Human Trophoblast Differentiation In Vitro Within 3D Matrix-Free Cultures
Abstract
The placenta is a temporary organ that forms during pregnancy to support fetal development. Many placental functions are facilitated by trophoblasts, which are divided into subpopulations. The progenitor cytotrophoblasts (CTBs) differentiate into the multinucleated syncytiotrophoblast (STB) and invasive extravillous trophoblast (EVT) lineages. Recently, there has been great interest in developing 3D trophoblast cultures, but the mechanism regulating differentiation remains unknown. This thesis aims to characterize 3D trophoblast cultures and uncover pathways promoting subpopulation development. Trophoblast subpopulation markers were compared between 2D and 3D cultures with human trophoblast stem (TS) cells and immortalized HTR-8/SVneo (HTR) trophoblasts. While changes were limited with HTRs, 3D human TS cultures displayed increased differentiation, predominantly into STB along the periphery. Activation of the Hippo pathway was critical in driving STB formation in 3D human TS cultures. Overall, my thesis suggests that 3D human TS cultures could be a more suitable model for investigating trophoblast biology.