title: Human placental multipotent mesenchymal stromal cells modulate trophoblast migration via Rap1 activation.
abstract: BACKGROUND
  Little is known about the interaction between human placental multipotent mesenchymal stromal cell (hPMSC) and trophoblast. We hypothesize that hPMSCs produce hepatocyte growth factor (HGF) which may interact with trophoblasts and regulate their migration during placentation.
  
  
  METHODS
  hPMSCs were isolated from term placentas and conditioned medium was collected after 2 days of culture in hypoxic (<1% O2) or control (20% O2) conditions. Selective agonist and inhibitor or siRNA for protein kinase A (PKA) or Rap1 were combined with Rap1-GTP pull down assays, flow cytometry, integrin β1 activation assays and adhesion and migration studies to investigate HGF signaling effects in trophoblasts. The hPMSC abundance and HGF level in preeclamptic placentas were compared with gestational age-matched controls.
  
  
  RESULTS
  HGF was expressed by hPMSCs and was decreased in hypoxia. HGF induced cAMP production and Rap1 activation in trophoblasts, which in turn activated integrin β1. The HGF and PKA activator 6-Bnz-cAMP induced Rap1 activation with increased trophoblast adhesion and migration. The alterations were inhibited by PKA inhibitor H89 or Rap1 siRNA. HGF and cAMP expression were reduced in preeclamptic placentas. hPMSC number was decreased in preeclamptic placenta compared to controls (0.68 ± 0.1% vs. 1.32 ± 0.5%; P = 0.026). hPMSC conditioned medium enhanced trophoblast migration which was inhibited by c-Met blocking antibody, but migration was reduced by conditioned medium from hPMSC cultured in hypoxia.
  
  
  CONCLUSIONS
  hPMSCs secrete HGF and increase trophoblast cAMP production. The cAMP effector PKA modulates adhesion and migration of trophoblast via signaling to Rap1 and integrin β1.
authors.affiliation: Division of High Risk Pregnancy, Mackay Memorial Hospital, Taipei, Taiwan, ROC. cpchen@ms2.mmh.org.tw
authors.forename: C-P
authors.initials: CP
authors.lastname: Chen
authors.forename: J-P
authors.initials: JP
authors.lastname: Huang
authors.forename: T-Y
authors.initials: TY
authors.lastname: Chu
authors.forename: J D
authors.initials: JD
authors.lastname: Aplin
authors.forename: C-Y
authors.initials: CY
authors.lastname: Chen
authors.forename: Y-H
authors.initials: YH
authors.lastname: Wu
mesh_terms: D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005260:Female; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D010920:Placenta / Q000166:cytology*; D011225:Pre-Eclampsia / Q000378:metabolism; D011247:Pregnancy; D055746:Stage-Specific Embryonic Antigens / Q000378:metabolism; D014327:Trophoblasts / Q000502:physiology*; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D055746:Stage-Specific Embryonic Antigens; C066584:stage-specific embryonic antigen-4; D017228:Hepatocyte Growth Factor; D017868:Cyclic AMP-Dependent Protein Kinases; D020827:rap1 GTP-Binding Proteins
keywords: Hepatocyte growth factor; Integrin β1; Placental multipotent mesenchymal stromal cells; Protein kinase A; Rap1