Biomimetic micro-structured hydrogel scaffolds for tissue engineered heart valves

描述（由申请人提供）：美国每年有超过90,000人因心脏瓣膜疾病住院治疗，但治疗心脏瓣膜功能障碍的方法很少，对瓣膜疾病的机制了解更少。心脏瓣膜的基本功能是由瓣膜小叶组织内纤维细胞外基质蛋白的独特微观结构安排实现的，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和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特征是其各向异性和相互连接的层状结构，为瓣膜间质细胞（VICs）提供了异质性的细胞周围环境。目前正在研究的用于组织工程心脏瓣膜（TEHVs）的聚合物网状支架不具备这些特性，而且关于生产细胞小叶支架的最佳策略也没有达成共识。包括我们在内的许多团队已经研究了用于VIC生物学和病理学研究的天然和合成凝胶基支架，但这些支架通常是在均匀结构内部或顶部植入VIC。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。我们建议将心脏瓣膜的这些异质结构和材料特性整合到水凝胶生物材料中。水凝胶生物材料（特别是聚乙二醇二丙烯酸酯，PEGDA）具有可调节的结构和力学，易于生物功能化，并且易于包封细胞，因此被用作tev支架。对这些材料的研究；然而，人们一般关注的是它们的生物活性，而不是发展先进的材料行为。这项工作的目标是应用新颖的模式和分层方法来生成先进的3D水凝胶，模拟主动脉瓣组织的复杂微观结构和材料行为。我们在心脏瓣膜微观结构、材料行为和机械生物学的表征方面拥有专业知识，并且最近在PEGDA水凝胶中产生了新的结构和不同材料行为的区域。这些先进的结构将对下一代TEHV支架产生巨大的影响，也可以作为更忠实的三维研究瓣膜细胞生物学和疾病机制的仿生平台。为实现这一目标，将执行以下目标：比较静电纺丝、激光印刷光刻和双光子吸收共聚焦图图化方法产生的各向异性水凝胶，显示出类似阀的生物形状应力-应变曲线。2. 优化半互穿方法开发复合层压板水凝胶支架。3. 在复合层压水凝胶的层中绘制互连结构。

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.