Correlative Light and Electron Microscopy to Study Microglial Interactions with β-Amyloid Plaques

Area of Science:

• Neuroscience
• Biochemistry
• Pathology

Background:

• Alzheimer's disease (AD) is characterized by amyloid-beta (Aβ) plaques in the brain.
• Identifying these plaques is crucial for studying AD pathology, especially in early stages or specific brain regions.
• Traditional methods for Aβ plaque detection are often incompatible with subsequent electron microscopy (EM) processing.

Purpose of the Study:

• To provide a detailed protocol for identifying Aβ plaques in Alzheimer's disease mouse models.
• To enable pre-screening of brain sections for Aβ plaques before time-consuming electron microscopy (EM) preparation.
• To facilitate the selection of relevant brain sections for ultrastructural analysis.

Main Methods:

• In vivo injection of Methoxy-X04, a fluorescent dye that selectively binds to Aβ plaques.
• Pre-embedding immunostaining for ionized calcium-binding adapter molecule 1 (IBA1) to identify microglia.
• Tissue processing for electron microscopy (EM) while preserving Aβ plaque visibility.

Main Results:

• Methoxy-X04 allows for selective labeling and pre-screening of brain sections containing Aβ plaques.
• This method enables efficient selection of sections for further analysis, even when plaques are sparse.
• Aβ plaques remain visible after EM processing, allowing precise localization for ultrastructural examination.

Conclusions:

• This protocol streamlines the identification of Aβ plaques in AD mouse models.
• It significantly improves efficiency for researchers studying early AD pathology and performing ultrastructural analysis.
• The method ensures Aβ plaque visibility is maintained throughout the EM preparation workflow.