A recommended and verified procedure for in situ tryptic digestion of formalin ‐fixed paraffin‐embedded tissues for analysis by matrix‐assisted laser desorption/ionization imaging mass spectrometry

This month's Special Feature by Judd and colleagues from Vanderbilt University outlines key considerations when preparing formalin ‐fixed paraffin‐embedded (FFPE) tissues for matrix‐assisted laser desorption/ionization (MALDI) imaging mass spectrometry (MALDI IMS). MALDI IMS is a untargeted tool for imaging tissue and providing spatial information about the constituent analytes, but this powerful strategy is yet to reach its full potential. In part this is because before any research tool can successfully transition into the clinical laboratory, rugged and reliable sample preparation protocols have to be developed and widely adopted. Formalin fixation is the standard process in clinical pathology because it is well ‐suited to preserving tissue for optical microscopy, but cross‐links and other chemical modifications are introduced during the process that present challenges when the objective is molecular imaging. Currently, reported strategies for FFPE tissue preparation in advance of imaging differ markedl y in complexity and efficacy. This tutorial presents a strategy, derived from systematic testing and optimization of key parameters, for the reproducible in situ digestion of proteins in FFPE tissue and for the subsequent MALDI IMS analysis.
Source: Journal of Mass Spectrometry - Category: Chemistry Authors: Tags: Cover story Source Type: research