Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, 1300 Coulter St., Amarillo, Texas 79106, USA.
Pharm Res. 2013 Jun;30(6):1663-76. doi: 10.1007/s11095-013-1011-x. Epub 2013 Mar 7.
To test the hypothesis that thrombus-specific tissue plasminogen activator (tPA)-loaded nanocarriers enhance thrombolytic efficacy and attenuate hemorrhagic complications.
A series of pegylated and non-pegylated tPA-loaded liposomes were prepared and their surfaces were decorated with the peptide sequence (CQQHHLGGAKQAGDV) of fibrinogen gamma-chain that binds with GPIIb/IIIa expressed on activated platelets. All formulations were characterized for physical properties, stability and in vitro release profile. The thrombolytic activities of tPA-loaded liposomes were tested by visual end-point detection, fibrin agar-plate and human blood clot-lysis assays. The thrombus-specificity of the peptide-modified-liposomes was evaluated by studying the binding of fluorescent peptide-liposomes with activated platelets. The pharmacokinetic profile and thrombolytic efficacy were evaluated in healthy rats and an inferior vena-cava rat model of thrombosis, respectively.
Both pegylated and non-pegylated peptide-modified-liposomes showed favorable physical characteristics and colloidal stability. Formulations exhibited an initial burst release (40-50% in 30 min) followed by a continuous release of tPA (80-90% in 24 h) in vitro. Encapsulated tPA retained >90% fibrinolytic activity as compared to that of native tPA. Peptide-grafted-liposomes containing tPA demonstrated an affinity to bind with activated platelets. The half-life of tPA was extended from 7 to 103 and 141 min for non-pegylated and pegylated liposomes, respectively. Compared to native tPA, liposomal-tPA caused a 35% increase in clot-lysis, but produced a 4.3-fold less depletion of circulating fibrinogen.
tPA-loaded homing-peptide-grafted-liposomes demonstrate enhanced thrombolytic activity with reduced hemorrhagic risk.
验证血栓靶向组织型纤溶酶原激活剂（tPA）纳米载体是否能增强溶栓效果并减少出血并发症。
制备了一系列聚乙二醇化和非聚乙二醇化的 tPA 载脂蛋白体，并在其表面修饰纤维蛋白原 γ 链的肽序列（CQQHHLGGAKQAGDV），该序列与激活血小板上表达的 GPIIb/IIIa 结合。对所有制剂的物理性质、稳定性和体外释放曲线进行了表征。通过目测终点检测、纤维蛋白琼脂板和人血凝块溶解试验来检测 tPA 载脂蛋白体的溶栓活性。通过研究荧光肽-脂蛋白体与激活血小板的结合，评估肽修饰脂蛋白体的血栓靶向性。分别在健康大鼠和下腔静脉血栓形成大鼠模型中评价其药代动力学特征和溶栓效果。
聚乙二醇化和非聚乙二醇化肽修饰脂蛋白体均具有良好的物理特性和胶体稳定性。制剂在体外显示出初始突释（30 分钟内 40-50%），随后 tPA 持续释放（24 小时内 80-90%）。与天然 tPA 相比，包封的 tPA 保持了>90%的纤维蛋白溶解活性。含有 tPA 的肽接枝脂蛋白体显示出与激活血小板结合的亲和力。tPA 的半衰期分别从 7 分钟延长到 103 分钟和 141 分钟。与天然 tPA 相比，脂蛋白体-tPA 使凝块溶解增加了 35%，但对循环纤维蛋白原的消耗减少了 4.3 倍。
载有 tPA 的归巢肽修饰脂蛋白体具有增强的溶栓活性，同时降低出血风险。
