Characterization and Biomimetic Fabrication Study of Fetal Membranes for Understanding and Prevention of Preterm Birth

Preterm birth is defined as a baby being born before 37 weeks gestation and is a large problem, affecting 10% of all pregnancies in the United States and world annually. Preterm birth can result in lifelong complications for the infant or even death, considering the fetus continues developing vital organs throughout the last few weeks of pregnancy. Over the course of pregnancy, several layers and sub-layers are formed in order to protect the fetus from the external environment. Two of the most crucial layers that were heavily focused on throughout this project were the amnion and the chorion layers, which combine to make the placental membrane that surrounds the fetus. Preterm birth most often occurs due to mechanical failure of the membranes. Collagen proteins make up the strength and elasticity of the fetal membranes, supporting the fetus. If these proteins fail, this increases the chance of preterm birth occurring. A degrading enzyme, known as collagenase, often affects the membranes through bacteria and infections, breaking down the collagen fibers and leading to premature rupture of membranes or preterm pre-labor rupture of membranes. To study this process, a few different routes were taken. Artificial gels were tested on a nanoindentation machine to gather preliminary data to compare nanoindentation on real tissue. Artificial biomimetic membranes were also electrospun and mechanically tested on a macroscale. The goal of the biomimetic electrospun fiber mat is to be used to patch the woman's rupture site after pre-labor rupture of membranes occurs. Four different mat categories were fabricated: not treated crosslinked (NX), not treated uncrosslinked (NU), treated crosslinked (TX), and treated uncrosslinked (TU). Treatment indicates that they were placed in the oven. Human fetal membranes were also mechanically tested on a macroscale after being submerged and incubated at two different set times in a control solution and varying levels of collagenase concentrations, including 45 U/mL and 135 U/mL. Fourier transform infrared spectroscopy of natural tissues was then used to analyze the integrity of the collagen molecules. The results for this study indicate that through nanoindentation, the elastic modulus of two different types of hydrogels were consistently lower than anticipated. In regard to electrospinning, the uncrosslinked fiber mats have significantly greater strength than the crosslinked fiber mats. The fetal membrane results showed that overall, there was significant decrease in elastic modulus when membranes were submerged in a high collagenase concentration. Strength of the fetal membranes decreased significantly as collagenase concentration and incubation time increased. These findings suggest that collagenase buildup within the human body can potentially lead to preterm birth. Overall, this work sought to study the biomechanical properties of fetal membranes. In current literature, there have been strength and elastic modulus values of placental membranes obtained through different modes of testing, but never through biaxial puncture testing. This project focused on a new approach of mechanically testing placental membranes