The Anti-tumor Effect Of Polymethylmethacrylate Bone Cement In Different Viscous States:An Experimental Study In Rabbit Model

Object: To investigate anti-tumor effect of viscous PMMA bone cement in the prometaphase and the later phase.Materials and methods: 1. Establishment of paraspinal tumor models. New Zealand white rabbits were transplanted with VX2 carcinoma in the lumbar paraspinal soft tissue with CT-guided percutaneous puncture technique. Paraspinal tumor models were examined after half of a month with PET-CT. The value of SUVmax and SUVmean of paraspinal tumor was measured. 2. Methods of experimental grouping and treatment. Paraspinal tumor models were randomly divided into 3 groups,each of which consisted of 10 rabbits. Group A simulated PVP with bone cement injecting in its relative early viscous state,while Group B simulated PKP with bone cement injecting in its late more viscous state, and Group C was control group with injection of saline. With the application of CT-guided percutaneous puncture technique, 1.0 ml viscous PMMA bone cement (in the prometaphase, Group A; in later phase, Group B) or saline (group C) was respectively injected into the tumor. Five rabbits were randomly taken to be examined with PET-CT at 1st and 7th day after operation respectively in each group. The value of SUVmax and SUVmean of the paraspinal tumor in these rabbits was measured again. Then the rabbits were sacrificed and the tissue of tumor was collected for pathological examination. 3. Outcome measures: (1) The value of SUV: The value of SUVmax and SUVmean of each tumor in different group and at different time was measured. (2) HE stain: The morphological change and necrosis of peripheral and distant tumor cells from the bone cements were observed with HE stain. (3)Apoptosis measurement with TUNEL: TUNEL was used to detect apoptosis of paraspinal peripheral and distant tumor cells from the bone cements. The apoptosis index (AI) was calculated. 4. Statistical methods: SPSS 13.0 was used. The value of SUVmax and SUVmean of each tumor before and after operation was analyzed with Repeated Measures Analysis of Variance. The value of SUVmax and SUVmean of each tumor in different group and time was analyzed by Factorial Analysis. The AI in different group, and at different time and area was analyzed by Factorial Analysis.Results: 1.PET-CT findings: The value of the SUV of the tumor in Group A and Group B had statistical difference (P<0.05) among before treatment, 1 day and 7 day after treatment. The value of the SUV of the tumor dropped markedly, especially in 1 day after the PMMA cement injected. But the value of the SUV of the tumor after operation in Group C was gradually increased. At different time after treatment, the value of SUV of the tumor in Group A and Group B were statistically different from control group(P<0.05). But there wasn't statistical difference between Group A and Group B(P>0.05). 2. HE stain results suggested that there were typical nuclei concentration, nuclei cleavage, nuclei dissolution and necrosis of tumor cells near the PMMA bone cement in 1 day after treatment. Tumor cells could be found in necrosis tissues, especially somewhere distant from PMMA cement. The tumor cells near the PMMA bone cement proliferated more significantly at 7th day after treatment than 1st day, while tumor cells distant from the PMMA bone cement proliferated actively. No remarkable necrosis of tumor cells was found in the control group in different time. 3. TUNEL apoptosis examination showed that the apoptosis index (AI) among different group, time and place had statistical difference (P<0.05). The apoptosis of tumor cells increased more significantly in group A and group B in 1 day after operation, while only partial apoptosis distant from the PMMA cement was found. But it wasn't significant between Group A and Group B. The apoptosis of tumor cells was reduced clearly at 7th day after treatment. The AI was not significant in each group at 7th day after operation. No apoptosis of tumor cells in Group C was found.Conclusion: PMMA cement could significantly induce necrosis and apoptosis of tumor cells in-vivo in short term. The anti-tumor effect on the tumor cell near PMMA cement was more remarkable than the tumor cell away from the cement. The anti-tumor effect gradually decreased after treatment as time went on. In short term, the anti-tumor effect of viscous PMMA bone cement was not significant between the prometaphase and the later phase.