title: Solvent-free tissue processing using supercritical carbon dioxide.
abstract: OBJECTIVE
  Xylene is most often employed in tissue processing protocols for paraffin embedding, but poses a health hazard. The aim of this study was to evaluate a solvent-free processing protocol that uses supercritical carbon dioxide (scCO(2) ) as an intermediate.
  
  
  RESULTS
  A series of tests (with bovine tissues) was run, evaluating dehydration and tissue shrinkage in our new scCO(2) -based protocol as compared with routine processing using a graded ethanol and xylene series. A series of tests was then run to evaluate the significance of processing parameters for the outcome. Finally, a validation series was performed with optimal conditions, testing various human tissues with several staining methods. The tissue water content after paraffination was the same with our new scCO(2) -based protocol and the routine xylene-based protocol. Tissue shrinkage was similar with the two methods, at ∼15%, which is also similar to values in the literature. In the validation series, the human tissues showed good morphology with strong staining, probably because of stronger antigenicity.
  
  
  CONCLUSIONS
  This scCO(2) -based protocol has been shown to be a good solvent-free, alternative form of tissue processing. Although not the focus of this article, the time needed for tissue processing with this new protocol is within 4 h, and there is no need to change macroscopy/sectioning protocols.
authors.affiliation: Department of Pathology and Medical Biology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Erik P
authors.initials: EP
authors.lastname: Bleuel
authors.forename: Thijs P C
authors.initials: TP
authors.lastname: Roebers
authors.forename: Edwin
authors.initials: E
authors.lastname: Schulting
authors.forename: Wilfred F A
authors.initials: WF
authors.lastname: den Dunnen
mesh_terms: D000818:Animals; D002245:Carbon Dioxide; D002417:Cattle; D000431:Ethanol; D005260:Female; D006652:Histological Techniques / Q000379:methods*; D006801:Humans; D016612:Paraffin Embedding / Q000379:methods; D015203:Reproducibility of Results; D012997:Solvents; D014021:Tissue Preservation / Q000379:methods*; D014992:Xylenes
chemical_list: D012997:Solvents; D014992:Xylenes; D002245:Carbon Dioxide; D000431:Ethanol