Use of GATA3 and TWIST1 Immunofluorescence Staining to Assess In Vitro Syncytial Fusion Index.

In human placenta, the multinucleated syncytiotrophoblast (ST) allows all the exchanges between the maternal and fetal circulation and is also the site of placental hormonal functions. Absence or disturbances of ST formation are associated with a defect or pathologies of pregnancy such as preeclampsia (PE) and intrauterine growth retardation (IUGR). All along pregnancy, the ST is regenerated by fusion of underlying mononucleated villous cytotrophoblasts (VCT). The protocol described here provides details on how GATA3 or TWIST1 immunostaining and analysis can be used to easily assess the in vitro differentiation of human placental cytotrophoblast.