Perinatal cardiomyocyte pruning driven by metabolic maturation: Opportunity for intervention

项目摘要 心肌细胞数是心脏功能的基本决定因素，由于细胞进行性丧失， 当心脏受到压力时，例如当有儿童或成人心脏病时，这一点变得特别重要。 尽管密集的医疗努力集中在疾病过程中保护心肌细胞上，而且有强烈的 (尚未实现)对通过干细胞疗法恢复数量的兴趣，还没有做任何工作来解决 围产期心肌细胞的大量丢失。这是一个治疗机会，可以增加终生心脏 实质上是肌细胞的数量。目前尚不清楚围产期细胞丢失的确切时间， 而临近出生的心脏环境中的信号驱动着细胞的丢失。 在发生心肌细胞丢失的同一时间段，胎儿面临日益严重的缺氧，胎儿心脏 经历代谢成熟，为出生后立即到来的高脂牛奶饮食做准备，以及 甲状腺激素会增加很多倍。这三种因素的相互作用可能对心肌细胞有贡献。 氧化应激和细胞凋亡造成的损失。此外，值得注意的是，男性胎儿在子宫发育过程中存在“风险”。 可能导致对病理性发育规划的敏感性增加的策略。我们怀疑 这些信号通路的相互作用使心脏在出生前就变得易感，但氧化应激和 细胞死亡可以被抗氧化剂抑制。 在这项研究中，我们将使用一个大型动物模型(绵羊)来检验这两个单独的(在培养中)的影响 对新陈代谢和细胞凋亡的调节，以及它们在更复杂的子宫环境中的作用。我们会 使用海马生物分析仪测量不同代谢底物的心肌细胞呼吸 在不同的测试条件下。我们还将测量细胞死亡，如细胞数量，酶释放 和活性，以及凋亡和自噬途径的激活。我们将把这些结果与活性氧联系起来。 细胞死亡途径的物种生成和激活。我们还将确定是否补充褪黑激素 减少氧化应激，防止近期内心肌细胞数量的减少。 意义：心力衰竭可以通过增加健康心肌细胞的数量来减少。肌细胞 在一个代表着一个强大机会的事件中，捐赠在出生时就会大幅减少 进行干预。我们的目标是通过靶向代谢之间的联系来增加出生时的心肌细胞数量 适用于人类生理学的翻译模型中的成熟、缺氧和细胞丢失。

Project Summary Cardiac myocyte number is a fundamental determinant of heart function which, due to progressive cell loss, becomes especially important when the heart is stressed, such as when there is pediatric or adult heart disease. Although intensive medical effort is focused on sparing myocytes during the disease process and there is intense (as-yet unrealized) interest in restoring numbers through stem cell therapies, no work has been done to address the large perinatal loss of cardiac myocytes. This is a therapeutic opportunity to increase life-long cardiac myocyte number substantially. What is not known are the exact timing of the cell loss in the peripartum period, and the signals in the near-birth cardiac milieu driving the cell loss. In the same window during which myocyte loss occurs, the fetus faces increasing hypoxia, the fetal heart undergoes metabolic maturation in preparation for the high-fat milk diet to come immediately after birth, and thyroid hormone increases many-fold. The interaction of these three factors likely contribute to cardiac myocyte loss via oxidative stress and apoptosis. Further, male fetuses are notable for having “risky” in utero growth strategies which may lead to increased sensitivity to pathological developmental programming. We suspect that the interactions of these signaling pathways render hearts susceptible before birth, but that oxidative stress and cell death can be suppressed by an antioxidant. In this study we will use a large animal model (sheep) to examine both isolated (in culture) effects of these regulators on metabolism and apoptosis, as well as their role in the more complex in utero environment. We will use the Seahorse Bioanalyzer to measure cardiomyocyte respiration with different metabolic substrates and under different test conditions. We will also measure cell death, as assessed by cell number, enzyme release and activity, and apoptotic and autophagic pathway activation. We will tie these results in to reactive oxygen species generation and activation of cell death pathways. We will also determine if melatonin supplementation to reduce oxidative stress prevents the near-term loss of cardiac myocyte number. Significance: Heart failure can be reduced by increasing the number of healthy cardiac myocytes. Myocyte endowment is substantially reduced around the time of birth in an event that represents a powerful opportunity for intervention. We aim to increase myocyte number at birth by targeting the connection between metabolic maturation, hypoxia and cell loss in a translational model applicable to human physiology.