The role of extracellular matrix proteins on placental angiogenesis in severe fetal growth restriction

Impaired vascular development is a central finding in severe fetal growth restriction (FGR) with abnormal Doppler velocimetry. Angiogenesis involves complex interactions between endothelial cells (ECs) and extracellular matrix (ECM). Our laboratory previously found that FGR ECs exhibit deficient angiogenic properties, a deficit that is further worsened in the presence of ECM generated from FGR placentae but partially rescued by control ECM. Our objective was to identify the effects of individual ECM substrates on EC function to better characterize the impaired angiogenic pathway characteristic of FGR. ECs were isolated from term control (n=8) or severe FGR (n=8) human placentae and plated on six individual ECM proteins: fibronectin; collagens I, III, and IV; laminin; and thrombospondin. Adhesion was assessed by colorimetric staining. Live cell microscopy was used to determine proliferation. Migration was analyzed via relative wound density following wound scratch. Apoptosis was evaluated by immunoblotting for cleaved caspase 3. T tests, ANOVAs, and nonlinear regressions were performed. There was no difference between adhesion of control and FGR ECs to individual ECM substrates. Control ECs proliferated more rapidly than FGR ECs (p< 0.01; figure 1). Deficient growth of FGR ECs was not rescued by any ECM substrate. Migration of FGR ECs was impaired relative to control ECs when accounting for all substrates (p=0.02). This finding persisted specifically in the presence of collagen I (p=0.03; figure 2) but not other substrates. Apoptosis was not detected for either type of ECs on any substrate. ECs from placentae affected by severe FGR display impaired proliferation and migration. This growth deficit appears to be independent of individual ECM substrates. FGR migratory defects persist on collagen I but not other substrates. Our data suggest that no singular ECM protein is responsible for the aberrant angiogenesis seen in severe FGR and rather there are likely multiple mechanisms underlying this pathology.View Large Image Figure ViewerDownload Hi-res image Download (PPT)