Killing effect of ¹³¹I brachytherapy on C6 brain glioma cells:An experimental study

Objective To study the effective dose and effective dose rate of killing the cultured C6 glioma cells for a novel 131I liquid-filled brachytherapy applicator in order to direct the clinical treatment of glioma. Methods Those cultured C6 glioma cells in the tissue culture flasks,placed at distance of 5mm and 30mm respectively from a novel 60mCi 131I-filled radiotherapy cyst,were detected in the aspects of its apoptosis and survival rates every 4 days（72h each time） by cloning efficiency and flow cytometry with Annexin V-FITC/PI double staining. Results Apoptosis occurred in some C6 glioma cells 72h after exposed to 60mCi 131I,with an apoptotic rate of 16.42%±1.66%.Death was observed in proliferating C6 glioma cells.The survival rate of C6 glioma cells decreased 72h after exposed to 60mCi 131I with a minimal survival rate of 59.0%±2.39%.Apoptosis of C6 glioma cells occurred when the dose of 131I brachytherapy was ＜400mGy/h.The effective dose of 131I brachytherapy for killing C6 glioma cells was 47.64-61.65mGy/h.Apoptosis of C6 glioma cells decreased with the increasing dose of 131I brachytherapy.The effective absorption dose for inducing apoptosis of C6 glioma cells was 47.64-61.65mGy/h with an accumulative absorption dose of ≥3.9Gy 72h after exposed to 60mCi 131I. Conclusion A radiotherapy cyst can induce apoptosis of some C6 glioma cells 72h after exposed to 60mCi 131I and decrease the survival rate of C6 glioma cells.The effective dose of 131I radiotherapy for C6 glioma cells is≥ 47.64-61.65mGy/h and its 72h accumulative dose is 3.9Gy.