The effects of successive high-energy shock-wave tumor administration on tumor blood flow

Mechanical high-intensity focused ultrasound destruction of soft tissue: working mechanisms and physiologic effects

The best known method of high-intensity focused ultrasound is thermal ablation, but interest in non-thermal, mechanical destruction is increasing. The advantages of mechanical ablation are that thermal protein denaturation remains limited and less damage is created to the surrounding tissue by thermal diffusion. The two main techniques for mechanical fragmentation of tissue are histotripsy and boiling histotripsy. These techniques can be used for complete liquefaction of tumor tissue into submicron fragments, after which the fragmented tissue can be easily removed by natural (immunologic) responses. Interestingly it seems that there is a correlation between the degree of destruction and tissue specific characteristics based on the treatment settings used. In this review article, the technical aspects of these two techniques are described, and an overview of the in vivo pathologic and immunologic responses is provided.

Radial shock waves effectively introduced NF-kappa B decoy into rat achilles tendon cells in vitro

The purpose of this study was to test if radial shock waves could enhance the introduction of nuclear factor-kappa B (NF-kappaB) decoy oligodeoxynucleotides, which is reported to markedly inhibit NF-kappaB activation and suppress pro-inflammatory cytokine gene expression, using rat Achilles tendon cells. In the presence of NF-kappaB decoy labeled with or without fluorescein isothiocyanate (FITC) in culture media, radial shock waves were applied to the tendon cells in variable conditions and cultivated for 24 h. The transfection rate was assessed by counting FITC-positive cells, and IL-1-induced NF-kappaB activation in the cells was assessed. Radial shock waves significantly enhanced introduction of NF-kappaB decoy-FITC into the tendon cells. IL-1-induced NF-kappaB activation was significantly inhibited by pretreatment of the cells with NF-kappaB decoy combined with radial shock wave exposure. The present study demonstrated the effectiveness of radial shock waves on introduction of NF-kappaB decoy into tendon cells. Radial shock wave treatment combined with local NF-kappaB decoy administration could be a novel therapeutic strategy for chronic tendinopathy.

The effects of radial shock waves on gene transfer in rabbit chondrocytes in vitro

OBJECTIVE

The purpose of this study was to develop a new technique of gene transfer utilizing radial shock waves. The effects of radial shock waves on gene transfer in rabbit chondrocytes were examined by varying the parameters of exposure conditions in vitro.

METHODS

Chondrocytes were obtained from New Zealand white rabbits and cultured in a monolayer. A luciferase-encoding gene expression vector, or vector alone, was added to chondrocyte cell suspensions, and the cells were then exposed to radial shock waves. Parameters such as pressure amplitude, number of pulses, frequency, and DNA concentration were varied, and luciferase activity was measured 48h after transfection. Transfection efficiency of radial shock waves was compared with the FuGENE6 transfection method using a green fluorescence protein (GFP)-encoding gene vector by fluorescent-activated cell sorter (FACS) analysis.

RESULTS

Radial shock wave exposure significantly increased luciferase activity over 140-fold as compared to the control under the optimal exposure conditions. Both pressure amplitude and number of pulses were relevant to transfection efficiency and cell viability, but frequency was not. Transfection efficiency increased in a dose-dependent manner with DNA concentration. FACS analysis showed 4.74% of GFP-encoding gene using radial shock waves. FuGENE6 transfection was almost similar in transfection efficiency to radial shock wave.

CONCLUSION

In spite of certain degree of cell disruption, radial shock waves significantly augmented reporter gene transfection in rabbit chondrocytes in vitro. Radial shock waves may potentially contribute to the treatment of the cartilage morbidities by enhancing the potency of tissue healing and gene transfection of growth factors.

The influence of high-energy shock waves on the development of metastases

The hypothesis that exposure of a solid tumor to high-energy shock waves (HESW) could lead to an increase of metastases was investigated in an animal model. The highly metastatic AT-6 Dunning R3327 rat prostate cancer subline was implanted in the hind limb of a Fisher-Copenhagen rat and was exposed to 6000 shock waves delivered by an experimental lithotripter, or sham-treated, as soon as the tumor had reached a volume of 175-225 mm3. The tumor-bearing leg was amputated 24 h later and the number of metastases was examined 12 weeks thereafter at autopsy. Metastases were seen in 82% of the animals exposed to HESW and in 25% of the sham-treated animals. There was no significant difference in weight of the lungs that contained metastases, between sham and treated animals. These results were confirmed in a second experiment. We conclude that the metastatic spread of tumors with a high metastatic potential may be enhanced by shock-wave exposure.