title: High-intensity focused ultrasound combined with herpes simplex virus thymidine kinase gene-loaded ultrasound-targeted microbubbles improved the survival of rabbits with VX₂ liver tumor.
abstract: BACKGROUND
  To explore the anti-tumor effect of high-intensity focused ultrasound (HIFU) combined with herpes simplex virus thymidine kinase (HSV-TK) gene-loaded ultrasound-targeted microbubbles on VX2 rabbit liver tumors.
  
  
  METHODS
  Seventy-five New Zealand white rabbits were randomly divided into five groups after the models of VX2 rabbit liver tumors were established: (a) HIFU group; (b) HIFU and HSV-TK group (HIFU + HSV-TK); (c) HIFU, HSV-TK and ultrasound group (HIFU + HSV-TK + US); (d) HIFU, HSV-TK gene-loaded microbubbles and ultrasound group (HIFU + HSV-TK-MBs + US); and (e) HSV-TK gene-loaded microbubbles and ultrasound group (HSV-TK-MBs + US). After 2 weeks of VX2 liver tumor implantation, rabbits in groups (a), (b), (c) and (d) received HIFU to establish rabbit models of residual tumor by ablating 80% of the tumor volume. After HIFU ablation, rabbits in different groups received MBs wrapped around HSV-TK or HSV-TK solution via marginal ear veins and/or local ultrasonic irradiation to the tumor. Six rabbits in each group were sacrificed 48 h after the corresponding treatment, and tumors were extracted for in vitro experiments. Thymidine kinase mRNA was detected by the real-time polymerase chain reaction. The green fluorescent protein expression in liver tumor was detected by western blotting and immunohistochemistry. Tumor cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling. The growth curves of VX2 liver tumors and survival curves of rabbits were compared.
  
  
  RESULTS
  Forty-eight hours after treatment, TK mRNA and protein were the highest in the HIFU + HSV-TK + US + MBs group and the HSV-TK + US + MBs group (p < 0.05). At 48 h after treatment, the apoptotic index of tumor cells in HIFU + HSV-TK-MBs + US group was the highest (p < 0.05). Compared to other groups, HIFU combined with MBs wrapped HSV-TK suicide gene significantly inhibited tumor growth in vivo (p < 0.05) and prolonged the survival time of animals (p < 0.05).
  
  
  CONCLUSIONS
  HIFU combined with HSV-TK gene-loaded ultrasound-targeted MBs significantly inhibited the growth of VX2 rabbit liver tumors in vivo and prolonged the survival time of the animals, providing a novel gene delivery method and a novel strategy for liver tumor treatment.
authors.affiliation: Department of Hepatobiliary Surgery, Second Affiliated Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Shi-Ji
authors.initials: SJ
authors.lastname: Zhou
authors.forename: Sheng-Wei
authors.initials: SW
authors.lastname: Li
authors.forename: Ji-Jian
authors.initials: JJ
authors.lastname: Wang
authors.forename: Zuo-Jin
authors.initials: ZJ
authors.lastname: Liu
authors.forename: Guo-Bing
authors.initials: GB
authors.lastname: Yin
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Gong
authors.forename: Chang-An
authors.initials: CA
authors.lastname: Liu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D045423:Microbubbles / Q000627:therapeutic use*; D011817:Rabbits; D018139:Simplexvirus / Q000235:genetics*; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism; D016896:Treatment Outcome; D036761:Ultrasound, High-Intensity Focused, Transrectal / Q000379:methods*
chemical_list: D013937:Thymidine Kinase