Biomimetic micro-structured hydrogel scaffolds for tissue engineered heart valves

描述(申请人提供)：心脏瓣膜疾病每年需要90,000多名美国人住院治疗，但治疗心脏瓣膜功能障碍的选择很少，对潜在瓣膜疾病的机制更是知之甚少。心脏瓣膜的基本功能是通过瓣叶组织内纤维细胞外基质蛋白的独特微结构安排而实现的，但这些瓣膜结构-功能关系尚未转化为下一代瓣膜组织工程研究以及瓣膜细胞生物学和疾病的体外分析。主动脉瓣的主要微结构属性是其各向异性和相互连接的层状结构，这为瓣膜间质细胞(VIC)提供了异质的细胞周围环境。正在研究的用于组织工程心脏瓣膜(TEHs)的聚合物网状支架没有提供这些特性，并且对于生产细胞叶支架的最佳策略几乎没有达成共识。包括我们在内的许多小组已经研究了用于VIC生物学和病理学研究的天然和合成凝胶支架，但这些支架通常在均质结构内或之上种植VIC。电纺可以产生层状结构和各向异性，但这种方法对操作参数高度敏感。我们建议将心脏瓣膜的这些异质结构和材料特性集成到水凝胶生物材料中。水凝胶生物材料(尤其是聚乙二醇二丙烯酸酯，PEGDA)具有结构和力学可调、易于生物功能化、易于包埋细胞等优点，因此成为TEHV支架材料的研究热点。关于这些材料的研究；然而，通常侧重于它们的生物活性，而不是先进材料行为的发展。这项拟议工作的目标是应用新的图案化和分层方法来生成先进的3D水凝胶，以模拟主动脉瓣组织的复杂微结构和材料行为。我们在表征心脏瓣膜微结构、材料行为和机械生物学方面拥有专业知识，并使用图案化技术来控制生物配体的呈现，最近还在PEGDA水凝胶中产生新的结构和不同的材料行为区域，处于生产这些材料的理想位置。这些先进的结构将对下一代TEHV支架产生巨大的影响，也可以作为更忠实的仿生平台用于瓣膜细胞生物学和疾病机制的三维研究。为了实现这一目标，将实现以下目标：1.比较静电纺丝、激光印刷光刻和双光子吸收共聚焦图案化方法产生的各向异性水凝胶，显示出阀状生物形状的应力-应变曲线。2.优化半互穿法制备复合材料层状水凝胶支架。3.将互连结构图案化为复合材料层压水凝胶的各层。

DESCRIPTION (provided by applicant): Heart valve diseases require hospitalization of more than 90,000 Americans each year, but there are very few options for treating heart valve dysfunction, and even less is known about the mechanisms the underlie valve disease. The essential function of heart valves is made possible by the unique microstructural arrangement of fibrous extracellular matrix proteins within the valve leaflet tissue, but these valvular structure- function relationships have not been translated into the next generation of valve tissue engineering investigations and for in vitro analyses of valvular cell biology and disease. The primary microstructural attributes of aortic valves are their anisotropic nature and their interconnected, layered structure, which provide valvular interstitial cells (VICs) with heterogeneous pericellular environments. These characteristics are not provided by the polymer mesh scaffolds being investigated for tissue engineered heart valves (TEHVs), and there is little consensus about optimal strategies to produce a cellular leaflet scaffolds. Many groups including ours have investigated natural and synthetic gel-based scaffolds for studies of VIC biology and pathology, but these have generally seeded VICs within or atop homogeneous structures. Electrospinning can produce layered structures and anisotropy, but this approach is highly sensitive to operating parameters. We propose to integrate these heterogeneous structure and material characteristics of heart valves into hydrogel biomaterials. Hydrogel biomaterials (particularly poly ethylene glycol diacrylate, PEGDA) are appealing for use as TEHV scaffolds because they have tunable structure and mechanics, can be readily bio- functionalized, and can easily encapsulate cells. Research concerning these materials; however, has generally been focused on their biological activities, as opposed to the development of advanced material behavior. The goal of the proposed work is to apply novel patterning and layering methodologies to generate advanced 3D hydrogels that mimic the complex microstructure and material behavior of aortic valve tissues. We are ideally positioned to generate these materials, having expertise in the characterization of heart valve microstructure, material behavior, and mechanobiology as well as the use of patterning to govern biological ligand presentation and more recently to generate novel structures and regions of differential material behavior within PEGDA hydrogels. These advanced structures will have tremendous impact on the next generation of TEHV scaffolds and could also be used as more faithful biomimetic platforms for 3D investigations of valvular cell biology and disease mechanisms. The following aims will be performed to accomplish this goal: 1. Compare electrospinning, laser printing photolithography, and 2-photon absorption confocal patterning approaches to generate anisotropic hydrogels demonstrating a valve-like biological-shape stress-strain curve. 2. Optimize semi-interpenetrating approaches to develop composite laminate hydrogel scaffolds. 3. Pattern interconnecting structures into the layers of the composite laminate hydrogels.