Super-resolution correlative light and electron microscopy: Spotlight on the cells’ ultrastructure!

28 August 2018

Researchers from the Dept. of Cell Biology, theme Nanomedicine, and the ‘Microscopy Imaging Center’ (MIC, a Radboudumc Technology Center) recently developed and optimized a pipeline for correlative imaging using super-resolution (SR) microscopy and scanning electron microscopy (SEM).

This state-of-the-art imaging approach allows the correlative visualization of up to three cellular components by SR fluorescence microscopy and the cellular ultrastructure by SEM. In other words, one can fluorescently label up to three different proteins and accurately determine their localization with respect to specific cellular ultrastructures.

Correlative light and electron microscopy (CLEM) was so far performed using conventional light microscopy (LM) and EM. Although this offered unique and complementary information from the same cell or tissue sample, the interpretation of those correlative images was challenged by the fact that the lateral resolution of conventional LM (~250 nm) is much worse than the lateral resolution of EM (~2 nm), something referred to as the “resolution gap”. The correlative imaging pipeline developed by the research team at the Radboudumc, called SR-CLEM, narrows this gap as it combines the ultrastructure provided by EM with super-resolved  fluorescent images by Airyscan imaging (lateral resolution ~140 nm). Ben Joosten and Koen van den Dries used SR-CLEM to study  the nanoscale architecture of podosomes, small cytoskeletal structures used by leukocytes to transmigrate basement membranes or by osteoclasts to remodel bone tissue, and published their results in Frontiers in Immunology, the most-cited open-access journal in the JCR category of Immunology.
“With the recent development of a fully customized home-built Stochastic Optical Reconstruction Microscope (STORM, lateral resolution ~10 nm), we aim at further bridging the resolution gap by correlating STORM with SEM” says Alessandra Cambi (head of the department of Cell Biology).

Jack Fransen (MIC manager) highlights that SR-CLEM is now available to all researchers within the Radboudumc. This approach is particularly interesting for elucidating the organization of complex multimolecular cellular structures as well as for characterizing microorganisms, nanomaterials or nanoparticles and their interaction with cells.  If researchers want to integrate correlative imaging in their research or have information requests, they can contact the MIC.