[Comparison of embryotoxicity of di(2-ethylhexyl) phthalate using mouse and human embryonic stem cell test models in vitro].

Objective: To establish a mouse embryonic stem cell test (mEST) model and human embryonic stem cell test (hEST) model, to evaluate the embryotoxicity of di(2-ethylhexyl) phthalate (DEHP).

Methods: We developed mEST and hEST models according to the European Centre for the Validation of Alternative METHODS (ECVAM). We used penicillin G (PN-G) as the standard negative reference and 5-fluorouracil (5-FU) as the standard positive reference, respectively, to verify validity of the models. Based on model validity, mouse embryonic stem cells D3 (mESC-D3), mouse Balb/c-3T3 (3T3), and human embryonic stem cells H9 (hESC-H9) were administered different concentrations of DEHP (15.6, 31.2, 62.5, 125.0, 250.0, 500.0, and 1 000.0 μg/ml) for 7 days. A cell counting Kit-8 was used to detect the 50% inhibitory proliferation concentration (IC50) of mESC-D3 cells, 3T3 cells, and hESC-H9 with DEHP. mESC-D3 and hESC-H9 were treated with DEHP (15.6, 31.2, 62.5, 125.0, 250.0 μg/ml, and 500.0 μg/ml) for 10 days based on the cytotoxicity results. At day 10, the expression of cardiomyocyte differentiation gene alpha-myosin heavy chain (α-MHC) was detected by real-time PCR and the 50% inhibition of cardiomyocycte differentiation (ID50) determined. Based on the values of IC50 and ID50, functions Ⅰ, Ⅱ and Ⅱ could be calculated by three linear discriminant functions in the EST model and the embryotoxicity of DEHP described by comparing the three functions.

Results: Nontrophoblast lineage both ES cells were cultured under optimal conditions and highly expressed hESC markers OCT4 , SSEA4, and TRA-1-60. The embryoid bodies formed were uniform in size and shape, and these results were highly repeatable. The PN-G and 5-FU results coincided with the prediction by ECVAM. Validation of our EST models was satisfactory. RESULTS of the three endpoints of DEHP in mEST were 197.3 μg/ml (IC50 3T3), 210.0 μg/ml (IC50 D3) and 246.8 μg/ml (ID50 D3). DEHP was evaluated to be a nonembryotoxic compound based on values of function Ⅰ (7.78), function Ⅱ (7.58) and function Ⅲ (-7.79). The three endpoints of DEHP in hEST were 195.4 μg/ml (IC50 3T3), 184.8 µg/ml (IC50 D3), and 84.3 µg/ml (ID50). By comparing the values of function Ⅰ (3.21), function Ⅱ (5.77), and function Ⅲ (-6.46), DEHP was evaluated to be weakly embryotoxic.

Conclusion: DEHP was determined to be a nonembryotoxic compound by mEST and weakly embryotoxic by hEST. Therefore, hEST is a more sensible model for the evaluation of DEHP embryotoxicity.