Visualization of Differential Cardiolipin Profiles in Murine Retinal Cell Layers by High-Resolution MALDI Mass Spectrometry Imaging

The precise fattyacyl chain configuration of cardiolipin(CL),a tetrameric mitochondrial-specific membrane lipid, exhibits dependenceon cell and tissue types. A powerful method to map CL profiles intissue sections in a spatially resolved manner is matrix-assistedlaser desorption ionization mass spectrometry imaging (MALDI-MSI).To build on and explore this potential, we employed a quadrupole time-of-flightmass spectrometer along with optimized sample preparation protocols.We imaged the CL profiles of individual murine retinal cell layersat a pixel size of 10 & mu;m. In combination with tandem MS, weobtained detailed insights into the CL composition of individual retinalcell layers. In particular, we found differential expression of thepolyunsaturated fatty acids (PUFA) linoleic, arachidonic, and docosahexaenoicacids. PUFAs are prone to peroxidation and hence regarded as criticalfactors in development and progression of retinal pathologies, suchas age-related macular degeneration (AMD). The ability of MALDI-MSIto provide cues on the CL composition in neuronal tissue with closeto single-cell resolution can provide important insights into retinalphysiology in health and disease.