Application of the comet assay for the evaluation of DNA damage from frozen human whole blood samples: Implications for human biomonitoring

• Published in: Toxicology letters 2020-02, Vol.319, p.58-65
• Main Authors: Gajski, Goran, Gerić, Marko, Živković Semren, Tanja, Tariba Lovaković, Blanka, Oreščanin, Višnja, Pizent, Alica
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age Factors; Aged; Baseline values; Blood; Blood Preservation - adverse effects; Body Mass Index; Comet assay; Comet Assay - methods; Cryopreservation; DNA Damage; Epidemiology; Freezing; Human biomonitoring; Humans; Life Style; Male; Middle Aged; Monitoring, Physiologic; Storage conditions; Whole blood; Young Adult
• ISSN: 0378-4274; 1879-3169
• DOI: 10.1016/j.toxlet.2019.11.010

•Whole blood was stored at −80 °C without the addition of cryopreservatives for a period of 5 years.•Whole blood freezing and prolonged storage do not severely affect comet assay values.•The comet assay could be applied to frozen blood samples, if properly stored, after at least 5 years. This study proposes the application of the comet assay for the evaluation of DNA damage from frozen human whole blood samples that could be readily used in human biomonitoring and epidemiological studies. It was done on simply frozen whole blood samples collected from male volunteers (N = 60) aliquoted in small volumes and stored at −80 °C without the addition of cryopreservatives for a period of 5 years. To test the applicability of the alkaline comet assay for the evaluation of DNA damage in frozen whole blood, samples were quickly thawed at 37 °C and immediately embedded in an agarose matrix followed by an alkaline comet assay procedure. We concluded that the whole blood freezing and prolonged storage do not severely affect comet assay values, although background values were higher compared to our historical control data from the fresh whole blood. Even the influence of the variables tested, such as age, body mass index, smoking habit and alcohol consumption were in agreement with our previous data using fresh blood. The obtained results suggest that the comet assay could be applied to frozen blood samples, if properly stored, even for decades, which would certainly facilitate large-scale human biomonitoring and long-term epidemiological studies.