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Updated: May 31, 2026
10:21
Protocol for HER2 FISH Using a Non-cross-linking, Formalin-free Tissue Fixative to Combine Advantages of Cryo-preservation and Formalin Fixation
Published on: December 25, 2017
Formalin fixation at low temperature better preserves nucleic acid integrity
Gianni Bussolati1, Laura Annaratone, Enzo Medico
1Department of Biomedical Sciences and Human Oncology, University of Turin, Turin, Italy.
Plos One
|June 24, 2011
Summary
Cold-fixation (CF) preserves nucleic acids in tissues by preventing RNAse activation during fixation. This method enables reliable gene expression profiling from formalin-fixed samples, comparable to frozen tissues.
Area of Science:
- Molecular Biology
- Histology
- Biotechnology
Background:
- Formalin fixation degrades nucleic acids, limiting downstream applications like gene expression profiling.
- RNA fragmentation is hypothesized to result from RNAse activation between formalin penetration and tissue fixation.
Purpose of the Study:
- To develop a novel tissue fixation method that preserves nucleic acid integrity.
- To enable reliable microarray-based gene expression profiling from fixed tissues.
Main Methods:
- A cold-fixation (CF) procedure involving cold storage under vacuum before fixation in formalin and ethanol.
- Assessment of DNA and RNA preservation through nucleic acid amplification.
- Comparison of gene expression profiles from CF samples with frozen samples using microarrays.
Main Results:
- The CF procedure effectively preserved DNA and RNA, allowing amplification of RNA segments up to 660 bp.
- Histological and immunohistochemical features remained comparable to standard fixation methods.
- Microarray gene expression profiles from CF samples showed high concordance with frozen samples for specific probe regions.
Conclusions:
- Cold-fixation (CF) is a viable method for preserving both tissue morphology and nucleic acids.
- CF facilitates reliable gene expression profiling from formalin-fixed tissues, overcoming limitations of standard fixation.
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