Precise Lipid Localization from Tissue Sections using a Chemical Inkjet Printer for MALDI Matrix Deposition

Introduction

The importance of lipids in cell life is demonstrated by the number of diseases related to their metabolic alteration such as in Alzheimer’s, diabetes, cancer and many other disease states. The most well known roles for lipids in cell function are chemical energy storage and structural components of cell membranes. However, the whole pallet of their function is not yet totally understood partly due to their complexity and the need for new technology and tools for their study. MALDI profiling and MALDI tissue imaging mass spectrometry are two of the most powerful techniques currently available for this type of research. These approaches allow for the direct detection and mapping of biomolecules from different types of a tissue sections. Both are based on easy but crucial sample preparation combined with performance of the mass spectrometer. One of the most important sample preparation steps is accurate and regio- specific deposition of matrix onto the tissue section. Manual matrix deposition techniques face the challenge of depositing a reproducible and uniform matrix layer yielding to efficient analyte extraction, desorption/ionization and detection. Therefore the most reliable and reproducible way to obtain accurate matrix printing on cell tissue sections and their specific cell regions would be by using automated techniques. The objective of this MALDI tissue imaging study was to control the matrix deposition to keep biomolecules specific localization. This goal was achieved by using a chemical inkjet printer (Shimadzu ChIP 1000). The matrix microprinting involved direct and automated control of the dispensed volume of solution (in the pico liter range), and its homogenous and precise location on the tissue sample. Indeed, the solution allocation follows a grid pattern of spots that can be set up in the printer software. In this particular study an optimized methodology was successfully applied to the detection and mapping of gangliosides from wild type mouse brain sections. Furthermore, phosphatidylcholines (PC) and sphingomyelins (SM) were directly analyzed and mapped from a single mouse brain section model of a traumatic brain injury (TBI).

January 10, 2011 GMT