On the Mechanism of Plasma Inducing Cell Apoptosis

A cold atmospheric-pressure plasma, which has been widely used for biomedical applications, may potentially affect the cell cycle and cause cell apoptosis. In this paper, a human hepatocellular carcinoma cell (HepG2) is treated by a single-electrode plasma jet device. Further investigation by using flow cytometric analysis demonstrates that plasma treatment increases the percentage of apoptotic cells being associated with cell cycle arrest at the G2/M phase. Moreover, the reverse transcription polymerase chain reaction assay shows that the cyclin B1 and Cdc2 are decreased at the transcription level after plasma treatment, while the expression of the p21 Cdk inhibitor, as well as that of tumor suppressor p53, is enhanced. On the other hand, the levels of certain pro- or antiapoptotic genes are checked, and the experimental results suggest that the plasma induces apoptosis by shifting the Bax/Bcl-2 ratio to trigger HepG2 cell apoptosis. The results of the present investigation indicate that the plasma jet device may have potential therapeutic activities, such as sterilization of living tissue and tumor therapy of the postoperative treatment process.