目的：探讨环五肽RGD（TyrRGD）靶向的纳米金颗粒（GNPs）偶联VEGF小干扰RNA（TyrRGD-GNPs-VEGFsiRNA）复合物对兔肝脏VX2肿瘤射频消融（RFA）损伤效应的影响。方法：采取开腹肝脏种植VX2肿瘤组织块的方法建立兔VX2肝癌模型。首先将6只肝癌兔均分为两组分别注射TyrRGD-GNPs-VEGFsiRNA复合物和GNPs，注射48 h后，透射电镜检测两者在肿瘤标本中的聚集和分布情况。然后将30只肝癌兔均分为3组，分别注射TyrRGD-GNPs-VEGFsiRNA复合物、GNPs、生理盐水48 h后，行RFA治疗，48 h后切取标本，行病理学观察，测量肿瘤毁损体积，TUNEL法检测残癌细胞凋亡。最后将27只肝癌兔均分为3组，分别行RFA+TyrRGD-GNPs-VEGFsiRNA注射，RFA+生理盐水注射、生理盐水注射，饲养至自然死亡，记录生存时间。结果：TyrRGD-GNPs-VEGFsiRNA复合物在肿瘤中的聚集明显优于GNPs（14.2颗/500 nm视野vs. 0颗/500 nm视野，P<0.01）。注射TyrRGD-GNPs-VEGFsiRNA复合物后的RFA治疗毁损体积明显大于注射GNPs和生理盐水（5.12 cm3 vs. 1.78 cm3 vs. 1.49 cm3，P<0.01），且前者残癌区肿瘤细胞凋亡数明显高于后两者（111.7个vs. 36.3个vs. 34.7个，P<0.01），而后两者上述指标差异均无无统计学意义（均P>0.05）。RFA+TyrRGD-GNPs-VEGFsiRNA治疗的肝癌兔较RFA+生理盐水治疗、单纯生理盐水治疗的肝癌兔的平均生存时间明显延长（70.9 d vs.51.2 d vs. 43.9 d，P<0.01）。结论：TyrRGD-GNPs-VEGFsiRNA复合物能在肝脏肿瘤中靶向聚集，具有扩大RFA毁损范围和促进肿瘤细胞凋亡的作用，从而增强RFA疗效。
VEGF siRNA-gold nanoparticles modified by RGD targeting peptide enhances the damaging effect of radiofrequency ablation on VX2 liver tumor in rabbits
Objective: To investigate the impact of RGD peptide (TyrRGD) modified gold nanoparticles (GNPs) conjugated to VEGF siRNA (TyrRGD-GNPs-VEGFsiRNA) on damaging effect of radiofrequency ablation (RFA) for rabbit VX2 tumor. Methods: Rabbit models of VX2 liver were established by direct implantation of VX2 tumor fragment into the liver via laparotomy. Firstly, 6 liver tumor-bearing rabbits were equally divided into 2 groups and underwent injection of TyrRGD-GNPs-VEGFsiRNA or naked GNPs respectively, and the collection and distribution of the two substances in the tumor samples were detected by transmission electron microscopy 48 h after injection. Next, 30 liver tumor-bearing rabbits were equally divided into 3 groups and underwent RFA treatment 48 h after injection of TyrRGD-GNPs-VEGFsiRNA, naked GNPs or normal saline, respectively, and the tumor specimens were harvested 48 h later, after which, pathological observation was performed, the ablation volume of the tumor was measured and the apoptosis in the residual cancer was detected by TUNEL staining. Finally, 27 liver tumor-bearing rabbits were equally divided into 3 groups and underwent treatment of RFA plus TyrRGD-GNPs-VEGFsiRNA injection, RFA plus normal saline injection or normal saline injection only, and then were fed until they naturally died and the survival times were recorded. Results: The accumulation of TyrRGD-GNPs-VEGFsiRNA in the tumor was significantly greater than that of naked GNPs (14.2/500-nm field vs. 0/500-nm field, P<0.01). The ablation volume by RFA after injection of TyrRGD-GNPs-VEGFsiRNA was significantly larger than that after injection of either naked GNPs or normal saline (5.12 cm3 vs. 1.78 cm3 vs. 1.49 cm3, P<0.01), moreover, the cell number of apoptosis in the residual cancer in the former was significantly higher than those in the two latter groups (111.7 vs. 36.3 vs. 34.7, P<0.01), but both above two parameters showed no statistical difference between the two latter groups (both P>0.05). The mean survival time for liver tumor-bearing rabbits undergoing RFA plus TyrRGD-GNPs-VEGFsiRNA injection was significantly prolonged compared with those undergoing RFA plus saline injection or normal saline injection only (70.9 d vs. 51.2 d vs. 43.9 d, P<0.01). Conclusion: TyrRGD-GNPs-VEGFsiRNA can targetedly aggregate in liver tumor, and it also has the effect of expanding the extent of RFA damage and promoting the apoptosis of the tumor cells, and thereby enhance the efficacy of RFA treatment.