1 research outputs found
Simultaneous Imaging of Amyloid‑β and Lipids in Brain Tissue Using Antibody-Coupled Liposomes and Time-of-Flight Secondary Ion Mass Spectrometry
The
spatial localization of amyloid-β peptide deposits, the
major component of senile plaques in Alzheimer’s disease (AD),
was mapped in transgenic AD mouse brains using time-of-flight secondary
ion mass spectrometry (ToF-SIMS), simultaneously with several endogenous
molecules that cannot be mapped using conventional immunohistochemistry
imaging, including phospholipids, cholesterol and sulfatides. Whereas
the endogenous lipids were detected directly, the amyloid-β
deposits, which cannot be detected as intact entities with ToF-SIMS
because of extensive ion-induced fragmentation, were identified by
specific binding of deuterated liposomes to antibodies directed against
amyloid-β. Comparative investigation of the amyloid-β
deposits using conventional immunohistochemistry and fluorescence
microscopy suggests similar sensitivity but a more surface-confined
identification due to the shallow penetration depth of the ToF-SIMS
signal. The recorded ToF-SIMS images thus display the localization
of lipids and amyloid-β in a narrow (∼10 nm) two-dimensional
plane at the tissue surface. As compared to a frozen nontreated tissue
sample, the liposome preparation protocol generally increased the
signal intensity of endogenous lipids, likely caused by matrix effects
associated with the removal of salts, but no severe effects on the
tissue integrity and the spatial distribution of lipids were observed
with ToF-SIMS or scanning electron microscopy (SEM). This method may
provide an important extension to conventional tissue imaging techniques
to investigate the complex interplay of different kinds of molecules
in neurodegenerative diseases, in the same specimen. However, limitations
in target accessibility of the liposomes as well as unspecific binding
need further consideration