A versatile correlative light and electron microscopy protocol for human brain and other biological models

Correlative light and electron microscopy (CLEM) combines light microscopy (LM) for target identification using genetic labels, dyes, antibodies, and morphological features with electron microscopy (EM) for high-resolution subcellular structure analysis. We describe an optimized room-temperature CLEM protocol for ultrastructural investigation of post-mortem human brain tissues, which is adaptable to cell lines and animal tissues. This versatile 8-day protocol encompasses sample fixation for optimal ultrastructural preservation, immunofluorescence staining, imaging, and multi-modal image correlation, and is executable within standard EM laboratories. Serving as a critical tool for characterizing human tissue and disease models, room-temperature CLEM facilitates the identification and quantification of subcellular morphological features across brain regions and can act as a preliminary step to assess sample suitability for cryo-EM studies.