Testing The Health And Therapeutic Potential Of In Vitro Derived Oocytes For The Restoration Of Female Fertility And The Treatment of Infertility

在卵巢组织内冷冻和储存非常早期的卵子已成功地用于保护可能因癌症治疗的破坏性影响而丧失卵巢功能的女孩和年轻妇女的生育能力。小块卵巢可以通过手术从患者身上取出，并在液氮温度下储存所需的时间。当患者想要组建家庭时，她储存的卵巢组织被移植回她的体内，目的是自然地或在体外受精(IVF)等辅助生殖技术的帮助下产生受精卵和怀孕。目前，全球已有150多名婴儿使用这项技术出生。然而，移植恢复生育能力的方法并不适用于所有癌症患者。对于患有白血病等血液疾病和/或乳腺癌等癌症的女孩和妇女来说，移植的组织有可能再次引发癌症。对于这些患者来说，更安全的选择是将早期卵子从冷冻解冻的卵巢组织培养到实验室中的成熟-这项技术被称为卵子的体外生长和成熟(IVGM)。然后，实验室培育的卵子可以通过试管受精进行受精，这样健康的胚胎(S)就可以转移到患者身上，产生想要的怀孕。这些技术还可以用于治疗使用捐赠者卵子进行辅助受孕的健康但不育的妇女。在实验室中开发出从卵子的最早阶段开始培养的方法是非常具有挑战性的。朝着这一目标取得了前所未有的进展。现在，在实验室里可以在人类和牛、羊等反刍动物身上生产完整大小的成熟卵子。两种不同的培养方法显示出巨大的前景，它们是：(I)21天的快速生长系统(FasGro)；(Ii)40-60天的缓慢生长系统(SloGro)。FasGro和SloGro系统是同时为人类和反刍动物的卵子开发的。然而，目前还不清楚这些方法中哪种最适合生产健康的卵子，这些卵子可以受精来生产胚胎，供未来移植以产生怀孕和婴儿。在IVGM等新技术被用于恢复癌症幸存者的生育能力或治疗不育女性之前，必须在合适的动物模型中对它们进行严格的测试，以证明它们既安全又有效。该项目旨在测试IVGM卵子作为恢复妇女生育能力的治疗方法的潜力。绵羊卵巢组织将被用作人类卵巢的模拟物。具体地说，该项目将在实验室使用FasGro和SloGro方法从冷冻解冻的绵羊卵巢组织中培养卵子。该项目将测试实验室培育的卵子的健康状况，以及它们使用试管婴儿受精的能力，并生产出将被植入并产生怀孕和活后代的胚胎。实验室提取的鸡蛋和胚胎的营养和遗传指纹将与显微镜成像相结合，用作健康筛查，以确认与体内自然生长的类似细胞相比，试管婴儿卵子是否正常。将在绵羊身上进行胚胎移植试验，以确定哪种IVGM卵子生产方法在生产健康羔羊方面最有效。将在对实验室培育的卵子产生的新生儿进行后续研究时，对健康和发育情况进行关键测量。随着这些动物成长为成年，监测将继续进行，并将与自然受孕的动物进行比较。这项研究对于选择最好的IVGM方法并确保该技术在用于治疗患者之前既有效又安全至关重要。

The freezing and banking of very early-staged eggs within ovarian tissue has been successfully used to preserve the fertility of girls and young women who are likely to lose their ovarian function as a result of the destructive effects of cancer treatments. Small pieces of the ovary can be surgically recovered from patients and stored at liquid nitrogen temperatures for as long as required. When the patient wishes to start her family, her stored ovarian tissue is transplanted back into her body with aim of producing fertile oocytes and a pregnancy either naturally or with the help of assisted reproduction technologies such as in vitro fertilisation (IVF). Over 150 babies have now been born worldwide using this technology. However, the transplantation method for fertility restoration is not suitable for all cancer patients. For girls and women with blood diseases such as leukaemia, and/or cancers such as breast cancer there is a risk that the cancer will be restarted from the transplanted tissues. For these patients a safer option is to grow the early staged eggs from the frozen-thawed ovarian tissue to maturity in the laboratory- a technology called the in vitro growth and maturation (IVGM) of eggs. The laboratory grown eggs can then be fertilised using IVF so that healthy embryo(s) can be transferred to the patient to produce the desired pregnancy. These technologies can also be used treat healthy but infertile women who are undergoing assisted conception using donor eggs. The development of methods to grow eggs from their earliest stages in the laboratory is very challenging. Never-the-less advances are being made towards this goal. It is now possible to produce full sized, mature eggs in the laboratory in both humans and ruminant species such as cows and sheep. Two different culture approaches are showing significant promise these are: (i) a fast growth system over 21 days (FasGro); and (ii) a slow growth system over 40-60 days (SloGro). The FasGro and SloGro systems have been developed in parallel for both human and ruminant eggs. However, it is not yet clear which of these methods is best at producing healthy eggs that can be fertilised to produce embryos for future transfer to produce a pregnancy and baby. Before new technologies such as IVGM can be used to restore the fertility of cancer survivors or to treat infertile women it is essential that they are rigorously tested in a suitable animal model to prove they are both safe and effective. This project aims to test the potential of IVGM eggs to used as a treatment to restore fertility in women. Sheep ovary tissues will be used as a mimic for human ovaries. Specifically, the project will grow eggs in the laboratory from frozen-thawed sheep ovary tissues using the FasGro and SloGro methods. The project will test the health of the laboratory-grown eggs and their ability to be fertilised using IVF and to produce embryos that will implant and produce a pregnancy and live offspring. The nutritional and genetic fingerprints of laboratory-derived eggs and embryos will be combined with microscope imaging and used as health screens to confirm whether the IVGM eggs are normal when compared to similar cells grown naturally in the body. An embryo transfer trial will be conducted in sheep to establish which IVGM egg production method is most effective at delivering healthy lambs. Key measurements of health and development will be made in follow-up studies of the newborn offspring from laboratory-grown eggs. Monitoring will continue as the animals grow to adulthood and will be compared to naturally conceived animals. This research is vital to enable selection of the best IVGM method and to ensure that the technology is both efficient and safe before it is used to treat patients.