全氟溴辛烷脂质纳米粒对大鼠缺血-再灌注模型中存活心肌的靶向显影研究

Site-targeted imaging enhancement of viable myocardium after ischemia-reperfusion by a novel nano-scale ultrasound contrast agent: a vivo study

目的制备一种靶向识别存活心肌的全氟溴辛烷脂质纳米粒超声造影剂,观察其体内靶向显影效果.方法制备表面标记有生物素及荧光的全氟溴辛烷脂质纳米粒,检测其粒径、表面电位、浓度等理化性质.将生物素标记的单核细胞趋化蛋白‐1 (MCP‐1)抗体,罗丹明标记的亲和素、生物素及FITC标记的纳米粒依次注入大鼠缺血-再灌注模型体内,观察造影剂显影效果. 12 h后取心脏标本进行冰冻切片,并在荧光显微镜下观察荧光显示情况.结果自制全氟溴辛烷脂质纳米粒电镜下呈球形,分散均匀,粒径(172 .30 ± 52 .06) nm ,表面电位为(-33 .10 ± 6 .50) mV ,浓度为(2 .28 ± 0 .46)× 1011/ml .观察缺血-再灌注大鼠短轴切面,靶向造影后,前壁近内膜下心肌回声较造影前明显增强,而余室壁未见明显增强.取模型心脏冰冻切片后于荧光显微镜下观察,前壁心肌内可见大量纳米粒聚集成团,发出明亮的绿色及红色荧光.而余室壁心肌内未见纳米粒聚集,亦未见荧光显示.结论自制全氟溴辛烷脂质纳米粒能够对存活心肌进行靶向识别并增强显影,有望为临床上识别存活心肌提供新的影像学检测手段.

Objective To prepare a kind of lipid nanoparticle ultrasound contrast agents with the ability to target to viable myocardium for diagnosis. Methods The agent was a biotinylated, fluorescent-labelled, lipid-coated, liquid perfluorocarbon emulsion. Physico-chemical properties of the agent were measured, including size distribution, Zeta Potential, concentration and so on. Ischemia-reperfusion models were created in rats, and then exposed to biotinylated anti-MCP-1 monoclonal antibody, rhodamine avidin and biotinylated, FITC-labelled nanoparticles, respectively. Echocardiography was taken before and after injection. Frozen sections of their hearts were observed under fluorescence microscope. Results The particle diameter, zeta potential and concentration of lipid nanoparticles were (172.30±52.06)nm,(-33.10±6.50)mV and (2.28±0.46)×1011/ml, respectively. From the short-axis view, the myocardium under endocardium of anterior wall was enhanced obviously. While myocardium of other walls were still. The lipid nanoparticles located in the myocardium of anterior wall and gave out bright green and red fluorescence under fluorescence microscope, while neither lipid nanoparticles nor fluorescence were found in other sites of ventricular myocardium. Conclusions The viable myocardium can be targeted and acoustically enhanced by the self-made nano-scale ultrasound contrast agent. This new agent has potential to improve sensitivity and specificity for noninvasive identifying viable myocardium.