The influence of cold atmospheric plasma on cell cycle and apoptosis

Non-inflammatory growth suppression of tissues can be achieved by controlled induction of programmed cell death (apoptosis), or by suppressing cell proliferation in other way, but without inflicting accidental cell death (necrosis). Our previous works showed that treatment with cold atmospheric plasma usually did not induce necrosis, but triggered sub-lethal cell reactions (detachment, apoptosis) in various cell types. In this work we quantitatively resolve the influence of plasma treatment on cell cycle and apoptotic behaviour. We use several types of cells (vascular, epithelial, etc.) and perform flow cytometric analysis of their DNA profiles. We clearly observe dose-dependent influences on cell proliferation: this can be either suppressed or enhanced by plasma, dependent on the dosage. Apoptosis is abundant, but it manifests itself 48-72 h after treatment, which is rather long compared to the cell cycle. We argue that our type of apoptotic trigger is different from the commonly known ones (e.g. apoptosis induced by DNA damage). A tentative explanation will be proposed.