The destruction of biological activity such as senescence and apoptosis caused by oxidative stress could play a pivotal role in the poor therapeutic efficiency of bone marrow mesenchymal stem cells (BMSCs) transplantation. Mitoquinone (MitoQ) has a highly effective mitochondrial antioxidant effect, and has been widely used in many oxidative damage models. This study aimed to investigate the protective effect of MitoQ on the oxidative stress-mediated senescence of canine BMSCs and the underlying mechanism. The senescence of BMSCs was determined by senescence-associated β-galactosidase staining and quantitative real-time PCR. The expression of p-Nrf2 protein was detected by Western blotting. The results demonstrated that, as BMSCs were expanded in vitro, the senescent phenotype appeared. And the senescence of BMSCs may be caused by oxidative stress, manifested by increasing the level of ROS and decreasing the activity of antioxidant enzymes. Treatment of MitoQ down-regulated the mRNA levels of senescence-related and apoptosis-related genes, but up-regulated the mRNA levels of proliferation-related genes. Meanwhile, ROS generation and senescent activity were reduced in MitoQ-treated BMSCs. Further mechanism studies showed that MitoQ obviously promoted Nrf2 phosphorylation, and also facilitated the translocation of Nrf2 into the nucleus. Moreover, treatment of MitoQ increased the mRNA levels of downstream antioxidant genes and enhanced the activities of superoxide dismutase, catalase, and glutathione peroxidase. Thus, our study revealed that MitoQ, via the Nrf2/ARE signaling pathway, exerts an antioxidant effect as well as potentially delays OS-mediated senescence during BMSCs that were expanded in vitro, which may serve as a novel strategy to optimize the clinical application of BMSCs.

氧化应激引起的衰老、凋亡等生物活性的破坏可能是导致骨髓间充质干细胞（BMSCs）移植治疗效果不佳的关键。米托醌 (MitoQ) 具有高效的线粒体抗氧化作用，已广泛应用于多种氧化损伤模型。本研究旨在探讨MitoQ对氧化应激介导的犬骨髓间充质干细胞衰老的保护作用及其机制。通过衰老相关的β-半乳糖苷酶染色和定量实时PCR确定BMSCs的衰老。Western blotting检测p-Nrf2蛋白的表达。结果表明，随着 BMSCs 在体外扩增，出现衰老表型。而 BMSCs 的衰老可能是由氧化应激引起的，表现为 ROS 水平升高，抗氧化酶活性降低。MitoQ 处理下调衰老相关和凋亡相关基因的 mRNA 水平，但上调增殖相关基因的 mRNA 水平。同时，在 MitoQ 处理的 BMSCs 中，ROS 的产生和衰老活性降低。进一步的机制研究表明，MitoQ 明显促进了 Nrf2 的磷酸化，也促进了 Nrf2 易位进入细胞核。此外，MitoQ 的处理增加了下游抗氧化基因的 mRNA 水平，并增强了超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶的活性。因此，我们的研究表明 MitoQ 通过 Nrf2/ARE 信号通路，