Development and Stem Cell Program and Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia.
Applied Embryology Department, High Institute for Infertility Diagnosis and Assisted Reproductive Technologies, AL-Nahrain University, Baghdad, Iraq.
Hum Reprod. 2021 Feb 18;36(3):771-784. doi: 10.1093/humrep/deaa300.
Do mitochondria-targeted therapies reverse ageing- and oxidative stress-induced spindle defects in oocytes from mice and humans?
Exposure to MitoQ or BGP-15 during IVM protected against spindle and chromosomal defects in mouse oocytes exposed to oxidative stress or derived from reproductively aged mice whilst MitoQ promoted nuclear maturation and protected against chromosomal misalignments in human oocytes.
Spindle and chromosomal abnormalities in oocytes are more prevalent with maternal aging, increasing the risk of aneuploidy, miscarriage and genetic disorders such as Down's syndrome. The origin of compromised oocyte function may be founded in mitochondrial dysfunction and increased reactive oxygen species (ROS).
STUDY DESIGN, SIZE, DURATION: Oocytes from young and old mice were treated with MitoQ and/or BGP-15 during IVM. To directly induce mitochondrial dysfunction, oocytes were treated with H2O2, and then treated the MitoQ and/or BGP-15. Immature human oocytes were cultured with or without MitoQ. Each experiment was repeated at least three times, and data were analyzed by unpaired-sample t-test or chi-square test.
PARTICIPANTS/MATERIALS, SETTING, METHODS: Immature germinal vesicle (GV) stage oocytes from 1-, 12- and 18-month-old mice were obtained from preovulatory ovarian follicles. Oocytes were treated with MitoQ and/or BGP-15 during IVM. GV-stage human oocytes were cultured with or without MitoQ. Mitochondrial membrane potential and mitochondrial ROS were measured by live-cell imaging. Meiotic spindle and chromosome alignments were visualized by immunofluorescent labeling of fixed oocytes and the 3-dimensional images were analyzed by Imaris.
MitoQ or BGP-15 during IVM protects against spindle and chromosomal defects in oocytes exposed to oxidative stress and in oocytes from aged mice (P < 0.001). In human oocytes, the presence of MitoQ during IVM promoted nuclear maturation and had a similar positive effect in protecting against chromosomal misalignments (P < 0.001).
LIMITATIONS, REASONS FOR CAUTION: Our study identifies two excellent candidates that may help to improve fertility in older women. However, these potential therapies must be tested for efficacy in clinical IVM systems, and undergo thorough examination of resultant offspring in preclinical models before utilization.
Our results using in-vitro systems for oocyte maturation in both mouse and human provide proof of principle that mitochondrially targeted molecules such as MitoQ and BGP-15 may represent a novel therapeutic approach against maternal aging-related spindle and chromosomal abnormalities.
STUDY FUNDING/COMPETING INTEREST(S): The project was financially supported by the National Health and Medical Research Council and Australian Research Council, Australia. U.A.-Z. was supported by the Iraqi Higher Education and Scientific Research Ministry PhD scholarship and O.C. was supported by TUBITAK-1059B191601275. M.P.M. consults for MitoQ Inc. and holds patents in mitochondria-targeted therapies. R.L.R. is an inventor on patents relating to the use of BGP-15 to improve gamete quality.
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线粒体靶向治疗能否逆转小鼠和人类卵母细胞中衰老和氧化应激引起的纺锤体缺陷？
在体外成熟过程中暴露于 MitoQ 或 BGP-15 可防止暴露于氧化应激或来自生殖衰老小鼠的卵母细胞中的纺锤体和染色体缺陷，而 MitoQ 可促进核成熟并防止人类卵母细胞中的染色体错位。
卵母细胞中的纺锤体和染色体异常在母体衰老时更为普遍，增加了非整倍体、流产和遗传疾病（如唐氏综合征）的风险。卵母细胞功能受损的原因可能源于线粒体功能障碍和活性氧（ROS）增加。
研究设计、大小和持续时间：在体外成熟过程中，用 MitoQ 和/或 BGP-15 处理年轻和年老小鼠的卵母细胞。为了直接诱导线粒体功能障碍，用 H2O2 处理卵母细胞，然后用 MitoQ 和/或 BGP-15 处理。用或不用 MitoQ 培养未成熟的人类卵母细胞。每个实验至少重复三次，并通过独立样本 t 检验或卡方检验分析数据。
参与者/材料、地点、方法：从 1 个月、12 个月和 18 个月大的小鼠的原始卵母细胞中获得未成熟的生发泡（GV）期卵母细胞。在体外成熟过程中用 MitoQ 和/或 BGP-15 处理卵母细胞。用或不用 MitoQ 培养 GV 期人类卵母细胞。通过活细胞成像测量线粒体膜电位和线粒体 ROS。通过固定卵母细胞的免疫荧光标记可视化减数分裂纺锤体和染色体排列，并通过 Imaris 分析 3 维图像。
在体外成熟过程中用 MitoQ 或 BGP-15 处理可防止氧化应激和衰老小鼠卵母细胞中的纺锤体和染色体缺陷（P < 0.001）。在人类卵母细胞中，MitoQ 在体外成熟过程中的存在促进了核成熟，并具有类似的防止染色体错位的积极作用（P < 0.001）。
局限性、谨慎的原因：我们的研究确定了两种可能有助于改善老年妇女生育能力的优秀候选药物。然而，这些潜在的治疗方法必须在临床 IVM 系统中进行疗效测试，并在临床前模型中对由此产生的后代进行彻底检查，然后才能使用。
我们在小鼠和人类体外成熟卵母细胞中使用的体内系统研究结果提供了原理证明，即 MitoQ 和 BGP-15 等靶向线粒体的分子可能代表了一种针对与母体衰老相关的纺锤体和染色体异常的新治疗方法。
研究资金/竞争利益：该项目由澳大利亚国家健康与医学研究委员会和澳大利亚研究委员会资助。U.A.-Z. 得到了伊拉克高等教育和科研部博士奖学金的支持，O.C. 得到了 TUBITAK-1059B191601275 的支持。M.P.M. 为 MitoQ Inc. 提供咨询服务，并拥有与靶向线粒体治疗相关的专利。R.L.R. 是一项关于使用 BGP-15 改善配子质量的专利的发明人。
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