Structural origin of fibrin clot mechanical properties

纤维蛋白凝块机械性能的结构起源

• 批准号: 8903542
• 负责人: JOHN W WEISEL
• 金额: $ 40.8万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8903542
• 关键词: Affinity; Angioplasty; Applications Grants; Atomic Force Microscopy; Behavior; Binding; Biocompatible Materials; Biomechanics; Biomedical Research; Blood Platelets; Blood Vessels; Blood coagulation; Blood flow; Characteristics; Chemicals; Clinical; Clot retraction; Coagulation Process; Complex; Confocal Microscopy; Data; Dissociation; Elasticity; Electron Microscopy; Exhibits; Fiber; Fibrin; Fibrinogen; Health; Hemorrhage; Hemostatic Agents; Hemostatic function; Human; Individual; Kinetics; Lateral; Lead; Length; Lipoproteins; Maps; Measures; Mechanics; Microscopic; Modeling; Modification; Molecular; Molecular Structure; Mutation; Myocardial Infarction; Nodule; Obstruction; Outcome; Pharmacia brand of estropipate; Physiological; Plasma; Plasma Proteins; Play; Polymers; Property; Proteins; Reaction; Recombinants; Research; Resolution; Roentgen Rays; Role; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis; Stretching; Stroke; Structure; Surface; Therapeutic; Therapeutic Embolization; Thermodynamics; Thromboembolism; Thrombosis; Thrombus; Venous; Wit; base; biophysical techniques; clinically significant; comparative; computerized; conformational conversion; crosslink; in vivo; inhibitor/antagonist; insight; molecular domain; molecular dynamics; multi-scale modeling; mutant; nanomechanics; network models; new therapeutic target; novel; novel strategies; optical traps; polymerization; prevent; reconstruction; response; screening; simulation; single molecule; therapeutic target; thrombolysis; two-dimensional; wound

DESCRIPTION (provided by applicant): A new field of biomedical research, biomechanics of hemostasis and thrombosis, has been quickly developing over the past few years. The mechanical properties of fibrin are naturally variable and largely determine whether clots stanch bleeding, or lead to thrombosis or hemorrhage, and this makes them a desirable therapeutic target. In this application, fibrin mechanics will be studied with respect to structural changes during physiologically relevant fibrin deformations at increasing levels of complexity, including individual molecules, fibrin oligomers, and whole fibrin clots as well as ex vivo thrombi. The structural basis of the viscoelastic properties of fibrin is going to be examined using a uniquely broad, integrated approach based on state-of-the- art biophysical techniques, such as single-molecule optical trap-based force spectroscopy, wide angle X-ray scattering, Fourier Transform infrared spectroscopy, high-resolution rheometry, atomic force microscopy, confocal and electron microscopy, combined with computational molecular dynamics simulations and multiscale modeling. In Specific Aim 1, the structural transitions in fibrin at the molecular level induced by mechanical force will be studied. Understanding of the unfolding of the coiled-coils, αC regions, and γ-nodules will define the molecular changes that occur in vivo as a result of blood flow, clot retraction, and wound stretching. The α-helix to β-sheet transition in the coiled-coils is an important mechanism of fibrin mechanics and potentially tunable for clinical purposes. Straightening of the αC polymers and unfolding of the ?-nodules also play major roles in fibrin mechanical properties. In Specific Aim 2, nanomechanics of the A:a knob-hole bonds that hold fibrin together will be studied at the single-molecule level. Preliminary data show that at the A:a bonds exhibit counterintuitive "catch" bond behavior, meaning that the strength of the bond increases with increasing force. This novel finding is a basis for further in depth studies because of its general importance for the field of biomolecular interactions and potential physiological significance. Using a new approach, Binding- Unbinding Correlation Spectroscopy, that we developed we will extensively characterize the two-dimensional kinetics and thermodynamics of formation and dissociation of single A:a bonds. In Specific Aim 3, mechanical properties of clinically significant clots and thrombi will be studied, with a logical progression from the molecular and microscopic levels to increasingly complex macroscopic structures formed in vivo. Screening of chemicals and structural modifications that potentially stabilize or destabilize fibrin molecular domains will be performed to reveal potential modulators of fibrin mechanical properties for therapeutic purposes. These studies would advance the field of hemostasis and thrombosis by leading to new structure- and mechanics-based approaches to prevent and treat bleeding and thrombosis.

描述（由申请人提供）：生物医学研究的一个新领域——止血和血栓形成的生物力学，在过去几年中得到了迅速发展。纤维蛋白的机械特性自然是可变的，并且在很大程度上决定了凝块是否能够止血，或者导致血栓形成或出血，这使得它们成为理想的治疗靶点。在此应用中，将研究纤维蛋白力学在复杂程度不断增加的生理相关纤维蛋白变形过程中的结构变化，包括单个分子、纤维蛋白低聚物、整个纤维蛋白凝块以及离体血栓。将使用基于最先进的生物物理技术的独特广泛的综合方法来检查纤维蛋白粘弹性特性的结构基础，例如基于单分子光阱的力谱、广角X射线散射、傅里叶变换红外光谱、高分辨率流变测量、原子力显微镜、共焦和电子显微镜，并结合计算 分子动力学模拟和多尺度建模。在具体目标 1 中，纤维蛋白在分子水平上的结构转变 将研究由机械力引起的。了解卷曲螺旋、αC 区域和 γ 结节的展开将定义体内由于血流、凝块回缩和伤口拉伸而发生的分子变化。卷曲螺旋中的 α 螺旋到 β 片层的转变是纤维蛋白力学的重要机制，并且可以针对临床目的进行调整。 αC 聚合物的拉直和 β-结节的展开也在纤维蛋白机械性能中发挥着重要作用。在具体目标 2 中，将在单分子水平上研究将纤维蛋白固定在一起的 A:a 旋钮孔键的纳米力学。初步数据显示，在 A:a 键表现出违反直觉的“捕捉”键行为，这意味着键的强度随着力的增加而增加。这一新颖的发现是进一步深入研究的基础，因为 其对于生物分子相互作用领域的普遍重要性和潜在的生理意义。使用我们开发的新方法“结合-解除结合相关光谱”，我们将广泛表征单个 A:a 键形成和解离的二维动力学和热力学。在具体目标 3 中，将研究具有临床意义的凝块和血栓的机械特性，从分子和微观水平到体内形成的日益复杂的宏观结构的逻辑进展。筛选可能稳定或不稳定的化学品和结构修饰 将进行纤维蛋白分子域研究，以揭示用于治疗目的的纤维蛋白机械特性的潜在调节剂。这些研究将通过基于结构和力学的新方法来预防和治疗出血和血栓形成，从而推动止血和血栓形成领域的发展。