Influence of high intensity focused ultrasound and shockwaves on the integrity of DNA in vitro

Purpose: Ultrasound shockwaves and high intensity, focused ultrasound (HIFU ) can induce various effects in tissue. Experimental studies have shown tha t acoustic energy has a potential for use in transfection, gene therapy and regulation. Next to cavitation, sonochemical effects play an important rol e. The goal of this study was to examine the influence of shockwaves and HI FU on DNA morphology. Materials and Methods: Polyurethane tubes Filled with a suspension of the M atLu R3327 Dunning prostate adenocarcinoma were immersed in 37 degreesC war m, degassed water. Shockwaves and HIFU of varying intensity were applied. D ifferent probes with and without water-air borderline served the examinatio n of cavitation effects. An equivalent cell solution was incubated with H2O 2 (0.15 %) as a positive control. Immediately after treatment, the Comet As say was applied. Results: The Olive Tail Moment (Olive TM) was used as standard parameter of DNA damage. The means of the Olive TMs were in both positive control and t reatment groups significantly higher than in the negative control, correspo nding to a significantly higher DNA damage. The presence of a water-air bor derline produced significantly more strandbreaks. Conclusions: This study has proved that acoustic energy can induce a signif icant amount of DNA damage in malignant cells in vitro. Based on earlier st udies and clinical experience, however, it can be assumed that this damage can be repaired by the cells' own repair mechanisms. We are presently exami ning the possibility of using the effect described here therapeutically by combining the treatment of malignant cells by ultrasound with the applicati on of a repair inhibitor.