Large tissue archiving solution for multiplexed labeling and super-resolution imaging

Tissue clearing and expansion microscopy have significantly advanced neuroscience by enabling the visualization of spatial information about biological components, from tissue-level architecture to nanoscale structures. Currently, their application is limited to tissues without prolonged fixation, which excludes long-term preserved specimens, such as human brains. To address this issue, we present a new multiplex labeling and expansion-applicable method for centimeter-sized archived tissue (MOCAT). We successfully applied MOCAT to formalin-fixed paraffin-embedded (FFPE) mouse, pig, and human brain blocks up to 15 years old. The reliability of MOCAT was demonstrated by the indistinguishable spatial and quantitative information of biomarkers obtained from FFPE intact mouse brains compared to that from freshly prepared SDS-delipidated intact mouse brains. Additionally, MOCAT-processed FFPE samples exhibited superior long-term antigenicity preservation and suitability for advanced expansion microscopy in human brain compared to those kept in 10% formalin. In summary, MOCAT combined with FFPE fulfills the demand for long-term tissue preservation and organ-level multiplex imaging in super-resolution.