Molecular Basis for Nonadhesive Properties of Fibrinogen Matrices

纤维蛋白原基质非粘附特性的分子基础

基本信息

批准号：
8253692
负责人：
Robert Ros
金额：
$ 41.94万
依托单位：
ARIZONA STATE UNIVERSITY-TEMPE CAMPUS
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-04-06 至 2015-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8253692
关键词：
Adhesions Adhesives Adsorption Animals Appearance Atomic Force Microscopy Attention Biocompatible Materials Blood Blood Cells Blood Platelets Blood Proteins Blood Vessel Prosthesis Caliber Cell Adhesion Cells Characteristics Clinical Deposition Development Endothelial Cells Endothelium Equilibrium Event Factor XIIIa Fibrin Fibrinogen Human Image Implant In Vitro Integrins Knowledge Lead Leukocytes Mechanics Mediating Medical Modeling Molecular Mutation Nanotechnology Perception Performance Pharmacia brand of estropipate Plasma Proteins Platelet Activation Play Process Property Prosthesis Recombinants Research Role Schools Science Signal Transduction Spectrum Analysis Stem cells Supporting Cell Surface Testing Thick Thrombosis Thrombus Vascular Graft base crosslink density design graft failure implantation in vivo monolayer nanometer nanoscale physical property progenitor public health relevance research study response surface coating

项目摘要

DESCRIPTION (provided by applicant): Adsorption of the blood protein fibrinogen (Fg) on the surface of biomaterials is a critical early event during the interaction of blood with implanted vascular grafts. Because of its rapid adsorption and the ability to support adhesion of platelets, Fg is generally viewed as a culprit responsible for the development of surface- induced thrombosis, especially in small-diameter vascular prostheses. The perception of Fg as a foe is perplexing in view of the fact that implanted vascular grafts are invariably coated with a fibrin layer which, like Fg, can support efficient platelet adhesion. Nevertheless, in humans, this fibrin layer remains largely without platelets, maintaining its characteristic a cellular appearance over the years. The discrepancy between the ability of immobilized Fg to support platelet adhesion, which was primarily inferred from in vitro experiments, and the situation in vivo, attests to a clear need for a greater understanding of the mechanisms that regulate the balance between adhesive and nonadhesive functions of Fg. We have recently identified a new nanoscale phenomenon whereby Fg dramatically reduces cell adhesion, and which may explain this discrepancy. Specifically, adsorption of Fg at high concentrations results in the formation of a multilayered extensible matrix (~2-10 nm thick) characterized by low adhesion forces. Conversely, adsorption of Fg at low density produces a monolayer, in which the molecules are directly attached to hard surfaces, resulting in high adhesion forces. Consistent with their distinct physical properties, a monolayer induces strong integrin- mediated signaling in platelets resulting in their firm adhesion and spreading. In contrast, a multilayered Fg matrix is nonadhesive due to its inability to induce a strong mechanotransduction response. The central hypothesis of this application is that the origin of the nonadhesive properties of Fg matrices is the formation of an extensible multilayer incapable of transducing strong mechanical forces via platelet integrins, resulting in weak signaling and cell spreading. Specific Aim 1 is to establish the structural features that enable the formation of an extensible Fg multilayer. Nanotechnology was developed to study the mechanical and adhesive properties of the fibrinogen matrices by single-cell and molecular force spectroscopy and AFM imaging. It will be used to determine how enzymatic crosslinking alters the mechanical and adhesive properties of Fg multilayer, as well as the role of several structural regions of Fg in the increased extensibility of Fg multilayer. This will be accomplished by using recombinant Fgs carrying selected mutations. Specific Aim 2 is to examine how the surfaces of several contemporary biomaterials trigger the formation of the mono- and multilayer Fg matrices and to characterize their mechanical and adhesive properties. Since the lack of endothelium on the blood surface of implanted vascular grafts has substantial medical importance, the possibility that multilayer Fg is incapable of supporting firm attachment of endothelial cells and endothelial progenitor cells under flow will be explored in Specific Aim 3. PUBLIC HEALTH RELEVANCE: Adsorption of the blood protein fibrinogen on implanted vascular grafts and its ability to interact with circulating blood cells plays a central role in their clinical performance. We have discovered a new nanoscale phenomenon whereby deposition of fibrinogen on surfaces creates a nonadhesive multilayer. The proposed studies will define the molecular mechanisms involved in the formation of fibrinogen multilayer and its role in controlling adhesion of platelets and endothelial progenitor cells. This knowledge should be translatable into the design of better vascular grafts.

描述（由申请人提供）：血液蛋白纤维蛋白原（Fg）在生物材料表面的吸附是血液与植入的血管移植物相互作用过程中的关键早期事件。由于其快速吸附和支持血小板粘附的能力，Fg 通常被视为导致表面诱导血栓形成的罪魁祸首，特别是在小直径血管假体中。鉴于植入的血管移植物总是涂有纤维蛋白层，与 Fg 一样，可以支持有效的血小板粘附，因此将 Fg 视为敌人的看法令人困惑。然而，在人类中，这种纤维蛋白层基本上没有血小板，多年来保持其细胞外观的特征。固定化 Fg 支持血小板粘附的能力（主要从体外实验推断）与体内情况之间的差异证明，显然需要更好地了解调节血小板粘附和非粘附功能之间平衡的机制。图。我们最近发现了一种新的纳米级现象，即 Fg 显着降低细胞粘附，这可能解释了这种差异。具体而言，高浓度 Fg 的吸附导致形成多层可延伸基质（约 2-10 nm 厚），其特征是低粘附力。相反，Fg 在低密度下的吸附会产生单层，其中分子直接附着在硬表面上，从而产生高粘附力。与它们独特的物理特性一致，单层在血小板中诱导强烈的整合素介导的信号传导，导致它们牢固地粘附和扩散。相比之下，多层 Fg 基质由于无法诱导强烈的机械转导反应，因此不具有粘附性。该应用的中心假设是，Fg 基质的非粘附特性的起源是形成可延伸的多层，无法通过血小板整联蛋白传导强机械力，从而导致信号传导和细胞扩散较弱。具体目标 1 是建立能够形成可延伸 Fg 多层的结构特征。开发纳米技术是为了通过单细胞和分子力光谱以及原子力显微镜成像来研究纤维蛋白原基质的机械和粘合特性。它将用于确定酶交联如何改变 Fg 多层的机械和粘合性能，以及 Fg 的几个结构区域在增加 Fg 多层的延伸性中的作用。这将通过使用携带选定突变的重组 Fgs 来实现。具体目标 2 是研究几种当代生物材料的表面如何触发单层和多层 Fg 基质的形成，并表征其机械和粘合性能。由于植入的血管移植物的血液表面缺乏内皮具有重要的医学重要性，因此多层 Fg 无法支持流动下内皮细胞和内皮祖细胞牢固附着的可能性将在具体目标 3 中探讨。公共健康相关性：血液蛋白纤维蛋白原在植入的血管移植物上的吸附及其与循环血细胞相互作用的能力在其临床表现中起着核心作用。我们发现了一种新的纳米级现象，纤维蛋白原沉积在表面上形成非粘性多层。拟议的研究将确定参与纤维蛋白原多层形成的分子机制及其在控制血小板和内皮祖细胞粘附中的作用。这些知识应该可以转化为更好的血管移植物的设计。