The human placenta is comprised of trophoblast subtypes – cytotrophoblasts, syncytiotrophoblasts (ST), and extravillous trophoblasts (EVT) – that are crucial for successful pregnancies. Understanding trophoblast functions is essential to treat pregnancy complications and investigate maternal-fetal immune tolerance. Trophoblasts secrete factors to instruct tolerance; however, the distinct trophoblast subtypes’ role in fetal tissue tolerance remain insufficiently understood. Inadequate models to study the human placenta in vitro limit the current understanding of human placental behavior and development. Synthetic hydrogel systems such as poly(ethylene) glycol (PEG)-maleimide offer a highly defined, tunable 3D environment to study trophoblast subtypes, which may overcome experimental variability in naturally derived hydrogels like Matrigel due to batch-to-batch variability. Here, a PEG hydrogel system with tunable degradability and placenta-derived extracellular matrix ligands is employed to evaluate the capacity of the hydrogel library to support the function and phenotypic protein expression of three trophoblast-like cell lines, assess the differentiation of trophoblast stem cells (TSC), and explore the effects of trophoblast supernatants on the modulation of protein expression and secretion by immune cell subsets present at the maternal-fetal interface. Degradable synthetic hydrogels support the greatest degree of trophoblast-like spheroid proliferation and function relative to standard Matrigel controls and culture conditions modulate trophoblast-like and TSC functional subtype as measured by proteomics analysis and functional secretion assays. PEG hydrogels support TSC viability and function comparable to Matrigel; however, ST-differentiated cells prefer PEG environments, while EVT-differentiated cells favor Matrigel, as assessed through phenotypic protein expression and secretion. These data highlight the influence of trophoblast culture condition and subtype on immune cell protein expression and inflammatory cytokine secretion in response to trophoblast supernatants. This model advances the understanding of in vitro placental modeling, which can provide insights on pregnancy-related complications and maternal-fetal immunotolerance.

Photocurable nanocomposites have great potential within advanced manufacturing, multifunctional materials, and most specifically tissue engineering. The properties and characteristics of these nanocomposites can be tailored to mimic those of various tissues and/or cartilage, allowing the bio-inspired synthetic materials to replace them. This project investigates the effect of methacrylate-functionalized (MA-SiO2) and vinyl-functionalized (V-SiO2) silica nanoparticle loading content on the thermal, mechanical, physical, and morphological characteristics of PEG nanocomposites. It was discovered that both V-SiO2 and MA-SiO2 did not considerably impact the glass-transition temperature or hydrophilicity of the material. The gel fraction of composites containing V-SiO2 decreases with the initial addition of 3.8 wt%, but then displays an increase with further addition (>7.4 wt%) until it reaches a plateau at 10.7 wt%. Whereas, the MA-SiO2 induced no significant changes in gel fraction with increased loading. An increase in mechanical properties was also observed with increasing concentration for both sets of series. However, due to the higher crosslink density, MA-SiO2 reached its ultimate mechanical stress threshold at a lower concentration of 7.4 wt%, while V-SiO2 maxed out at 10.7 wt%. Scanning electron microscopy coupled with transmission electron microscopy revealed that V-SiO2 displayed a bimodal size distribution, while MA-SiO2 displayed only one.