James Joanna L, Stone Peter R, Chamley Lawrence W
Department of Obstetrics and Gynecology, University of Auckland, Auckland 1001, New Zealand.
Hum Reprod. 2007 Aug;22(8):2111-9. doi: 10.1093/humrep/dem144. Epub 2007 Jun 19.
It is widely accepted that most if not all villous cytotrophoblasts from term placentae are committed to differentiate into syncytiotrophoblast, but that early in gestation villous cytotrophoblasts are bipotential and capable of differentiating into either extravillous trophoblasts (EVTs) or syncytiotrophoblast. In contrast, our previous work has suggested that two separate populations of cytotrophoblast exist in the first trimester, one committed to EVT differentiation and the other to syncytiotrophoblast differentiation. In this work, we have isolated and characterized the population of 'EVT progenitors'.
First trimester villous explants were cultured for 10 days then subjected to sequential trypsinization. Viable cells that adhered to Matrigel following trypsinization were cultured for up to 5 days and characterized by immunohistochemistry.
The isolation protocol yielded >90% cytokeratin positive trophoblasts, which expressed markers characteristic of EVT progenitors. Over 5 days of culture, these isolated putative EVT progenitors did not syncytialize, but approximately 20% differentiated into HLA-G positive EVTs.
It is likely that the isolated putative EVT progenitors are the population of EVT progenitors previously identified in vivo. The characteristics of these isolated putative EVT progenitors provides further evidence for separate progenitors of EVT and syncytiotrophoblast in the first trimester.
普遍认为，足月胎盘的大多数（如果不是全部）绒毛细胞滋养层细胞会分化为合体滋养层细胞，但在妊娠早期，绒毛细胞滋养层细胞具有双向分化潜能，能够分化为绒毛外滋养层细胞（EVT）或合体滋养层细胞。相比之下，我们之前的研究表明，孕早期存在两种不同的细胞滋养层细胞群体，一种倾向于分化为EVT，另一种倾向于分化为合体滋养层细胞。在本研究中，我们分离并鉴定了“EVT祖细胞”群体。
将孕早期绒毛外植体培养10天，然后进行连续胰蛋白酶消化。胰蛋白酶消化后贴附于基质胶的活细胞培养长达5天，并通过免疫组织化学进行鉴定。
分离方案获得了>90%细胞角蛋白阳性的滋养层细胞，这些细胞表达了EVT祖细胞的特征性标志物。在5天的培养过程中，这些分离得到的假定EVT祖细胞没有形成合体细胞，但约20%分化为HLA-G阳性的EVT。
分离得到的假定EVT祖细胞很可能是先前在体内鉴定出的EVT祖细胞群体。这些分离得到的假定EVT祖细胞的特征为孕早期EVT和合体滋养层细胞存在独立的祖细胞提供了进一步的证据。
