The epithelial-mesenchymal transition in extravillous trophoblast differentiation: Role in abnormally invasive placenta

Abstract

Objectives: One aspect of our studies of abnormally invasive placenta (AIP, placenta accreta) involves investigation of cytotrophoblast (CTB) differentiation into invasive extravillous trophoblast (EVT) in normal and AIP pregnancies. Differentiation involves a process with similarities to the epithelial-mesenchymal transition (EMT), observed in gastrulation, wound-healing and cancer metastasis. We asked whether the CTB to EVT change was an EMT process and whether it was further advanced in AIP. Methods: We compared CTB and EVT from normal, term pregnancies (n1⁄44,8) and EVT from placenta previa (EVT-PP; n1⁄44) and AIP pregnancies (EVT-AIP; n1⁄48) obtained in the mid-third trimester. All AIP pregnancies were placenta percreta as determined by histopathology. After EVT purification by Percoll gradient and immunomagnetic separation targeted to HLA-G, cellular RNA was extracted and analysed on targeted PCR arrays containing EMT-related genes (Qiagen). Results: The EVT/EVT-PP comparison showed no significant differences and EVT-PP results were included in the EVT group thereafter. CTB/EVT comparison showed alterations in 48 of 84 genes (p<0.05). Examples of the fold-change in specific genes illustrative of this process are shown in Table 1. By contrast the EVT/EVT-AIP comparison showed changes in only 14 genes, however this included up-regulation of several genes that have been shown to promote the EMT in other cell types (Table 2). Conclusions: The differentiation of CTB into EVT involves changes characteristic of EMT, including loss of cell-cell interaction proteins such as occludin, an integrin switch, up-regulation of proteases and inhibitors and alterations in other EMT-related cellular components. We conclude that CTB-EVT differentiation appears to be an EMT process. The EVT/EVT-AIP comparison shows clear signs of an enhanced EMT in the EVT-AIP, most notably in the up-regulation of the EMT master regulator, ZEB2 but also in expression changes observed for SNAI2, SPP1, MMP9, TIMP1 and TGFs. P1.29. VARIATIONS IN SUTURE TECHNIQUES AT CESAREAN SECTION AND ITS RELATION TO COMPLICATIONS IN SUBSEQUENT PREGNANCIES