Structural and Mechanical Changes to the Extracellular Matrix in Human Umbilical Arteries in Pregnancies Complicated...

The umbilical cord serves as a critical lifeline, connecting the fetus to the pregnant individual. Stillbirth, fetal death at or beyond 20 weeks' gestation, can occur due to developmental anomalies or complications of the umbilical cord. Gestational diabetes (GDM), which affects 8% of pregnancies in the United States, is associated with vascular abnormalities of the placenta and umbilical cord. While cellular and microstructural changes in the umbilical vasculature have been observed in pregnancies complicated by gestational diabetes, it is unknown if these influence the macroscale mechanical properties. Human umbilical arteries and veins from healthy pregnancies (n = 10) and from pregnancies with gestational diabetes requiring insulin for glucose management (n = 5) underwent quantitative histological analysis and circumferential ring testing to characterize the intact tissue and decellularized matrix. Collagen birefringence showed healthy umbilical arteries had a higher ratio of thick to thin collagen fibers than GDM. A two-way analysis of variance showed the viscoelastic behavior of the decellularized umbilical arteries was significantly affected by disease (p = 0.01) and pin strain (p = 0.02). GDM-decellularized umbilical arteries had a significantly (p = 0.04) lower first Piola-Kirchhoff stress than healthy at maximum pin strain. However, these differences did not persist within intact umbilical arteries. Additionally, there were no significant differences in the extracellular matrix content or mechanical properties between healthy and GDM umbilical veins. The results indicate umbilical arteries from pregnancies complicated by GDM have altered mechanical properties of the extracellular matrix, possibly due to decreased collagen fiber size.