Background: Over the past decade, cold atmospheric plasma (CAP), a near room temperature ionized gas has shown its promising application in cancer therapy. In contrast to conventional anti-cancer approaches and drugs, CAP is a selective anti-cancer treatment modality. Previous experimental studies have demonstrated that CAP treatment results in significant growth inhibition of tumor cells and is able to induce apoptosis and to modulate the immune response. In contrast to already existing plasma sources, a new endoscope-based plasma source first had to be developed for applications in head and neck surgery.

Methods: Cold atmospheric plasma (CAP) was generated via a new developed endoscope-based atmospheric pressure plasma jet (PLASMASKOP). Physiological and molecular effects of CAP treatment on various human head and neck squamous cell carcinoma (HNSCC) cell lines compared to human epithelial cell lines were analyzed by cell kinetic analyses, FACS analyses, COMET-Assays, Proteome and Western blot analyses. 3D respiratory epithelial organoids with embedded tumors were subsequently treated by a site-specific plasma treatment, and the molecular and biochemical effects were analyzed using transcriptomic and proteomics approaches.

Results: CAP treatment effectively attenuates malignant cell growth. The results demonstrated that even a single application of a short-term CAP treatment led to an attenuation of HNSCC cell growth and motility. We studied the detailed cellular adaptation reactions for a specified plasma intensity by time-resolved comparative proteome analyses of CAP treated vs. nontreated cells to elucidate the molecular mechanisms and to define potential biomarkers and networks for the evaluation of plasma effects on human tumor cells. Results were consistent in various HNSCC cell lines. CAP treatment-specific induced post translational protein modifications that promote tumor cell death were additionally identified and characterized by mass spectrometry (e.g. modified protein activity by reactive oxygen species).

Conclusion: In summary, the CAP application in head and neck surgery leads to strong anti-proliferative effects and opens up novel opportunities for the treatment of HNSCCs. As an intraoperative application, CAP may represent a promising option particularly for the treatment of tissue regions that are close to critical structures (e. g. nerves, adjacent organs).