Cytotoxicity characterization of catanionic vesicles in RAW 264.7 murine macrophage-like cells

In comparison with cationic liposomes, catanionic vesicles possess more attractive properties such as stability and lower cost, and these characteristics may make them suitable as a non-viral vehicle and for other biomedical applications such as vaccine adjuvants. However, very little is known about their possible cytotoxic mechanisms in cellular system. Also, this information is vital for the future development of safe biomedical systems. In the current study, the cytotoxic effect of catanionic vesicles, consisting of anionic surfactant (SDS), cationic surfactant (HTMAB), and cholesterol, in cultured RAW 264.7 murine macrophage-like cells was determined. The treatment of catanionic vesicles produced a dose-dependent effect on macrophage cells. RAW 264.7 cells exposed to catanionic vesicles exhibited morphological features of apoptosis such as chromatin condensation. Typical apoptotic ladders were observed in DNA extracted from RAW 264.7 cells treated by catanionic vesicles. Analysis from flow cytometry demonstrated an increase of hypodiploid DNA population (sub-G1) and a simultaneous decrease of diploid DNA content, indicating that DNA cleavage occurred after exposure of the cells with catanionic vesicles. In addition, it was shown that pretreatment of RAW 264.7 cells with the general caspase inhibitor (zVAD-fmk) did not prevent apoptosis induced by catanionic vesicles, suggesting that apoptosis in macrophage cells followed a caspase-independent pathway induced by catanionic vesicles. These data provide novel insight into the effect of catanionic vesicles on the mechanisms of cell death induced by catanionic vesicles.