On the mechanism of plasma inducing cell apoptosis

Summary form only given. In recent years, atmospheric pressure nonequilibrium plasmas (APNPs) have been used in many biomedical applications such as bacteria, yeasts, fungi and algae inactivation, surface treatment for cell sheet engineering to controlled cell cultivation, promote blood coagulation and root canal of teeth sterilization. The APNPs can operate at room temperature and APNPs can form numerous short-lived but highly active chemical particles, such as reactive oxygen species, hydroxyl radical (OH), and other excited species. These active chemical particles are essential for various biological processes in cells and human body, reactive oxygen species are involved in initiation, progression and metastasis of cancers and nitric oxide (NO) can induce apoptosis, necrosis or protect cells from death, depending on the cell type and the amount, duration, and site of NO production. Therefore, it is important to study the impact of plasma on cancer cells. In this paper, human hepatocellular carcinoma cell (HepG2) is treated by a single electrode plasma jet device. Further investigation by using the flow cytometric analysis demonstrates that the plasma treatment increases the percentage of apoptotic cells being associated with cell cycle arrest at G2/M phase. Besides, the Reverse Transcriptase PCR assay shows that the Cyclin B1 and Cdc2 are decreased in transcription level after plasma treatment, while the expression of the p21 Cdk inhibitor, as well as tumor suppressor p53, is enhanced. On the other hand, the levels of certain pro-apoptotic or anti-apoptotic genes are checked, the experimental results suggests that the plasma induces apoptosis through shifting the Bax/Bcl-2 ratio to trigger HepG2 cell apoptosis. Results of the present investigation indicate that the plasma jet device may have potential therapeutic activity, such as sterilization of living tissue and tumor therapy of the postoperative treatment process.