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）：止血和血栓形成的生物力学是生物医学研究的一个新领域，在过去几年中发展迅速。纤维蛋白的机械性质是天然可变的，并且在很大程度上决定了凝块是否止血，或导致血栓形成或出血，这使得它们成为理想的治疗靶点。在本申请中，将研究纤维蛋白力学在生理相关纤维蛋白变形过程中的结构变化，包括单个分子、纤维蛋白低聚物和整个纤维蛋白凝块以及离体血栓。纤维蛋白粘弹性的结构基础将使用基于最先进的生物物理技术的独特的广泛的综合方法进行检查，例如基于单分子光学陷阱的力谱，广角X射线散射，傅里叶变换红外光谱，高分辨率流变仪，原子力显微镜，共聚焦和电子显微镜，结合计算分子动力学模拟和多尺度建模。在特定目标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。理解卷曲螺旋、αC区和γ结节的展开将定义体内由于血流、凝块收缩和伤口拉伸而发生的分子变化。卷曲螺旋中的α-螺旋向β-折叠转变是纤维蛋白力学的重要机制，并且可能可用于临床目的。αC聚合物的拉直和？-结节在纤维蛋白机械性能中也起主要作用。在特定目标2中，将在单分子水平上研究将纤维蛋白保持在一起的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。这一新发现是进一步深入研究的基础， 它在生物分子相互作用领域的普遍重要性和潜在的生理意义。使用一种新的方法，结合-解结合相关光谱，我们开发的，我们将广泛的二维动力学和热力学的特点，形成和解离的单一A：a键。在特定目标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结构域以揭示用于治疗目的的纤维蛋白机械性质的潜在调节剂。这些研究将通过导致新的基于结构和力学的方法来预防和治疗出血和血栓形成，从而推进止血和血栓形成领域。