Insights into fetal brain and placental metabolism using high-resolution magic angle spinning magnetic resonance spectroscopy

在怀孕期间，适当的胎盘代谢对胎儿达到其生长潜能至关重要；然而，怀孕期间的代谢机制仍然知之甚少。提出了一种利用高分辨率魔角旋转（HRMAS）磁共振波谱（MRS）在实验小鼠中研究胎儿脑和胎盘代谢的方法。由于小鼠与人类胎儿大脑发育和胎盘结构的相似性，小鼠是回答代谢问题的理想妊娠模型。虽然人类妊娠期的1H MRS研究结果受到低信号灵敏度和低光谱分辨率的阻碍，但仍有一些有趣的发现。在这里，使用高场磁体（600 MHz）结合HRMAS将显著提高我们测量健康胎儿大脑和胎盘组织中已知和新的代谢物的能力。完整样品的HRMAS MRS提供了有关组织中代谢物位置的信息，并且由于它是非破坏性的，因此允许随后通过其他技术研究样品以提取补充的细胞水平信息。HRMAS MRS用于研究成人大脑和其他器官的组织活检样本，显示了将这项技术用于研究妊娠的巨大前景。迄今为止，MRS在小鼠妊娠模型中的潜力还有待探索。我们的第一个目标是建立收集组织样本的最佳方法，并优化磁共振扫描条件，以最大限度地减少组织成分的变化。然后，我们将使用这种方法来观察生物组织中高丰度的细胞核，如13C和31P，以提供更完整的组织代谢谱。利用创新的核磁共振实验和数据分析，如核弛豫率的测量和无监督聚类分析，我们将通过包括定量核磁共振特性来提高MRS数据的特异性和敏感性。我们的研究将包括男性和女性胎儿，使我们能够检测性别依赖的影响。我们还将研究大脑和胎盘不同区域之间的代谢物谱是否存在差异。确定健康妊娠期脑和胎盘代谢物的水平及其在妊娠期间的变化对了解脑和胎盘功能至关重要。这项工作将为研究怀孕期间的代谢提供新的方法，并且由于MRS可以在子宫内进行，因此本提案的基础研究结果可以转化为人类。磁共振成像通常用于妊娠，本研究的结果将通过更好地了解新陈代谢，为妇女和胎儿的健康提供重大益处。这项工作将为与妊娠相关的代谢异常的早期检测和新疗法的监测开辟潜在的诊断途径。

During pregnancy, appropriate placental metabolism is essential for fetuses to reach their growth potential; however, metabolic mechanisms during pregnancy remain poorly understood. I propose to develop a methodology to study fetal brain and placental metabolism using high-resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS) in experimental mice. The mouse is the ideal pregnancy model to answer questions about metabolism because of the similarities between mouse and human fetal brain development and placental structure. While the results of 1H MRS studies in human pregnancy have been hampered by low signal sensitivity and low spectral resolution, there have been some intriguing findings. Here, the use of a high field magnet (600 MHz) combined with HRMAS will significantly improve our ability to measure known and novel metabolites in healthy fetal brain and placental tissue. HRMAS MRS of intact samples provides information about the location of metabolites in the tissue and, because it is non-destructive, allows the samples to subsequently be studied by other techniques to extract complementary cellular level information. The use of HRMAS MRS to study tissue biopsy samples from adult brain and other organs shows the tremendous promise of using this technique to study pregnancy. To date, the potential for MRS in mouse models of pregnancy has yet to be explored. Our first goal will be to establish the best way to collect tissue samples and to optimize the MR scan conditions to minimize changes to the tissue composition. We will then use this methodology to look at nuclei that are of high abundance in biological tissue such as 13C and 31P to provide a more complete metabolic profile of the tissue. Using innovative NMR experiments and data analysis such as the measurement of nuclear relaxation rates and unsupervised clustering analysis, we will aim to enhance the specificity and sensitivity of the MRS data by including quantitative NMR properties. Our study will include both male and female fetuses, allowing us to detect sex dependent effects. We will also look at whether there are differences in metabolite profile between different areas of the brain and placenta. Determination of the levels of brain and placental metabolites in healthy pregnancy and how they change throughout gestation is critical for understanding brain and placental function. This work will offer novel approaches for studying metabolism during pregnancy and, because MRS can be performed in utero, the basic research findings of this proposal can be translated to humans. Magnetic resonance imaging is routinely being used in pregnancy and the results of this study will provide a significant benefit to women's and fetal health through a better understanding of metabolism. This work will open avenues for potential diagnostics for early detection of metabolic abnormalities associated with pregnancy and monitoring of novel therapies.