Targeted Delivery of Cardioprotective Drugs

描述(申请人提供)：心肌梗死是一种致残性疾病，梗死面积是死亡率的主要决定因素。为了限制梗塞范围和改善功能恢复，必须对缺血心肌进行再灌流。然而，再灌注本身会对先前缺血的心肌造成不可逆转的损伤。心脏损伤的很大一部分是由再灌流开始时立即开始的细胞凋亡引起的。因此，再灌注损伤被认为是治疗持续急性心肌梗死患者的一个重要的新的药理靶点。我们建议开发两种药物的靶向脂质体配方，这两种药物已被证明通过独立的机制保护心肌。载药脂质体将被人膜联蛋白V修饰，用于靶向心肌细胞表面暴露在细胞凋亡早期的磷脂酰丝氨酸。在再灌注开始前立即静脉注射这种脂质体可以作为血管成形术和/或溶栓治疗的辅助治疗，这是心肌梗死患者的标准护理。所提出的策略的优点是：1)从再灌流的第一时刻起，当细胞凋亡仍然是可逆的时候，在心肌细胞内输送大量的药物，2)避免大剂量方案的不良反应，这是免费药物所必需的，以及3)两种药物通过独立的机制在细胞内输送，增加了成功治疗的可能性。靶向载药脂质体将在心肌细胞的原代培养中进行评估。我们将建立早期凋亡细胞内化的机制(S)，并评估膜联蛋白靶向载药脂质体的治疗潜力。在小鼠心肌缺血/再灌注模型中，将研究脂质体在体内的生物分布、靶向药物传递和保护作用。如果成功，建议的策略将确立使用膜联蛋白靶向治疗性脂质体作为心肌梗死辅助治疗的可行性。它还将推动开发针对早期凋亡细胞的靶向输送的治疗性脂质体的新技术。 公共卫生相关性：我们建议测试为两种药物开发靶向脂质体配方的可行性，这两种药物已被证明通过独立的机制保护缺血心肌免受致命性再灌注损伤。载药脂质体将被人膜联蛋白V修饰，用于靶向在细胞凋亡早期暴露在心肌细胞表面的磷脂酰丝氨酸。在再灌注开始前立即静脉注射这种脂质体可以作为血管成形术和/或溶栓治疗的辅助治疗，这是急性心肌梗死患者的标准护理。

DESCRIPTION (provided by applicant): Myocardial infarction is a disabling disease, with infarct size being a major determinant of mortality. To limit infarct size and improve functional recovery, the ischemic myocardium has to be reperfused. However, reperfusion itself causes irreversible damage to the previously ischemic myocardium. A significant part of cardiac injury is caused by apoptosis that starts immediately at the beginning of reperfusion. Therefore, reperfusion injury is considered an important new pharmacologic target for the treatment of patients with ongoing acute myocardial infarction. We propose to develop a targeted liposomal formulation of two drugs proven to protect myocardium through independent mechanisms. Drug-carrying liposomes will be decorated with human annexin V for targeting to phosphatidylserine exposed on the surface of cardiomyocytes at the early stages of apoptosis. Intravenous administration of such liposomes immediately before the beginning of reperfusion could serve as an adjunct therapy for angioplasty and/or thrombolytic administration, which are the standard of care for patients with myocardial infarction. The advantages of the proposed strategy are: 1) delivery of pharmacologically significant amounts of drugs in cardiomyocytes from the first moments of reperfusion, when apoptosis is still reversible, 2) avoiding adverse effects of high-dose regimens that are necessary for free drugs, and 3) intracellular delivery of two drugs working via independent mechanisms increases the probability of successful treatment. Targeted drug-loaded liposomes will be evaluated in primary cultures of cardiomyocytes. We will establish mechanism(s) of internalization in early apoptotic cells and evaluate the therapeutic potential of annexin-targeted drug-loaded liposomes. Biodistribution, targeted drug delivery and the protective effects of the liposomes in vivo will be studied in a mouse model of myocardial ischemia/reperfusion. If successful, the proposed strategy will establish the feasibility of using annexin- targeted therapeutic liposomes as an adjunct therapy for myocardial infarction. It will also advance new technologies in developing therapeutic liposomes for targeted delivery to early-stage apoptotic cells. PUBLIC HEALTH RELEVANCE: We propose to test feasibility of developing a targeted liposomal formulation for two drugs proven to protect ischemic myocardium from lethal reperfusion injury through independent mechanisms. Drug-carrying liposomes will be decorated with human annexin V for targeting to phosphatidylserine exposed on the surface of cardiomyocites at the early stages of apoptosis. Intravenous administration of such liposomes immediately before the beginning of reperfusion could serve as an adjunct therapy for angioplasty and/or thrombolytic administration, which are the standard of care for patients with acute myocardial infarction.