脂质体递药系统靶向大鼠缺血心肌及减少缺血再灌注损伤的研究

Study on liposome drugs targeting to ischemic myocardium and reducing ischemia-reperfusion injury in rats

目的验证脂质体药物在心肌缺血区域的炎症靶向效应,探讨其减少心肌细胞缺血再灌注损伤的治疗优势。方法采用薄膜分散-超声-膜挤出法制备胺碘酮及丙酮酸乙酯(EP)脂质体,并对其进行粒径、包封率检查。通过阻断和恢复冠状动脉血流制备大鼠心肌缺血再灌注损伤(MI-RI)模型,并通过缺血再灌注(I-R)前后心电图变化验证模型。尾静脉给药,考察荧光脂质体在I-R心肌中的炎症靶向效性;取24只SD大鼠(随机分为4组,每组6只),考察胺碘酮脂质体对MI-RI心律失常事件的影响;另取24只SD大鼠(随机分为4组,每组6只),评估丙酮酸乙酯(EP)脂质体对MI-RI中凋亡蛋白Bax,Bcl-2和caspase-3表达水平的影响。结果制备的脂质体药物粒径均匀,制备后24 h内药物渗漏不高于18%。在大鼠心肌I-R后可见心电图ST段及T波的缺血性动态演变,再灌注后心电图记录到了室性心动过速事件,其中I-R+胺碘酮脂质体组心律失常评分明显降低,(P<0.01),且低于胺碘酮溶液组(1.5±0.96 vs 3.0±0.82,P<0.05)。离体荧光成像显示,I-R+IR-775脂质体组荧光强度最高,即荧光脂质体药物可以靶向聚集到心肌缺血部位。与I-R+空白脂质体组和I-R+EP溶液组相比,I-R+EP脂质体组在48 h后显著降低了Bax和caspase-3蛋白表达水平,提高了Bcl-2蛋白的表达,Bax/Bcl-2比值明显下降(P<0.05)。结论脂质体药物在MI-RI中具有显著的炎症靶向效应,脂质体载药结构增强了胺碘酮和EP对MI-RI的治疗效果。

Objective To verify the inflammatory targeting effect of liposome drugs in myocardial ischemia area and explore the therapeutic advantages of liposome drugs in reducing myocardial ischemia reperfusion injury(MI-RI).Methods Amiodarone and ethyl pyruvate(EP)liposomes were prepared by thin film dispersion-ultrasonic-film extrusion method,and their particle size and entrapment efficiency were examined.We established MI-RI model by blocking and restoring coronary blood flow,and though rats′Electrocardiogram changes before and after ischemia-reperfusion(I-R)to verify.The inflammatory targeting effect of fluorescent liposomes in I-R myocardium was investigated by caudal vein administration;24 SD rats were randomly divided into 4 groups with 6 rats in each group to assess the effect of amiodarone liposome on MI-RI arrhythmia events;Another 24 SD rats were divided as above to evaluate the effect of ethyl pyruvate(EP)liposomes on the expression of apoptotic proteins Bax,Bcl-2 and Caspase-3 in MI-RI.Results The particle size of the liposome was uniform,and the drug leakage was no more than 18%within 24 hours after preparation.The ischemic dynamic evolution of ST segment and T wave and ventricular tachycardia events in Electrocardiogram was catched before and after myocardial I-R.Arrhythmia score displayed that I-R+amiodarone liposome group was significantly lower than amiodarone solution group(P<0.01).In vitro fluorescence imaging,the fluorescence intensity of I-R+IR-775 liposome group was the highest,that is,fluorescent liposome drugs could target and aggregate to the site of myocardial ischemia.Compared with I-R+blank liposome group and I-R+EP solution group,I-R+EP liposome group significantly decreased the expression of Bax and caspase-3 protein,increased the expression of Bcl-2 protein and decreased the ratio of Bax/Bcl-2(P<0.05).Conclusions This study confirmed that liposome drugs have a significant inflammatory targeting effect in MI-RI,and the liposome drug-carrying structure enhances the therapeutic effect of amiodarone and EP on MI-RI.