Effects of Pregnancy-Specific Glycoproteins on Trophoblast Motility in Three-Dimensional Gelatin Hydrogels

Introduction: Trophoblast invasion is a complex biological process necessary for establishment of pregnancy; however, much remains unknown regarding what signaling factors coordinate the extent of invasion. Pregnancy-specific glycoproteins (PSGs) are some of the most abundant circulating trophoblastic proteins in maternal blood during human pregnancy, with maternal serum concentrations rising to as high as 200–400 μg/mL at term. Methods: Here, we employ three-dimensional (3D) trophoblast motility assays consisting of trophoblast spheroids encapsulated in 3D gelatin hydrogels to quantify trophoblast outgrowth area, viability, and cytotoxicity in the presence of PSG1 and PSG9 as well as epidermal growth factor and Nodal. Results: We show PSG9 reduces trophoblast motility whereas PSG1 increases motility. Further, we assess bulk nascent protein production by encapsulated spheroids to highlight the potential of this approach to assess trophoblast response (motility, remodeling) to soluble factors and extracellular matrix cues. Conclusions: Such models provide an important platform to develop a deeper understanding of early pregnancy.