PrimeGen Biotech, Irvine, CA 92618, USA.
Differentiation. 2010 Mar;79(3):159-70. doi: 10.1016/j.diff.2010.01.001. Epub 2010 Feb 6.
General belief in reproductive biology is that in most mammals female germ line stem cells are differentiated to primary oocytes during fetal development and oogenesis starts from a pool of primordial follicles after birth. This idea has been challenged previously by using follicle kinetics studies and demonstration of mitotically active germ cells in the postnatal mouse ovary (Johnson et al., 2004; Kerr et al., 2006; Zhang et al., 2008). However, the existence of a population of self-renewing ovarian germ line stem cells in postnatal mammals is still controversial (Eggan et al., 2006; Telfer et al., 2005; Gosden, 2004). Recently, production of offspring from a germ line stem cell line derived from the neonatal mouse ovary was reported (Zou et al., 2009). This report strongly supports the existence of germ line stem cells and their ability to expand in vitro. Recently, using a transgenic mouse model in which GFP is expressed under a germ cell-specific Oct-4 promoter, we isolated and generated multipotent cell lines from male germ line stem cells (Izadyar et al., 2008). Using the same strategy we isolated and derived cell lines from postnatal mouse ovary. Interestingly, ovarian germ line stem cells expanded in the same culture conditions as the male suggesting that they have similar requirements for their self-renewal. After 1 year of culture and many passages, ovarian germ line stem cells maintained their characteristics and telomerase activity, expressed germ cell and stem cell markers and revealed normal karyotype. As standard protocol for differentiation induction, these cells were aggregated and their ability to form embryoid bodies (EBs) was investigated. EBs generated in the presence of growth factors showed classical morphology and expressed specific markers for three germ layers. However, in the absence of growth promoting factors EBs were smaller and large cells with the morphological and molecular characteristics of oocytes were formed. This study shows the existence of a population of germ line stem cell in postnatal mouse ovary with multipotent characteristics.
人们普遍认为，在大多数哺乳动物中，雌性生殖系干细胞在胎儿发育过程中分化为初级卵母细胞，并且出生后卵母细胞发生的起始于原始卵泡池。先前的卵泡动力学研究和对出生后小鼠卵巢有丝分裂活性生殖细胞的证明挑战了这一观点（Johnson 等人，2004 年；Kerr 等人，2006 年；Zhang 等人，2008 年）。然而，出生后哺乳动物中是否存在自我更新的生殖系干细胞群体仍存在争议（Eggan 等人，2006 年；Telfer 等人，2005 年；Gosden，2004 年）。最近，据报道，从新生小鼠卵巢的生殖系干细胞系中产生了后代（Zou 等人，2009 年）。该报告强烈支持生殖系干细胞的存在及其在体外扩增的能力。最近，我们使用一种转基因小鼠模型，其中 GFP 在生殖细胞特异性 Oct-4 启动子的控制下表达，从雄性生殖系干细胞中分离并生成多能细胞系（Izadyar 等人，2008 年）。使用相同的策略，我们从出生后小鼠的卵巢中分离并衍生出细胞系。有趣的是，在与雄性相同的培养条件下，卵巢生殖系干细胞扩增，这表明它们对自我更新具有相似的要求。在培养 1 年并传代多次后，卵巢生殖系干细胞保持其特征和端粒酶活性，表达生殖细胞和干细胞标志物，并显示正常核型。作为分化诱导的标准方案，将这些细胞聚集在一起，并研究其形成类胚体（EB）的能力。在生长因子存在的情况下生成的 EB 显示出经典的形态，并表达三个胚层的特异性标记物。但是，在没有生长促进因子的情况下，EB 较小，并且形成具有卵母细胞形态和分子特征的大细胞。这项研究表明，出生后小鼠卵巢中存在具有多能性特征的生殖系干细胞群体。
