Cardiac Regenerative Therapy with Cyclin A2

描述（由申请人提供）：心血管疾病导致的发病率和死亡率归因于成年哺乳动物心肌细胞缺乏显著的复制潜力。因此，响应于缺血性损伤的肌细胞损失通常导致瘢痕形成和通常不可逆的心脏功能下降。肌细胞增殖的停止与细胞周期的停滞有关。细胞周期蛋白A2是调节细胞周期两个主要转变（G1/S和G2/M）的唯一细胞周期蛋白。它也是哺乳动物心脏中唯一在出生后完全沉默的细胞周期蛋白。我们先前已经证明在转基因小鼠模型中，细胞周期蛋白A2在小鼠心肌中的组成性表达促进出生后心脏的有丝分裂。此外，我们已经表明，细胞周期蛋白A2是至关重要的介导心肌梗死（MI）后，在转基因小鼠诱导心脏再生。细胞周期蛋白A2的再生能力似乎涉及增强的内源性心脏祖细胞的增殖，除了在梗死周围区的成熟心肌细胞的潜在去分化。我们还证明，通过腺病毒载体外源性给予编码细胞周期蛋白A2的cDNA可以改善遗传上幼稚的成年大鼠心肌梗死后的心脏功能，并且检查的所有增殖指数均显着增加。我们现在的目的是探讨是否细胞周期蛋白A2将影响心肌梗死后的心脏修复在一个大型动物模型。这些是关键的临床前研究，将成为未来人体临床试验的基础。我们将利用由CMV启动子驱动的腺病毒细胞周期蛋白A2和一种新的腺相关载体（AAV 9）以心脏特异性的方式将细胞周期蛋白A2 cDNA递送到梗死的猪心。我们将测试直接心肌注射和顺行冠状动脉灌注方法。我们将对接受细胞周期蛋白A2的动物与接受空载体的动物进行心脏功能分析。我们将研究细胞周期蛋白A2对内源性心脏祖细胞的影响，并确定细胞周期蛋白A2是否可以调节这些细胞在猪模型中的增殖。我们还将研究细胞周期蛋白A2对梗死周围区和远端区的成熟心肌细胞的影响。我们的建议提供了一个新的和令人兴奋的方法，心脏再生的干细胞移植作为一种方法，以实现肌细胞生成的争议性结果面前。由于心血管疾病仍然是西方世界的头号杀手，细胞周期蛋白A调节可能对人类疾病谱产生重大影响。公共卫生相关性：充血性心力衰竭是美国住院的主要原因，心血管疾病仍然是西方世界的头号杀手。心血管疾病的发病率和死亡率是由于心肌梗死（MI）等损伤后心脏无法再生。我们已经发现，细胞周期蛋白A2，一个关键的发育基因，能够再生心肌梗死的小动物模型的心脏细胞。我们现在将在大型动物中测试细胞周期蛋白A2在MI后再生心脏的能力，作为未来人体临床试验设计的基础。

DESCRIPTION (provided by applicant): The morbidity and mortality due to cardiovascular disease is attributed to the lack of significant replicative potential of adult mammalian cardiomyocytes. Thus myocyte loss in response to ischemic injury typically results in scar formation and a decline of cardiac function that is usually irreversible. The cessation of myocyte proliferation is associated with an arrest of the cell cycle. Cyclin A2 is the sole cyclin regulating two major transitions of the cell cycle, both G1/S and G2/M. It is also the only cyclin to be completely silenced in mammalian hearts after birth. We have previously demonstrated in a transgenic mouse model that constitutive expression of cyclin A2 in the mouse myocardium elicits mitoses in postnatal hearts. Furthermore, we have shown that cyclin A2 is critical in mediating cardiac regeneration after myocardial infarction (MI) is induced in the transgenic mice. The regenerative ability of cyclin A2 appears to involve enhanced proliferation of endogenous cardiac progenitor cells, in addition to potential dedifferentiation of mature cardiomyocytes in the peri-infarct zone. We have also demonstrated that exogenously administered cDNA encoding cyclin A2 via adenoviral vector can ameliorate cardiac function post-MI in genetically naive adult rats with a significant increase in all proliferative indices examined. We now aim to explore whether cyclin A2 will affect cardiac repair after MI in a large animal model. These are critical pre-clinical studies that will form the basis of future human clinical trials. We will utilize both adenoviral cyclin A2 driven by the CMV promoter and a novel adeno-associated vector (AAV9) to deliver cyclin A2 cDNA to the infarcted porcine heart in a cardiac-specific manner. We will test both direct myocardial injection and antegrade coronary infusion methods. We will perform analyses of cardiac function in animals that receive cyclin A2 compared to those that receive null vectors. We will examine the effects of cyclin A2 on endogenous cardiac progenitor cells, and determine whether cyclin A2 can regulate proliferation of these cells in the porcine model. We will also examine the effect of cyclin A2 on the mature cardiomyocytes of the peri-infarct and distal zones. Our proposal offers a new and exciting approach to cardiac regeneration in the face of controversial results of stem cell transplantation as a method to achieve myogenesis. As cardiovascular disease remains the number one killer in the western world, cyclin A modulation may have a major impact on the spectrum of human disease. PUBLIC HEALTH RELEVANCE: Congestive heart failure is the leading cause of hospitalization in the U.S. and cardiovascular disease remains the number one killer in the western world. The morbidity and mortality of cardiovascular disease is due to the fact that the heart cannot regenerate after an injury such as myocardial infarction (MI). We have found that cyclin A2, a key developmental gene, is able to regenerate heart cells in small animal models of MI. We will now test the ability of cyclin A2 to regenerate the heart after MI in large animals as a basis for the future design of human clinical trials.