Comparison of DNA damage in fresh and frozen blood samples: implications for the comet assay in human biomonitoring studies

• Published in: Archives of toxicology Vol. 98; no. 10; pp. 3467 - 3476
• Main Authors: Matković, Katarina, Gerić, Marko, Kazensky, Luka, Milić, Mirta, Kašuba, Vilena, Cvitković, Ante, Sanković, Mandica, Šumanovac, Antun, Møller, Peter, Gajski, Goran
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2024; Springer Nature B.V
• Subjects: Assaying; Bioassays; Biomedical and Life Sciences; Biomedicine; Biomonitoring; Blood cells; Blood levels; Comet assay; Cryopreservation; Damage assessment; Damage detection; Damage prevention; Deoxyribonucleic acid; DNA; DNA damage; Environmental Health; Epidemiology; Feasibility studies; Fieldwork; Freeze-thaw; Freezing; Genotoxicity and Carcinogenicity; Occupational health; Occupational Medicine/Industrial Medicine; Pharmacology/Toxicology; Sample preservation; Thawing; Peripheral blood cells; Human biomonitoring; Frozen samples; Fresh samples; Comet assay
• ISSN: 0340-5761; 1432-0738; 1432-0738
• DOI: 10.1007/s00204-024-03823-1

The use of the comet assay in large biomonitoring studies may present logistical and technical challenges because of the processing of numerous samples. Proper sample preservation becomes imperative to prevent spurious DNA breakage. Previous research has shown the feasibility of conducting the comet assay on frozen blood samples, highlighting the potential of freezing at – 80 °C in preserving DNA integrity. Nonetheless, this approach presents challenges, including potential DNA damage during freezing and thawing, variability in processing, and the need for standardized protocols. Our objective was to evaluate whether there are comparable results in DNA migration assessed by the comet assay between fresh and frozen blood samples on a larger scale ( N  = 373). In our findings, elevated DNA migration was evident in frozen samples relative to fresh ones. Additionally, smoking, alcohol consumption, and season were linked to increased DNA damage levels in whole blood cells. Based on our results and available literature, conducting the comet assay on frozen blood samples emerges as a practical and efficient approach for biomonitoring and epidemiological research. This method enables the assessment of DNA damage in large populations over time, with samples, if properly cryopreserved, that may be used for years, possibly even decades. These observations hold significant implications for large-scale human biomonitoring and long-term epidemiological studies, particularly when samples are collected during fieldwork or obtained from biobanks. Continued method optimization and validation efforts are essential to enhance the utility of this approach in environmental and occupational health studies, emphasizing caution when comparing data obtained between fresh and frozen blood samples.