Biomimetic micro-structured hydrogel scaffolds for tissue engineered heart valves

描述（由申请人提供）：心脏瓣膜疾病每年需要超过90，000名美国人住院治疗，但治疗心脏瓣膜功能障碍的选择很少，对瓣膜疾病的潜在机制了解更少。心脏瓣膜的基本功能通过瓣膜小叶组织内纤维细胞外基质蛋白的独特微结构排列而成为可能，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。主动脉瓣的主要微观结构属性是其各向异性性质及其相互连接的分层结构，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（TEHV）的聚合物网状支架没有提供这些特征，并且关于产生细胞小叶支架的最佳策略几乎没有共识。包括我们在内的许多小组已经研究了天然和合成凝胶基支架用于维克生物学和病理学研究，但这些研究通常将VIC接种在均匀结构内或顶部。静电纺丝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。 我们建议将这些异质结构和材料特性的心脏瓣膜到水凝胶生物材料。水凝胶生物材料（特别是聚乙二醇二丙烯酸酯，PEGDA）吸引人用作TEHV支架，因为它们具有可调的结构和力学，可以容易地生物功能化，并且可以容易地包封细胞。然而，关于这些材料的研究通常集中在它们的生物活性上，而不是先进材料行为的发展。 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观结构和材料行为。我们的理想定位是生成这些材料，在心脏瓣膜微观结构，材料行为和机械生物学的表征以及使用图案化来管理生物配体呈现方面具有专业知识，最近在PEGDA水凝胶内生成新的结构和差异材料行为区域。这些先进的结构将对下一代TEHV支架产生巨大的影响，也可以用作更忠实的仿生平台，用于瓣膜细胞生物学和疾病机制的3D研究。为实现这一目标，将采取以下措施：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，以生成各向异性水凝胶，展示瓣膜状生物形状的应力-应变曲线。2.优化半互穿方法以开发复合层压水凝胶支架。3.将互连结构图案化到复合层压水凝胶的层中。

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.