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Updated: Jan 22, 2026
11:30
Use of Frozen Tissue in the Comet Assay for the Evaluation of DNA Damage
Published on: March 24, 2020
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Applying the comet assay to fresh vs frozen animal solid tissues: A technical approach
A Azqueta1, J M Enciso1, L Pastor1
1Department of Pharmacology and Toxicology, University of Navarra, Pamplona, Spain. IdisNa, Navarra Institute for Health Research.
Summary
Storing rodent tissues at -80°C preserves DNA integrity for comet assays. Comparable DNA strand break levels were observed in fresh and frozen liver, lung, and kidney tissues, supporting cryopreservation for genotoxicity studies.
Area of Science:
- Toxicology
- Molecular Biology
- Genetics
Background:
- The in vivo comet assay is a standard method for detecting DNA damage.
- Logistical challenges often prevent immediate processing of fresh tissues for comet assays.
- Standardized protocols for cryopreserving rodent tissues for comet assays are lacking.
Purpose of the Study:
- To evaluate the impact of cryopreservation on DNA integrity in rodent tissues.
- To compare DNA strand breaks (SBs) and Fpg-sensitive sites in fresh versus frozen tissues.
- To determine optimal freezing and thawing procedures for comet assay applications.
Main Methods:
- Tissues (liver, kidney, lung) from untreated and methyl methanosulfonate-treated rats were snap-frozen.
- Samples were stored at -80°C for up to 1 year.
- Two thawing procedures were tested, and DNA SBs and Fpg-sensitive sites were quantified using the comet assay.
Main Results:
- Comparable levels of DNA SBs were found in fresh and frozen liver (up to 1 year) and lung (up to 3 months) tissues.
- Similar DNA SB levels were detected in fresh and frozen kidney tissues (up to 1 year).
- Variability in Fpg-sensitive site levels in frozen kidney tissues requires further investigation.
Conclusions:
- Cryopreservation of rodent liver, lung, and kidney tissues at -80°C is a viable method for comet assay analysis.
- The comet assay can reliably detect DNA strand breaks in frozen tissues stored for extended periods.
- Further research is needed to standardize Fpg-sensitive site analysis in cryopreserved kidney tissues.
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