Biocompatible Heterograft Biomaterials

这个基本项目的目标是研究一种新的治疗方法， 用于儿科心脏手术的异种移植物衍生生物材料的交联反应。该提案的总体假设是，三缩水甘油胺（TGA）交联和相关反应（包括与双膦酸盐的反应）增强生物相容性，改善生物力学，并抑制异种移植心脏瓣膜去代（由于细胞外基质（ECM）的结构蛋白的主要修饰以及与TGA交联ECM的细胞相互作用以及随后的基因表达变化）。这是一个转化项目，目标是为儿科心脏手术创造创新的生物材料。将与项目2、临床核心（C）、核心D（微阵列）、核心E （形态学）和核心F（生物统计学和生物信息学）。目标1. TGA交联的机理：这里的重点将是TGA化学和生物材料的相互作用与研究的反应条件，交联形成，并由此产生的生物力学效应。我们还将研究反应，反应动力学，以及对交联和生物力学的净效应， TGA和2，2巯基乙氨基亚乙基-1，1-二膦酸盐（MABP），一种由我们小组定制合成的二膦酸盐，可与TGA处理的基质共价连接，以防止猪生物瓣膜瓣尖和主动脉壁钙化（见进展报告）。 目标二。为了研究基因表达模式，以及负责TGA交联赋予钙化抗性的细胞和ECM机制：我们将研究TGA和TGA + MABP对钙化的抑制，因为这与TGA交联ECM的细胞相互作用有关。我们将重点关注TGA相关的骨桥蛋白（OPN）（一种与钙化抑制相关的ECM蛋白）上调和腱生蛋白-C（TNC）（一种与心脏瓣膜钙化相关的ECM蛋白）下调。我们将使用绵羊主动脉瓣间质细胞（SAVIC）的细胞培养研究来模拟细胞-ECM相互作用，比较有和没有MABP的TGA与对照底物。目标3：在体内研究TGA交联加MABP抑制异种移植物钙化、增强生物相容性和改善生物力学相互作用的机制。 我们将在皮下和循环模型中研究TGA诱导的ECM结构蛋白修饰与细胞ECM相互作用，导致基因表达谱的变化与OPN上调，相关的钙化抑制，增强生物相容性和增强生物力学性能。临床检索（钙化和非钙化生物假体和同种移植物）也将进行DNA微阵列分析和免疫组织化学研究，以研究与 利益机制。

The obiective of this basic project is to investigate a novel therapeutic approach involving protein crosslinking reactions for use with heterograft-derived biomaterials utilized in pediatric cardiac surgery. The overall hypothesis of this proposal is that triglycidyl amine (TGA) crosslinking and related reactions, including those with bisphosphonates, enhance biocompatibility, improve biomechanics, and inhibit heterograft heart valve deqeneration due to major modifications of the structural proteins of the extracellular matrix (ECM), and cellular interactions with the TGA crosslinked ECM with subsequent changes in gene expression. This is a translational project with the goal of creating innovative biomaterials for pediatric cardiac surgery. Collaborative interactions will occur with Project 2, the Clinical Core (C), Core D (Microarray), Core E (Morphology) and Core F (Biostatistics and Bioinformatics). Aim 1. Mechanisms of TGA crosslinking: The focus here will be on TGA chemistry and biomaterial interactions with studies of reaction conditions, crosslink formation, and resultant biomechanical effects. We will also study the reactions, reaction kinetics, and net effects on crosslinking and biomechanics involving TGA and 2,2 mercaptoeothylamino-ethylidene-1, 1-bisphosphonate (MABP), a bisphosphonate custom synthesized by our group that can be covalently linked to TGA treated substrates to prevent both porcine bioprosthetic cusp and aortic wall calcification (see Progress Report). Aim 2. To study the gene expression patterns, as well as cellular and ECM mechanisms responsible for TGA crosslinking conferring resistance to calcification: We will investigate TGA and TGA plus MABP inhibition of calcification as this relates to cellular interactions with the TGA-crosslinked ECM. We will focus on TGA-related up-regulation of osteopontin (OPN), an ECM protein associated with calcification inhibition, and down-regulation of tenascin-C (TNC), an ECM protein associated with heart valve calcification. We will use cell culture studies with sheep aortic valve interstitial cells (SAVIC) to model celI-ECM interactions comparing TGA with and without MABP to control substrates. Aim 3. To investigate in vivo the mechanisms responsible for TGA-crosslinking plus MABP inhibiting heterograft calcification, enhancing biocompatibility, and improving biomechanical interactions. We will investigate in subdermal and circulatory models TGA-induced ECM structural protein modifications with resulting cellular ECM interactions that lead to changes in gene expression profiles with upregulation of OPN, with associated calcification inhibition, enhanced biocompatibility, and enhanced biomechanical properties. Clinical retrievals (calcified and noncalcified bioprostheses and homografts) will also be subjected to DNA-microarray analyses and immunohistochemistry studies to investigate correlates with the mechanisms of interest.