Combinatorial Effects of Plasma-Treated Solution and Plasma-Treated Hydrogel with Cisplatin in Vulvar Cancer Cells

Background: Vulvar squamous cell carcinoma (VSCC) is a rare, but increasingly prevalent malignancy with limited therapeutic options in the advanced disease state. Cisplatin-based chemoradiation remains the standard of care but is constrained by cumulative toxicity. Precancerous lesions, including high-grade squamous intraepithelial lesions (HSIL) and differentiated vulvar intraepithelial neoplasia (dVIN), similarly require effective yet tolerable treatments. Non-invasive physical plasma (NIPP), a source of reactive oxygen and nitrogen species (RONS), has emerged as a promising approach for redox-based tumor modulation. This study aimed to evaluate the anti-tumor efficacy of two NIPP modalities, plasma-treated solution (PTS) and plasma-treated hydrogel (PTH) in combination with cisplatin in VSCC cells. Methods: PTS and PTH were applied as monotherapies and in sequential combination with cisplatin (plasma-first vs. cisplatin-first). RONS kinetics, cell viability, and treatment interactions were assessed following plasma monotherapy and sequential combination with cisplatin. Apoptosis and redox balance were evaluated by caspase-3/7 activity and GSH/GSSG ratios, respectively. Results: PTS induced a rapid oxidative burst, whereas PTH enabled delayed and sustained RONS release. Both modalities reduced cell viability in a time-dependent manner, with rapid cytotoxic effects observed for PTS. Plasma pre-treatment enhanced cisplatin efficacy, with higher synergy scores in the plasma-first sequence. Increased caspase-3/7 activity and decreased GSH/GSSG ratios, observed in the combination treatment of NIPP and cisplatin, indicated enhanced oxidative stress and apoptotic priming. Conclusions: PTS and PTH exhibit intrinsic anti-tumor activity and sensitize VSCC cells to cisplatin through redox modulation. These findings support the integration of plasma-based strategies into combinatorial therapeutic approaches for VSCC and its precancerous lesions.