Generation of human induced trophoblast stem cells

Human trophoblast stem cells (hTSC) derived from blastocysts and first-trimester cytotrophoblasts offer an unprecedented opportunity to study the human placenta. However, access to human embryos and first trimester placentas is limited thus preventing the establishment of hTSC from a variety of genetic backgrounds associated with placental disorders. In the present study, we show that hTSC can be generated from numerous genetic backgrounds using post-natal cells via two alternative methods: (I) somatic cell reprogramming of adult fibroblasts using the Yamanaka factors, and (II) cell fate conversion of naive and extended pluripotent stem cells. The resulted induced and converted hTSC (hiTSC/hcTSC) recapitulated hallmarks of hTSC including long-term self-renewal, expression of specific transcription factors, transcriptome-side signature, and the potential to differentiate into syncytiotrophoblast and extravillous trophoblast cells. We also clarified the developmental stage of hTSC and show that these cells resemble post-implantation NR2F2+ cytotrophoblasts (day 8-10). Altogether, hTSC lines of diverse genetics origins open the possibility to model both placental development and diseases in a dish. Highlights ### Competing Interest Statement Dimitri MEISTERMANN is supported by FINOX forward grant initiative. Gael CASTEL and Laurent DAVID have a provisional patent filled on the generation of human induced trophoblast stem cells.