ABSTRACT
Objective To investigate the killing effect of polymethylmethacrylate (PMMA) on spinal metastasis of transplanted VX2 carcinoma in experimental rabbit models. Methods Spinal metastasis of transplanted VX2 carcinoma model was successfully established in 18 rabbits. The experimental rabbits were randomly and equally divided into three groups with 6 rabbits in each group. Under CT guidance , PMMA or saline was injected into the center of VX2 tumor; in group A 0.3 ml of PMMA was used, in group B 0.1 ml of PMMA was used and in group C (control group) 0.3 ml saline was used. Twenty-four hours after the injection, the animals were sacrificed. Four tissue samples were obtained from the sites at 1 mm , 5 mm, 10 mm and 15 mm away from the PMMA mass in each rabbit of group A and group B , while four tissue samples were collected from different four sites from the tumor ’s center to border in each rabbit of group C. TdT-mediated dUTP nick-end labeling (TUNEL) method was used to determine the tumor cell apoptosis rate. Results After successful establishment of rabbit model, injection of PMMA was performed in sixteen among the eighteen rabbits. Technical success rates were 83.3% in both group A and B, and the success rate was 100% in group C. The difference in technical success rate was not significant. The mean tumor cell apoptosis rates of spinal VX2 carcinoma at 1 mm, 5 mm and 10 mm away from the PMMA mass in group A were (65.75±18.81)%, (50.00±14.24)% and(14.95±8.98)% respectively. The mean apoptosis rate in the control group was (9.79 ±5.24)%; the differences between the group A and the control group were statistically significant (P<0.05). The mean tumor cell apoptosis rate of spinal VX2 carcinoma at 15 mm away from the PMMA mass in group A was (10.30 ±8.13)%, which was not significantly different with that of the control group. The mean tumor cell apoptosis rates of spinal VX2 carcinoma at 1 mm and 5 mm away from the PMMA mass in group B were (49.20±15.57)% and(17.75±9.28)% respectively, which was significantly different with that of the control group(P<0.05); the mean tumor cell apoptosis rates at 10 mm and 15 mm away from the PMMA mass in group B were not significantly different with those of the control group. Statistically significant differences in the mean tumor cell apoptosis rates determined at 1 mm, 5 mm and 10 mm away from the PMMA mass existed between group A and group B(P<0.001). Conclusion PMMA can promote the apoptosis of tumor cells, properly increasing the injected amount of PMMA can enlarge the extent of tumor cell apoptosis.