title: Coculture with endothelial cells enhances osteogenic differentiation of periodontal ligament stem cells via cyclooxygenase-2/prostaglandin E2/vascular endothelial growth factor signaling under hypoxia.
abstract: BACKGROUND
  During periodontitis and orthodontic tooth movement, periodontal vasculature is severely impaired, leading to a hypoxic microenvironment of periodontal cells. However, the impact of hypoxia on periodontal cells is poorly defined. The present study investigates responses of cocultured endothelial cells (ECs) and periodontal ligament stem cells (PDLSCs) to hypoxia.
  
  
  METHODS
  Osteogenic differentiation, molecular characterization, and various behaviors of PDLSCs and human umbilical venous ECs under hypoxia were assessed by quantitative real-time reverse-transcription polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay. Moreover, the effect of ECs on PDLSC osteogenic differentiation was tested using NS398 (cyclooxygenase 2 blocker), SU5416 (vascular endothelial growth factor [VEGF] receptor inhibitor), AH6809, L-798106, and L-161982 (EP1/2/3/4 antagonists).
  
  
  RESULTS
  First, hypoxia promoted osteogenic differentiation in PDLSCs and enhanced EC migration, whereas PD98059 (extracellular signal-regulated protein kinase [ERK] inhibitor) blocked, and cocultured ECs further enhanced, hypoxia-induced osteogenic differentiation. Second, NS398 impaired EC migration and prostaglandin E2 (PGE2)/VEGF release, whereas cocultured PDLSCs and exogenous PGE2 partially reversed it. Third, NS398 (pretreated ECs) decreased PGE2/VEGF concentrations. NS398-treated ECs and AH6809/SU5416-treated PDLSCs impaired cocultured EC-induced enhancement of PDLSC osteogenic differentiation.
  
  
  CONCLUSIONS
  Hypoxia enhances ERK-mediated osteogenic differentiation in PDLSCs. Coculture with EC further augments PDLSC osteogenic differentiation via cyclooxygenase-2/PGE2/VEGF signaling.
authors.affiliation: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
authors.forename: Lixing
authors.initials: L
authors.lastname: Zhao
authors.forename: Yeke
authors.initials: Y
authors.lastname: Wu
authors.forename: Lijun
authors.initials: L
authors.lastname: Tan
authors.forename: Zhenrui
authors.initials: Z
authors.lastname: Xu
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Zhihe
authors.initials: Z
authors.lastname: Zhao
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Li
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.forename: Pu
authors.initials: P
authors.lastname: Yang
authors.forename: Tian
authors.initials: T
authors.lastname: Tang
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology; D018920:Coculture Techniques; D051546:Cyclooxygenase 2 / Q000187:drug effects / Q000502:physiology*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000502:physiology*; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D009578:Nitrobenzenes / Q000494:pharmacology; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D010513:Periodontal Ligament / Q000166:cytology*; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013234:Stem Cells / Q000187:drug effects / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects / Q000502:physiology*; D044004:Xanthones / Q000494:pharmacology
chemical_list: D020533:Angiogenesis Inhibitors; D052246:Cyclooxygenase 2 Inhibitors; D005419:Flavonoids; D007211:Indoles; C508711:L-161982; D009578:Nitrobenzenes; D011448:Prostaglandin Antagonists; D047428:Protein Kinase Inhibitors; D011758:Pyrroles; D013449:Sulfonamides; D013876:Thiophenes; D014230:Triazoles; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D044004:Xanthones; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; C053876:6-isopropoxy-9-oxoxanthene-2-carboxylic acid; C116890:Semaxinib; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D015232:Dinoprostone; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one