Correlative light and electron microscopy for human brain and other biological models

Correlative light and electron microscopy (CLEM) combines light microscopy, for identifying a target via genetic labels, dyes, antibodies, and morphological features, with electron microscopy, for analyzing high-resolution subcellular ultrastructures. Here, we describe the step-by-step instructions to perform a CLEM experiment, optimized for the investigation of ultrastructural features in human brain tissue. The procedure is carried out at room-temperature and can be also adapted to other human and animal tissue samples. The procedure requires 8-days to complete and includes the stages of sample fixation for optimal ultrastructural preservation, immunofluorescence staining, image acquisition, 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. Key pointsO_LIThe protocol for correlative light and electron microscopy (CLEM) is optimized for analyzing chemically fixed human brain tissues. It focuses on maintaining the integrity of ultrastructural features, thereby minimizing artifacts and structural alterations. C_LIO_LIExamining brain tissues at the ultrastructural level can provide an unprecedented amount of detail which may help advance our understanding of the mechanisms underlying neurodegenerative disorders. C_LI