Abstract:

Objective To observe the cell count changes of A549 cell line and human embryonic lung diploid cell line 2BS after irradiated by ¹²⁵I seeds with different doses,and to study the growth inhibition of ¹²⁵ I on  this two kinds of cell lines，and to determine its clinical safety dose in treatment of  non-small cell lung.Methods ¹²⁵I seeds with different doses （low dose:0.2 mCi,mediate dose:0.4 mCi, high dose:0.8 mCi）were chosen and  put  into A549 cells  and human embryonic lung diploid cell line 2BS  in vitro,the  cells on the 2nd,4th,6th and 8th days after irradiation  were collected, the alive  cells were counted by cells dyeing experiments,then  the growth curves were drawn,and  the IC50 of the radioactive ¹²⁵I seeds to both two  cell lines were calculated.Results Compared with  blank and control groups，the cell proliferation trend of A549 cells in low dose group was not significantly influenced（P＞0.05）,but the growth  of A549 cells in mediate and high dose groups were inhibited in a time-dependent manner,there were   significant differences(P<0.05),
the most obvious change was on  the 6th day.The IC₅₀ of the radioactive 125I seeds to A549 cells was about 0.4 mCi.While the growth inhibition of ¹²⁵I 2BS  had no statistically significant differences between various dose groups(P>0. 05),and the IC₅₀ of the radioactive ¹²⁵I seeds to 2BS cell line was about 1.65 mCi.Conclusion 0.4 mCi of radioactive ¹²⁵I seeds  has already had the obvious damage effect on A549 cells,0.8 mCi of radioactive ¹²⁵I seeds has the   stronger effect.The IC₅₀ of the radioactive ¹²⁵I seeds to 2BS cells is about 1.65 mCi,so the clinical safety dosage is 0.4-0.8 mCi.

Key words: ¹²⁵I；radioactive seeds；tumor；in vitro experiment