Stem Cell Biology Department, ICMR-National Institute for Research in Reproductive Health, Jehangir Merwanji Street, Parel, Mumbai, 400 012, India.
J Ovarian Res. 2020 Apr 17;13(1):39. doi: 10.1186/s13048-020-00647-2.
A recent study published in the journal Nature Communications from Karolinska Institute, Sweden was unable to detect stem cells in adult human ovarian cortex by single-cell RNAseq and by studying cell surface antigen profiles by flow cytometry studies. Their findings are startling since stem cells have been well characterized in the adult mammalian ovary of several species including mouse, rabbit, monkey, sheep, pig and humans. Ovarian stem cells include pluripotent, very small embryonic-like stem cells (VSELs) and slightly bigger ovarian stem cells (OSCs) which are easily visualized in smears obtained by gently scraping the ovary surface. The potential of ovarian stem cells to differentiate into oocyte-like structures in vitro and also resulting in the birth of mouse pups has been reported. A possible role of ovarian VSELs in initiation of ovarian cancers has also been delineated. The ovarian stem cells can also be collected by enzymatic digestion of ovarian tissue for various studies, taking care to always pellet the cells suspension at 1000 g since this high speed is required to collect the small-sized stem cell populations (VSELs & OSCs) with high nucleo-cytoplasmic ratio. These stem cells invariably get discarded when cells suspension is spun at lower speed. The cells were spun at 300 g for various experiments in the Karolinska study and this is the underlying reason for their negative results. Stem cells were inadvertently and unknowingly discarded and never got analyzed by single-cell RNAseq and flow cytometry experiments. To conclude, stem cells surely exist in adult mammalian ovary and their role during neo-oogenesis and primordial follicle assembly under physiological conditions is currently being investigated.
最近，瑞典卡罗林斯卡研究所（Karolinska Institute）在《自然通讯》杂志上发表的一项研究未能通过单细胞 RNAseq 以及通过流式细胞术研究细胞表面抗原谱来检测成年人类卵巢皮质中的干细胞。他们的发现令人震惊，因为干细胞在包括小鼠、兔子、猴子、绵羊、猪和人类在内的几种哺乳动物的卵巢中已经得到了很好的描述。卵巢干细胞包括多能的、非常小的胚胎样干细胞（VSELs）和稍大的卵巢干细胞（OSCs），它们在轻轻刮擦卵巢表面获得的涂片上很容易被观察到。已经报道了卵巢干细胞在体外分化为卵母细胞样结构的潜力，并且还导致了小鼠幼仔的出生。卵巢 VSELs 在卵巢癌发生中的可能作用也已经被描绘出来。卵巢干细胞也可以通过卵巢组织的酶消化来收集，用于各种研究，注意始终将细胞悬浮液在 1000g 下沉淀，因为这是收集具有高核质比的小尺寸干细胞群体（VSELs 和 OSCs）所需的高速。当细胞悬浮液以较低的速度旋转时，这些干细胞总是会被丢弃。在卡罗林斯卡研究所的这项研究中，各种实验将细胞旋转 300g，这就是他们得出阴性结果的原因。干细胞被不经意地和无意识地丢弃了，从未通过单细胞 RNAseq 和流式细胞术实验进行分析。总之，干细胞确实存在于成年哺乳动物的卵巢中，它们在新卵发生和原始卵泡形成过程中的作用目前正在研究中。
