The effect of local non‐thermal plasma therapy on the cancer‐immunity cycle in a melanoma mouse model

Non-thermal plasma promotes boar sperm quality through increasing AMPK methylation

Boar sperm quality, as an important indicator of reproductive efficiency, directly affects the efficiency of livestock production. Here, this study was conducted to improve the boar sperm quality by using a non-thermal dielectric barrier discharge (DBD) plasma. Our results showed that DBD plasma exposure at 2.1 W for 15 s could improve boar sperm quality by increasing exon methylation level of adenosine monophosphate-activated protein kinase (AMPK) and thus improving the glycolytic flux, mitochondrial function, and antioxidant capacity without damaging the integrity of sperm DNA and acrosome. In addition, DBD plasma could rescue DNA methyltransferase inhibitor decitabine-caused low sperm quality through reducing the oxidative stress and mitochondrial damage. Therefore, the application of non-thermal plasma provides a new strategy for reducing sperm oxidative damage and improving sperm quality, which shows a great potential in assisted reproduction to solve the problem of male infertility.

Medical gas plasma technology: Roadmap on cancer treatment and immunotherapy

Despite continuous therapeutic progress, cancer remains an often fatal disease. In the early 2010s, first evidence in rodent models suggested promising antitumor action of gas plasma technology. Medical gas plasma is a partially ionized gas depositing multiple physico-chemical effectors onto tissues, especially reactive oxygen and nitrogen species (ROS/RNS). Today, an evergrowing body of experimental evidence suggests multifaceted roles of medical gas plasma-derived therapeutic ROS/RNS in targeting cancer alone or in combination with oncological treatment schemes such as ionizing radiation, chemotherapy, and immunotherapy. Intriguingly, gas plasma technology was recently unraveled to have an immunological dimension by inducing immunogenic cell death, which could ultimately promote existing cancer immunotherapies via in situ or autologous tumor vaccine schemes. Together with first clinical evidence reporting beneficial effects in cancer patients following gas plasma therapy, it is time to summarize the main concepts along with the chances and limitations of medical gas plasma onco-therapy from a biological, immunological, clinical, and technological point of view.

Current Status and Future Trends of Cold Atmospheric Plasma as an Oncotherapy

Cold atmospheric plasma (CAP), a redox modulation tool, is capable of inhibiting a wide spectrum of cancers and has thus been proposed as an emerging onco-therapy. However, with incremental successes consecutively reported on the anticancer efficacy of CAP, no consensus has been made on the types of tumours sensitive to CAP due to the different intrinsic characteristics of the cells and the heterogeneous design of CAP devices and their parameter configurations. These factors have substantially hindered the clinical use of CAP as an oncotherapy. It is thus imperative to clarify the tumour types responsive to CAP, the experimental models available for CAP-associated investigations, CAP administration strategies and the mechanisms by which CAP exerts its anticancer effects with the aim of identifying important yet less studied areas to accelerate the process of translating CAP into clinical use and fostering the field of plasma oncology.

Non-Thermal Plasma Application in Medicine-Focus on Reactive Species Involvement

Non-thermal plasma (NTP) application in medicine is a dynamically developing interdisciplinary field. Despite the fact that basics of the plasma phenomenon have been known since the 19th century, growing scientific attention has been paid in recent years to the use of plasma in medicine. Three most important plasma-based effects are pivotal for medical applications: (i) inactivation of a broad spectrum of microorganisms, (ii) stimulation of cell proliferation and angiogenesis with lower plasma treatment intensity, and (iii) inactivation of cells by initialization of cell death with higher plasma intensity. In this review, we explain the underlying chemical processes and reactive species involvement during NTP in human (or animal) tissues, as well as in bacteria inactivation, which leads to sterilization and indirectly supports wound healing. In addition, plasma-mediated modifications of medical surfaces, such as surgical instruments or implants, are described. This review focuses on the existing knowledge on NTP-based in vitro and in vivo studies and highlights potential opportunities for the development of novel therapeutic methods. A full understanding of the NTP mechanisms of action is urgently needed for the further development of modern plasma-based medicine.

Current State of Cold Atmospheric Plasma and Cancer-Immunity Cycle: Therapeutic Relevance and Overcoming Clinical Limitations Using Hydrogels

Cold atmospheric plasma (CAP) is a partially ionized gas that gains attention as a well-tolerated cancer treatment that can enhance anti-tumor immune responses, which are important for durable therapeutic effects. This review offers a comprehensive and critical summary on the current understanding of mechanisms in which CAP can assist anti-tumor immunity: induction of immunogenic cell death, oxidative post-translational modifications of the tumor and its microenvironment, epigenetic regulation of aberrant gene expression, and enhancement of immune cell functions. This should provide a rationale for the effective and meaningful clinical implementation of CAP. As discussed here, despite its potential, CAP faces different clinical limitations associated with the current CAP treatment modalities: direct exposure of cancerous cells to plasma, and indirect treatment through injection of plasma-treated liquids in the tumor. To this end, a novel modality is proposed: plasma-treated hydrogels (PTHs) that can not only help overcome some of the clinical limitations but also offer a convenient platform for combining CAP with existing drugs to improve therapeutic responses and contribute to the clinical translation of CAP. Finally, by integrating expertise in biomaterials and plasma medicine, practical considerations and prospective for the development of PTHs are offered.

Acquired non-thermal plasma resistance mediates a shift towards aerobic glycolysis and ferroptotic cell death in melanoma

AIMS

To gain insights into the underlying mechanisms of NTP therapy sensitivity and resistance, using the first-ever NTP-resistant cell line derived from sensitive melanoma cells (A375).

METHODS

Melanoma cells were exposed to NTP and re-cultured for 12 consecutive weeks before evaluation against the parental control cells. Whole transcriptome sequencing analysis was performed to identify differentially expressed genes and enriched molecular pathways. Glucose uptake, extracellular lactate, media acidification, and mitochondrial respiration was analyzed to determine metabolic changes. Cell death inhibitors were used to assess the NTP-induced cell death mechanisms, and apoptosis and ferroptosis was further validated via Annexin V, Caspase 3/7, and lipid peroxidation analysis.

RESULTS

Cells continuously exposed to NTP became 10 times more resistant to NTP compared to the parental cell line of the same passage, based on their half-maximal inhibitory concentration (IC50). Sequencing and metabolic analysis indicated that NTP-resistant cells had a preference towards aerobic glycolysis, while cell death analysis revealed that NTP-resistant cells exhibited less apoptosis but were more vulnerable to lipid peroxidation and ferroptosis.

CONCLUSIONS

A preference towards aerobic glycolysis and ferroptotic cell death are key physiological changes in NTP-resistance cells, which opens new avenues for further, in-depth research into other cancer types.

Modulation of the Tumor-Associated Immuno-Environment by Non-Invasive Physical Plasma

Over the past 15 years, investigating the efficacy of non-invasive physical plasma (NIPP) in cancer treatment as a safe oxidative stress inducer has become an active area of research. So far, most studies focused on the NIPP-induced apoptotic death of tumor cells. However, whether NIPP plays a role in the anti-tumor immune responses need to be deciphered in detail. In this review, we summarized the current knowledge of the potential effects of NIPP on immune cells, tumor-immune interactions, and the immunosuppressive tumor microenvironment. In general, relying on their inherent anti-oxidative defense systems, immune cells show a more resistant character than cancer cells in the NIPP-induced apoptosis, which is an important reason why NIPP is considered promising in cancer management. Moreover, NIPP treatment induces immunogenic cell death of cancer cells, leading to maturation of dendritic cells and activation of cytotoxic CD8⁺ T cells to further eliminate the cancer cells. Some studies also suggest that NIPP treatment may promote anti-tumor immune responses via other mechanisms such as inhibiting tumor angiogenesis and the desmoplasia of tumor stroma. Though more evidence is required, we expect a bright future for applying NIPP in clinical cancer management.