The cold atmospheric pressure plasma jet interaction with the bio-target is studied in the plasma experiment, 2D fluid model simulations, and with MTT and iCELLigence assays of the viability of cancer cells. It is shown, for the first time, that the use of the grounded substrate under the media with cells considerably amplifies the effect of plasma cancer cell treatment in vitro. Plasma devices with cylindrical and plane geometries generating cold atmospheric plasma jets are developed and tested. The sequence of the streamers which forms the plasma jet is initiated with a voltage of 2.5–6.5 kV applied with the frequency 40 kHz. We suggest using the grounded substrate under the bio-target during the plasma jet treatment of cancer cells. The analysis of the measured plasma spectra and comparison of OH-line intensity for different voltages and gas flow rates allows us to find a range of optimal plasma parameters for the enhanced OH generation. The time-dependent viability is measured for human cell lines, A431 (skin carcinoma), HEK 293 (kidney embryonic cells), and A549 (human lung adenocarcinoma cells) after the plasma jet treatment. The results with cell-based experiments (direct treatment) performed with various plasma jet parameters confirm the maximum efficiency of the treatment with the optimal plasma parameters.

Vaccinia virus (VACV) oncolytic therapy has been successful in a number of tumor models. In this study our goal was to generate a double recombinant vaccinia virus (VV-GMCSF-Lact) with enhanced antitumor activity that expresses exogenous proteins: the antitumor protein lactaptin and human granulocyte-macrophage colony-stimulating factor (GM-CSF). Lactaptin has previously been demonstrated to act as a tumor suppressor in mouse hepatoma as well as MDA-MB-231 human adenocarcinoma cells grafted into SCID mice. VV-GMCSF-Lact was engineered from Lister strain (L-IVP) vaccinia virus and has deletions of the viral thymidine kinase and vaccinia growth factor genes. Cell culture experiments revealed that engineered VV-GMCSF-Lact induced the death of cultured cancer cells more efficiently than recombinant VACV coding only GM-CSF (VV-GMCSF-dGF). Normal human MCF-10A cells were resistant to both recombinants up to 10 PFU/cell. The selectivity index for breast cancer cells measured in pair cultures MCF-7/MCF-10A was 200 for recombinant VV-GMCSF-Lact coding lactaptin and 100 for VV-GMCSF-dGF. Using flow cytometry we demonstrated that both recombinants induced apoptosis in treated cells but that the rate in the cells with active caspase −3 and −7 was higher after treatment with VV-GMCSF-Lact than with VV-GMCSF-dGF. Tumor growth inhibition and survival outcomes after VV-GMCSF-Lact treatment were estimated using immunodeficient and immunocompetent mice models. We observed that VV-GMCSF-Lact efficiently delays the growth of sensitive and chemoresistant tumors. These results demonstrate that recombinant VACVs coding an apoptosis-inducing protein have good therapeutic potential against chemoresistant tumors. Our data will also stimulate further investigation of coding lactaptin double recombinant VACV in clinical settings.

The application of cold atmospheric plasma (CAP) in cancer therapy could be one of the new anticancer strategies. In the current work, we used cold atmospheric plasma jet for the treatment of cultured cells and mice. We showed that CAP induced the death of MX−7 mouse rhabdomyosarcoma cells with the hallmarks of immunogenic cell death (ICD): calreticulin and heat shock protein 70 (HSP70) externalization and high-mobility group box 1 protein (HMGB1) release. The intensity of HMGB1 release after the CAP treatment correlated directly with the basal extracellular HMGB1 level. Releasing from dying cells, HMGB1 can act as a proinflammatory cytokine. Our in vivo study demonstrated that cold atmospheric plasma induces a short-term two-times increase in serum HMGB1 level only in tumor-bearing mice with no effect in healthy mice. These findings support our hypothesis that CAP-dependent HMGB1 release from dying cancer cells can change the serum HMGB1 level. At the same time, we showed a weak cytokine response to CAP irradiation in healthy mice that can characterize CAP as an immune-safety physical antitumor approach.