Scalable Units for Building Vascularized Cardiac Graft

描述（由申请人提供）：最近的心肌组织工程研究表明，结合弹性和强度的机械坚固的微制造生物材料和基于细胞的策略，可以提高移植心脏和/或干细胞的存活率和血管整合。然而，创造具有有组织收缩功能的心肌移植物，以及在植入时快速血管化厚心肌移植物的方法仍然是尚未解决的问题，这些问题目前限制了新的心肌再生技术的规模和临床应用。构建血管化心脏移植物的可扩展单元包括心脏细胞、内皮细胞和缓慢可生物降解的弹性支架，这将是心肌再生的典范转变，因为缺血或先天性心脏病导致心肌丧失功能。提出的工作目标是：(1)设计弹性支架，为培养和排列心脏细胞提供实际空间；(2)将这些构建块与可灌注的通道网络结合起来，为培养内皮细胞提供血管内空间；(3)在啮齿动物模型心肌梗死（MI）后，表明所得到的心肌移植物可以提供机械支持和可移植的心脏细胞。在Aim 1中，我们将用聚甘油-皮脂酸酯和弹性蛋白制造弹性支架，并验证支架结构特征（即矩形孔隙与排列的弹性蛋白微纤维结合）将指导培养心脏细胞的伸长、排列和收缩性的假设。在目标2中，我们将结合构建块（即，弹性体支架与培养的心脏细胞）和可灌注通道网络，形成由血管内和实质空间组成的可扩展单元。我们将检验血管内空间灌注将提高实质空间心脏细胞存活的假设，我们将在体外用内皮细胞排列通道。在Aim 3中，我们将通过四个实验组来评估手术诱导心肌梗死后啮齿动物的心肌移植：(i)血管内内皮细胞和实质心脏细胞的弹性支架；（ii）只含心脏细胞的弹性支架，（iii）不含任何细胞的弹性支架，以及（iv）未经治疗的心肌梗死。我们将测试以下假设：弹性支架将保留心肌梗死后的心室功能，外源性心脏细胞将存活并与宿主心肌机电一体化，内皮化的通道将与宿主血管形成功能性吻合。这项工作的主要新颖之处在于设计和演示：(i)用于组织工程和再生医学的弹性构件支架，（ii）用于再生高度血管化组织（如心脏、骨骼和平滑肌、肝脏、肾脏）的由血管内和实质室组成的板层可扩展单元，以及（iii）用于再生其他各向异性、承重组织（如血管、韧带、肌腱、软骨和骨骼）的各向异性支架。

DESCRIPTION (provided by applicant): Recent research in myocardial tissue engineering has demonstrated the promise of mechanically robust microfabricated biomaterials that combine elasticity and strength, and cell-based strategies that enhance the survival and vascular integration of transplanted heart and/or stem cells. However, creation of myocardial grafts capable of organized contractile function, and a means to rapidly vascularize thick myocardial grafts upon implantation remain unsolved problems that currently limit the dimensions and clinical translation of new myocardial regenerative technologies. Scalable units for building vascularized cardiac grafts comprised of heart cells, endothelial cells, and slowly biodegradable elastomeric scaffolds would be a paradigm shift in the regeneration of myocardium rendered non-functional by ischemia or congenital heart disease. The goals of the proposed work are to: (i) design elastomeric scaffolds that provide parenchymal spaces for culturing and aligning heart cells, (ii) combine these building blocks with perfusable channel networks that provide intravascular spaces for culturing endothelial cells, and (iii) show that the resulting myocardial grafts can provide mechanical support and viable, transplanted heart cells after myocardial infarction (MI) in a rodent model. In Aim 1, we will create elastomeric scaffolds from poly (glycerol-sebacate) and elastin, and test the hypothesis that scaffold structural features (i.e., rectangular pores combined with aligned elastin microfibers) will guide the elongation, alignment, and contractility of cultured heart cells. In Aim 2, we will combine building blocks (i.e., elastomeric scaffolds with cultured heart cells) and perfusable channel networks to form scalable units comprised of intravascular and parenchymal spaces. We will test the hypotheses that perfusion of the intravascular spaces will enhance heart cell survival in the parenchymal spaces, and we will line the channels with endothelial cells in vitro. In Aim 3, we will evaluate the myocardial grafts in rodents after surgically induced MI by using four experimental groups: (i) elastomeric scaffolds with intravascular endothelial cells and parenchymal heart cells; (ii) elastomeric scaffolds with only heart cells, (iii) elastomeric scaffolds without any cells, and (iv) untreated MI. We will test the hypotheses that elastomeric scaffolds will preserve ventricular function post-MI, exogenous heart cells will survive and integrate electromechanically with host myocardium, and endothelialized channels will form functional anastomoses with host vessels. The main novelties of this work are the design and demonstration of: (i) elastomeric building-block scaffolds for tissue engineering and regenerative medicine, (ii) lamellar scalable units comprised of intravascular and parenchymal compartments for regenerating highly vascularized tissues (e.g., cardiac, skeletal and smooth muscle, liver, kidney), and (iii) anisotropic scaffolds for regenerating other anisotropic, load-bearing tissues (e.g., blood vessel, ligament, tendon, cartilage, and bone). PUBLIC HEALTH RELEVANCE: 70 million Americans suffer from cardiovascular disease at an annual cost of 400 billion dollars. Given the high prevalence of myocardial infarction (7 million), heart failure (5 million) and congenital cardiovascular defects (1 million), novel technologies that enable repair of dysfunctional myocardium can have a huge clinical impact. Previous attempts to generate tissue engineered cardiac grafts were limited by inadequate cellular survival, organization, and mechanical function. This work proposes to address these problems by designing and demonstrating scalable units for building vascularized cardiac grafts.