Macromolecular Structure of Arterial Walls

动脉壁和动脉瓣是复杂的大分子结构。这些结构的主要元件之一是支架，其提供强度和柔性以执行手头的任务，或者将血液保持在血管中以抵抗动脉压力，或者通过冠状动脉瓣膜的功能来维持压力。在过去的几年中，已经变得明显的是，这些大分子的实际微观结构和组成可以影响不同疾病状态的进展，最显着的是动脉粥样硬化和钙化。为了更好地理解这一过程，我们已经开始研究，利用一种新的光学成像技术来了解动脉血管床中大分子的精细结构，该技术依赖于胶原蛋白和弹性蛋白的非线性激发（NLE），以提供未固定新鲜样本中其结构的亚微米图像，以及低密度脂蛋白颗粒（LDL）的直接测量结合使用荧光显微镜和常规组织学方法。这些研究已经确定核心蛋白聚糖和双糖链蛋白聚糖是瓣膜小叶和肾口中LDL的主要结合位点。基于核心蛋白聚糖/双糖链蛋白聚糖和LDL相互作用位点的相对浓度，我们决定靶向LDL静电结合位点，以评估这种相互作用在动脉粥样硬化进展中的干扰。LDL赖氨酸氨基酸残基以及模型分子如硫酸肝素的特异性修饰已经证明，通过在专门设计的体外测定中显著抑制LDL与核心蛋白聚糖的结合，这种策略是可行的。主要问题之一是找到对LDL位点具有高亲和力且具有最小脱靶活性的分子。目前，我们正在与行业合作伙伴合作，以评估其他候选分子，试图阻止LDL-核心蛋白聚糖/双糖链蛋白聚糖相互作用。如果在体外成功找到高亲和力的抑制剂，我们将在易患动脉粥样硬化的转基因小鼠模型中开展研究。 考虑到这一目标，我们已经在正常和动脉粥样硬化倾向的转基因小鼠中开始了研究，以使用NLE显微镜来关联动脉大分子结构的发展。我们已经完成了初步的研究，其特点是在正常小鼠主动脉的大分子结构的发展，并开始在疾病易感模型中跟踪动脉粥样硬化的发展。我们最近还证明，CARS显微镜可以直接观察该组织的脂肪酸C-H键。我们将在后续研究中使用CARS来评价脂肪酸和脂质在血管壁中的沉积，完成我们在该动物模型中评价动脉粥样硬化疾病发展的微创方法。这项研究完成后，将提供一个深入分析的发展，动脉壁的大分子结构在哺乳动物模型，并允许背景的慢性研究与不同的策略，以减少动脉粥样硬化。

The arterial wall and arterial valves are complex macromolecular structures. One of the major elements of these structures is the scaffold that provides the strength and flexibility to perform the task in hand either retaining the blood in vessels against the arterial pressure or maintaining pressure via the function of coronary valves. In the last several years it has become apparent that the actual microstructure and composition of these macromolecules could influence the progress of different disease states most notably atherosclerosis and value calcification. To gain a better understanding of this process, we have embarked on studies to understand the fine structure of the macromolecules in arterial vascular bed using a novel optical imaging technique that relies on the non-linear excitation (NLE) of collagen and elastin to provide sub-micron images of their structure in unfixed fresh samples together with direct measures of low density lipoprotein particles (LDL) binding using fluorescence microscopy and conventional histology methods. These studies have identified decorin and biglycan as the major binding sites for LDL in the valve leaflet and renal ostia. Based on the relative concentration of the interaction sites of decorin/biglycan and LDL, we have decided to target the LDL electrostatic binding sites to evaluate the interference of this interaction in the progression of atherosclerosis. Specific modification of the LDL lysine amino acid residues as well as model molecules such as Heparin sulfate has demonstrated that this strategy is feasible by significantly inhibiting LDL association with decorin in specially designed in vitro assays. One of the major issues is to find molecules with high affinity to the LDL sites with minimum off target activity. Currently we are working with industry partners to evaluate other candidate molecules for attempting to block the LDL-decorin/biglycan interaction. If successful finding high affinity inhibitors, in vitro, we will initiate studies in the atherosclerotic prone transgenic mouse models. With this goal in mind, we have initiated studies in normal and atherosclerosis prone transgenic mice to correlate the development of the arterial macromolecular structures using NLE microscopy. We have completed the initial study that has characterized the development of the macromolecular structures in the normal mouse aorta and begun to follow the development of atherosclerosis in disease prone models. We have also recently demonstrated that CARS microscopy can directly observe the fatty acid C-H bonds this tissue. We will use CARS to evaluate the deposition of fatty acids and lipids in the vascular wall in the follow up study completing our minimally invasive approach for evaluation of the development of atherosclerotic disease in this animal model. This study when completed will provide an in depth analysis of the development of the macromolecular structures of the arterial wall in a mammalian model and permit the background for chronic studies with different strategies to reduce atherosclerosis.