Abstract
To understand how therapeutic ultrasound works, understanding its biological effects is deemed necessary. Here, the molecular aspect, particularly on apoptosis induction, gene expression, and gene transfection were investigated. Apoptosis induction was assayed by flow cytometry and by other methods targeting indicators of apoptosis. Gene expressions were evaluated using western blotting, real-time PCR, and micro-array analyses. And gene transfection was investigated using luciferase assay and other methods. The results showed that low intensity ultrasound can induce apoptosis in cancer cell lines and that it can be optimized using pulsed ultrasound. Ultrasound resulted to down-regulation or up-regulation of some genes. Of particular interest is the striking up-regulation of heme oxygenase-1 gene, a gene usually associated with oxidative stress. Introducing gene using ultrasound also showed promising results. We have shown that gene introduction is cavitation related such that it is enhanced by echo contrast agents and other factors cited above. Membrane damage is pivotal to the bioeffects that modifying the cell membranes either promotes or inhibits the desired effects. Although, ultrasound can enhanced liposome-mediated gene transfection, at optimized condition ultrasound alone can deliver gene more efficiently than liposome-mediated gene transfection. In summary, we conclude that ultrasound can be useful in therapy that requires apoptosis induction or gene introduction to cells. Further studies is however necessary to investigate the value of gene induction by ultrasound.
