Cold Plasma Jets

This study aimed to evaluate the effects of micron sized non-thermal atmospheric pressure plasma inside the animal body on breast cancer tumor. The μ-plasma jet consists of micron sized hollow tube in which pure helium gas is ionized by high voltage (4 kV) and high frequency (6 kHz). The efficiency of the plasma treatment in killing cancer cells was first investigated by cell viability measurements of treated 4T1 cells using flow cytometry and cell cycle analysis. For exploration of the in vivo effects of the plasma treatment, the BALB/c mice inoculated by 4T1 cell lines were exposed subcutaneously to plasma for 3 minutes. In addition, H&E staining, TUNEL and Western blotting assays were performed in order to observed the effects of the non-thermal plasma on the tumor cells. The results showed that the efficiency of the plasma in suppression of the tumor growth is comparable to that of a typical chemotherapy drug. Moreover, the results indicated that the plasma induces apoptosis in the tumor tissue and increases the ratio of the apoptotic to anti-apoptotic protein expression. We believe that these findings presented herein may extend our knowledge of the mechanisms by which the plasma exerts its promising anti-cancer effects. The cancer treatment by non-thermal atmospheric pressure plasma has attracted considerable attentions to the field of cancer therapy by using cold plasma 1–5. The conventional cancer therapy techniques are associated with many issues such as the normal tissue damage, time consuming treatment procedure and expensive therapies 6. The non-thermal plasma treatment has been introduced as a cost effective, rapid and low damage treatment which may represent an alternative for the conventional methods. Plasma contains the reactive species 7,8 , free radicals 9 , energetic ions 10 and also the transient electric fields inherent with plasma delivery 11,12 which are formed in the atmospheric room temperature medium and interact with the cells and other living organisms. It was shown that the plasma induced the apoptotic cell death in cancer cells while it had no adverse effect on the normal cell lines in the appropriate dosage 13,14. The results also indicated that by exposing the free radicals to cancer cells, the cells could produce the intracellular reactive oxygen species (ROS) which could cause apoptotic cell death 15. In addition, the role of nitric oxide (NO) generated by plasma is considerable 16,17. Moreover many other studies tried to figure out the mechanism of the cell death in cancer cells treated by the non-thermal plasma such as the cell signals activation induced by the reactive agents 18–21. Meanwhile, few studies have presented the effect of non-thermal plasma on the in-vivo tumor models 22,23. The reports have shown the tumor suppression with different dosage of the plasma treatment 23. The researchers also tried to figure out the mechanism of the plasma tumor interaction 23,24. One of the benefits of the plasma treatment in the in-vivo model is that the plasma has low harm effects on the normal tissue in the appropriated dosages 25 .