An experimental study on the change of the radiosensitivity of several tumor cell lines and primary cultured gingi cal fibrobrast

Radiation sensitivity data was generated for two human cancer cell lines (KB, RPMI 2650) and human primary gingival fibroblast was tested three times using a viable cell number counting with a hemocytometer, MTT (3-[4,5-dimethylthiazol 2-yl]-2,5-dipheny tetrazolium bromide) assay, and LDH (Lactate dehydrogenase) assay. Single irradiation of 2, 4, 6, 10, 15, 20 Gy were applied to the tumor cell lines and the primary cultured gingical fibroblast. The two fractions of 4 Gy an d 10 Gy were separated with a 4 hour time interval. The irradiation was done with 241.5 cGy/min dose rate using 137 Cs MK cell irradiator at room temperature. The obtained results were as followed : 1. There was significantly different viable cell numbers as the amount of radiation dose on the tested cells were cell number counted with a hemocytometer, In fractions, there were more viable cells remaining. 2. Phase-contrast microscopically, radiation-induced morphologic changes were pronounced on the tumor cells, however, almost no differences on the gingival fibroblast. 3. There was significantly different absorbance at 2 Gy on RPMI 2650, 4 Gy on KB and GF in MTT assay. In fractions, the absorbance was significantly higher on KB. 4. The level of extracellular LDH activity in the experimental group was significantly higher in the 2-4 Gy than the control group. 5. The total level of extracellular and intracellular LDH activity was decreased as increased amounts of radiation dose was applied.