Engineered Atrium: New Autologous Cells for Heart Repair

描述（由申请人提供）：自体心房附件组织虽然是人类心脏中唯一可消耗的部分，但尚未被作为心室心肌梗死修复的细胞来源。迄今为止，成人心肌细胞在组织工程中的应用一直受到其体外和体内快速凋亡的限制。然而，在初步研究中，体外诱导血红素加氧酶-1 (HO-1)，一种晚期预适应的介质，可以在体内植入后14天将成人心肌细胞存活率提高140%。此外，与直接植入未培养的贴片、未诱导HO-1的贴片或含有特异性HO-1抑制剂的贴片不同，近50%的治疗过的贴片在14天后开始自发、同步收缩。作为三维扁平贴片植入后，HO-1上调贴片中的肌细胞在血管间隙周围自发重塑，形成充满非凝血的泵腔。这些发现表明，成人心肌细胞可能比以前认为的具有更大的可塑性，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。实验将探讨临床相关的新策略，旨在满足目前使用自体成人心肌细胞的四个挑战：提高心肌细胞对缺血的耐受性；贴片与宿主脉管系统的整合；减少纤维化;并在植入心脏后使功能最大化。为了克服心肌细胞凋亡，HO-1的转录激活剂将被体外和静脉注射，测试一种新的渗透剂，作为一种改善药物递送到三维组织移植物中心细胞的手段。具有bFGF定时释放的水凝胶将与动员的网膜蒂一起应用，以促进与宿主血管的整合，并创造高容量的心外血源来支持贴片。将AAV基因局部递送HO-1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，将评估贴片肌纤维排列和收缩蛋白的缺血性重编程对贴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合作，共同致力于一个重要的治疗终点，并具有预期的早期临床适用性。与公众健康相关：心脏病是美国人死亡的主要原因。心脏病发作后，心肌质量不可逆转地减少，常常导致心力衰竭。目前正在研究的替代失去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，即患者自己的房室可消耗的心肌细胞可以被修改，使它们能够存活移植到受伤的心室，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.