The dual effect of ultrasound-targeted microbubble destruction in mediating recombinant adenoassociated virus delivery in renal cell carcinoma: transfection enhancement and tumor inhibition

BackgroundRecombinant adeno-associated virus (rAAV) is recognized as a promising vector for cancer gene therapy, although its low transfer efficiency in less permissive cells limits extensive application. Our previous studies reported that ultrasound-targeted microbubble (MB) destruction (UTMD) enhanced rAAV transfer in its permissive retinal cells. In the present study, we investigated whether UTMD increased rAAV transfer in less permissive human renal cell carcinoma (hRCC) cells and tumors. MethodshRCC cells were treated with rAAV2 under different conditions of UTMD, and the viral transfer efficiency and cell viability were analyzed. Fifty-two male nude mice (BALB/c) implanted with hRCC cells were randomly assigned to four groups consisting of rAAV, rAAV+ultrasound and rAAV+UTMD (20 mu l and 40 mu l of MBs). UTMD was initiated immediately after intratumoral viral injection, and viral transfer efficiency and tumor volumes were analyzed at 12weeks after infection. ResultsThe efficiency of non-augmented transfer of rAAV2 into hRCC cells was low (17.282.44%). The use of UTMD enhanced viral transfer efficiency by two- to three-fold, and enhanced viral genomic DNA by more than nine-fold, without decreasing cell viability. In vivo studies also showed that UTMD increased rAAV2 transfer in tumor. The enhancements were maintained for a period of 12weeks. Tumor growth in mice was inhibited by UTMD treatment, and UTMD treatment augmented by MBs (40 mu l) produced an even stronger effect. ConclusionsUTMD enhanced rAAV2 transfer into less permissive RCC cells and tumors, resulting in inhibition of tumor growth, which suggests that UTMD may be a useful delivery tool for cancer gene therapy. Copyright (c) 2014 John Wiley & Sons, Ltd.