Small extracellular vesicles derived from Nrf2-stimulated bone marrow mesenchymal stem cells ameliorated the testis damage and fertility disorder in doxorubicin-treated mice.

Bone marrow mesenchymal/stromal stem cell (BMSC)-derived small extracellular vesicles (sEVs) are promising therapeutic agents owing to their low immunogenicity and ability to cross biological barriers. Doxorubicin (DOX), a common chemotherapeutic agent, damages testicular tissue. This study aimed to enhance the antioxidant activity of sEVs by activating the Nrf2 gene in BMSCs and evaluate their therapeutic potential for DOX-induced fertility disorders. Testicular damage was induced by DOX in NMRI mice. BMSCs from Wistar rats were treated with Bardoxolone methyl (BaMet) to upregulate Nrf2. The sEVs were isolated through differential ultracentrifugation and validated for size, morphology, and protein expression. The antioxidant activity was assessed using specific kits. sEVs containing 10 μg of proteins were injected intravenously into DOX-injured mice. After 35 days, the testes were collected for histopathological, hormonal, and immunological analyses, along with the evaluation of sperm parameters. Male and female mice were paired to determine the pregnancy rates. BaMet-sEVs exhibited higher antioxidant activity and significantly improved serum testosterone levels, testicular cell populations, sperm viability, and motility in DOX-injured mice. In addition, BaMet-sEVs treatment enhanced fertility and increased the number of offspring. This study demonstrated the effectiveness of BaMet-sEVs in mitigating DOX-induced testicular damage.