Life Science Laboratory, Shimadzu Corporation, Kyoto 604-8511, Japan . ; Division of Advanced Clinical Proteomics, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan .
Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo 160-8582, Japan .
Proc Jpn Acad Ser B Phys Biol Sci. 2007 Nov;83(7):205-14. doi: 10.2183/pjab/83.205.
Significant advances have been made in the past decade in the field of mass spectrometry imaging (MS imaging). It is a relatively unestablished technique aimed at direct, high-sensitive and spatially exclusive detection of biological molecules from the surface of tissue sections, so that semi-quantitative distribution map of the analyte can be reconstituted from the mass spectra obtained. There is tremendous potential in its application especially in clinical field, such as biomarker discovery or pharmacokinetic study. However, vast majority of the work has been performed on frozen tissue sections, while it remains generally unpractical to produce frozen sections with clinically resected tumor samples. Here we report our novel sample preparation technique that enabled MS imaging from formalin-fixed paraffin embedded (FFPE) tissue section, including retrospective archive as old as 11 years. FFPE sections were first dewaxed with pre-warmed xylene, and exposed tissue surface was enzymatically digested in nanoliter scale droplets to retain analyte localization. As a result, we succeeded in obtaining MS images of peptide peaks derived from several proteins, identified by MS/MS analysis, using ovarian cancer FFPE sections. The qualities of mass spectra obtained by this method were not significantly different from those obtained from frozen sections. By this, we opened the door to retrospective study of past clinical cases in aim to discover molecular biomarker.
在过去的十年中，质谱成像（MS 成像）领域取得了重大进展。这是一种相对不成熟的技术，旨在直接、高灵敏度和空间特异性地检测组织切片表面的生物分子，从而可以从获得的质谱中重建分析物的半定量分布图。它在应用方面具有巨大的潜力，特别是在临床领域，如生物标志物发现或药代动力学研究。然而，绝大多数工作都是在冷冻组织切片上进行的，而对于临床切除的肿瘤样本，制作冷冻切片通常是不切实际的。在这里，我们报告了一种新的样本制备技术，使我们能够对福尔马林固定石蜡包埋（FFPE）组织切片进行 MS 成像，包括对 11 年前的回顾性存档。FFPE 切片首先用预热的二甲苯脱石蜡，然后在纳升尺度的液滴中对暴露的组织表面进行酶消化，以保留分析物的定位。结果，我们成功地获得了来自卵巢癌 FFPE 切片的几种蛋白质衍生的肽峰的 MS 图像，通过 MS/MS 分析进行了鉴定。通过这种方法获得的质谱质量与从冷冻切片获得的质谱质量没有显著差异。通过这种方法，我们打开了对过去临床病例进行回顾性研究的大门，以发现分子生物标志物。
