The human placental barrier facilitates many key functions during pregnancy, most notably the exchange of all substances between the mother and fetus. However, preclinical models of the placental barrier often lacked the multiple cell layers, syncytialization of the trophoblast cells and the low oxygen levels that are present within the body. Therefore, we aimed to design and develop an in vitro model of the placental barrier that would reinstate these factors and enable improved investigations of barrier function. BeWo placental trophoblastic cells and human umbilical vein endothelial cells were co-cultured on contralateral sides of an extracellular matrix-coated transwell insert to establish a multilayered barrier. Epidermal growth factor and forskolin led to significantly increased multi-nucleation of the BeWo cell layer and increased biochemical markers of syncytial fusion, for example syncytin-1 and hCGβ. Our in vitro placental barrier possessed size-specific permeability, with 4000-Da molecules experiencing greater transport and a lower apparent permeability coefficient than 70 000-Da molecules. We further demonstrated that the BeWo layer had greater resistance to smaller molecules compared to the endothelial layer. Chronic, physiologically low oxygen exposure (3-8%) increased the expression of hypoxia-inducible factor 1α and syncytin-1, further increased multi-nucleation of the BeWo cell layer and decreased barrier permeability only against smaller molecules (457 Da/4000 Da). In conclusion, we built a novel in vitro co-culture model of the placental barrier that possessed size-specific permeability and could function under physiologically low oxygen levels. Importantly, this will enable future researchers to better study the maternal-fetal transport of nutrients and drugs during pregnancy.

中文翻译：

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生理相关氧水平下体外胎盘屏障模型的建立。

人类胎盘屏障促进怀孕期间的许多关键功能，最显着的是母亲和胎儿之间所有物质的交换。然而，胎盘屏障的临床前模型通常缺乏多个细胞层、滋养层细胞的合胞化和体内存在的低氧水平。因此，我们旨在设计和开发胎盘屏障的体外模型，以恢复这些因素并改进屏障功能的研究。BeWo 胎盘滋养细胞和人脐静脉内皮细胞在细胞外基质包被的 transwell 插入物的对侧共培养以建立多层屏障。表皮生长因子和毛喉素导致 BeWo 细胞层的多核化显着增加，并增加了合胞体融合的生化标志物，例如合胞素 1 和 hCGβ。我们的体外胎盘屏障具有大小特异性渗透性，与 70 000-Da 分子相比，4000-Da 分子经历了更大的运输和更低的表观渗透系数。我们进一步证明，与内皮层相比，BeWo 层对较小分子具有更大的抵抗力。慢性生理性低氧暴露 (3-8%) 会增加缺氧诱导因子 1α 和合胞素 1 的表达，进一步增加 BeWo 细胞层的多核化并降低仅针对较小分子的屏障渗透性 (457 Da/4000 Da ）。综上所述，我们建立了一种新的胎盘屏障体外共培养模型，该模型具有大小特定的渗透性，并且可以在生理低氧水平下发挥作用。重要的是，这将使未来的研究人员能够更好地研究孕期营养物质和药物的母胎转运。