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The effects of local over-expression of VEGF on the uterine arteries and uterine artery endothelial cells of pregnant sheep
  1. V Mehta1,
  2. K Abi-Nader1,
  3. M Buitendyk1,
  4. B Torondel2,
  5. SW Shaw1,
  6. M Boyd3,
  7. E Benjamin1,
  8. IC Zachary2,
  9. JF Martin2,
  10. DM Peebles1,
  11. AL David1
  1. 1Institute for Women's Health, University College London, London, UK
  2. 2Cardiovascular Biology and Medicine, Rayne Institute, University College London, London, UK
  3. 3Biological Services Unit, Royal Veterinary College, London, UK

Abstract

Introduction Impaired utero-placental perfusion leads to fetal growth restriction. The authors have shown a significant increase in blood flow in the uterine arteries (UAs) of pregnant sheep and a significantly reduced contractile response following local transduction with an adenovirus encoding VEGF-A165 (Ad.VEGF-A). The authors have now studied the effects of local over-expression of the VEGF-DΔNΔC isoform and investigated the mechanism behind the VEGF (−A and −DΔNΔC) induced effects.

Method UAs of mid-gestation pregnant sheep were injected with adenovirus vectors (5×1011 particles) encoding the VEGF-DΔNΔC gene (Ad.VEGF-D) and a reporter β-galactosidase gene (Ad.LacZ) contra-laterally. Sheep were killed 4–7 days later. UAs were isolated and their vasoreactivity studied on an organ bath. Adventitial blood vessels were enumerated by anti-vWF immunohistochemistry.

Endothelial cells (ECs) were isolated from the UAs of control mid-gestation pregnant sheep, cultured and infected with Ad.VEGF-A vector. Protein was extracted from these uterine artery endothelial cells (UAECs) infected ex vivo and assayed for endothelial nitric oxide synthase (eNOS) levels by Western blotting.

Results There was a significant reduction in the UA contractile response following Ad.VEGF-D when compared to Ad.LacZ transduction (Emax 126.6±7.54 vs 159.9±10.96, p<0.001, n=5) and vasorelaxation was enhanced (pD2 (−log EC50) 9.05±0.14 vs 8.87±0.16, p=0.55, n=4).

eNOS levels increased with rising adenovirus vector concentrations in UAECs transduced ex vivo. There were significantly higher numbers of blood vessels in the perivascular adventitia of Ad.VEGF-D transduced vessels compared to Ad.LacZ transduced vessels (140.6±15.1 vs 91.7±9.9, p<0.05).

Conclusion Changes in eNOS levels and vascular remodeling may be the underlying mechanism of action of local VEGF over-expression in pregnant sheep UAs.

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