Effects Cryotherapy on Proliferation and Apoptosis of C6 Brain Glioma Cells in Rats

Objective To explore the changes in apoptosis level and proliferative activity of the C6 brain glioma cells after cryotherapy in rats. Methods The C6 cortex brain glioma model was established in rats by stereotaxic technique. When the tumor diameter was some 6 mm 15 days after the inoculation, 60 rats were randomly divided into control group and cryotherapy group, in which cryotheraphy was performed. The apoptosis was detected by TUNEL and flow cytometry, proliferating cell neuclear antigen (PCNA) was determined by immunohistochemistry, and the proliferative activity was evaluated by PCNA and MRI 15 days after the cryotherapy. The tumor volume was measured and tumor growth inhibition rate was computed. Results The density and index of apoptosis cells in the cryotherapy group were (36.73±9.54)/0.0625mm2 and (16.02%±3.87%) respectively and they in the control group were (4.87±2.80)/0.0625mm2 and (1.70±1.74)% respectively. There was significant difference in the density and index of apoptosis cells between both the groups (P0.01). The percentage of positive cell number of PCNA in the cryotherapy group (42.37%±7.63%) was significantly fewer than that (73.93%±9.60%) in the control group (P0.01). And the tumor volume (139.60mm3±27.28mm3) in the cryotherapy group was significantly smaller than that (414.40mm3±69.01mm3) in the control group (P0.01). The inhibition rate of the tumor in the cryotherapy group was 66.31%. Conclusion Besides the necrosis, the decrease in the proliferative level and the increase in the apoptosis cells may also be one of the mechanisms by which cryotherapy inhibits the tumor growing.