Construction of a 3D trophoblast model and validation by triiodothyronine (T3) treatment

During gestation, insufficient triiodothyronine hormone (T3) can lead to failures in trophoblastic activity or induce defects in fetal epigenetic mechanisms. As a consequence, multiple hormones become unbalanced, which can trigger different negative outcomes in the offspring. This study aims to propose the construction of a 3D trophoblast model, validated with different levels of thyroid hormone treatment. Different concentrations of T3, 1, 10 and 100 nM, were employed for 24, 48 and 72 h, corresponding to sub-physiological, physiological and supraphysiological concentrations, respectively, to investigate the effects on human chorionic gonadotropin (hCG), Lactate Dehydrogenase (LDH), and MTT levels in the 3D model. The generated 3D trophoblast model responded differently to the T3 concentrations: although no effect was observed regarding cell viability (MTT assay), there was an increase in cytotoxicity in the group treated with the highest concentration (100 nM; LDH assay) after 24 h. In addition, in the concentration-response curve of hCG, while a natural progressive increase in hCG is observed in control group, there was a clear reduction of hCG in the models treated with 1 nM and 100 nM T3; the 10 nM-treated group demonstrated no difference to control. The proposed 3D trophoblastic placental model was successfully established and validated. Utilizing this model, it was demonstrated that adequate concentrations of T3 are essential for the accurate prediction of cellular function and the prevention of cytotoxic effects. These findings underscore the critical importance of maintaining physiological levels of T3 during pregnancy to support appropriate secretion of hCG.