Per-pixel absolute quantitation for mass spectrometry imaging of endogenous lipidomes by model prediction of mass transfer kinetics in single-probe-based ambient liquid extraction
Per-pixel absolute quantitation for mass spectrometry imaging of endogenous lipidomes by model prediction of mass transfer kinetics in single-probe-based ambient liquid extraction
复制标题
通过基于单探针的环境液体萃取中传质动力学的模型预测，对内源脂质组进行质谱成像的每像素绝对定量
DOI：
10.1016/j.talanta.2021.122654
复制
发表时间：
2021
期刊：
影响因子：
6.1
通讯作者：
Lu Hongmei
中科院分区：
文献类型：
--
作者：
Luo Shifen;Wu Qian;Li Youmei;Lu Hongmei
随着质谱成像（MSI）的发展，提供空间分布定量信息的技术近年来引起了越来越多的关注。然而，对于生物样品中内源性化合物的MSI，局部变化的采样效率的不确定性总是阻碍准确的绝对定量。这里使用单探针对大鼠小脑中的环境液体提取 MSI，并将磷脂酰胆碱 (PC) 和脑苷脂 (CB) 的标准品掺杂在提取溶剂中。研究了探针停留在组织的单个像素中时环境液体中内源性脂质的提取动力学曲线。从结果来看，不同脑区不同脂质种类之间的提取动力学曲线存在差异，导致成像像素之间的提取效率存在差异，并且使用沉积在组织中的标准品进行校准无法补偿这种差异。在我们的方法中，建立了环境液体提取的理论动力学模型，并通过将每个成像像素中的实验提取动力学曲线拟合到该模型来预测组织每个像素中内源脂质的原始浓度。实验数据与动力学模型拟合良好，R2>0.86，仅每个像素提取18秒，即可准确预测原始脂质浓度，相对误差<23%。使用新方法，总共对 157 种脂质和小代谢物进行了成像，并实现了 19 个 PC 和 4 个 CB 的逐像素定量。与传统的定量MSI（q-MSI）方法相比，新的q-MSI方法具有更好的重现性和更宽的线性范围，脑组织脂质定量图像的对比度更好，热点和噪声更少。新方法的绝对定量结果经定量LC-MS方法验证，Pearson'r>0.9，相关图线性拟合线的斜率接近1。
With the development of mass spectrometry imaging (MSI), techniques providing quantitative information on the spatial distribution have attracted more attentions recent years. However, for MSI of endogenous compounds in bio-samples, the uncertainty of locally varied sampling efficiencies always hinders accurate absolute quantitation. Here single-probe was used for ambient liquid extraction MSI in rat cerebellum, and standards of phosphatidylcholines (PCs) and cerebrosides (CBs) were doped in extraction solvent. The extraction kinetic curves of endogenous lipids in the ambient liquid extraction during probe parking in single pixel of tissue were investigated. From the results, the extraction kinetic curves were varied between different lipid species in different brain regions, resulting in variations of extraction efficiencies between imaging pixels, and calibration with standards deposited in tissue could not compensate for the variations. In our approach, the theoretical kinetic model of ambient liquid extraction was established, and original concentrations of endogenous lipids in each pixel of tissue were predicted by fitting the experimental extraction kinetic curve in each imaging pixel to the model. The experimental data was demonstrated to be well fitted to the kinetic model with R2> 0.86, and only with 18-s extraction in each pixel, the original lipid concentrations were predicted accurately with relative errors <23%. With the new method, totally 157 lipids and small metabolites were imaged, and per-pixel quantitation was achieved for 19 PCs and 4 CBs. Compared with conventional quantitative MSI (q-MSI) method, the new q-MSI method had better reproducibility and wider linear range, and produced better contrast in the quantitative images of lipids in brain tissue with less hot spots and noises. The absolute quantitation results by the new method were verified by quantitative LC–MS method with Pearson'r > 0.9 and the slope of the linear fitting line of the correlation plot near 1.