Impaired function of trophoblast cells derived from translocated hESCs may explain pregnancy loss in women with balanced translocation (11;22)

Abstract

Purpose: The aim of the study was to study whether the trophoblasts carrying unbalanced translocation 11,22 [t(11;12)] display abnormal expression of trophoblastic genes and impaired functional properties that may explain implantation failure.

Methods: t(11;22) hESCs and control hESCs were differentiated in vitro into trophoblast cells in the presence of BMP4, and trophoblast vesicles (TBVs) were created in suspension. The expression pattern of extravillous trophoblast (EVT) genes was compared between translocated and control TBVs. The functional properties of the TBVs were evaluated by their attachment to endometrium cells (ECC1) and invasion through trans-well inserts.

Results: TBVs derived from control hESCs expressed EVT genes from functioning trophoblast cells. In contrast, TBVs differentiated from the translocated hESC line displayed impaired expression of EVT genes. Moreover, the number of TBVs that were attached to endometrium cells was significantly lower compared to the controls. Correspondingly, invasiveness of trophoblast-differentiated translocated cells was also significantly lower than that of the control cells.

Conclusions: These results may explain the reason for implantation failure in couple carriers of t(11;22). They also demonstrate that translocated hESCs comprise a valuable in vitro human model for studying the mechanisms underlying implantation failure.

Keywords: Human embryonic stem cells; Implantation; Translocation; Trophoblasts.

Fig. 1

Expression of extravillous trophoblast markers in trophoblast vesicles. a–b qRT-PCR analysis of extravillous trofoblast genes in mean of at least three control WT lines (blue) and Lis05_t(11;22) (red) hESCs. Relative transcription levels of each gene were analyzed in undifferentiated hESCs (day 0) and in TBVs after 7 days of in vitro trophoblastic differentiation. Data are presented as mean ± standard error and represent two–three experiments performed on each line. *P < 0.05

Fig. 2

Attachment of TBVs to endometrial cells. a Trophoblast vesicles (TBV) derived from BMP4-treated hESCs. b Bright field picture of a TBV attached to endometrial cells (ECC1) 2 days after plating. c Number of attached TBVs to endometrium cells per number of TBVs plated. Data represent at least three different biological experiments performed on each line. **P < 0.01

Fig. 3

Invasion of trophoblastic cells through transwells. a Immunofluorescent images of invaded cells at different time points following trophoblast differentiation. Control and translocated hESCs were plated on matrigel-coated transwells and treated with BMP-4 for 9 days. Nuclei of invaded cells were stained with DAPI. b Total fluorescence intensity of the invaded cells following trophoblast differentiation on matrigel-coated transwells. Data are presented as mean + SEM of five different fields analyzed by the ImageJ software. *P < 0.05