Potential Role of Hyperglycemia in Fetoplacental Endothelial Dysfunction in Gestational Diabetes Mellitus

Background: Gestational diabetes mellitus (GDM) is associated with structural and functional alterations in various tissues including endothelial dysfunction. The aim of this study was to explore the effects of hyperglycemia on fibroblast growth factor 2 (FGF2)- and vascular endothelial growth factor (VEGF)-stimulated placental angiogenesis and the underlying molecular signaling mechanisms. Methods: The density of fetal placental capillaries was examined using immunohistochemistry. Human umbilical vein endothelial cells (HUVECs) derived from GDM (dHUVECs) and normal healthy patients (nHUVECs) were used as cell models in this study. Cell proliferation, migration and tube formation were measured with an MTS assay, a transwell system and a matrigel assay, respectively. The activation of ERK1/2 was analyzed with Western blot. The specific inhibitor of extracellular signal-regulated kinases 1/2 (ERK1/2) PD98059 was used to elucidate the involved signaling pathway. Results: GDM did not alter the capillary density of the fetus-placenta. Both the GDM and hyperglycemic conditions inhibited the proliferation of the FGF2- but not the VEGF-stimulated HUVECs and the basal migratory capacity. Hyperglycemic condition significantly inhibited tube formation and ex vivo angiogenesis. Moreover, hyperglycemia inhibited the FGF2- but not the VEGF-induced activation of ERK1/2. PD98059 significantly inhibited the FGF2-activated ERK1/2 phosphorylation and the FGF2-stimulated cell proliferation in HUVECs. Conclusion: Both GDM and hyperglycemia may impair placental angiogenesis by reducing HUVEC proliferation, migration and tube formation. Hyperglycemia-inhibited cell proliferation stimulated by FGF2 probably contributed to the suppression of the MEK1/2/ERK1/2 pathways in the HUVECs