Local Over-Expression of VEGF-DΔNΔC in the Uterine Arteries of Pregnant Sheep Results in Long-Term Changes in Uterine Artery Contractility and Angiogenesis

Abstract

BackgroundThe normal development of the uteroplacental circulation in pregnancy depends on angiogenic and vasodilatory factors such as vascular endothelial growth factor (VEGF). Reduced uterine artery blood flow (UABF) is a common cause of fetal growth restriction; abnormalities in angiogenic factors are implicated. Previously we showed that adenovirus (Ad)-mediated VEGF-A165 expression in the pregnant sheep uterine artery (UtA) increased nitric oxide synthase (NOS) expression, altered vascular reactivity and increased UABF. VEGF-D is a VEGF family member that promotes angiogenesis and vasodilatation but, in contrast to VEGF-A, does not increase vascular permeability. Here we examined the effect of Ad.VEGF-DΔNΔC vector encoding a fully processed form of VEGF-D, on the uteroplacental circulation.MethodsUtA transit-time flow probes and carotid artery catheters were implanted in mid-gestation pregnant sheep (n = 5) to measure baseline UABF and maternal haemodynamics respectively. 7–14 days later, after injection of Ad.VEGF-DΔNΔC vector (5×1011 particles) into one UtA and an Ad vector encoding β-galactosidase (Ad.LacZ) contralaterally, UABF was measured daily until scheduled post-mortem examination at term. UtAs were assessed for vascular reactivity, NOS expression and endothelial cell proliferation; NOS expression was studied in ex vivo transduced UtA endothelial cells (UAECs).ResultsAt 4 weeks post-injection, Ad.VEGF-DΔNΔC treated UtAs showed significantly lesser vasoconstriction (Emax144.0 v/s 184.2, p = 0.002). There was a tendency to higher UABF in Ad.VEGF-DΔNΔC compared to Ad.LacZ transduced UtAs (50.58% v/s 26.94%, p = 0.152). There was no significant effect on maternal haemodynamics. An increased number of proliferating endothelial cells and adventitial blood vessels were observed in immunohistochemistry. Ad.VEGF-DΔNΔC expression in cultured UAECs upregulated eNOS and iNOS expression.ConclusionsLocal over-expression of VEGF-DΔNΔC in the UtAs of pregnant mid-gestation sheep reduced vasoconstriction, promoted endothelial cell proliferation and showed a trend towards increased UABF. Studies in cultured UAECs indicate that VEGF-DΔNΔC may act in part through upregulation of eNOS and iNOS.

The impact of IUGR on pancreatic islet development and β-cell function

“…Furthermore, most nutritional interventions are associated with increased adiposity and not increased linear growth. More promising are interventions which increase uterine blood flow (Carr, et al 2016; David, et al 2008; Mehta, et al 2014; Oyston, et al 2016; Satterfield, et al 2010; von Dadelszen, et al 2011). Despite this progress, animal studies are required to evaluate the effect of these interventions on the fetal pathophysiological processes described in this review and to refine further the therapies to specific complications of placental insufficiency.…”

Ethics and social acceptability of a proposed clinical trial using maternal gene therapy to treat severe early‐onset fetal growth restriction

“…is a multinational, multidisciplinary collaboration that aims to carry out a phase I/IIa trial examining the safety and efficacy of maternal gene therapy as a treatment for severe early‐onset FGR. Preclinical studies have shown that vascular endothelial growth factor (VEGF) gene therapy, delivered locally via an adenoviral vector into the maternal uterine arteries, increases uterine artery volume blood flow and vasodilates the uterine arteries in pregnant sheep over days and weeks through increased expression of endothelial nitric oxide synthase and perivascular adventitial angiogenesis. In animal models of FGR, it has also been shown to safely increase fetal growth velocity.…”

The role of aspirin, heparin, and other interventions in the prevention and treatment of fetal growth restriction

“…In normal sheep pregnancy, injection of Ad.VEGF (1 Â 10 11 particles), compared with injection of a control nonvasoactive vector, increased uterine artery volume blood flow within 7 days of injection, and long term, this increase in flow persisted for at least 4 weeks until the end of gestation. [83][84][85] The mechanism is mediated via shortterm VEGF expression detectable in the perivascular adventitia of the treated vessels. This is associated with increased endothelial nitric oxide synthase expression, which results in reduces vascular constriction.…”