Document Type



Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence



Publication Details

International Journal of Radiation Biology, March 2013, Vol. 89 (3), p. 182-90.

DOI: 10.3109/09553002.2013.734942


Purpose: The aim of this study was to compare levels of apoptosis, necrosis, mitotic cell death and senescence after treatment with both direct radiation and irradiated cell conditioned medium. Materials and methods: Human keratinocytes (HaCaT cell line) were irradiated (0.005, 0.05 and 0.5 Gy) using a cobalt 60 teletherapy unit. For bystander experiments, the medium was harvested from donor HaCaT cells one hour after irradiation and transferred to recipient HaCaT cells. Clonogenic assay, apoptosis, necrosis, mitotic cell death, senescence and cell cycle analysis were measured in both directly irradiated cells and bystander cells Results: A reduction in cell survival was observed for both directly irradiated cells and irradiated cell conditioned medium (ICCM) treated cells. Early apoptosis and necrosis was observed predominantly after direct irradiation. An increase in the number of cells in G2/M phase was observed at 6 and 12 hours which led to mitotic cell death after 72 hours following direct irradiation and ICCM treatment. No senescence was observed in the HaCaT cell line following either direct irradiation or treatment with ICCM. Conclusion: This study has shown that directly irradiated cells undergo apoptosis, necrosis and mitotic cell death whereas ICCM treated cells predominantly undergo mitotic cell death