From single cells to complex tissues: advances in ambient ionization mass spectrometry for observing small molecules in biological samples

代谢物是参与所有生物过程的小生物分子，如脂质、糖和氨基酸。代谢组学领域是生物样品中代谢物的靶向和非靶向分析。分析生物体的动态代谢组可以帮助理解基本的生物学过程，并提供客观的疾病诊断。然而，生物学中代谢物的结构多样性是巨大的，包括非极性物种，如胆固醇和信号脂质，以及高极性分子，如氨基酸。使问题进一步复杂化的是，在生物体中发现的代谢物的自然丰度可以有好几个数量级的变化。测量组织中代谢物的传统分析方法通常需要在质谱分析之前对样品进行均质化和提取代谢物。因此，在异质性组织中，详细描述代谢物定位到特定细胞区域的空间信息丢失了。为了在该领域取得进一步的进展，迫切需要新的分析技术来绘制各种样品中复杂的生物分子混合物。在这项研究的过程中，我的小组将创建和设计新的环境电离质谱分析工具来分析动态的有机代谢组。这些工具将被开发和验证，使用从单一哺乳动物细胞到复杂异质组织的模型生物系统。在短期内，我们将建立一个新的平台，利用质谱成像全面绘制组织中代谢物的分布，结合单一样品中代谢物和蛋白质的综合技术，并测量活的单细胞中的代谢物谱。协同使用，这些新技术形成了一个创新的分析管道，以分析来自不同生物样品的代谢物。这种新型管道的未来应用将有助于阐明代谢物在基本生物学途径中的作用，或暴露于化学毒物影响的代谢途径。此外，该发现基金将开发新技术来研究个体单细胞代谢与组织中细胞代谢之间的关系。这一重要的信息将提供一个新的视角来帮助理解细胞在孤立条件下与天然组织环境下的行为。最终，在我的研究项目中开发的技术将利用变革的方法来揭示复杂生物样品中代谢物的空间分布，并将观察到的代谢物与空间定义的蛋白质丰度和已知功能联系起来。

Metabolites are small biomolecules such as lipids, sugars, and amino acids that are involved in all biological processes. The field of metabolomics is the targeted and non-targeted profiling of metabolites in biological samples. Profiling an organism's dynamic metabolome can help understand fundamental biological processes, and provide objective diagnosis of diseases. However, the structural diversity of metabolites in biology is vast, and includes non-polar species such as cholesterols and signalling lipids, and highly polar molecules like amino acids. To complicate matters further, the natural abundance of metabolites found in organisms can range by several orders of magnitude. Traditional analytical approaches for measuring metabolites in tissues typically requires homogenization of samples and extraction metabolites before analysis by mass spectrometry. As a result, the spatial information detailing metabolite localization to specific cellular regions in heterogeneous tissues is lost. In order to make further advances in the field, there is an urgent need for new analytical techniques to map complex mixtures of biomolecules in a wide array of samples. Through the course of this research, my group will create and engineer new ambient ionization mass spectrometry tools to profile dynamic organismal metabolomes. These tools will be developed and validated using model biological systems spanning from single mammalian cells to complex heterogeneous tissues. In the short term, we will build a new platform to comprehensively map the distribution of metabolites in tissue using mass spectrometry imaging, combine an integrate technologies for mapping metabolites and proteins in a single sample, and measure the metabolite profiles in living single cells. Used synergistically, these new techniques form an innovative analytical pipeline to profile metabolites from a diverse set of biological samples. Future applications of this novel pipeline will aid in elucidating the role of metabolites in fundamental biological pathways, or impacted metabolic pathways from exposure to chemical toxicants. Further, this Discovery Grant will develop new technology to study the relationship between individual single-cell metabolism to the metabolism of cells in tissue. This important information will provide a new perspective to help understand how cells behave in isolated conditions versus their native tissue environments. Ultimately, the technology developed in my research program will leverage transformative approaches to reveal the spatial distribution of metabolites in complex biological samples, and link observed metabolites to spatially defined protein abundances and known functions.