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Gas Plasma Exposure of Glioblastoma Is Cytotoxic and Immunomodulatory in Patient-Derived GBM Tissue
Glioblastoma multiforme (GBM) is the most common primary malignant adult brain tumor. Therapeutic options for glioblastoma are maximal surgical resection, chemotherapy, and radiotherapy. Therapy resistance and tumor recurrence demand, however, new strategies. Several experimental studies have suggested gas plasma technology, a partially ionized gas that generates a potent mixture of reactive oxygen species (ROS), as a future complement to the existing treatment arsenal. However, aspects such as immunomodulation, inflammatory consequences, and feasibility studies using GBM tissue have not been addressed so far. In vitro, gas plasma generated ROS that oxidized cells and led to a treatment time-dependent metabolic activity decline and G2 cell cycle arrest. In addition, peripheral blood-derived monocytes were co-cultured with glioblastoma cells, and immunomodulatory surface expression markers and cytokine release were screened. Gas plasma treatment of either cell type, for instance, decreased the expression of the M2-macrophage marker CD163 and the tolerogenic molecule SIGLEC1 (CD169). In patient-derived GBM tissue samples exposed to the plasma jet kINPen ex vivo, apoptosis was significantly increased. Quantitative chemokine/cytokine release screening revealed gas plasma exposure to significantly decrease 5 out of 11 tested chemokines and cytokines, namely IL-6, TGF-β, sTREM-2, b-NGF, and TNF-α involved in GBM apoptosis and immunomodulation. In summary, the immuno-modulatory and proapoptotic action shown in this study might be an important step forward to first clinical observational studies on the future discovery of gas plasma technology’s potential in neurosurgery and neuro-oncology especially in putative adjuvant or combinatory GBM treatment settings.
Gas plasma-treated prostate cancer cells augment myeloid cell activity and cytotoxicity
Despite recent improvements in cancer treatment, with many of them being related to foster antitumor immunity, tumor-related deaths continue to be high. Novel avenues are needed to complement existing therapeutic strategies in oncology. Medical gas plasma technology recently gained attention due to its antitumor activity. Gas plasmas act via the local deposition of a plethora of reactive oxygen species (ROS) that promote the oxidative cancer cell death. The immunological consequences of plasma-mediated tumor cell death are only poorly understood, however. To this end, we exposed two prostate cancer cell lines (LNCaP, PC3) to gas plasma in vitro, and investigated the immunomodulatory effects of the supernatants in as well as of direct co-culturing with two human myeloid cell lines (THP-1, HL-60). After identifying the cytotoxic action of the kINPen plasma jet, the supernatants of plasma-treated prostate cancer cells modulated myeloid cell-related mitochondrial ROS production and their metabolic activity, proliferation, surface marker expression, and cytokine release. Direct co-culture amplified differentiation-like surface marker expression in myeloid cells and promoted their antitumor-toxicity in the gas plasma over the untreated control conditions. The results suggest that gas plasma-derived ROS not only promote prostate cancer cell death but also augment myeloid cell activity and cytotoxicity. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.