P<0.05);而MBc及MB在缺血再灌注肾的VI值较各自假手术肾轻度增大(P<0.05).在微血管生理血流剪切应力环境下MBp可与小鼠P-选择素Fc段(PSFc)实现有效的靶向性特异结合.结论 超声分子成像技术可对肾脏急性微血管炎症进行有效的可视性评价,该技术将可用于可视性评价微血管炎症或相关的血管内皮反应.MBp在微血管生理血流条件下具有良好的靶向黏附效能.     

携IgG单抗靶向超声造影剂的构建及其靶向效能的体外评价

目的 构建携羊抗小鼠IgG单抗靶向超声造影剂(UCA-IgG)及体外评价其靶向黏附效能.方法 采用"亲和素-生物素"桥接法构建UCA-IgG,体外荧光法鉴定IgG单抗与生物素化造影剂特异结合.利用平行板流动腔在不同时间点、不同浓度小鼠IgG包被和不同剪切应力下,测定相应的UCA-IgG的结合数目及达到半数解离时的剪切应力.设不同浓度小鼠包被的平行板流动腔为实验组,羊抗小鼠IgG封闭组和空白组为对照组.结果 UCA-IgG发出明亮的绿色荧光,而普通脂质造影剂无荧光显示.实验组UCA-IgG结合数量随包被浓度的增高而增加(P<0.05),并与结合时间呈明显正相关(P<0.05),然而与剪切应力呈现双向性(P<0.05).而两对照组均未见明显的UCA-IgG结合.UCA-IgG达半数解离的剪切应力随包被浓度的增加而增大(P<0.05).结论 在不同血流动力学条件下UCA-IgG可与小鼠IgG特异有效结合,携羊抗小鼠IgG单抗造影剂可为其他特异靶向超声造影剂的体外研究提供有力的支持.     

携带抗P-选择素单抗靶向微泡和对比超声评价肾缺血再灌注损伤

目的探讨携带抗小鼠P-选择素单抗的靶向超声微泡（MBp）和对比超声（CEU）评价肾缺血再灌注损伤的可行性。方法12只实验小鼠随机均分为2组：缺血再灌注（IR组）和假手术组（SH组）,应用＂亲和素-生物素＂桥连法构建MBp。所有小鼠分别随机（间隔30min）经静脉弹丸注射给予普通脂质微泡（MB）和MBp,10min后行肾CEU检查,测量肾显影的声强度（VI）,最后进行肾组织免疫组化检测。结果第一帧CEU图像显示MBp及MB在IR组缺血再灌注肾分别可见显著及轻度的超声显影,而两者在SH组假手术肾均无明显的超声显影。VI值在IR组MBp较IR组MB及SH组MBp均明显增大（P〈0.05）;而在IR组MB较SH组MB轻度增大（P〈0.05）。免疫组化检测显示缺血再灌注肾血管内皮P-选择素表达较假手术肾明显增加。结论应用MBp行CEU检查可有效评价小鼠肾缺血再灌注损伤,将可用于评价微血管炎症或相关的血管内皮反应。     

携P选择素单抗靶向微泡在高剪切应力下体外血栓超声分子成像的效果

目的制备携P-选择素单抗的靶向超声微泡(MBp),通过体外流动腔模型评价其在高剪切应力下行血栓超声分子成像的效果。方法采用"亲和素-生物素"桥接法制备MBp和同型对照微泡(MB),应用自制琼脂糖流动腔模型模拟体内高剪切应力血流环境,将MBp和MB随机先后注入琼脂糖模型内,与小鼠血栓孵育30min后,PBS液15cm/s流速不间断冲洗血栓,分别在冲洗2、4、6、8和10min时行对比超声检查并测量声强度(VI)值。免疫组化评价小鼠血栓的P-选择素表达。结果冲洗前MBp组和MB组血栓VI值无明显差异(P0.05);冲洗后VI值在各时间点MBp组均较MB组大(P0.05)。冲洗10min后MBp组血栓仍有可视性对比增强,而MB组血栓在冲洗2min后已无可视性对比增强。免疫组化显示血栓表面有明显的P-选择素表达。结论以P-选择素为靶标的MBp在高血流剪切应力下与血栓的靶向结合稳定可靠,可用于动脉血栓的超声分子成像。     

P-选择素靶向超声微泡与普通超声微泡粘附途径和效能的对比研究

目的荧光显微镜直视下对比评价P-选择素靶向超声微泡与普通超声微泡在炎症内皮上的粘附途径和效能。方法构建携荧光FITC、抗P-选择素单抗的靶向超声微泡（MBp）和携荧光FITC普通超声微泡（MB）,随机经静脉弹丸式分别注入对照组（10只）和肿瘤坏死因子（TNF—α）处理组（10只）的小鼠提睾肌炎症模型。同时,20高倍荧光显微镜观测5min内两组不同微泡在提睾肌微血管中的粘附数量和粘附途径。结果TNF—α处理组MBp粘附数量为（12±2．6）个／视野,而MB粘附数量为（3±1．2）个／视野,两者差异有统计学意义（P〈0．01）;且TNF—α处理组MBp粘附数量分别为对照组MBp和MB的（6．4±1．7）倍和（9．9±2．1）倍（P〈0．01）。TNF-Ⅱ处理组和对照组分别有（69．6±2．6）％和（56．6±25．4％）的MBp通过直接与内皮细胞结合实现粘附,而MB内皮粘附率仅为（24．6±23．3）％和（20．0±27．4）％。结论与MB比较,MBp能高效、特异地粘附于炎症组织血管内皮上,应用其可有效评价血管内皮炎症反应或其他组织损伤。     

模拟动脉间歇脉搏血流评价携血管细胞黏附分子-1单抗靶向微泡黏附效能

目的 应用平行板流动腔模拟间歇脉动的动脉血流评价携血管细胞黏附分子-1单抗靶向微泡(MBv)进行高剪切应力下靶向的可行性.方法 采用"亲和素-生物素"桥接法构建MBv在1000ng/ml小鼠血管细胞黏附分子-1 Fc段(VFc)包被的平行板流动腔中,分为连续输注组及间歇输注组,在不同剪切应力(0.5～16 dyn/cm2)下,分别检测不同结合时间点(1～6 min)靶向微泡的结合数量.并用解离实验检测MBv达半数解离的剪切应力.所有实验均重复3次取平均值.结果 两组在0.5～2 dyn/cm2时均见有明显的MBv结合.间歇输注组MBv在各个剪切应力的靶向结合效率均明显较连续输注组高(P＜0.05),且只有间歇输注组MBv能在4～8 dyn/cm2条件下实现靶向结合.解离实验显示靶向微泡达半数解离的剪切应力为(20.7±3.1)dyn/cm2.结论 在间歇脉动的液体流动状态下,MBv可在更高的血流剪切应力条件下与VCAM-1特异有效结合,有望用于进行动脉系统的超声分子成像.     

携抗P-选择素单抗靶向微泡在炎症模型微循环中黏附机制及行为方式的研究

目的 荧光显微镜直视下对比评价携抗P-选择素单抗靶向微泡与同型对照微泡在微循环中的黏附机制及行为方式.方法 构建携荧光FITC的抗P-选择素单抗靶向微泡(MBp)和同型对照微泡(MBiso),并随机经静脉注入小鼠提睾肌炎症模型.20倍荧光显微镜直视下观察并记录5min内两种微泡在提睾肌微循环中的黏附情况,并对不同黏附方式的微泡进行计数.应用image-pro-plus分析软件对微泡进行定点追踪,并对其黏附过程中速度的变化进行定量测定.结果 荧光显微镜下观察可见MBp组与内皮黏附数量高达(8.4±2.1)个/视野,MBiso组仅为(0.8±0.8)个/视野,两者间差异有统计学意义(P＜0.01);MBp和MBiso组白细胞黏附数量分别为(3.6±0.6)个/视野、(2.2±0.8)个/视野,两者间差异无统计学意义(P＞0.05).微泡黏附过程速度变化曲线显示MBp和MBiso分别以流动速度逐渐和迅速降低两种方式实现对靶组织的黏附.结论 MBp和MBiso具有不同的黏附方式,MBp能更高效、特异地黏附于炎症组织血管内皮上,为评价血管内皮炎症反应或其他组织损伤的应用提供了理论基础.     

定点追踪技术评价携Sialyl Lewisx和抗P-选择素单抗靶向微泡在高剪切应力下的黏附行为

目的构建携Sialyl Lewisx和抗P-选择素单抗靶向微泡,用定点追踪技术在体外高剪切应力下评价其黏附行为。方法构建携Sialyl Lewisx靶向微泡(MB-S)、携抗P-选择素单抗靶向微泡(MB-P)、携Sialyl Lewisx和抗P-选择素单抗双配体靶向微泡(MB-D)。利用平行板流动腔和Image-Pro-Plus软件绘制微泡滚动的时间-速度折线图。微泡第1帧的速度为V1,第2帧至黏附前倒数第3帧的平均速度为V2,黏附前倒数第2帧的速度为V3。结果 MB-P高速滚动,速度骤降为0;MB-S从高速平缓过渡到低速,再渐降低至0;MB-D从高速过渡到低速,再骤降为0。3种微泡V1差异无统计学意义(P>0.05);MB-P的V2明显高于MB-S和MB-D(P<0.01);MB-S和MB-D间V2差异无统计学意义(P>0.05)。V3在3种微泡中的顺序为MB-P>MB-D>MB-S(P<0.01)。结论Sialyl Lewisx介导高效滚动,抗P-选择素单抗介导微泡速度的骤降,两者在微泡靶向黏附时可发挥互补作用。     

Dynamics of Targeted Microbubble Adhesion Under Pulsatile Compared with Steady Flow

Hemodynamic flow variations at low fluid shear stress are thought to play a critical role in local atherosclerotic plaque initiation and development and to affect plaque instability. Targeted microbubbles are being developed as intravascular agents for identifying atherosclerotic lesions using ultrasound. How variations in local hydrodynamic flow influence the adhesiveness of targeted microbubbles is not well understood. We postulated that rates of targeted microbubble binding and accumulation differ when subjected to steady flow (SF) as compared with oscillatory or pulsatile flow (PF), because PF imposes non-uniform blood rheology and periodic acceleration and deceleration of blood velocity, when compared with SF. We assessed the binding rates of targeted microbubbles in seven randomly assigned PF and seven matched SF replicate runs at low (<1 Pa) and intermediate (≥1 and <2.5 Pa) wall shear stress (WSS) by drawing 4.8 × 10⁶ microbubbles mL⁻¹ over streptavidin-coated substrates, immobilized within a parallel plate flow chamber at a calculated density of 81 binding sites μm^-2. Selective binding and accumulation of targeted microbubbles was recorded in a single field of view using real-time video microscopy. Microbubble accumulation was modeled to obtain flow-mediated microbubble binding kinetics (amplitude, A, and rate constant, k). PF elicited higher microbubble accumulation rates, in comparison to SF. The rates of microbubble accumulation differed significantly between PF and SF (p < 0.05) at intermediate WSS but not at low WSS (p > 0.05). The rate of microbubble accumulation decreased as WSS increased.     

Deformable gas-filled microbubbles targeted to P-selectin.

Ultrasound contrast microbubbles have been successfully targeted to a number of intravascular disease markers. We hypothesized that targeted delivery could be improved further, by making the microbubbles deformable, leading to increased microbubble-endothelium adhesion contact area and stabilized adhesion. Activated leukocytes utilize such strategy; they deform after binding to inflamed endothelium in the vasculature. Lipid-shell microbubbles were targeted to the endothelial inflammatory protein P-selectin with a monoclonal anti-P-selectin antibody attached to the microbubble shell. Deformable microbubbles were created by controlled pressurization with partial gas loss, which generated an average excess shell surface area of approximately 30% and the formation of outward-projected wrinkles and folds. Targeted microbubble adhesion and deformability were assessed in the parallel plate flow chamber under shear flow. Sustained adhesion of deformable microbubbles at wall shear stresses between 0.4 and 1.35 dyn/cm(2) was consistently better than adhesion of wrinkle-free microbubbles. Over this shear range, targeted wrinkled microbubbles were deformed by shear flow, unlike wrinkle-free microbubbles. In a murine cremaster inflammation model, a significant improvement of deformable microbubble targeting was observed by intravital microscopy. Overall, the mechanical aspects of adhesion, such as particle shape, deformability and surface microstructure, are important in engineering efficient site-targeted particle-based agents for medical imaging and therapy.     

Targeted ultrasound contrast agent for molecular imaging of inflammation in high‐shear flow

Targeted ultrasound contrast materials (gas‐filled microbubbles carrying ligands to endothelial selectins or integrins) have been investigated as potential molecular imaging agents. Such microbubbles normally exhibit good targeting capability at the slower flow conditions. However, in the conditions of vigorous flow, binding may be limited. Here, we describe a microbubble capable of efficient binding to targets both in slow and fast flow (exceeding 4 dyne/cm² wall shear stress) using a clustered polymeric form of the fast‐binding selectin ligand sialyl Lewis^X. Microbubbles were prepared from decafluorobutane gas and stabilized with a monolayer of phosphatidylcholine, PEG stearate and biotin‐PEG‐lipid. Biotinylated PSLe^x (sialyl Lewis^X polyacrylamide) or biotinylated anti‐P‐selectin antibody (RB40.34) was attached to microbubbles via a streptavidin bridge. In a parallel plate flow chamber targeted adhesion model, PSLe^x bubbles demonstrated specific adhesion, retention and slow rolling on P‐selectin‐coated plates. Efficiency of firm targeted adhesion to a P‐selectin surface (140 molecules/µm²) was comparable for antibody‐carrying bubbles and PSLe^x‐targeted bubbles at 0.68 dyne/cm² shear stress. At fast flow (4.45 dyne/cm²), PSLe^x‐targeted bubbles maintained their ability to bind, while antibody‐mediated targeting dropped more than 20‐fold. At lower surface density of P‐selectin (7 molecules/µm²), targeting via PSLe^x was more efficient than via antibody under all the flow conditions tested. Negative control casein‐coated plates did not retain bubbles in the range of flow conditions studied. To confirm echogenicity, targeted PSLe^x‐bubbles were visualized on P‐selectin‐coated polystyrene plates by ultrasound imaging with a clinical scanner operated in pulse inversion mode; control plates lacking targeted bubbles did not show significant acoustic backscatter. In vivo, in a murine model of inflammation in the femoral vein setting, targeting efficacy of intravenously administered PSLe^x‐microbubbles was comparable with targeting mediated by anti‐P‐selectin antibody, and significantly exceeded the accumulation of non‐targeted control bubbles. In the inflamed femoral artery setting, PSLe^x‐mediated microbubble targeting was superior to antibody‐mediated targeting. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparison of Magnetic Microbubbles and Dual-modified Microbubbles Targeted to P-selectin for Imaging of Acute Endothelial Inflammation in the Abdominal Aorta

Purpose

Ultrasound molecular imaging (UMI) has potential to evaluate an inflammatory profile of endothelium. However, it is less successful in large arteries. This study compared magnetic microbubbles (MBs) selectively targeted to endothelial P-selectin and dual-targeting MBs in vitro and in vivo.

Procedures

MBs were modified with P-selectin antibody (MB_PM) or isotype control antibody (MB_CM) via a magnetic streptavidin bridge, and MBs were conjugated to P-selectin antibody (MB_P) or both P-selectin antibody and PAA-sialyl Lewis^x (MB_D) via regular streptavidin linker. Adherence of MBs was determined by using a parallel plate flow chamber at variable shear stress (0.5–24 dyn/cm²). Adhesive and magnetic behaviors of MBs were analyzed at 4.0 dyn/cm² or at a flow rate of 50 mm/s. Attachment of MBs to P-selectin was determined with contrast-enhanced ultrasound (CEU) imaging of murine abdominal aorta inflammation. The expression of P-selectin was assessed by immunohistochemistry.

Results

The adhesive efficacy of MB_D was greater than MB_P and MB_CM, but lower than MB_PM under all shear stress conditions (P?<?0.05). The behaviors of fast-binding and rolling slow down were noted in MB_D and MB_PM; meanwhile, magnetic shifting of MBs centerline was presented in MB_PM. Contrast video intensity (VI) from adhered MB_PM to P-selectin of the inflammatory aorta was significantly higher than those from MB_D and MB_P (P?<?0.05).

Conclusions

MB_PM may be a better molecular probe than MB_D for detection of P-selectin on aorta with CEU, likely due to the shifting of axial distribution. Thus, it may improve the detection of the inflammatory profile on large arteries by UMI.

     

A Novel Microfluidic Chip for Assessing Dynamic Adhesion Behavior of Cell-Targeting Microbubbles

The primary aim of this study was to develop a microfluidic chip to study the dynamic adhesion behavior of cell-targeted microbubbles. The microfluidic device is composed of polydimethylsiloxane and is fabricated using the soft lithography technique. Each chamber of the microfluidic chip comprises eight U-shaped microsieves, by which various flow velocity distributions are generated. LyP-1-conjugated microbubbles were prepared by coating the surface of the phospholipid shell of microbubbles with LyP-1 peptides via biotin-avidin linkage. Under static conditions, the resulting targeted microbubbles are able to bind onto the surface of cells on incubation with breast cancer cells. Under dynamic fluid conditions, the cell targeting efficiency of the microbubbles was assessed at various flow velocity distributions in a chamber. Accumulation of targeted microbubbles was strongly influenced by flow velocity. Better retention of targeted microbubbles on cell surfaces was achieved at low mean flow velocities (<0.03 cm/s), in agreement with our computer simulation results. In conclusion, our results indicate that the microfluidic system is a useful platform for studying the microbubble-cell adhesive interaction.     

制备RGDS/rt-PA双负载靶向微泡并初步评价其靶向性溶栓效果

目的 制备RGDS/rt-PA双负载靶向微泡,分析其对富血小板血栓（PRT）的靶向性和溶栓效果。方法 制备不同剂量梯度的RGDS及rt-PA单负载靶向微泡,以其最佳结合剂量、按照不同加入顺序（先加入RGDS,再加入rt-PA;先加入rt-PA,再加入RGDS;将RGDS及rt-PA混匀后加入）分别制备RGDS/rt-PA双负载靶向微泡,检测其结合率。比较裸微泡、单负载及双负载微泡的物理特性（直径、浓度及pH值）,不同剂量梯度的同一配体与微泡的单负载结合率,同一剂量梯度的不同配体与微泡的单负载结合率,加入顺序不同的配体与微泡的双负载结合率。制备体外PRT模型,检测RGDS/rt-PA双负载靶向微泡的声学显像特征、靶向溶栓能力。结果 不同微泡间的物理特性差异均无统计学意义（P均>0.05）。不同剂量梯度的rt-PA、RGDS与微泡单负载结合率的差异均有统计学意义,同一剂量梯度的rt-PA与微泡单负载的结合率均低于RGDS （P均<0.05）。加入顺序不同的配体与微泡的双负载结合率的差异有统计学意义（F=16.090,P=0.004）。将RGDS/rt-PA双负载靶向微泡注入血栓模型管腔后,超声可见均匀分布的点状高回声,血栓边界回声明显增强;扫描电镜下可见纤维蛋白网状结构明显破坏、纤维束断裂成细沙状,并可见变形融合的血细胞。结论 RGDS/rt-PA双负载靶向微泡性质稳定,与配体的结合率高,声学显像特征好,具备一定的PRT靶向性及溶栓能力。     

平行板流动腔法评价生物素化脂质微泡制备效果

目的 制备生物素化脂质微泡,并应用平行板流动腔检测流体切应力对生物素化脂质微泡与链亲和素结合稳定性的影响,为进一步开展超声分子成像研究奠定基础.方法 采用声振法制备出表面携有生物素分子的脂质微泡,与普通脂质微泡对照,应用平行板流动腔模型,设置不同流体剪切应力,观察与链亲和素靶向结合的生物素化微泡的黏附效果.结果 在不同浓度链亲和素包被的平行板流动腔中均见生物素化微泡结合;随着链亲和素包被浓度的提高,靶向结合的生物素化脂质微泡抗流体剪切应力能力明显提高.结论 应用平行板流动腔模型能成功检测生物素化微泡的靶向黏附效果,该模型可推广应用于其他靶向微泡制备成功后靶向黏附能力的体外检测.     

A Method for Differentiating Targeted Microbubbles in Real Time Using Subharmonic Micro-Ultrasound and Interframe Filtering

This study introduces a new method for differentiating targeted microbubbles in the presence of flowing microbubbles and tissue using micro-ultrasound. The method relies on subharmonic (SH) imaging for segmenting microbubble signals from tissue signals, and low-pass interframe filtering for segmenting bound targeted microbubbles from flowing microbubbles. The method is evaluated with 30 frames per second SH B-mode imaging in vitro, using a wall-less vessel flow phantom. The SH B-mode cineloops were postprocessed using an interframe moving average filter to segment the regions of bound microbubbles on the inner surface of the vessel phantom. The bound bubbles were then disrupted with sufficiently high ultrasound pressures, so that the dynamic process of targeted microbubble binding under flowing conditions could be observed. These preliminary results show that the proposed method is a feasible solution to the challenge of differentiating targeted microbubbles in the presence of tissue and freely flowing microbubbles at high frequencies, which in turn should improve the specificity of targeted microbubble detection. (E-mail: aneedles@visualsonics.com)     

低免疫原性靶向微泡的制备研究

目的 制备低免疫原性靶向微泡.方法 采用不同膜磷脂成份制备表面包埋或暴露生物素的靶向微泡(MBb或MBe),荧光鉴定"生物素-链亲和素"桥连技术构建靶向微泡的可靠性.以普通微泡(MBc)为参照,酶联免疫吸附法体外检测三组微泡与人血清反应后的补体3a(C3a)水平;平行平板流动腔实验检测各组微泡与包被有链亲和素培养皿的黏附力.结果 MBe及MBb均发出明亮的环形绿色荧光,而MBc未见荧光.MBb组的C3a水平[(1.037±0.047)ng/m1]明显低于MBe组[(1.326±0.042)ng/m1](P＜0.05),与MBc组[(1.004±0.031)ng/m1]差异无统计学意义(P＞0.05).平行平板流动腔实验显示MBb组黏附的微泡数[(15.2±11.3)个/视野]少于MBe组[(103.2±28.3)个/视野](P＜0.05),与MBc组[(17.8±11.9)个/视野]差异无统计学意义(P＞0.05).结论 成功制备屏蔽表面免疫原性物质的靶向微泡,为进一步活体实验提供了基础数据.