Impact of non-thermal plasma treatment on MAPK signaling pathways of human immune cell lines.

In the field of wound healing research non-thermal plasma (NTP) increasingly draws attention. Next to its intensely studied antibacterial effects, some studies already showed stimulating effects on eukaryotic cells. This promises a unique potential in healing of chronic wounds, where effective therapies are urgently needed. Immune cells do play an important part in the process of wound healing and their reaction to NTP treatment has yet been rarely examined. Here, we studied the impact of NTP treatment using the kinpen on apoptotic and proliferative cell signaling pathways of two human immune cell lines, the CD4(+)T helper cell line Jurkat and the monocyte cell line THP-1. Depending on NTP treatment time the number of apoptotic cells increased in both investigated cell types according to a caspase 3 assay. Western blot analysis pointed out that plasma treatment activated pro-apoptotic signaling proteins like p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase 1 and 2 (JNK 1/2) in both cell types. Stronger signals were detected in Jurkat cells at comparable plasma treatment times. Intriguingly, exposure of Jurkat and THP-1 cells to plasma also activated the pro-proliferative signaling molecules extracellular signal-regulated kinase 1/2 (ERK 1/2) and MAPK/ERK kinase 1 and 2 (MEK 1/2). In contrast to Jurkat cells, the anti-apoptotic heat shock protein 27 (HSP27) was activated in THP-1 cells after plasma treatment, indicating a possible mechanism how THP-1 cells may reduce programmed cell death. In conclusion, several signaling cascades were activated in the examined immune cell lines after NTP treatment and in THP-1 monocytes a possible defense mechanism against plasma impacts could be revealed. Therefore, plasma might be a treatment option for wound healing.

Non-thermal plasma treatment is associated with changes in transcriptome of human epithelial skin cells.

Non-thermal atmospheric pressure plasma has recently gained attention in the field of biomedical and clinical applications. In the area of plasma medicine research, one promising approach is to promote wound healing by stimulation of cells involved. To understand basic molecular and cellular mechanisms triggered by plasma treatment, we investigated biological effects of an argon plasma jet kinpen on human epithelial skin cells. For assessment of transcriptome changes cell culture medium was plasma treated and applied to the HaCaT keratinocyte cell culture (indirect treatment). Consequently, whole-genome microarrays were used to analyze this interaction in detail and identified a statistically significant modification of 3,274 genes including 1,828 up- and 1,446 downregulated genes. Particularly, cells after indirect plasma treatment are characterized by differential expression of a considerable number of genes involved in the response to stress. In this regard, we found a plasma-dependent regulation of oxidative stress answer and increased expression of enzymes of the antioxidative defense system (e.g. 91 oxidoreductases). Our results demonstrate that plasma not only induces cell reactions of stress-sensing but also of proliferative nature. Consistent with gene expression changes as well as Ingenuity Pathway Analysis prediction, we propose that stimulating doses of plasma may protect epithelial skin cells in wound healing by promoting proliferation and differentiation. In conclusion, gene expression profiling may become an important tool in identifying plasma-related changes of gene expression. Our results underline the enormous clinical potential of plasma as a biomedical tool for stimulation of epithelial skin cells.