Enhancement of Lipid Signal in MALDI MS imaging obtained from Formalin Fixed Human Brain Tissue

Abstract

Matrix assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is used to perform mass spectrometric analysis directly on biological samples providing accurate visual/anatomical spatial information of molecules within the tissue. A current limitation of MALDI‐IMS is that it is largely performed on fresh frozen tissue whereas clinical tissue samples stored long term are fixed in formalin. It has been shown that fresh frozen tissue sections applied with an ammonium formate (AF) wash prior to matrix application in the MALDI‐IMS procedure display an increase in observed signal intensity and sensitivity for lipid molecules detected in the brain while maintaining the special distribution of molecules throughout the tissue. In this work we investigate the effectiveness of this AF wash on post‐fixed rat and human brain tissue sections in an effort to increase the viability of formalin fixed tissue imaging in a clinical setting. Results herein demonstrate that the AF wash significantly improved MALDI‐IMS spectra for gangliosides, including GM1 in fresh frozen rat brain, formalin‐fixed rat brain and formalin fixed human brain samples. AF wash also demonstrated improvements in MALDI‐IMS image quality while retaining the spatial distribution of molecules. Results indicate that this method will allow analysis of gangliosides from formalin‐fixed clinical samples, which can open additional avenues for neurodegenerative disease research.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.