Effect of near field ultrasound on carboplatin treatment of ovarian carcinoma cells.

It has long been shown that therapeutic ultrasound has the potential to affect cells surfaces and membranes. In this study, the effects of ultrasound in near field mode, the anti-cancer drug carboplatin and their combined application were studied on human carcinoma cells A2780. Four modes of treatment were used: exposure to ultrasonic field, application of carboplatin, exposure to ultrasound followed by carboplatin and carboplatin treatment followed by exposure to near field ultrasound. The value of viability was measured by standard MTT test. The value of ultrasound intensity was set 1 W·cm-2 and 1 MHz frequency was used. The real value of acoustic pressure during in vitro experiments was assessed by hydrophone. The results showed that a combined effect of ultrasound and carboplatin influenced the viability of human carcinoma cells A2780 more than the application of ultrasound or carboplatin alone. It could be assumed that exposure of cells to ultrasonic field had an immediate effect on the structure of cell surface and consequently on the entry of carboplatin into the cell. The results of our experiments demonstrated possibility of using therapeutic ultrasound in potentiating the cytostatic treatment of human carcinoma cells.

Determination of free cisplatin in medium by differential pulse polarography after ultrasound and cisplatin treatment of a cancer cell culture.

The in vitro study was carried out for detection of the cisplatin in free form and in culture medium, depending on various conditions of sonodynamic human ovarian cancer cells A2780 treatment by differential pulse polarography (DPP). For sonodynamic treatment, we used cisplatin alone and combined cisplatin/ultrasound treatments. The ultrasound exposure intensity of 1.0 and 2.0 W∙cm-2 in far field for incubation periods 1, 24 and 48 h was used. The parameters of DPP measurements were - 1 s drop time, 5 mV.s-1 voltage scan rate, 50 mV modulation amplitude and negative scanning direction; platinum wire served as counter electrode and Ag|AgCl|3 M KCl as reference electrode. The results showed the dependence of free platinum quantities in culture medium on incubation time and treatment protocol. We found difference in concentration of free cisplatin between conventional application of cisplatin and sonodynamic treatment. The sonodynamic combined treatment of cisplatin and ultrasound field showed a higher cisplatin content in the culture medium than cisplatin treatment alone; a difference of 20% was observed for incubation time 48 h. The results also showed the influence of a time sequence of ultrasound and cytostatics in the sonodynamic treatment. The highest amount of free cisplatin in the solution was found for primary application of cisplatin and the subsequent ultrasound exposure. The quantity of free cisplatin increased with time, namely for time intervals 1-24 h. There was no difference between the DPP signal of cisplatin in reaction mixture containing cells in small quantities and micro-filtered mixture without cells. Thus, the DPP method is suitable for the detection and quantification of free cisplatin in the culture medium of cell suspension. Ultrasound field can be important factor during cytostatic therapy.