What are the effects of whole blood storage conditions on comet assay in terms of DNA damage and repair?

Abstract

The comet assay is a rapid, simple and sensitive method for the detection of DNA damage and repair at the level of individual cells, with a wide range of applications in human biomonitoring and molecular epidemiology. It is common practice to perform the comet assay on fresh samples to preserve the integrity of the DNA and to obtain reliable results, which is why most published studies have been designed using fresh blood samples. There are limitations associated with the use of fresh samples for this assay and the need for appropriate storage for some studies. The aim of this study was to determine changes in DNA damage and DNA repair kinetics during medium- and long-term storage of human whole blood (WB) samples without adding cryopreservatives. Whole blood samples were divided into small portions and tested after overnight storage at + 4 °C. Frozen samples were stored at −20 and −80 °C for 3 different time points: 30, 90 and 180 days. Frozen samples were compared with fresh samples stored at + 4 °C in terms of DNA damage and repair. For WB samples stored at −80 °C, showed an increase in purine base damage (PBD) and DNA repair alterations were determined while no increase in basal DNA damage was observed. According to the results of our study, storage of WB samples for comet assay in small portions at −20 °C for up to 90 days does not cause any additional damage and does not cause any alter DNA repair kinetics.