P16 Validating a placenta on a chip – Mimicking the maternofoetal barrier using human induced pluripotent stem cell derived trophoblast

The placenta is a unique cardiovascular organ that receives blood supplies from both the maternal and the fetal system. Dysfunction of the placenta can lead to gestational hypertension and lifelong cardiovascular consequences for both mother and baby. Yet our ability to study placenta dysfunction often relies on sourcing trophoblasts from either term-placenta or trophoblasts cell lines. We aimed to validate a 3D placenta-on-a-chip model that can be used in high-throughput system using human induced pluripotent stems cells (HiPSC) derived-trophoblast. Methods 2D and 3D culture were compared by seeding a commercially available HiPSC line (ChiPS4) into Petri dish or into a OrganoPlate (Mimetas) pre-coated with Geltrex and subsequently differentiated into trophoblasts. Trophoblast and pluripotent markers at the RNA (PCR, RNAseq) and protein level (immunoblot, immunohistochemistry) were investigated over differentiation days(D)0–6. The integrity of the POC barrier was assessed daily by adding 10 kDa/155 kDa-dextran linked to a fluorescent dye to the perfusable channel. Results In both 2D and 3D culture HiPSC differentiation (days2–6) induced upregulation of trophoblast markers (KRT-7, GATA3), and down-regulation of pluripotent markers (Nanog, POU51). In the OrganoPlate HiPSC-trophoblast formed a hollow tube-structure from D3. At D4 differentiation there was an increase in syncytiotrophoblast whereas down-regulation of extra-villainous trophoblasts gene-clusters (RNA-seq). Interestingly, immunochemistry showed a defined area in close proximity to the ECM appeared as a preferential site for cell fusion and β-hCG production. The placenta-on-a-chip formed a leak tight barrier from D4 differentiation which retained the 155 kDa and 10 kDa-dextran in the placenta-on-a-chip. Comparison of 2D and 3D culture showed good similarity, but interestingly in 3D culture there were enhanced representation of total genes in GO terms and Reactome pathways associated with ECM, growth factor and interferon signalling pathways. Conclusion We successfully characterised a 3D placenta-on-a-chip model using HiPSC derived trophoblasts in perfusable multi-chip OrganoPlates which can be used to study the maternofoetal barrier. This work was funded by; Horizon 2020 Marie Skłodowska-Curie (765274, iPLACENTA); EU Framework 7, (626633, IVSCP); and Tenovus Scotland, T18–23.