Multiple myeloma (MM) is the second most common hematologic malignancy. MM stem cells (MMSCs) are thought to be the main causes of in vivo engraftment and eventual recurrence. As a notable new technology, cold atmospheric plasmas (CAPs) show a promising anti-tumor effect, due to their production of various ROS. In this study, we found that different types of plasma could inhibit MM’s ability to form cell colonies, suppress MM in vivo engraftment, and extend survival times. We demonstrated that NAC (a ROS scavenger) could block ROS increases and reverse the inhibition of MM’s cell-colony-formation ability, which was induced by the plasma treatment. By using a stem cell signaling array, we found that the Notch pathway was inhibited by the plasma treatment; this was further confirmed by conducting real-time PCRs of three MM cell lines. Together, these results constitute the first report of plasma treatment inhibiting MM in vivo engraftment and prolonging survival time by suppressing the Notch pathway via ROS regulation.

With increasing drug resistance of Pseudomonas aeruginosa, a new sterilization method is needed. Plasma has been shown to be an effective method of sterilization, but no researchers have studied the effect of plasma on bacterial metabolism. In this paper, we studied the emission spectrum, liquid phase active particles, and other physical and chemical properties of a portable plasma device. Pseudomonas aeruginosa were then treated with activated water generated by surface plasma discharge. Using gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, we obtained the differential metabolite pathways. The results showed that, after plasma activated water treatment, the carbohydrate metabolism of the bacteria was inhibited and the metabolic processes of protein and amino acid decomposition were enhanced. Therefore, water activated by atmospheric-pressure cold plasma can significantly change bacterial metabolites, thus promoting bacterial death.