Effect of Lipids on Vascular Graft Healing

描述(由申请人提供)： 人造移植物广泛应用于血管重建手术，但其长期通畅性有限，部分原因是氧化型低密度脂蛋白(OxLDL)可能导致细胞功能改变。我们发现：1)移植物材料在体外刺激单核细胞氧化低密度脂蛋白，2)氧化低密度脂蛋白抑制内皮细胞在体外的迁移，3)移植的移植物含有脂质氧化产物，4)高胆固醇血症导致内皮细胞在移植物上的迁移减少。我们也有初步数据表明，溶血磷脂酰胆碱(LysoPC)是一种脂类氧化产物，占oxLDL抑制活性的大部分，它会引起氧化应激，激活蛋白激酶C-Delta(PKCDelta)，而PKCDelta抑制EC迁移。基于这些数据，我们提出一个假设，即合成血管移植物中形成的特定脂质氧化产物抑制了EC的迁移，从而限制了体内人工血管的内皮化。该项目的目标是确定假体中活跃的氧化途径，氧化脂质抑制EC迁移的机制，特别是活性氧物种(ROS)和PKC Delta激活的作用，以及改善迁移的方法。为了验证我们的假设，我们将通过评估特定氧化途径的分子标记物来确定假体移植物中脂质被氧化的机制。此外，我们还将确定合成移植物中存在的溶菌素PC的类型。我们将通过研究oxLDL和ROS对PKCDelta的激活以及随后对细胞骨架蛋白的影响来研究它们抑制EC迁移的一个机制。最后，我们将研究抗氧化剂和降脂剂在植入正常和高胆固醇血症兔的假体上促进EC迁移的能力。这项拟议的研究将调查脂类和脂蛋白及其氧化修饰的衍生物在合成血管移植物有限内皮化中的作用。研究还将讨论抗氧化剂控制脂质氧化和促进EC愈合的有效性。这将有助于更好地了解脂质在移植物失败的病理生理学中的作用，并最终找到促进人工移植物内皮化和延长小直径血管移植物通畅性的方法。我

DESCRIPTION (provided by applicant): Prosthetic grafts are used widely in vascular reconstructive surgery, but their long-term patency is limited, in part due to altered cell function that could be caused by oxidized low density lipoprotein (oxLDL). We have shown that: 1) graft material stimulates monocytic cells to oxidize LDL in vitro, 2) this oxLDL inhibits endothelial cell (EC) migration in vitro, 3) explanted grafts contain lipid oxidation products, and 4) hypercholesterolemia leads to reduced EC migration onto grafts in rabbits. We also have preliminary data that lysophosphatidylcholine (lysoPC), a lipid oxidation product that accounts for most of oxLDL's inhibitory activity causes an oxidative stress that activates protein kinase C-delta (PKCdelta), and PKCdelta inhibits EC migration. Based on these data, we propose as a hypothesis that specific lipid oxidation products formed within synthetic vascular grafts inhibit EC migration, thereby limiting endothelialization of prosthetic grafts in vivo. The goals of this project are to determine the oxidation pathways active in prosthetic grafts, the mechanism by which oxidized lipids inhibit EC migration, particularly the role of reactive oxygen species (ROS) and activation of PKCdelta, and methods to improve migration. To test our hypothesis, we will identify the mechanism by which lipids in the prosthetic graft are oxidized by assessing molecular markers of specific oxidation pathways. In addition, we will identify the types of lysoPC that are present in synthetic grafts. We will investigate one mechanism by which oxLDL and ROS inhibit EC migration by studying their activation of PKCdelta and the subsequent effects on cytoskeletal proteins. Finally, we will investigate the ability of antioxidants and lipid lowering agents to improve EC migration onto prosthetic grafts implanted in normal and hypercholesterolemic rabbits. The proposed studies will investigate the role of lipids and lipoproteins, and their oxidatively-modified derivatives, in the limited endothelialization of synthetic vascular grafts. Studies will also address the efficacy of antioxidants to control lipid oxidation and promote EC healing. This will lead to a better understanding of the role of lipids in the pathophysiology of graft failure, and ultimately, to methods promoting endothelialization of prosthetic grafts and prolonging patency of small-diameter vascular grafts. I