HTR8/SVneo, but not JEG3, cells display trophoblast progenitor cell-like characteristics indicative of self-renewal, repopulation activity and expression of “stemness”- associated transcription factors

Introduction: JEG3 and HTR8/SVneo cells are popular trophoblastic cell lines for use as models of extravillous trophoblast. Recently, choriocarcinoma is thought to constitute a population of tumor with preserved stem cell properties. Furthermore, a side-population of HTR8/SVneo cells demonstrated self-renewal characteristics. Aim of this study was to correlate expression of various transcription factors associated with “stemness”, cell fate and trophoblast stem cells in these popular cell lines with stem/progenitor cell-like functions e.g. self-renewal and repopulation activity.

Methods: JEG3 and HTR8/SVneo cells were propagated in hanging drops to assess spheroid formation, then multi-passaged. The expression of NOTCH1, SOX2, OCT4, NANOG and CDX2 was investigated per immunocytochemistry and immunfluorescence, and then correlated with spheroid formation capacity. HTR8/SVneo spheroids were confronted with placental explants (after elective ceasarian sections).

Results: HTR8/SVneo, and to a much lesser degree JEG3, displayed self-renewal properties by forming spheroids that could be multi-passaged (> 5 versus 1 passage respectively). HTR8/SVneo expressed most transcription factors (CDX2+, NOTCH1+, SOX2+, NANOG+) in contrast to JEG3 (CDX2+, NOTCH1+). HTR8/SVneo spheroid cells cover and seem to repopulate chorionic villi of placental explants.

Discussion: These results indicate that HTR8/SVneo (spheroid) cells possess progenitor cell functions, which are possibly attained through corrupted “stemness”-associated transcription factor networks. HTR8/SVneo cells are probably a better model of the cytotrophoblast- than the extravillous trophoblast- phenotype.