Experimental Study On Percutaneous Radiofrequency Ablation For Rabbit VX2 Lung Cancer

PART ONE Establishment of Modified Rabbit Lung VX₂ TumorObjective:To establish more ideal rabbit lung tumor model suitable for radiofrequency.Materials and Methods:By CT guided,16 New Zealand white rabbits were implanted in right lung with P407 gels,which carried VX₂,tissue suspension.Results:Ten to fourteen days after implantation,tumors were found in 16 rabbits by CT scan.14 of them have single nodule in right lung,whose diameter was from 0.8-1.0 cm,The achievement ratio of model was 100%(16/16).There were multi-nodule in 2 rabbits combined with pleural effusion.Mediastinum was involved in 4 rabbits.Implantation metastases in chest wall were found in 2 rabbits.Conclusion:The rabbit lung VX₂ tumor models are established successfully.The volume of solid tumor formed in lung is big enough for study of radiofrequency.The model is much easier to establish.It can avoid dispersing growth of tumor resulted by overflow of suspension,which reduces complication.PART TWO Experimental Study on Radiofrequency for Rabbit's Lung in vivoObjective:To investigate radiofrequency ablation's effect for rabbit's lung in vivo with different electrode diameter at different original power output.Then select electrode diameter and power/time combination suitable for animal models.Materials and Methods:RF-2000 radiofrequency machine has a new thin-diameter puncturing electrode,which has a 465MHz frequency and a 2cm diameter when opened most.When ablating normal rabbit's lung with electrode diameter of 5mm,8mm,11mm respectively and original power output of 10W,20W,30W additionally,temperature curves of selected spots were simultaneously recorded by electrode coupled temperature-measuring system.Results:With the same electrode diameter but different original power output,there's no obvious difference in ablation area and highest temperature correspondingly.However, difference in ablation time was obvious,which appears the larger the power output was,the less time the ablation needed.As pathology shows,ablation was thoroughly when power output was 10W.When 30W,ablation effect was not quite well because of interval distribution of coagulation and necrosis in radiofrequency area,although ablation time is shortest. Conclusion:Electrode diameter of 8mm can meet the need of ablating lung cancer with radiofrequency.Best effect can be got with longer time at lower power output.PART THREE Compare Study on Thermal with Subthermal Radiofrequency Ablation for Rabbit Lung VX2 TumorObjective:To find out better radiofrequency method which is more effective to ablate tumors by improving common thermal radiofrequency treatment.Materials and Methods:50 New Zealand white rabbit lung VX2 tumor models were divided into 3 groups:thermal group(20),subthermal group(20),control group(10). Observe their living time,activity of SDH in tumor tissue after radiofrequency ablation, content of HSP90 and count of CD4Tcells,CD8Tcells,CD4/CD8 ratio in venous blood.Results:SDH of two experimental groups showed negative 72hs after radiofrequency ablation.However,HSP90 content and CD4Tcells,CD8Tcells,CD4/CD8 ratio of subthermal group was markedly higher than that of thermal group.Meanwhile,living time of subthermal group was much longer.Conclusions:Subthermal radiofrequency ablation for tumor focus is safe and reliable,with a much better therapeutic effect than common thermal radiofrequency ablation.PART FOUR Accessory Effect of Dendritic Cells(DC) to Radiofrequency Ablation for TumorsObjective:To investigate the enhanced anti-tumor immunity of radiofrequency ablation combined with dendritic cells,which were cultivated in vitro.Materials and Methods:Activate the hemopoietic stem cells,which were got from normal rabbit's bone marrow in aseptic environment,with GM-CSF,IL-4,TNFs from recombinant rabbit.Then cultivate the stem cells to mature dendritic cells.Divide 40 tumor rabbits into 3 groups:simple radiofrequency group(15),radiofrequency and DCs combination group(15) and control group(10).Inject equal quantity of saline fluids,mature DCs fluids, mature DCs fluids into the 3 groups respectively into lung tumor focus treated by subthermal radiofrequency ablation.Observe infiltration of DCs in tumor focus,content of IL-2,CD4Tcells,CD8Tcells,CD4/CD8 ratio in peripheral blood and living time of the animals.Result:Living time of radiofrequency and DCs combination group was longer than that of simple radiofrequency group.Content of IL-2,CD4Tcells,CD8Tcells,CD4/CD8 ratio in peripheral blood of radiofrequency and DCs combination were markedly higher.Conclusion:Radiofrequency combined with DCs induced in vitro can enhance anti-tumor immunity of radiofrequency therapy.That means DCs does have accessory effect for rabbit lung VX2 tumor.