An improved protocol for targeted differentiation of human iPSCs into HLA-G expressing trophoblasts cells enabling modelling of placenta-related disorders.

Abnormalities at any stage of trophoblast development may result in pregnancy-related com-plications. Many of these adverse outcomes are discovered later in pregnancy, but the underly-ing pathomechanisms constitute during the first trimester. Acquiring developmentally relevant material to elucidate the disease mechanisms is difficult. Human pluripotent stem cell (hPSC) technology can provide a renewable source of relevant cells. BMP4, A83-01, and PD173074 (BAP) treatment drives trophoblast commitment of hPSCs towards syncytiotrophoblast (STB) but lacks extravillous trophoblast (EVT) cells. EVTs mediate key functions during placentation, remodel-ing of uterine spiral arteries, and maintenance of immunological tolerance. We optimized the protocol for more efficient generation of HLA-Gpos EVT-like trophoblasts from primed hiPSCs. Increasing the concentrations of A83-01 and PD173074, while decreasing bulk cell density re-sulted in the increase of HLA-G of up to 71%. Gene expression profiling support the advance-ments of our treatment regarding the generation of trophoblast cells. The reported differentia-tion protocol will allow the on-demand access to human trophoblast cells enriched for HLA-Gpos EVT-like cells, allowing the elucidation of placenta-related disorders and to investigate the im-munological tolerance towards the fetus, overcoming the difficulties in obtaining primary EVTs without the need for a complex differentiation pathway via naïve pluripotent or trophoblast stem cells. Samples included are: Isis human induced pluripotent stem cells (hiPSC), D9 BAP differentiated Isis hiPSC, D9 BhAhP differentiated Isis hiPSC, and D21 BhAhP differentiated Isis hiPSC. All with a biological replicate.