Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
Center for Renal Precision Medicine, Division of Nephrology, Department of Medicine, The University of Texas Health, San Antonio, Texas 78229, United States.
J Am Soc Mass Spectrom. 2022 Aug 3;33(8):1577-1580. doi: 10.1021/jasms.2c00120. Epub 2022 Jul 8.
Investigation of the spatial distribution of -glycans in tissue specimens has emerged as a powerful tool in clinical research, in part, because altered -glycans are often a hallmark of disease progression. Mass spectrometry imaging of -glycans relies on peptide -glycanase spraying and tissue incubation for efficient release of -glycans from their carrier proteins. Unstandardized and uncontrolled incubation steps often cause significant delocalization of released -glycans, resulting in the inability to link given -glycan composition to a specific microanatomical region in the tissue. Herein, we optimized the incubation step to provide accurate and sensitive MALDI-MSI of -glycans. Specifically, we tested saturated solutions of various salts that maintain constant relative humidity in the incubation chamber. We showed that the best performance was achieved using a saturated solution of KNO that maintains an 89% RH. Under these conditions, near maximal sensitivity was achieved with the minutest ion delocalization, which we demonstrated at a 35 μm spatial resolution, where we observed six distinct spatial patterns that colocalize to distinct microanatomical compartments in a kidney nephrectomy tissue section.
研究表明，-聚糖在组织标本中的空间分布是临床研究中的有力工具，这在一定程度上是因为聚糖的改变通常是疾病进展的标志。-聚糖的质谱成像依赖于肽-聚糖酶喷雾和组织孵育，以有效地将-聚糖从其载体蛋白中释放出来。未标准化和不受控制的孵育步骤通常会导致释放的-聚糖发生明显的定位变化，从而无法将特定的-聚糖组成与组织中的特定微解剖区域联系起来。在此，我们优化了孵育步骤，以提供准确和敏感的 MALDI-MSI-聚糖。具体来说，我们测试了各种盐的饱和溶液，这些溶液可在孵育室中保持恒定的相对湿度。我们发现，使用保持 89%RH 的 KNO3 饱和溶液可获得最佳性能。在这些条件下，我们以 35 μm 的空间分辨率证明了最小的离子定位实现了近乎最大的灵敏度，我们在肾切除术组织切片中观察到六个不同的空间模式，这些模式与不同的微解剖隔室共定位。
