Engineered Atrium: New Autologous Cells for Heart Repair

描述（由申请人提供）：虽然自体心耳组织是人类心脏的唯一消耗部分，但尚未将其作为心室心肌梗死修复的细胞来源。迄今为止，成体心肌细胞在组织工程中的应用受到其在体外和体内快速凋亡的限制。然而，在初步工作中，证明了离体诱导血红素加氧酶-1（HO-1）（一种晚期预处理的介质）可以在体内植入后14天将成年心肌细胞存活率提高140%。此外，几乎50%的治疗补丁开始自发，同步收缩14天，不像补丁直接植入没有文化，补丁培养没有HO-1诱导，或补丁培养与特定HO-1抑制剂。作为三维扁平斑块植入后，HO-1上调的斑块中的肌细胞在血管间隙周围自发重塑，形成充满非凝血血液的泵室。这些发现表明，成年心肌细胞可能比以前认为的更具可塑性，并且经过优化，可能适合作为梗死修复和心脏组织工程的自体细胞来源。实验将研究临床相关的新策略，旨在满足当前使用自体成年心肌细胞的四个挑战：提高心肌细胞对缺血的耐受性;将补丁与宿主血管系统整合;减少纤维化;以及在心脏植入后最大化功能。为了克服肌细胞凋亡，HO-1的转录激活因子将被递送离体和静脉内，测试一种新的透化剂作为改善药物递送到三维组织移植物的中央细胞的手段。定时释放bFGF的水凝胶将与动员的网膜蒂一起应用，以促进与宿主血管系统的整合，并产生高容量的心外血液来源以支持贴片。HO-1的局部AAV基因递送至贴片将用于探索HO-1对间质纤维化的长期基质调节作用。最后，将评估补片肌纤维排列和收缩蛋白的缺血重编程对补片生物力学和心室功能的影响。该项目的一个独特方面是有机会使用心脏手术患者的人类心房组织代替小鼠组织作为平行实验的供体来源。因此，实验策略将在未来可能受益于这项新技术的患者群体的组织中进行测试。该项目是外科医生，生物工程师和基质生物学家之间的多学科努力，共同努力实现具有预期早期临床适用性的重要治疗终点。与公共卫生的相关性：心脏病是美国的主要死亡原因。心脏病发作后，心肌质量不可逆转地丢失，通常导致心力衰竭。目前正在研究的替代失去的肌肉的方法建议使用胚胎干细胞或尚未显示转化为心肌的细胞类型。该项目研究了一种新颖但可能的可能性，即可以修改患者自己的心房消耗性心肌细胞，使其能够在移植到受伤的心室中以预防和治疗心力衰竭。

DESCRIPTION (provided by applicant): Autologous atrial appendage tissue has not been pursued as a cell source for ventricular myocardial infarct repair although it is the only expendable portion of the human heart. To date, the use of adult cardiomyocytes in tissue engineering has been limited by their rapid apoptosis in vitro and in vivo. In preliminary work, however, it was demonstrated that ex vivo induction of heme oxygenase-1 (HO-1), a mediator of late pre- conditioning, could increase adult cardiomyocyte survival by 140% at 14 days following in vivo implantation. Furthermore, almost 50% of treated patches began spontaneous, synchronized contraction by 14 days, unlike patches implanted directly without culture, patches cultured without HO-1 induction, or patches cultured with specific HO-1 inhibitors. Implanted as three-dimensional flattened patches, myocytes in patches with HO-1 upregulation spontaneously remodeled around vascular spaces to form pumping chambers filled with non- clotting blood. These findings suggest that adult cardiomyocytes may have more plasticity than previously thought, and that, with optimization, might be suitable as an autologous cell source for infarct repair and cardiac tissue engineering. Experiments will investigate clinically relevant novel strategies designed to meet four current challenges to the use of autologous adult cardiomyocytes: improving myocyte tolerance to ischemia; integrating patches with host vasculature; reducing fibrosis; and maximizing function after implantation on the heart. To overcome myocyte apoptosis, transcriptional activators of HO-1 will be delivered both ex vivo and intravenously, testing a new permeabilizing agent as a means to improve drug delivery to the central cells of three-dimensional tissue grafts. Hydrogels with timed release of bFGF will be applied with mobilized omental pedicles to foster integration with host vasculature and create a high volume extracardiac blood source to support the patch. Local AAV gene delivery of HO-1 to the patch will be used to explore the long-term matrix modulatory effects of HO-1 on interstitial fibrosis. Finally, the consequences of patch myofiber alignment and ischemic re-programming of contractile proteins on patch biomechanics and ventricular function will be assessed. A unique aspect of the project is the opportunity to use human atrial tissue from cardiac surgical patients to replace mouse tissue as a donor source in parallel experiments. Thus, experimental strategies will be tested in tissue from the very patient population likely to benefit from this new technology in the future. This project is a multidisciplinary effort between surgeons, bioengineers, and matrix biologists, working together toward an important therapeutic endpoint with expected early clinical applicability. Relevance to public health: Heart disease is the leading cause of death in the United States. After a heart attack, heart muscle mass is irreversibly lost, often leading to heart failure. Current methods under investigation to replace lost muscle propose using embryonic stem cells or cell types that have not been shown to transform into heart muscle. This project investigates the novel, but likely possibility that the patient's own expendable heart muscle cells from the atrial chamber could be modified to allow them to survive transplantation onto the injured ventricle to prevent and treat heart failure.