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.
|Number of pages||9|
|State||Published - Oct 1 2003|
ASJC Scopus subject areas
- Pathology and Forensic Medicine