Engineering Functional Cardiac Tissue Chambers

描述：一个多世纪以来，心脏病一直是西方世界面临的最具破坏性的医疗保健问题之一，也是美国的头号杀手。由于心肌自我修复的能力充其量似乎微乎其微，心脏病患者往往会受到永久性损伤，影响泵功能，并恶化为慢性心力衰竭状态。2006年，仅在美国，心脏病造成的相关经济损失就有望超过2500亿美元。因此，最近人们对以细胞为基础的替代、修复或再生受损心肌的新方法感到非常兴奋。然而，这种策略的实际好处被不一致的结果和非常低的移植细胞移植物存活率所掩盖。由于缺乏对所涉及的基本机制的控制和了解，这些技术的成功受到了限制。这在一定程度上是由于现有实验方法中缺少一个环节。在培养皿中取得成功并不能确保转化为动物模型，而在动物模型中进行试验往往涉及到如此复杂的因素组合，以至于很难解释结果。心肌生理学研究的核心方法之一是使用分离的器官或组织制剂。然而，生存能力最多只有几个小时或几天，这不足以测试长期的愈合反应。显然，对心脏疾病和修复机制的理解将受益于一种简化的心脏模型，该模型可以在组织培养实验室中创建，以进行高通量的体外测试。因此，该方案的总体目标是利用组织工程学的原理来创造第一个简化的心腔，或心脏器官，它展示了室泵功能的基本特征，并可以作为理想的代理心脏，用于体外有效地评估新的治疗策略。通过允许独立控制腔室几何形状、组织成分、循环生化因子和机械负荷条件，该系统将提供前所未有的能力来研究调节心肌利基环境的影响。与更传统的心脏贴片或条不同，工程组织腔将允许直接测量压力和体积之间的相关功能关系，最终将心脏描述为泵。这项建议的主要方面被认为是探索性和发展性的，符合R21筹资机制的目标。总体目标将通过以下具体目标实现：目标1：开发一种多功能的高通量集成生物反应器系统，用于工程心脏组织腔的创建、刺激和评估。目的：检测机械和生化因素对工程化心脏组织腔(Etch)的主要结构、功能和分子特征的影响。特别是，我们将测试在ETCH共培养中，壁应力调节人间充质前体细胞和新生大鼠心肌细胞之间的相互作用的假设。

DESCRIPTION: For more than a century, heart disease has been one of the most devastating health care issues facing the Western world, and is the single leading killer in America. Because the capacity for cardiac muscle to repair itself appears to be minimal at best, cardiac patients are often left with permanent damage that compromises pump function and deteriorates to a chronic state of heart failure. The associated economic cost of heart disease in the US alone is expected to exceed $250 billion dollars in 2006. Therefore, there has recently been tremendous excitement about novel cell-based approaches for replacing, repairing or regenerating damaged myocardium. However, the practical benefit of such strategies has been obscured by inconsistent results and very low survival rates of implanted cell grafts. The success of these techniques has been limited by a lack of control and understanding of the underlying mechanisms involved. This is partly due to a missing link in the available experimental methods. Success in the petri dish does not ensure translation to the animal model, and testing in animal models often involves such a complex combination of factors that it is difficult to interpret the outcomes. One approach that has been central to the study of cardiac muscle physiology is the use of isolated organ or tissue preparations. However, viability is limited to a few hours or days at best, which is insufficient to test a long term healing response. Clearly, the understanding of heart disease and mechanisms of repair would benefit from a simplified heart model that could be created in a tissue culture laboratory for high throughput in vitro testing. Therefore, the overall objective of this proposal is to use the principles of tissue engineering to create the first simplified heart chamber, or cardiac organoid, that exhibits the essential characteristics of ventricular pump function and can serve as an idealized surrogate heart for efficient evaluation of novel therapeutic strategies in vitro. By allowing independent control of chamber geometry, tissue composition, circulating biochemical factors, and mechanical loading conditions, this system would offer an unprecedented ability to study the effects of modulating a myocardial niche environment. Unlike more traditional cardiac patches or strips, the engineered tissue chamber would allow direct measurement of relevant functional relationships between pressure and volume that ultimately characterize the heart as a pump. Key aspects of this proposal are considered to be exploratory and developmental in nature, consistent with the objectives of the R21 funding mechanism. The overall objective will be achieved with the following specific aims: Aim 1: To develop a versatile high-throughput integrated bioreactor system for the creation, stimulation, and evaluation of engineered cardiac tissue chambers. Aim 2: To test the effects of mechanical and biochemical factors on the key structural, functional, and molecular features of engineered cardiac tissue chambers (ETCH). In particular we will test the hypothesis that wall stress modulates the interaction between human mesenchymal precursor cells and neonatal rat cardiac myocytes in ETCH co-cultures.