Objective To explore the biological characteristics of remnant VX2 tumor cells after electrochemical treatment (EChT) in experimental rabbits. Methods Rabbit models of hepatic VX2 tumor were established by using transplantation method. EChT was carried out in rabbit models. By controlling the pH profile around the tumor's margin, the remnant tumors were created. With the help of immunohistochemistry, TUNEL, microinjection in vivo, gelatin zymography, electric microscope, etc. the biological characteristics of the remnant VX2 tumor cells were evaluated. Results (1) Biopsy revealed that the remnant tumor cells were surrounded by a great deal of fibrous tissue in the first week. In the second week the number of remnant tumor cells was increased, and more fibrous tissues were found around the lesions. Ultramicroscopic structure showed that before the treatment enlarged proportion of nucleoplasm, obvious nuclear heteromorphosis, many babyish mitochondria and fewer intercellular junctions could be seen. In the first and second week after EChT, mitochondria in cytoplasm became larger and more mature, and the intercellular junction grew in number. (2) In the first and second week after EChT, positive indices of PCNA and Ki - 67 of the study group were significantly lower than those of the control group, while the apoptosis index and Bax positive index of the study group were significantly higher than those of the control group. A significant parallel relationship existed between apoptosis index and Bax positive index. (3) In the first and second week after EChT, Cx32 positive index and LY transferring scope in the study group were markedly higher than those in the control group. After microinjection in vivo the spread extent of LY transferring was positively correlated with the positive index of Cx32. (4) Relative content of MMP-9 determined by gelatin zymography was consistent with that determined by immunohistochemistry, which in the study group was significantly lower than that in the control group in the first and second week after EChT. Conclusion Within two weeks after EChT, the proliferation activity of the remnant tumor cells decreases dramatically, while the apoptosis index increases strikingly. As the secretion of MMP-9 decreases and the function of GJIC has been grossly improved, the invasive potentiality of the remnant tumor cells remarkably decreases. Tumor residue is hard to be avoided in EChT for larger liver tumors. Therefore, in order to improve the clinical efficacy a full understanding of the biological characteristics of the remnant tumor cells is very helpful in selecting appropriate re - examination time as well as in selecting the re-treat opportune moment.%目的 探讨电化学治疗(EChT)兔肝VX2肿瘤后残余肿瘤细胞生物学特性的变化.方法 采用移植方法建立兔肝VX2肿瘤模型后行EChT,通过控制肿瘤边缘的酸碱度造成肿瘤残余,采用免疫组化、TUNEL法、活组织细胞内显微注射、明胶酶谱法及电子显微镜观察等方法探讨残余肿瘤细胞生物学特性的变化.结果 ①病理学观察显示EChT后第1周时残余肿瘤细胞被大量纤维组织包绕；治疗后第2周,残余肿瘤细胞数目增多,其周围仍可见较多的纤维组织.超微结构观察显示,治疗前肿瘤细胞核质比例增大,核异型性明显,线粒体数目较多但发育幼稚,细胞间连接较少.EChT后第1、2周,胞质内线粒体体积增大,发育较成熟,细胞间连接增多.②增殖细胞核抗原(PCNA)及Ki-67阳性指数在第1、2周时均比对照组明显降低；凋亡指数及Bax阳性指数在EChT后第1、2周时均明显高于对照组；凋亡指数与Bax阳性指数呈显著正相关.③Cx32阳性指数及LY扩散范围在治疗后第1、2周均明显高于对照组；显微注射后LY CH荧光染料在肿瘤组织内的扩散范围与Cx32阳性指数呈显著正相关.④明胶酶谱法检测基质金属蛋白酶-9(MMP-9)相对含量的结果显示与免疫组化染色结果一致,治疗后第1、2周均明显低于对照组.EChT治疗后2周内残余肿瘤细胞的增殖活性明显降低,凋亡指数明显增加,缝隙连接细胞间通讯(GJIC)功能明显改善,侵袭能力明显降低.结论 较大肝癌行EChT治疗时肿瘤残余将难于完全避免,残余癌细胞生物学特性的变化对正确选择治疗后复查及再次治疗时机,提高疗效有重要意义.
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