Studies on electron beam induced DNA damage and repair kinetics in lymphocytes by alkaline comet assay

Abstract

Background: Exposure to ionizing radiaon is known to induce oxidave stress followed by damage to crical biomolecules like lipids, proteins and DNA through radiolysis of cellular water. Since radiaon has been widely used as an important tool in therapy of cancer, the detailed invesgaon regarding the DNA damage and repair kinecs would help to predict the radiaon sensivity of cells. The present study is focused on quanficaon of DNA damage and repair kinecs of human peripheral blood lymphocytes a%er 8 MeV pulsed electron beam irradiaon in vitro . Materials and Methods: DNA damage and repair kinecs in human blood cells were studied using alkaline comet assay. The dose-response curves for the dose range of 0-5 Gy were established using 8 MeV electron beam. Repair kinecs was studied by incubang the cells from 0 to 90 min at 37°C a%er irradiaon. For quanficaon of DNA damage, percentage Tail DNA, Tail length, Tail moment and Olive Tail moment were used as a comet parameter. Results and Conclusion: The study reveals that, inducon of DNA damage by 8 MeV pulsed electron beam is near linear with a negligible negave quadrac component at high doses. This small quadrac component is a5ributed to high dose rate during the pulsed irradiaon. The DNA repair hal%ime and mean repairme for human blood lymphocytes were found to be varying between 9.29 - 23.78 min and 13.41 - 34.31 min respecvely. The repair rate is found to be maximum in inial 15 minutes and almost constant a%er 60 min.