Progress in deciphering trophoblast cell differentiation during human placentation.

The maintenance of gestational well-being requires the proper development of both the embryo and the placenta. Placental trophoblast cells are the major building blocks of the developing placenta. Abnormal trophoblast differentiation underpins placental-based pregnancy complications. However, the mechanisms that govern trophoblast differentiation remain largely unclear. Recent studies shed light on several proteins and regulators that are involved in governing trophoblast differentiation. The advancement of new tools and novel technologies, such as the human trophoblast stem cell culture system, 3D placental organoids and single-cell multi-omics, has brought incredible insights to the field. Here we review the current literature, paying particular attention to articles published between 2017 and 2019 that have promoted our understanding of human trophoblast cell differentiation and its roles in pregnancy and its complications. At the same time, we address challenges and questions arising in the field of human placental development and disease.