Engineered Atrium: New Autologous Cells for Heart Repair

描述(由申请人提供)：自体心耳组织虽然是人类心脏唯一的消耗性部分，但尚未被用作室性心肌梗死修复的细胞来源。到目前为止，成年心肌细胞在体外和体内的快速凋亡限制了其在组织工程中的应用。然而，在初步工作中，研究表明，体外诱导血红素加氧酶-1(HO-1)作为晚期预适应的媒介，可以在体内植入后14天将成年心肌细胞的存活率提高140%。此外，几乎50%的处理贴片在14天后开始自发、同步收缩，不同于直接植入而没有培养的贴片、没有HO-1诱导的贴片或者培养了特定HO-1抑制剂的贴片。移植成三维扁平补片的心肌细胞，在HO-1上调的补片中，在血管间隙周围自发重塑，形成充满非凝血的泵室。这些发现表明，成年心肌细胞可能比之前认为的更具可塑性，经过优化，可能适合作为心肌梗死修复和心脏组织工程的自体细胞来源。实验将研究临床上相关的新策略，旨在应对目前使用自体成年心肌细胞面临的四个挑战：提高心肌细胞对缺血的耐受性；将补片与宿主血管系统整合；减少纤维化；以及在植入心脏后最大化功能。为了克服心肌细胞的凋亡，HO-1的转录激活剂将在体外和静脉内传递，测试一种新的渗透剂作为一种手段来改善三维组织移植物中央细胞的药物传递。定时释放碱性成纤维细胞生长因子的水凝胶将与可移动的大网膜蒂一起应用，以促进与宿主血管系统的整合，并创造大量的心外血源来支持补片。将HO-1局部AAV基因转移到贴片上，以探讨HO-1对间质纤维化的长期基质调节作用。最后，将评估斑块肌纤维排列和收缩蛋白的缺血重编程对斑块生物力学和心功能的影响。该项目的一个独特方面是有机会在平行实验中使用心脏手术患者的人心房组织取代老鼠组织作为供体来源。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。与公共健康相关：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丧失，通常会导致心力衰竭。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被证明能转化为心肌的细胞类型。该项目调查了这一新颖但可能的可能性，即患者自己的房室可消耗性心肌细胞可以被修改，使其能够移植到受伤的心室上存活，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.