title: Immature myeloid cells accumulate in mouse placenta and promote angiogenesis.
abstract: OBJECTIVE
  We sought to determine whether CD11b(+)Gr1(+) immature myeloid cells (IMCs), which have been shown to promote tumor angiogenesis, accumulate in the placenta and similarly contribute to blood vessel formation.
  
  
  METHODS
  Experiments were performed on 6- to 8-week-old C57Bl/6J female mice. Placentas from pregnant mice or B16F10 tumors that were subcutaneously implanted were analyzed by flow cytometry and confocal microscopy. To determine the proangiogenic potential of IMCs, Matrigel plug assays were performed.
  
  
  RESULTS
  IMCs infiltrate the placenta in the proximity of blood vessels, reaching peak concentration at midpregnancy. When isolated from either placentas or B16F10 melanoma tumors, IMCs actively promoted endothelial cell migration into Matrigel plugs in vivo. Furthermore, placental IMCs, similar to tumor-derived IMCs, expressed matrix metalloproteinase-9 and Bv8, 2 pivotal proangiogenic proteins.
  
  
  CONCLUSIONS
  IMCs that express matrix metalloproteinase-9 and Bv8 infiltrate placentas of pregnant mice and actively promote angiogenesis. These cells show striking similarity to IMCs that populate malignant tumors.
authors.affiliation: Laboratory for Reproductive Immunology, Department of Obstetrics and Gynecology, Hillel Yaffe Medical Center, Hadera and Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel. ofainaru@techunix.technion.ac.il
authors.forename: Ofer
authors.initials: O
authors.lastname: Fainaru
authors.forename: Shay
authors.initials: S
authors.lastname: Hantisteanu
authors.forename: Mordechai
authors.initials: M
authors.lastname: Hallak
mesh_terms: D000818:Animals; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells / Q000502:physiology*; D018919:Neovascularization, Physiologic; D010920:Placenta / Q000098:blood supply* / Q000166:cytology*; D011247:Pregnancy