title: The role of VEGF-A165b in trophoblast survival.
abstract: BACKGROUND
  Pre-eclampsia remains a dominant cause of maternal and fetal mortality in developed countries. In a previous prospective study we identified a fall in the VEGF-A isoform VEGF-A165b in the plasma of patients in the first trimester to be a predictor of later pre-eclampsia. VEGF-A165b has been shown to have potent cytoprotective properties in many cell types. We therefore tested the hypothesis that VEGF-A165b may be cytoprotective for placental trophoblasts.
  
  
  METHODS
  We used an immortalised first trimester trophoblast cell line exposed to chemical toxicity, and physiological (<2% O2) and atmospheric oxygen (21% O2) in the presence or absence of VEGF-A165b, angiogenic VEGF-A165a, a non-specific anti-VEGF-A blocking antibody (bevacizumab), or a specific anti-VEGF-A165b antibody. Cell viability and cytotoxicity were measured by trypan blue and LDH assay respectively.
  
  
  RESULTS
  Under high (21%) levels of oxygen, trophoblast viability was increased, and cytotoxicity reduced by exogenous recombinant VEGF-A165b (p < 0.05, n = 10) or VEGF-A165a. The cytoprotective effect was not seen under lower (<2%) oxygen conditions, where VEGF-A165b was upregulated. However inhibition of VEGF-A with blocking antibodies (bevacizumab or anti-VEGF-A165b) had marked cytotoxic effects under low oxygen conditions presumably through the blockade of autocrine survival pathways.
  
  
  CONCLUSIONS
  These results show that when trophoblasts are exposed to lower oxygen tensions (as they are early in the 1st trimester) endogenous VEGF-A165b contributes to their survival through an autocrine pathway. In contrast in high oxygen conditions exogenous VEGF-A isoforms have a greater effect on trophoblast survival.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Bills
authors.forename: Maryam
authors.initials: M
authors.lastname: Hamdollah-Zadeh
authors.forename: Peter W
authors.initials: PW
authors.lastname: Soothill
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Harper
authors.affiliation: Cancer Biology, Division of Oncology, University of Nottingham, Queen's Medical Centre, Nottingham NG2 7QT, UK. David.Bates@nottingham.ac.uk.
authors.forename: David O
authors.initials: DO
authors.lastname: Bates
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000068258:Bevacizumab / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D010100:Oxygen / Q000494:pharmacology*; D020033:Protein Isoforms / Q000494:pharmacology / Q000502:physiology; D014327:Trophoblasts / Q000187:drug effects* / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*
chemical_list: D020533:Angiogenesis Inhibitors; D020033:Protein Isoforms; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab; D010100:Oxygen