title: A tissue fixative that protects macromolecules (DNA, RNA, and protein) and histomorphology in clinical samples.
abstract: Preservation of macromolecules (DNA, RNA, and proteins) in tissue is traditionally achieved by immediate freezing of the sample. Although isolation of PCR-able RNA has been reported from formalin-fixed, paraffin-embedded tissues, the process has not been shown to be reproducible because high molecular weight RNA is usually degraded. We investigated the potential value of a new universal molecular fixative (UMFIX, Sakura Finetek USA, Inc., Torrance, California) in preservation of macromolecules in paraffin-embedded tissue. Mouse and human tissues were fixed in UMFIX from 1 hour to 8 weeks. They were then processed by a rapid tissue processing (RTP) system, embedded in paraffin, and evaluated for routine histology as well as for the quality and quantity of DNA, RNA, and proteins. Formalin-fixed tissues were processed by RTP and evaluated in a similar manner. Fresh-frozen samples were used as controls. The morphology of UMFIX-exposed tissue was comparable to that fixed in formalin. High molecular weight RNA was preserved in tissue that was immediately fixed in UMFIX and stored from 1 hour to 8 weeks at room temperature. There were no significant differences between UMFIX-exposed and frozen tissues on PCR, RT-PCR, real-time PCR, and expression microarrays. Similarly, physical and antigenic preservation of proteins in UMFIX tissue was similar to fresh state. Both RNA and proteins were substantially degraded in formalin-fixed and similarly processed specimens. We concluded that it is now possible to preserve histomorphology and intact macromolecules in the same archival paraffin-embedded tissue through the use of a novel fixative and a rapid processing system.
authors.affiliation: Department of Pathology, Jackson Memorial Medical Center, University of Miami, Miami, Florida, USA. vvincek@med.miami.edu
authors.forename: Vladimir
authors.initials: V
authors.lastname: Vincek
authors.forename: Mehdi
authors.initials: M
authors.lastname: Nassiri
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Nadji
authors.forename: Azorides R
authors.initials: AR
authors.lastname: Morales
mesh_terms: D000818:Animals; D016477:Artifacts; D004247:DNA / Q000302:isolation & purification*; D005260:Female; D005404:Fixatives; D006801:Humans; D008099:Liver / Q000737:chemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D016612:Paraffin Embedding; D010338:Pathology, Clinical / Q000379:methods*; D011506:Proteins / Q000302:isolation & purification*; D012313:RNA / Q000302:isolation & purification*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016707:Tissue Fixation / Q000379:methods*
chemical_list: D005404:Fixatives; D011506:Proteins; D012313:RNA; D004247:DNA