The effect of electrochemotherapy for the lungmetastasis mouse osteosarcoma cell

本实验用小鼠骨肉瘤细胞为实验动物，观察了双极电极电化学疗法（ECT）对骨肉瘤细胞的作用。将Dunn骨肉瘤细胞移植于C3 H小鼠皮下，2周后肿瘤生长，腹腔注射甲氨蝶呤（MTX）10 mg/kg，30分钟后行ECT。对照组、单纯MTX组、单纯电脉冲组和ECT组，均分为4组，以时间依赖性的方式评价肿瘤体积增长率。结果显示，ECT组一次切除肿瘤，肿瘤缩小率达40%。此外，我们改变了电脉冲的方向为4或6个方向。当肿瘤小于5 mm时，肿瘤被消灭，但大于5 mm的肿瘤细胞仍然存活。因此，我们开发了多针型（9针）的新电极。将该装置与凝胶一起直接插入肿瘤中进行心电图检查，并在50 V下进行ECT。无论肿瘤大小是否低于5 mm，肿瘤都完全缩小，但部分识别出皮肤烧伤。我们将电压降低到25 V，并在60个方向的电脉冲频率下执行ETC。结果较好，所有肿瘤细胞均被消灭，且未发现皮肤灼伤。下一步，我们检查了ECT对神经血管束的副作用。采用Dunn骨肉瘤浸润股动脉AVN的小鼠模型，在相同条件下进行ECT。结果表明，肿瘤细胞全部死亡，但对神经血管束的影响较小，未发生下肢循环和运动功能的损害。本研究以小鼠肺转移模型、兔肺转移模型为研究对象，对该方法的疗效进行了验证和阐明。

We clarified the effect of Electrochemotherapy (ECT) with bipolar electrode to the osteosarcoma cell with a mouse. Dunn osteosarcoma cell was transplanted in under the skin with C3H mouse, when tumor grew at 2 week later, we injected Methotrexate (MTX) 10mg/kg into the intraperitonium and executed ECT after 30 minutes. Control group, only MTX group, only electropulse group and ECT group, all divided into 4 groups, we evaluated to the tumor volume increasing rate in time-dependent. The result was shown that 40% tumor reduction in the ECT group at one time execution. Furthermore we changed the direction of electropulse to 4 or 6 directions. When the tumor size was below 5mm, tumor was exterminated but over 5mm tumor cells were locally still alive. Therefore we developed new electrode as multi needle type (9 needles). This device was inserted in the tumor directly with the gel for an electrocardiogram and ECT was done in 50V. The tumor reduced completely whether tumor size was below 5mm or not, but a skin burn was partially recognized. We lowered the voltage to 25V and executed ETC under electropulse frequency of 60 directions. The result was a better and all tumor cells were exterminated, furthermore skin burn was not recognized. Next step we examined the side effect of the ECT to a neurovascular bundle. The mouse model with the Dunn osteosarcoma infiltrated femoral AVN was used and ECT was executed under the same conditions. The result was shown that all tumor cells was death but the influence to a neurovascular bundle was little, the injury of circulation and motor function of leg was not occurred. We have established this method with a mouse model, lung metastasis model with a rabbit as a future schedule consecutively, that would examine and clarify to the curative effect.