Optimization of low-power ultrasound with micro-bubbles in inducing early apoptosis of DU145 cells / 中华医学超声杂志（电子版）

ABSTRACT

Objective To optimize the parameters of the low-frequency/low-energy ultrasound combined with micro-bubbles in inducing early apoptosis of DU145 cells (an androgen-independent prostatic cancer cells). Methods In our study, the impact of ultrasonic power, micro-bubbles/cell suspension volume rate and irradiation time were investigated. Three levels of each factor were deifned as ultrasonic power (60, 80, 100 mW), micro-bubbles/cell suspension volume rate (10%, 20%, 30%), irradiation time (30, 60, 90 s). According to the three-factor three-level orthogonal design, nine experiments were carried out. The early apoptosis was detected by lfow cytometry. A new experiment was designed with the optimized parameters. Another group without ultrasound irradiation was designed as the control group. Flow cytometry and transmission electron microscope (TEM) were used to detect the early apoptosis. Results In descending order, the inlfuence of these factors on the cell early apoptosis wereultrasonic power>micro-bubbles/cell suspension volume rate>irradiation time. Moreover, the inlfuence of each factor level were80 mW>60 mW>100 mW in ultrasonic power, 20%>30%>10%in micro-bubbles/cell suspension volume rate, 60 s>90 s >30 s in irradiation time. The early apoptosis rate of experiment group was 10.41%, while the control group was 0.94%. TEM showed apoptotic cells in the experiment group. Conclusions The optimized parameter of low-frequency/low-energy ultrasound with micro-bubbles in inducing early apoptosis of DU145 cells are ultrasonic power of 80 mW, micro-bubbles/cell suspension volume rate of 20%, and irradiation time of 60 s. With the optimized parameters, the early apoptosis rate of the experiment group has signiifcant higher than the control group.