Reproducible Sectioning and Sample Preparation for Mass Spectrometry Imaging of Cancer Metabolism in Frozen Lung Tissue.

Mass Spectrometry Imaging (MSI) for small molecules has emerged as the optimal technique to ascertain meaningful biology from spatial distributions of metabolites, lipids, and other classes of molecules. The success or failure of this approach rests on the sample preparation. Each tissue can have its unique challenges. In addition, the established histological processes for embedding frozen tissue, such as optimal cutting temperature medium, produce large polyethylene glycol clusters that suppress and interfere with the signal of biological molecules. To address these challenges, we provide a reproducible protocol for sectioning lung cancer tissue using a commercially available histological embedding matrix using tissues from genetically engineered mouse models of lung adenocarcinoma with a fluorescent reporter cassette to highlight additional microscopy methods used in parallel with mass spectrometry imaging to select regions of interest to compare tumor and adjacent lung tissue. These improvements to existing techniques produce high-quality sections of frozen tissue for histology and mass spectrometry imaging.