Aberrations in oligodendrocyte development resulting from congenital heart disease and its surgical treatment

 描述（由申请方提供）：出生时患有先天性心脏病（CHD）的新生儿常见脑发育延迟和白色物质（WM）损伤。这两种情况都已在临床MRI研究中得到证实。新生儿心脏手术后，这些CHD患者中新的WM损伤也很常见，很可能继发于心肺转流（CPB）的有害作用。新的WM损伤更可能出现在由CHD诱导的宫内缺氧引起的未成熟脑中。然而，先天性心脏病中发育延迟和脑白质损伤的细胞机制以及体外循环对未成熟脑的影响仍然知之甚少。深入了解这些机制将有助于预防和/或开发CHD患者新生儿WM损伤的有效治疗方法。以往的研究表明，在新生啮齿动物脑缺氧和缺血改变少突胶质祖细胞（OPCs）的生成和迁移。在小鼠模型中，长时间缺氧也会延迟OPC分化，导致WM髓鞘形成不足。WM低髓鞘化是临床应用的脑不成熟量表的一个组成部分。因此，我们将测试以下假设：i）由于术前缺氧导致WM中OPC生成和分化受损，导致WM髓鞘形成不足和脑不成熟; ii）CPB的炎症作用以及循环停止的再灌注和再氧合都加剧了受损的生成和延迟的OPC迁移和成熟。将使用的第一个模型将是仔猪缺氧模型。在这个实验范例中猪脑的不成熟发育与在患有CHD的新生儿中观察到的非常相似。将使用暴露于缺氧和CPB的仔猪，采用组合范例研究CPB对未成熟脑的影响。为了分析猪脑中OPC的成熟，我们已经产生了来源于猪干/祖细胞的OPC。将使用免疫组织化学方法测量OPC的增殖。OPC迁移将通过使用体内超顺磁性氧化铁标记的新型细胞跟踪MRI技术连续监测。将通过荧光标记物组织学确定从OPC到成熟少突胶质细胞的发育。将通过系列体积分析和扩散张量成像分析WM的显微结构成熟。最后，微结构成熟和脑不成熟之间的相关性将被定义。这些研究将明确CHD新生儿脑不成熟和WM损伤的关键细胞机制。研究结果将有助于决策有关的最佳时机和手术技术。拟议的研究有可能确定和评估治疗脑不成熟和WM损伤的新策略，并确定CHD患者围产期护理的新标准。由此产生的改善神经发育的结果将是巨大的好处，这些人与冠心病。

 DESCRIPTION (provided by applicant): Delayed brain development and white matter (WM) injury are common in neonates with congenital heart disease (CHD) at the time of birth. Both have been documented by clinical MRI studies. New WM injury is also common in these same individuals with CHD following neonatal cardiac surgery, most likely secondary to the deleterious effects of cardiopulmonary bypass (CPB). New WM injury is more likely to be seen in the immature brain resulting from CHD-induced in utero hypoxia. However, cellular mechanisms underlying delayed maturation and WM injury in CHD and effects of CPB on immature brain remain poorly understood. Insights into these mechanisms would allow prevention and/or development of effective treatment for neonatal WM injury in patients with CHD. Previous studies have documented that in the neonatal rodent brain hypoxia and ischemia alter generation and migration of oligodendrocyte progenitor cells (OPCs). Prolonged hypoxia also delays OPC differentiation in a mouse model leading to WM hypomyelination. WM hypomyelination is one component of a clinically-applied scale for brain immaturity. Therefore, we will test the following hypotheses: i) Impairment of OPC generation and differentiation in the WM due to preoperative hypoxia results in WM hypomyelination and brain immaturity; ii) Both the inflammatory effects of CPB as well as the reperfusion and reoxygenation of circulatory arrest exacerbate the impaired generation and delayed OPC migration and maturation. The first model that will be used will be a piglet hypoxia model. Immature development of the porcine brain in this experimental paradigm is very similar to that observed in newborns with CHD. The impact of CPB on the immature brain will be investigated with a combined paradigm using piglets exposed to both hypoxia and CPB. To analyze OPC maturation in the porcine brain, we have generated OPCs derived from porcine stem/progenitor cells. Proliferation of OPCs will be measured using immunohistochemical methods. OPC migration will be continuously monitored by novel cell tracking MRI techniques using superparamagnetic iron oxide labeling in vivo. Development from OPCs to mature oligodendrocytes will be defined by fluorescent marker histology. Microstructural maturation of WM will be analyzed by serial volumetric analysis and diffusion tensor imaging. Finally correlation between microstructural maturation and brain immaturity will be defined. The proposed studies will define crucial cellular mechanisms underlying the causes of brain immaturity and WM injury in the neonate with CHD. The findings will assist decision-making regarding optimal timing and techniques of surgery. The proposed studies have the potential to identify and assess novel strategies to treat brain immaturity and WM injury, and define new standards of perinatal care in the patient with CHD. The resulting improved neurodevelopmental outcomes would be of enormous benefit to those individuals with CHD.