Disciplina de Biologia Molecular, Departamento de Bioquímica, Universidade Federal de São Paulo, SP, Brazil.
Matrix Biol. 2012 Jun;31(5):308-16. doi: 10.1016/j.matbio.2012.03.001. Epub 2012 Apr 6.
Heparin and its derivatives are known to regulate a variety of pathophysiological events related to vascular biology. In the present manuscript we examine a variety of heparinomimetics biochemically (electrophoretic behavior and enzymatic degradation) and pharmacologically (in vitro anticoagulant activity and in vivo hemorrhagic and antithrombotic tests) as well as their interactions with cells from the vessel wall using a time resolved fluorometric method and confocal microscopy. Data were determined for unfractionated heparin (UFH), enoxaparin, synthetic heparin pentasaccharide, C3 heparin derived oligosaccharides and phosphosulfomannan (PI-88). While being structurally distinct from UFH, all compounds exhibited anticoagulant, antithrombotic and hemorrhagic activities. In addition, besides the pentasaccharide, they all stimulated the synthesis of an antithrombotic heparan sulfate present at the cell surface and secreted by endothelial cells. Also, like UFH, they interacted with both endothelial and smooth muscle cells and dislodged UFH from its binding sites in a dose dependent manner but, with distinct saturable curves showing that the binding of polymeric structures to extracellular matrix (ECM) proteins does not depend on a glycosaminoglycan backbone. The data also suggest a common pathway, which does not depend on the presence of the conventionally accepted antithrombin binding pentasaccharide, for ECM dependent activity of the heparinomimetic stimulated synthesis of antithrombotic heparan sulfate. Notably, although of similar molecular weight as well as polymeric backbone, the synthetic heparin pentasaccharide showed significant hemorrhagic action and negligible antithrombotic activity in a venous thrombosis model, contrasting with C3, that displayed negligible hemorrhagic effect and potent antithrombotic action. These results provide evidence that structurally unrelated polymers can elicit similar hemostatic activities and show that polymeric sequence is not always crucial for certain activities. The results also suggest that non-GAG structures may provide an alternative route for the pharmaceutical control of hemostasis.
肝素及其衍生物已知可调节与血管生物学相关的多种病理生理事件。在本手稿中，我们从生化（电泳行为和酶降解）和药理学（体外抗凝活性和体内出血和抗血栓试验）方面检查了各种肝素类似物，以及使用时间分辨荧光法和共聚焦显微镜检查它们与血管壁细胞的相互作用。数据确定了未分级肝素（UFH）、依诺肝素、合成肝素五糖、C3 肝素衍生寡糖和磷酸硫酸甘露聚糖（PI-88）。虽然在结构上与 UFH 不同，但所有化合物都表现出抗凝、抗血栓和出血活性。此外，除了五糖外，它们还都刺激了存在于细胞表面并由内皮细胞分泌的抗血栓性肝素硫酸酯的合成。此外，与 UFH 一样，它们与内皮细胞和平滑肌细胞相互作用，并以剂量依赖的方式从其结合位点上置换 UFH，但具有独特的饱和曲线，表明聚合结构与细胞外基质（ECM）蛋白的结合不依赖于糖胺聚糖骨架。数据还表明，对于肝素类似物刺激的抗血栓性肝素硫酸酯合成的 ECM 依赖性活性，存在一种不依赖于传统上公认的抗凝血酶结合五糖的共同途径。值得注意的是，尽管分子量和聚合主链相似，但在静脉血栓形成模型中，合成肝素五糖表现出明显的出血作用和可忽略不计的抗血栓作用，而 C3 则表现出可忽略不计的出血作用和有效的抗血栓作用。这些结果提供了证据表明结构上不相关的聚合物可以引起类似的止血活性，并表明聚合序列并不总是某些活性的关键。结果还表明，非 GAG 结构可能为止血的药物控制提供替代途径。
