Figure 1
From: The Cell Activation Phenomena in the Cold Atmospheric Plasma Cancer Treatment
A schematic illustration of the CAP-based cell activation during the direct CAP treatment. In two cases, the concentration of reactive species in the CAP-treated medium is the same. The CAP-treated (activated) cells are sensitive to the cytotoxicity of the CAP-originated reactive species. In contrast, the indirect CAP treatment based on the CAP-treated medium on the cancer cells without the activation will only cause a noticeable weaker cytotoxicity. This model explains the stronger anti-cancer effect of a direct CAP treatment on cancer cells compared with an indirect CAP treatment. A CAP treatment not only provides the dozens of reactive species in the extracellular environment, but also decreases the threshold of the cancer cells to the cytotoxicity of the reactive species through the activation. This is a fundamental feature of the CAP treatment. The activation state of the CAP-treated cancer cells may be due to the short-lived reactive species or other unknown factors.
