Spectral profiles of cultured neuronal and glial cells derived from HRMAS (1)H NMR spectroscopy

Abstract

In the investigations of brain function and pathology in vivo by magnetic resonance spectroscopy (MRS), a decrease in the relative concentration of N-acetyl aspartate (NAA) has been correlated with neuronal cell damage or loss, while a relative increase in the resonance intensity of creatine has been correlated with gliosis. However, neither metabolite is confined strictly to one cell-type. In this study, pattern recognition of spectra derived from high-resolution magic angle spinning (HRMAS) (1)H NMR spectroscopy was used to distinguish three neural cell types; cortical astrocytes, cerebellar neurones and O-2A progenitors. The intact cells contained significant amounts of lipid resonances (-CH(2)CH(3) and -CH(2)CH(2)CH(2)-) in all three cell-types, even when a T(2)-edited Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence was used, selectively attenuating resonances from macromolecules. Creatine was also detected in all three cell types. Principle component analysis (PCA) readily differentiated the NMR spectra, based on the individual metabolic profile derived from the cohort of cell type examined using conventional solvent-suppressed and CPMG pulse sequences. Creatine was not found to contribute to this separation. Moreover, the large lipid content of neuronal cells contributed most to the separation from the other cell types. This suggests that during MRS in vivo, where lipid resonances are commonly 'edited out' by T(2) delays, significant information may be sacrificed concerning relative contribution from individual cell types.