title: Preservation of nucleic acids and tissue morphology in paraffin-embedded clinical samples: comparison of five molecular fixatives.
abstract: Formalin fixation preserves tissue morphology at the expense of macromolecule integrity. Freshly frozen samples are the golden standard for DNA and RNA analyses but require laborious deep-freezing and frozen sectioning for morphological studies. Alternative tissue stabilisation methods are therefore needed. We analysed the preservation of nucleic acids, immunohistochemical staining properties and tissue morphology in paraffin-embedded clinical tissue samples fixed with Z7, RCL2, PAXgene, Allprotect and RNAlater. Formalin-fixed and deep-frozen samples were used as controls. Immunohistochemical analyses showed good preservation of antigenicity in all except Allprotect and RNAlater-fixed samples. RNA quality, based on RNA integrity number value by Bioanalyzer, was comparable with freshly frozen samples only in PAXgene-fixed samples. According to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses, RNA from PAXgene samples yielded results similar to freshly frozen samples. No difference between fixatives was seen in DNA analyses (PCR and real-time PCR). In conclusion, PAXgene seems to be superior to other molecular fixatives and formaldehyde.
authors.affiliation: Laboratory of Cancer Biology, Institute of Biomedical Technology, BioMediTech, University of Tampere, Tampere, Finland.
authors.forename: Synnöve
authors.initials: S
authors.lastname: Staff
authors.forename: Paula
authors.initials: P
authors.lastname: Kujala
authors.forename: Ritva
authors.initials: R
authors.lastname: Karhu
authors.forename: Annika
authors.initials: A
authors.lastname: Rökman
authors.forename: Joanna
authors.initials: J
authors.lastname: Ilvesaro
authors.forename: Saara
authors.initials: S
authors.lastname: Kares
authors.forename: Jorma
authors.initials: J
authors.lastname: Isola
mesh_terms: D005187:Fallopian Tubes / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005404:Fixatives; D005557:Formaldehyde; D006801:Humans; D009696:Nucleic Acids / Q000235:genetics*; D010053:Ovary / Q000378:metabolism / Q000473:pathology*; D010232:Paraffin; D016612:Paraffin Embedding; D016707:Tissue Fixation / Q000379:methods*; D014599:Uterus / Q000378:metabolism / Q000473:pathology*
chemical_list: D005404:Fixatives; D009696:Nucleic Acids; D005557:Formaldehyde; D010232:Paraffin
keywords: Fixation; Immunohistochemistry; Morphology