Combination of the BeWo b30 placental transport model and the embryonic stem cell test to assess the potential developmental toxicity of silver nanoparticles

Abstract

Background: Silver nanoparticles (AgNPs) are used extensively in various consumer products because of their antimicrobial potential. This requires insight in their potential hazards and risks including adverse effects during pregnancy on the developing fetus. Using a combination of the BeWo b30 placental transport model and the mouse embryonic stem cell test (EST), we investigated the capability of pristine AgNPs with different surface chemistries and aged AgNPs (silver sulfide (Ag 2 S) NPs) to cross the placental barrier and induce developmental toxicity. The uptake/ association and transport of AgNPs through the BeWo b30 was characterized using ICP-MS and single particle (sp)ICP-MS at different time points. The developmental toxicity of the AgNPs was investigated by characterizing their potential to inhibit the differentiation of mouse embryonic stem cells (mESCs) into beating cardiomyocytes. Results: The AgNPs are able to cross the BeWo b30 cell layer to a level that was limited and dependent on their surface chemistry. In the EST, no in vitro developmental toxicity was observed as the effects on differentiation of the mESCs were only detected at cytotoxic concentrations. The aged AgNPs were significantly less cytotoxic, less bioavailable and did not induce developmental toxicity. Conclusions: Pristine AgNPs are capable to cross the placental barrier to an extent that is influenced by their surface chemistry and that this transport is likely low but not negligible. Next to that, the tested AgNPs have low intrinsic potencies for developmental toxicity. The combination of the BeWo b30 model with the EST is of added value in developmental toxicity screening and prioritization of AgNPs.

Translocation of (ultra)fine particles and nanoparticles across the placenta; a systematic review on the evidence of in vitro, ex vivo, and in vivo studies

“…Moreover, to study transplacental transfer, cells were cultured on Transwell inserts, which consist of a permeable membrane separating an apical and a basolateral compartment. Transwells were used to study uptake and transplacental transport of NPs across (i) placental trophoblast monolayers of human placental choriocarcinoma (BeWo b30) cells that strongly resemble cytotrophoblast cells ( N = 6) [ 22 – 26 , 28 ], human SV40-transformed trophoblast (3A-sub-E) cells ( N = 1) [ 27 ], or human first trimester trophoblast cells (HTR-8/SVneo (ATCC®, CRL-3271™)) ( N = 2) [ 29 , 30 ] (ii) co-cultures of trophoblastic cells (i.e. , BeWo b30) and endothelial cells (i.e.…”

“…, human villous mesenchymal fibroblasts) ( N = 1) [ 32 ]. Transwell inserts were made from polycarbonate [ 31 , 33 – 36 ] or polyethylene terephthalate [ 34 ] with a 0.4 μm [ 22 – 26 , 28 ] or 3 μm [ 31 , 33 – 36 ] pore size. Moreover, a total of 4 studies [ 31 , 34 – 36 ] pre-coated the insert with human placental collagen IV to aid cell adherence and growth.…”

“…Multiple studies focused on the effect of particle size and concluded a size-dependent particle transport as larger particles were primarily internalized by the cells with limited transfer to the basolateral compartment [ 26 , 27 , 32 ]. Moreover, surface modification was found to steer particle transport and cell-particle interactions [ 22 , 24 , 31 – 33 ]. Sodium oleate-coating increased both transcellular transport and cellular uptake, while PEGylation or poly(ethyleneimine) (PEI)-coating resulted in enhanced placental cell association and thus less transport.…”

“…Sodium oleate-coating increased both transcellular transport and cellular uptake, while PEGylation or poly(ethyleneimine) (PEI)-coating resulted in enhanced placental cell association and thus less transport. On the other hand, carboxylation, starch-, or dextran-coating were shown to enhance the transport across the cell barrier while decreasing cell-particle interactions and thus internalization [ 22 , 24 , 31 – 33 ].…”

“…Among these particles, only Ag NPs [ 37 ], Au NPs [ 31 , 38 ], and PS NPs [ 40 – 43 ] showed transplacental transfer in an ex vivo perfusion model, whereas SiO 2 NPs [ 25 ] and TiO 2 NPs [ 34 ] were retained in the placental tissue. Similarly, Ag NPs [ 22 ], Au NPs [ 31 , 32 ], iron oxide NPs [ 24 , 33 ], SiO 2 NPs [ 24 ], and PS NPs [ 35 ] were shown to cross the in vitro placental barrier. Solely 22 studies based their findings on visual confirmation of particle presence or a significant difference in NP content from the control group in the fetal compartment/tissue.…”