A Gold Key to Open the Door to Archival Biomedical Tissue Treasure

Formalin-fixed, paraffin-embedded (FFPE) tissue sections have widely been adopted for more than a century as the standard method for morphological study, particularly in the field of diagnostic pathology, most of the criteria for pathological diagnosis are established by the observation of FFPE tissue sections. With remarkable achievements in morphologic research field during the past one more century, FFPE tissue samples have been accumulated worldwide that are accompanied with complete clinical data including follow-up results of treatment, or, experimental data collected previously, resulted in an invaluable resource of research. Three more decades ago, immunohistochemistry (IHC) started to show its power and beauty in the field of histopathology, however, at the early stage it was largely limited on frozen tissue sections only. Formalin fixation masks the proteins (antigen) in the tissue sections that unfortunately become inaccessible for antibody in IHC. Numerous scientists urged to find a way to apply IHC staining on FFPE tissue sections based on a dream that formalin-modified proteins may be retrievable.