Morphological and chemical studies of pathological human and mice brain at the subcellular level: Correlation between light, electron, and nanosims microscopies

Abstract

Neurodegenerative diseases induce morphological and chemical alterations in well-characterized regions of the brain. Understanding their pathological processes requires the use of methods that assess both morphological and chemical alterations in the tissues. In the past, microprobe approaches such as scanning electron microscopy combined with an X-ray spectrometer, Proton induced X-ray emission, secondary ion mass spectrometry (SIMS), and laser microprobe mass analysis have been used for the study of pathological human brain with limited success. At the present, new SIMS instruments have been developed, such as the NanoSIMS-50 ion microprobe, that allow the simultaneous identification of five elements with high sensitivity, at subcellular spatial resolution (about 50-100 nm with the Cs(+) source and about 150-200 nm with O(-) source). Working in scanning mode, 2D distribution of five elements (elemental maps) can be obtained, thus providing their exact colocalization. The analysis can be performed on semithin or ultrathin embedded sections. The possibility of using transmission electron microscopy and SIMS on the same ultrathin sections allows the correlation between structural and analytical observations at subcellular and ultrastructural level to be established. Our observations on pathological brain areas allow us to establish that the NanoSIMS-50 ion microprobe is a highly useful instrument for the imaging of the morphological and chemical alterations that take place in these brain areas. In the human brain our results put forward the subcellular distribution of iron-ferritin-hemosiderin in the hippocampus of Alzheimer disease patients. In the thalamus of transgenic mice, our results have shown the presence of Ca-Fe mineralized amyloid deposits.

Elemental imaging at the nanoscale: NanoSIMS and complementary techniques for element localisation in plants

“…The remainder of this review will cover how the NanoSIMS can be used in conjunction with complementary techniques to provide more information than can be achieved with the NanoSIMS alone [21,61].…”

“…Despite the large-scale heterogeneity found in soil samples, the NanoSIMS is increasingly being applied in this area to study the localisation of microorganisms in the soil matrix [10][11][12][13]. Biological applications of the NanoSIMS include the localisation of labelled drugs in cancer cells [14,15], bacteria [16][17][18] and cyanobacteria [19,20] and many different mammalian tissues, ranging from brain tissue [21] to mouse cochlea [17] and hair [22][23][24]. The NanoSIMS has also been used in conjunction with atomic force microscopy to investigate the composition and distribution of lipid membranes [25,26].…”

Metal and complementary molecular bioimaging in Alzheimer's disease

“…However, micron to submicron imaging is more common since, in order to generate sufficient secondary ions for detection with a very small spot size, the ablation depth needs to increase. Submicron imaging at hundreds of nanometers is more common, and is sufficient for cellular differentiation or observing small pathological features (Quintana et al, 2007; Musat et al, 2012). It is notable that the mass spectrometry techniques also enable more specialized imaging of isotopes across a surface, as well as providing more general elemental imaging.…”

Comment to “Mapping and Characterization of Iron Compounds in Alzheimer's Tissue”

“…NanoSIMS microscopy has been already used with success for the visualization of the morphological and chemical alterations taking place in well-characterized regions in pathological brain, in particular in the study of iron distribution in Alzheimer disease tissue [3,4]. Multielemental analysis (nitrogen, phosphorus, sulphur and iron) were performed on semi-thin or ultra-thin sections of Transmission Electron Microscopy (TEM) preparations brain tissue.…”

“…As we have indicated, in a recent article [4],due to the difficulty in correlating the synchrotron derived techniques with cell and tissue structure, it might be interesting to perform parallel studies, on the same samples, with microfocus XRF and multi-element nanoSIMS imaging; both being techniques suitable for total iron mapping at the cellular and sub-cellular level over a relatively large area. The study of large areas is necessary for statistical analysis and for comparison of normal and pathological tissues.…”