Molecular and Microstructural Imaging of Cardiomyocyte Apoptosis and Autophagy

摘要： 缺血再灌注过程中心肌损伤的演变仍不完全清楚。现在 有充分的证据表明，心肌细胞（CM）可以通过发生坏死、凋亡或坏死来对损伤作出反应。 自噬然而，这些不同形式的心肌细胞（CM）损伤的全部意义，以及它们的 彼此之间的相互作用仍然知之甚少。心肌细胞（CM）凋亡之间的相互作用 自噬是特别感兴趣的，因为两者都是高度调节和需要能量的过程， 在再灌注期间易于调节。因此，该提议的总体目标是使用新的分子和 显微结构成像技术，最近在我们的中心，图像心肌细胞凋亡和 体内自噬通过使用这些技术，我们旨在更好地了解程序性CM死亡是如何发生的 以及如何预防。这一提议的核心假设是， 由于缺血和再灌注的平衡，中层心肌最容易发生细胞凋亡， 存在于这个区域，但它们也是最容易通过自噬的发展来挽救的， 其通过去除功能障碍的线粒体和其它促凋亡刺激物来保护CM。使用 AnxCLIO-Cy 5.5用于CM凋亡的MRI和荧光成像， 溶酶体组织蛋白酶参与CM自噬，弥散谱MRI显示心肌纤维 我们的目标是：1）确定缺血严重程度和缺血程度的透壁变化如何影响缺血性心脏病的预后。 再灌注对心肌细胞凋亡和自噬的影响; 2）研究再灌注对心肌细胞凋亡和自噬的影响。 后处理对心肌细胞凋亡和自噬的影响 细胞凋亡和自噬对心肌纤维结构完整性的影响。所提出的成像方法是 高度翻译，并将允许在细胞水平上的CM损失的方面与CM的读出相关。 可以在小鼠和人类中获得的心肌结构和功能。拟议的研究有 通过促进策略的制定以增加挽救治疗，可能会显著影响临床护理 中层心肌细胞，从而将高度透壁和耐受性差的心肌梗死 形成耐受良好的内膜下梗死。叙述： 心肌（心脏肌肉）可以通过几种方式对血液供应不足做出反应，其中一些可能是 保护性的和有害的。我们的目标是在这个建议中使用新的分子和微观结构成像 更好地了解心肌对急性损伤的反应，从而促进 开发新的心脏保护策略。这种战略的制定有可能 显著减少心力衰竭患者人数的迅速增加，因此具有重大的临床和 公共卫生意义。

Abstract: The evolution of myocardial injury during ischemia reperfusion remains incompletely understood. It is now well documented that a cardiomyocyte (CM) can react to injury by undergoing necrosis, apoptosis or autophagy. However, the full significance of these various forms of cardiomyocyte (CM) injury, as well as their interaction with each other, remains poorly understood. The interplay between cardiomyocyte (CM) apoptosis and autophagy is of particular interest since both are highly regulated and energy requiring processes that are amenable to modulation during reperfusion. The overall aim of this proposal is thus to use novel molecular and microstructural imaging techniques, recently developed in our centers, to image cardiomyocyte apoptosis and autophagy in vivo. By using these techniques we aim to better understand how programmed CM death occurs during myocardial reperfusion and how to prevent this. The central hypothesis of this proposal is that CMs in the midmyocardium are the most susceptible to apoptosis due to the balance of ischemia and reperfusion that exist in this zone, but that they are also the most amenable to salvage through the development of autophagy, which protects the CM by removing dysfunctional mitochondria and other pro-apoptotic stimuli. Using AnxCLIO-Cy5.5 for MRI and fluorescence imaging of CM apoptosis, a near-infrared fluorochrome activated by the lysosomal cathepsins involved in CM autophagy, and diffusion spectrum MRI to visualize myocardial fiber architecture we aim to: 1) determine how the transmural variation in the severity of ischemia and the degree of reperfusion influence the development of cardiomyocyte apoptosis and autophagy, 2) study the effects of postconditioning on cardiomyocyte apoptosis and autophagy 3) determine the impact of cardiomyocyte apoptosis and autophagy on the integrity of myocardial fiber architecture. The proposed imaging approach is highly translational and will allow aspects of CM loss at the cellular level to be correlated with readouts of myocardial structure and function that can be obtained in both mice and humans. The proposed study has the potential to impact clinical care significantly by facilitating the development of strategies to increase the salvage midmyocardial cardiomyocytes, and thus convert highly transmural and poorly tolerated myocardial infarcts into well-tolerated subendocardial infarcts. Narrative: The myocardium (heart muscle) can respond to a lack of blood supply in several ways, some of which may be protective and others deleterious. We aim in this proposal to use novel molecular and microstructural imaging techniques to better understand the response of the myocardium to acute injury, and thus to facilitate the development of novel cardio-protective strategies. The development of such strategies has the potential to significantly reduce the rapidly rising number of patients with heart failure, and is thus of major clinical and public health significance.