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：
8434902
负责人：
Robert Ros
金额：
$ 39.92万
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/8434902
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.

描述（由申请人提供）：在生物材料表面上吸附血蛋白纤维蛋白原（FG）是血液与植入的血管移植物相互作用期间的关键早期事件。由于其快速的吸附和支持血小板粘附的能力，FG通常被视为造成罪魁祸首，负责表面诱发的血栓形成，尤其是在小直径的血管假体中。鉴于植入的血管移植物总是用纤维蛋白层覆盖的事实，对FG作为敌人的感知使人感到困惑，而纤维蛋白层始终可以支持有效的血小板粘附。然而，在人类中，这种纤维蛋白层在很大程度上没有血小板，多年来一直保持其特征性的细胞外观。固定的FG支持血小板粘附的能力之间的差异，这是主要是从体外实验推断出的，体内的情况，证明了对调节粘合剂和非粘附功能之间平衡的机制的明确需求FG。我们最近确定了一种新的纳米级现象，从而大大降低了细胞粘附，并可以解释这种差异。具体而言，在高浓度下FG的吸附导致形成以低粘附力为特征的多层延伸矩阵（〜2-10 nm厚）。相反，在低密度下FG的吸附会产生单层，其中分子直接附着在硬表面上，从而导致高粘附力。与其独特的物理特性一致，单层诱导血小板中的强结构信号传导，从而导致其牢固的粘附和扩散。相比之下，多层FG基质由于无法诱导强大的机械转导响应而无粘合剂。该应用的中心假设是，FG矩阵的非粘合性特性的起源是形成了可扩展的多层通过血小板整合素传递强机械力的能力，从而导致信号传导和细胞扩散。特定目的1是建立能够形成可扩展的FG多层的结构特征。开发了纳米技术来研究通过单细胞和分子力光谱和AFM成像的纤维蛋白原基质的机械和粘合特性。它将用于确定酶促交联如何改变FG多层的机械性和粘合性特性，以及FG的几个结构区域在FG多层增强的扩展性中的作用。这将通过使用携带选定突变的重组FG来实现。具体目的2是检查几种当代生物材料的表面如何触发单层和多层FG矩阵的形成，并表征它们的机械性和粘合性特性。由于植入的血管移植物的血表面缺乏内皮具有很大的医学意义，因此在特定的目标3中，多层FG无法支撑内皮细胞和流量内皮祖细胞的牢固附着的可能性。