Heparin has an apoptotic effect in addition to its anticoagulant, anti-inflammatory, antihypertensive, and antiproliferative effects. In this study, we detected the effect of heparin on the cell cycle of lymphoblasts by flow cytometry (FCM) and tried to determine which phase in the cell cycle of lymphoblasts contains heparin-sensitive points. Twelve children with newly diagnosed acute lymphoblastic leukemia (ALL) were included in the study. Lymphoblasts were incubated in different levels of heparin concentrations (0, 10, and 20 U/mL) and the percentages of lymphoblasts at each phase of the cell cycle were simultaneously measured by FCM at 0, 1, and 2 hours (h). The percentages of lymphoblasts at the G2/M and S phases were significantly increased in 20 U/mL heparin concentration compared to 0 U/mL heparin concentration at 1h (from 1.18% to 10.21% and from 1.03% to 13.63%, respectively; p<0.000), indicating an arrest of cell cycle at the G2/M and S phases by heparin. These findings provide new insights into the molecular mechanism of the apoptotic effect of heparin.

Keywords: Cell cycle, Heparin, Leukemi