Scaffold-Free Tissue-engineered Cardiac Patch Processed with a novel 3D Bio-Printer for Myocardial Restoration

摘要 该项目的最终目标是开发一种组织工程心脏来治疗终末期心力衰竭患者 通过替换患病的心脏作为第一步，我们正在开发一种组织工程心脏补片， 促进原位心肌再生和功能恢复。 心力衰竭是一个主要的健康问题，患病率不断增加，部分原因是心脏病的幸存者增加。 急性心肌梗死、预期寿命延长和生活方式选择。每年有53,000人死亡 与心力衰竭有关。虽然心脏移植目前是治疗严重心脏病的金标准疗法， 在美国，由于缺乏捐赠者，它每年只能为大约2,000名患者提供服务。 已经开发了诸如左心室辅助装置（LVAD）的机械支持技术， 治疗晚期心力衰竭，作为心脏移植的替代方案。LVAD治疗的主要问题是， LVAD设计为仅支持左侧心脏，但不支持右侧心脏，目前没有 耐用的长期右心室辅助装置可用。另一种称为脑室手术的手术技术 恢复（SVR）也是心力衰竭治疗的重要策略。大多数SVR技术利用大的 合成心脏补片来恢复心脏的几何形状。然而，大的惰性斑块迅速 被宿主包裹并且不能恢复心肌功能，这限制了心脏功能的恢复。为了 为了改善晚期心力衰竭患者的手术治疗结果和生活质量， 开发一种有助于恢复心脏功能的新生物材料至关重要。 最近，已经发明了一种新颖的三维（3D）生物打印机。3D生物打印机是一个机器人系统， 这有助于通过将细胞球状体放置在基于预处理的针阵列中来制造3D细胞结构， 设计3D数据。该系统允许使用任何所需的细胞/生物材料创建任何形状的3D结构 在任何坐标位置。在心脏手术领域中使用该系统尚未进行研究， 在其他器官（例如血管、肝脏）中的应用已经开始显示出有希望的结果。 在这项概念验证研究中，我们将创建一个无支架的3D组织工程心脏补片。贴片 将由3层组成：内皮细胞、心肌细胞和外膜成纤维细胞。这些补丁将被测试 在猪右心室补片置换模型中，通过机电标测进行评估，心脏 磁共振成像，以及组织学检查。这项初步研究的目的是 证明了新的组织工程补片1）在猪体内提供了良好的耐久性和强度 制备，2）提供增强的位点特异性宿主细胞再增殖，和3）恢复功能性心肌。 在建议的研究和该项目的未来研究的结论，我们可以提供一个有前途的 用于原位心肌再生的材料，每年最终可以挽救超过50，000名患者的死亡 严重心力衰竭

ABSTRACT The ultimate goal of this project is to develop a tissue-engineered heart to treat patients of end-stage heart failure by replacing the diseased heart. As the initial step, we are developing a tissue-engineered cardiac patch to promote in-situ myocardial regeneration and functional restoration. Heart failure is a major health problem with increasing prevalence, caused in part by increased survivors from acute myocardial infarction, increased life expectancy, and lifestyle choices. There are 53,000 deaths per year related to heart failure. While heart transplantation is currently a gold standard therapy for the treatment of severe heart failure, it only serves for about 2,000 patients per year in the United States due to a shortage of donors. Mechanical support technologies such as left ventricular assist device (LVAD) have been developed for treatment of advanced heart failure as an alternative to heart transplant. A major issue for LVAD therapy is that LVADs are designed to support the left-side heart only but not for right-side heart and that currently there is no durable long-term right ventricular assist device available. Another surgical technique called Surgical Ventricular Restoration (SVR) is also an important strategy for heart failure treatment. Most SVR techniques utilize a large synthetic cardiac patch to restore the geometry of the heart. However, the large inert patches are rapidly encapsulated by the host and do not restore myocardial function, which limit recovery of heart functions. In order to improve the outcomes of surgical treatments and the quality of life of advanced heart failure patients, it is critical to develop a new biomaterial that contributes restoring the heart function. Recently, a novel three dimensional (3D) bio-printer has been invented. The 3D bio-printer is a robotic system that facilitates the fabrication of 3D cellular structures by placing cell spheroids in needle arrays based on pre- designed 3D data. This system allows to create any shape of 3D structure using any desired cells/biomaterials in any coordinate location. No study has been done using this system in the field of cardiac surgery while several applications in other organs (e.g. blood vessel, liver) have started showing promising results. In this proof-of-concept study, we will create a scaffold-free 3D tissue-engineered cardiac patch. The patch will consist of 3 layers: endothelial cells, cardiomyocytes, and adventitial fibroblasts. The patches will be tested in a porcine right ventricular patch replacement model and assessed with Electromechanical mapping, Cardiac Magnetic Resonance Imaging, as well as histological examinations. The goal of this preliminary study is to demonstrate that the new tissue-engineered patch 1) provides the decent durability and strength in a porcine preparation, 2) provides enhanced site-specific host cell repopulation, and 3) restores functional myocardium. At the conclusion of the proposed study and future studies of the project, we could provide a promising material for in-situ myocardial regeneration, which could eventually save over 50,000 patients dying every year from advanced heart failure.