多聚体微泡靶向治疗颈动脉不稳定斑块的实验研究

People in the Xinjiang area are especially vulnerable to carotid artery plaque, whose characteristics include young, multitudinous and high occurrence rate for the lifestyle and eating habits. Although the angiogenesis inhibitor is proved to be able to stable carotid artery plaque, there is no effective method for target application. As an important drug delivery carrier, the ultrasound microbubble contrast agent are proved to be used for targeted therapy of lesions. Our previous study also showed that the combination of polymer microbubble and drug could accomplish efficacious targeted remedy. Therefore, we speculate that the combination of polymer microbubbles and angiogenesis inhibitor should be an effective targeted therapy method for carotid artery unstable plaque. According to the hypothesis, on basis of the design and manufacture of the new style polymer microbubbles by sound cavitation method, the combination of polymer microbubble and drug was formed by covering the angiogenesis inhibitor. Then, the combination of polymer microbubbles in carotid artery unstable plaque mode of zealand rabbits was click broken by ultrasonic irradiation. The study plans to evaluate the effects of the different drug concentrations, dosing and time factors on carotid plaque morphology and systemic therapeutic response. As a result, the study expects to explore the feasibility of the combination of polymer microbubble as a noninvasive, targeted therapy，rapid and effective new therapeutic method for carotid artery unstable plaque.

新疆地区人民由于生活及饮食习惯，导致颈动脉斑块形成人群具有年龄小、人数多、不稳定斑块发生率高的特点。虽然新生血管抑制因子被证明可以稳定斑块，但无有效的方法靶向应用实施。超声微泡造影剂作为一种重要的药物递送载体，被证实可以实现病灶的靶向治疗，我们前期研究亦表明多聚体型微泡药物结合体具有有效的疾病靶向治疗效果。因此我们推测多聚体超声微泡结合新生血管抑制因子形成微泡-药物复合体对颈动脉不稳定斑块应具有靶向治疗作用。本课题针对这一假设，拟通过声空化的方法制备新型多聚体型微泡，并使其结合新生血管抑制因子形成微泡-药物复合体。进而，在超声照射下，于新西兰兔颈动脉不稳定斑块模型新生血管部位将微泡-药物复合体定点击碎。观察评估不同的药物浓度、给药方式及给药时间等因素对颈动脉斑块的形态影响及全身的治疗反应。探索验证微泡作为新型载体实现无创、靶向、快速治疗不稳定斑块的可行性及最佳靶向治疗方式。

新疆各民族人群饮食结构中动物脂肪及盐分摄入量较高，从而导致颈动脉斑块形成人群具有年龄小、人数多、不稳定斑块发生率高、病损程度重的特点。颈动脉斑块的出现明显增加心肌梗死、卒中以及周围血管疾病的危险，目前尚无针对性的治疗措施。本实验首次探索将多聚体微泡和新生血管抑制因子 PEDF 相结合形成新型药物载体，将药物 PEDF 按浓度分为对照组、0.4ug 实验组、2ug 实验组、10ug 实验组和 50ug 实验组，应用跨膜按梯度法包裹入脂质体，并与应用声空化方法制备得到的表面具有 PEG 结合臂的多聚体微泡 400ul 结合，分别置于荧光显微镜下观察，应用流式细胞仪检测PEDF与超声微泡的最大结合率，采用荧光分光光度法测定载药超声微泡的包封率及体外释药特性。成功制备了与PEDF最大结合率为（96.14±1.21）%的多聚体超声微泡。脂质体对PEDF的包封率约为（79.20±2.31）%，体外释放浓度于微泡击破后 1 min 内达到峰值，持续释放 10 min 后浓度显著减低。进而在超声照射下，于新西兰兔颈动脉不稳定斑块模型新生血管部位将微泡-药物复合体定点击碎。评估并验证了不同的药物浓度、给药方式及给药时间等因素对颈动脉斑块的形态影响及全身的治疗反应，探索了微泡作为新型载体实现无创、靶向、快速治疗不稳定斑块的可行性及最佳靶向治疗方式，证实研制的新型加载PEDF的多聚体微泡不仅可以抑制颈动脉斑块的形成并且可以消除斑块，这意味着加载 PEDF 的多聚体微泡结合超声治疗具有临床应用潜力，为针对颈动脉不稳定斑块的无创、有效、靶向治疗奠定了实验室基础。

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