**Background:** Deoxynivalenol (DON) is a trichothecene mycotoxin that frequently contaminates food and feed globally. DON exposure induces reactive oxygen species (ROS) production and oxidative stress, which is an early event in its toxicity. The liver is the primary organ responsible for detoxifying DON, yet the effects of low-dose exposure remain poorly controlled. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) have shown therapeutic potential for liver injury, but their mechanism in combating DON-induced oxidative damage was unclear. The authors hypothesized that the lipid membrane of BMSC-exos, rich in polyunsaturated fatty acids (PUFAs) and with a small particle size (40–160 nm), might preferentially react with free radicals, serving as a "helpful defensive line" against hepatic oxidative damage.
**Methods:** Eight-week-old SPF C57BL/6J male mice were randomly divided into four groups (N=12 each): control, DON (2 mg/kg bw/day), DON + L-exo (4 mg/kg bw/day BMSC-exos), and DON + H-exo (16 mg/kg bw/day BMSC-exos). All treatments were administered via oral gavage for 30 days. BMSC-exos were isolated from rat bone marrow stem cells using the exoEasy Maxi kit and characterized by TEM, NTA, and Western blot (CD9, CD63, CD81 markers). Liver function was assessed by serum ALT and AST levels. Inflammatory cytokines (IL-6, TNF-α) were measured by ELISA. Hepatic lipid peroxidation was evaluated by MDA and 4-HNE content. Antioxidant enzyme activities (total SOD, Cu/Zn SOD, Mn SOD, CAT, GPX) were measured using commercial kits. Untargeted lipidomics of BMSC-exos was performed using UHPLC-MS/MS, identifying 144 lipids. Hepatic oxylipin profiling was conducted using HPLC-MS/MS, detecting 62 oxylipins. Statistical analysis included OPLS-DA, volcano plot analysis (p < 0.05, FC > 2 or < 0.5), and Pearson correlation.
**Key Results:** BMSC-exos characterization confirmed typical cup-like morphology, size distribution of 30–200 nm, and positive expression of CD63, CD9, and CD81. Lipidomics revealed 144 lipids in BMSC-exos, including 61 phosphatidylcholines (PCs), 46 sphingomyelins (SMs), 19 phosphatidylethanolamines (PEs), 13 free fatty acids (FFAs), 2 phosphatidylinositols (PIs), 2 ceramides (Cers), and 1 triacylglycerol (TAG). PC had the highest unsaturation index (UI) at 65%. DON exposure significantly increased serum ALT, AST, IL-6, and TNF-α levels compared to control. BMSC-exos at 16 mg/kg bw/day significantly inhibited ALT, IL-6, and TNF-α levels. Hepatic MDA and 4-HNE were significantly increased after DON exposure, and BMSC-exos significantly decreased these lipid peroxidation markers. SOD and Cu/Zn SOD activities were increased after high-dose BMSC-exos administration, while CAT and GPX were not significantly changed. Oxylipin profiling detected 62 oxylipins in the liver. OPLS-DA showed complete separation between DON and DON+H-exo groups, indicating BMSC-exos significantly altered the DON-induced hepatic oxylipin profile. Most oxylipins were further elevated after BMSC-exos administration compared to DON alone. Pathway enrichment analysis identified arachidonic acid and linoleic acid metabolic pathways as primarily affected. Venn diagram analysis of differential metabolites (VIP > 1, p < 0.05) identified 18-HETE, 9-HODE, 9,10-EpOME, and 12,13-diHOME as key oxylipins altered by BMSC-exos in a dose-dependent manner. Correlation analysis showed Cu/Zn SOD had the strongest positive correlation with targeted oxylipins, while 4-HNE was negatively correlated.
**Clinical Implications:** This study provides evidence that BMSC-exos can ameliorate DON-induced liver damage through a novel mechanism involving their PUFA-rich lipid membranes acting as sacrificial targets for free radicals, thereby reducing lipid peroxidation and inflammation. The dose-dependent hepatoprotective effect, with significant benefits at 16 mg/kg bw/day, suggests potential therapeutic applications for mycotoxin-induced liver injury. The finding that BMSC-exos resist free radicals through their PUFAs rather than altering liver content to change the oxylipin profile supports the "first defensive line" hypothesis. The synergistic role of Cu/Zn SOD with BMSC-exos in terminating lipid peroxidation chain reactions highlights a potential combined therapeutic approach. Future research directions include engineering BMSC-exos with encapsulated antioxidants to optimize their protective effects against oxidative damage.