In vitro study of haematoporphyrin monomethyl ether-mediated sonodynamic effects on C6 glioma cells

Objectives To study the cytotoxicity induced by haematoporphyrin monomethyl ether (HMME)-mediated sonodynamic therapy (SDT) on C6 glioma cells. Methods The potent photosensitizer HMME was used as the sensitizer. Rat C6 glioma cells were incubated with HMME ( 10 mu g/mL) in the dark for 2 h and then subjected to ultrasound treatment at 1.0 MHz and 0.5 W/cm(2) for 2 min. The growth inhibition rate at different time points after SDT was determined by MTT assay. The apoptotic rate and cell circle profiles were examined with flow cytometry. Fine structures were observed with transmission electron microscope (TEM). The sonodynamic effect on the glioma cells was also studied in the absence or presence of various reactive oxygen species (ROS) scavengers. Results The growth inhibition rate of C6 glioma cells after SDT significantly increased. SDT also increased the apoptosis and proliferation rate (APR). TEM examination showed the morphological features of apoptosis or necrosis. The addition of NaN3 showed a strong protective effect again SDT. Conclusions Our data indicated that SDT could kill C6 glioma cells in vitro and possibility through induction of apoptosis and necrosis. Singlet oxygen (O-1(2)) may play an important role in SDT.