Science关注:完全体外培育的卵细胞,能否解决不孕难题?
2018/02/11
从冻结卵细胞到培育人工精细胞,科学家们在生殖领域取得了多项“零突破”。现在,科学家们又第一次实现了人类卵细胞从发育初期到成熟期整个生命周期的体外培育。但是,这些卵细胞是否足够健康、能否与精子结合,仍然有待验证。

实验室培育卵细胞(图片来源:David Albertini)

这一创新成果发表在最新一期的《Molecular Human Reproduction》期刊上。“借助这一成果,我们可以解析卵细胞在不同阶段的发育情况,从而为不孕治疗、再生医学提供新线索。”团队负责人、爱丁堡大学的生殖生物学家Evelyn Telfer强调道。

这一方法适用于一些特殊的癌症患者,在她们接受化疗(可能会损伤生殖细胞)之前,从卵巢中提取出尚未成熟的卵细胞,让其在实验室发育,并存储至需要接受下一步使命之时。

图片来源:Molecular Human Reproduction(doi.org/10.1093/molehr/gay002)

最新成果

早在2008年,Evelyn Telfer和团队就在“体外培育卵细胞”尝试中取得了重要进展,完成了其中一半的工作。

卵母细胞最初包裹在原始卵泡中,青春期后,每月通常只有一个原始卵泡开始生长,并释放出发育成熟的卵细胞。想要体外培育卵细胞,需要寻找合适的“培养基”,以此替代天然的卵泡环境支撑细胞发育的整个过程。通过研究,Evelyn Telfer团队从卵巢中采集出原始卵泡,并在体外培育至卵泡发育的中间阶段。

2015年,芝加哥西北大学的科研团队完成了“最后一棒”——体外培养发育中卵泡,最终获得成熟的卵细胞。

现在,Evelyn Telfer团队首次完成了卵细胞整个发育周期的体外培养。他们从10名经历择期剖腹产的女性卵巢中采集样本,共获得87枚卵泡,最终在实验室共获得9枚发育成熟的卵细胞。

4大步骤

图片来源:Prof Evelyn Telfer and Dr Marie McLaughlin, the University of Edinburgh

根据最新研究成果,卵细胞体外培育需要4大步骤。首先,从卵巢组织中采集非常小、不成熟的卵细胞,放置于实验室的培养液中培育。

第二步,卵泡开始生长,经历最初的发育,长至最初的两倍大。

第三步,从卵泡中小心分离出脆弱、尚未成熟的卵细胞及其周围的一些细胞,将它们转移至营养更为丰富的膜蛋白上,继续发育。

最后,卵细胞发育成熟,做好受精的准备。

还在继续

但是,这些完全在体外培养成熟的卵细胞并没有“真正胜利”。

“研究团队尚未对其进行遗传分析,并不确定它们的健康状况。”来自于日本京都大学的Mitinori Saitou教授对此表示担忧,因为在实验室培育的过程并不能反映卵细胞真实发育的细节。他所在的团队曾利用小鼠胚胎干细胞培育出成熟且具有生育能力的卵细胞,

Evelyn Telfer教授表示:“在实验室培育卵细胞可以扩大现有生育治疗的范围。目前,我们正致力于优化培育卵细胞发育的条件,并评估它们的健康程度。我们希望,能够得到监管部门的批准,从而验证它们能否完成受精。”

参考资料:

Lab-grown eggs could pave way towards new fertility treatments

These lab-grown human eggs could combat infertility—if they prove healthy

所有文章仅代表作者观点,不代表本站立场。如若转载请联系原作者。
查看更多
  • Metaphase II oocytes from human unilaminar follicles grown in a multi-step culture system

    STUDY QUESTION Can complete oocyte development be achieved from human ovarian tissue containing primordial/unilaminar follicles and grown in vitro in a multi-step culture to meiotic maturation demonstrated by the formation of polar bodies and a Metaphase II spindle? SUMMARY ANSWER Development of human oocytes from primordial/unilaminar stages to resumption of meiosis (Metaphase II) and emission of a polar body was achieved within a serum free multi-step culture system. WHAT IS KNOWN ALREADY Complete development of oocytes in vitro has been achieved in mouse, where in vitro grown (IVG) oocytes from primordial follicles have resulted in the production of live offspring. Human oocytes have been grown in vitro from the secondary/multi-laminar stage to obtain fully grown oocytes capable of meiotic maturation. However, there are no reports of a culture system supporting complete growth from the earliest stages of human follicle development through to Metaphase II. STUDY DESIGN, SIZE, DURATION Ovarian cortical biopsies were obtained with informed consent from women undergoing elective caesarean section (mean age: 30.7 ± 1.7; range: 25–39 years, n = 10). PARTICIPANTS/MATERIALS, SETTING, METHODS Laboratory setting. Ovarian biopsies were dissected into thin strips, and after removal of growing follicles were cultured in serum free medium for 8 days (Step 1). At the end of this period secondary/multi-laminar follicles were dissected from the strips and intact follicles 100–150 μm in diameter were selected for further culture. Isolated follicles were cultured individually in serum free medium in the presence of 100 ng/ml of human recombinant Activin A (Step 2). Individual follicles were monitored and after 8 days, cumulus oocyte complexes (COCs) were retrieved by gentle pressure on the cultured follicles. Complexes with complete cumulus and adherent mural granulosa cells were selected and cultured in the presence of Activin A and FSH on membranes for a further 4 days (Step 3). At the end of Step 3, complexes containing oocytes >100 μm diameter were selected for IVM in SAGE medium (Step 4) then fixed for analysis. MAIN RESULTS AND THE ROLE OF CHANCE Pieces of human ovarian cortex cultured in serum free medium for 8 days (Step 1) supported early follicle growth and 87 secondary follicles of diameter 120 ± 6 μm (mean ± SEM) could be dissected for further culture. After a further 8 days, 54 of the 87 follicles had reached the antral stage of development. COCs were retrieved by gentle pressure from the cultured follicles and those with adherent mural granulosa cells (n = 48) were selected and cultured for a further 4 days (Step 3). At the end of Step 3, 32 complexes contained oocytes >100 μm diameter were selected for IVM (Step 4). Nine of these complexes contained polar bodies within 24 h and all polar bodies were abnormally large. Confocal immuno-histochemical analysis showed the presence of a Metaphase II spindle confirming that these IVG oocytes had resumed meiosis but their developmental potential is unknown. LIMITATIONS, REASONS FOR CAUTION This is a small number of samples but provides proof of concept that complete development of human oocytes can occur in vitro. Further optimization with morphological evaluation and fertilization potential of IVG oocytes is required to determine whether they are normal. WIDER IMPLICATIONS OF THE FINDINGS The ability to develop human oocytes from the earliest follicular stages in vitro through to maturation and fertilization would benefit fertility preservation practice. STUDY FUNDING/COMPETING INTEREST(S) Funded by MRC Grants (G0901839 and MR/L00299X/1). No competing interests.

    展开 收起
发表评论 我在frontend\modules\comment\widgets\views\文件夹下面 test