Effects of Short-and Long-Lived ROS Generated by a Cold Atmospheric Plasma Jet on Human Xenograft A2058 Melanoma and Associated Side Effects in a Nude Mouse Model

This study evaluated the therapeutic efficacy of longlived and short-lived reactive oxygen species (ROS) generated by argon cold atmospheric plasma (Ar-CAP) under water-soaking conditions in a murine model of treating cutaneous melanoma. Potential side effects associated with Ar-CAP treatment in mice were also assessed. While direct CAP treatment and indirect treatment via injection of plasma-treated solutions have been reported in previous studies, the distinct modalities employed have made it challenging to delineate the specific contributions of longlived and short-lived ROS in vivo. In this study, direct and indirect CAP treatments were applied to melanoma xenografts under comparable conditions. Both modalities effectively inhibited tumor progression, with direct treatment leading to a more pronounced tumor volume reduction in the early stages. Over a six-month observation of CAP-treated nude mice, no significant adverse effects were noted in pain response, skin appearance, blood cell counts, or histopathological evaluation, aside from slight elevations in liver enzymes (AST and ALT). These results suggest that Ar-CAP treatment is both effective and well-tolerated, with short-lived ROS playing a key role in enhancing antitumor activity.