title: Prostaglandin E2 and vascular endothelial growth factor A mediate angiogenesis of human ovarian follicular endothelial cells.
abstract: OBJECTIVE
  Which receptors for prostaglandin E2 (PGE2) and vascular endothelial growth factor A (VEGFA) mediate angiogenesis in the human follicle around the time of ovulation?
  
  
  CONCLUSIONS
  PGE2 and VEGFA act via multiple PGE2 receptors (PTGERs) and VEGF receptors (VEGFRs) to play complementary roles in follicular angiogenesis.
  
  
  BACKGROUND
  Production of PGE2 and VEGFA by the follicle are prerequisites for ovulation. PGE2 is an emerging regulator of angiogenesis and has not been examined in the context of the human ovulatory follicle. VEGFA is an established regulator of follicular angiogenesis.
  
  
  METHODS
  Ovarian biopsies containing the ovulatory follicle were obtained from 11 women of reproductive age (30-45 years) undergoing surgery for laparoscopic sterilization. In some cases, women received hCG to substitute for the ovulatory LH surge before ovarian biopsy. In addition, aspirates from four women of reproductive age (18-31 years) undergoing gonadotrophin stimulation for oocyte donation were obtained for isolation of human ovarian microvascular endothelial cells (hOMECs).
  
  
  METHODS
  Ovarian biopsies were utilized for immunocytochemical detection of von Willebrand factor to identify endothelial cells. hOMECs were cultured with PGE2, PTGER receptor selective agonists, VEGFA, or VEGFR selective agonists. hOMECs were assessed for proliferation by Ki67 immunocytochemistry. hOMEC migration was determined by counting cells which migrated through a porous membrane in vitro. Sprout formation was quantified by determining sprout number and length from photographs take after culture of hOMECs in a 3-dimensional matrix.
  
  
  RESULTS
  Endothelial cells were not observed within the granulosa cell layer of human ovulatory follicles prior to an ovulatory dose of hCG and were first seen amongst granulosa cells 18-34 h after hCG. In vitro, PGE2 enhanced migration and sprout formation but did not alter hOMEC proliferation. Agonists selective for each PTGER increased migration with no change in proliferation. PTGER1 and PTGER2 agonists increased the number of sprouts, while only PTGER1 affected sprout length. VEGFA increased hOMEC proliferation, migration, and formation of structures resembling capillary sprouts. Signaling through VEGFR1 promoted hOMEC migration, proliferation, and the formation of few, long endothelial cell sprouts, while VEGFR2 stimulation promoted hOMEC migration and the formation of many, short sprouts. All effects of treatments in vitro were considered significant at P < 0.05.
  
  
  CONCLUSIONS
  While primary cultures of hOMECs respond to PGE2 and VEGFA differently than other cultured endothelial cells, hOMECs may not respond to PGE2 and VEGFA in vivo as they do in vitro.
  
  
  CONCLUSIONS
  Agonists and antagonists selective for PTGER1, PTGER2, VEGFR1, or VEGFR2 may have therapeutic value to promote or prevent ovulation in women.
  
  
  BACKGROUND
  This research was supported by grant funding from the Eunice Kennedy Shriver National Institutes of Child Health and Human Development (HD071875 to D.M.D., T.E.C., M.B.). The authors have no conflicts of interest to disclose.
authors.affiliation: Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23501, USA.
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Trau
authors.affiliation: Department of Obstetrics and Gynecology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Brännström
authors.affiliation: Department of Obstetrics and Gynecology, University of Kentucky College of Medicine, Lexington, KY, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Curry
authors.affiliation: Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23501, USA duffydm@evms.edu.
authors.forename: Diane M
authors.initials: DM
authors.lastname: Duffy
mesh_terms: D000328:Adult; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism / Q000502:physiology; D018919:Neovascularization, Physiologic; D006080:Ovarian Follicle / Q000098:blood supply* / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism / Q000502:physiology*
chemical_list: D006063:Chorionic Gonadotropin; D042461:Vascular Endothelial Growth Factor A; D007986:Luteinizing Hormone; D015232:Dinoprostone
keywords: PGE2 receptor; VEGF receptor; endothelial cell; follicle; ovary; ovulation; prostaglandin; vascular endothelial growth factor