Abstract
Cisplatin is an effective chemotherapeutic agent with dose-limiting toxicity in non-target tissues. Hyperbaric oxygen therapy (HBOT) and mitochondrial transplantation (MitoTr) have been explored as supportive strategies in preclinical models. We examined whether HBOT and/or MitoTr modulate cisplatin-associated reductions in MTT metabolic activity and oxidative balance in healthy human mesenchymal stem cells (hMSCs) under incubator versus hyperbaric conditions. Bone marrow-derived hMSCs were seeded at 5 × 103 cells/well and exposed to cisplatin at an experimentally determined MTT-based LD50 (148 μM; 150 μM used). A delayed adjunctive intervention protocol was applied after LD50-level exposure: cisplatin or vehicle for 24 h, followed by 4 h MitoTr co-incubation (10× or 100× cell-number-scaled dose), then three HBOT sessions (90 min, 2.1 ATA) or matched incubator control. Endpoints were MTT absorbance (NAD(P)H-dependent oxidoreductase activity), total antioxidant status, total oxidant status, and oxidative stress index, analyzed by two-way ANOVA with Tukey post hoc. At 150 μM cisplatin, MTT absorbance was markedly reduced in all cisplatin-containing groups under both conditions (all p < 0.001 vs controls), and neither HBOT nor MitoTr restored MTT signal to control levels. Among cisplatin-free groups, M10 under HBOT exceeded control HB MTT absorbance (p = 0.009), whereas M10 under incubator conditions did not differ from control. HBOT reduced baseline MTT absorbance in cisplatin-free groups relative to matched incubator controls (p < 0.001). MitoTr lowered oxidant status under incubator conditions; HBOT improved redox indices in mitochondria-free groups. Under the LD50-level conditions tested, neither HBOT nor MitoTr restored NAD(P)H-dependent oxidoreductase (MTT) activity in hMSCs. Under non-toxic conditions, both modalities produced context-dependent redox changes. Whether lower, clinically relevant cisplatin exposures would yield partial protection remains an open question.