title: Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces.
abstract: OBJECTIVE
  Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces.
  
  
  METHODS
  EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction.
  
  
  RESULTS
  Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces.
  
  
  CONCLUSIONS
  The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities.
  
  
  CONCLUSIONS
  In correlation with recent clinical studies these results underline the hypothesis that EPC could promote and increase neovascularization by secreting paracrine factors which support osseointegration of dental implants.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University medical centre of Johannes Gutenberg University Mainz, Augustusplatz 2, 55131, Mainz, Germany. ziebart@mkg.klinik.uni-mainz.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Ziebart
authors.forename: Anne
authors.initials: A
authors.lastname: Schnell
authors.forename: Christian
authors.initials: C
authors.lastname: Walter
authors.forename: Peer W
authors.initials: PW
authors.lastname: Kämmerer
authors.forename: Andreas
authors.initials: A
authors.lastname: Pabst
authors.forename: Karl M
authors.initials: KM
authors.lastname: Lehmann
authors.forename: Johanna
authors.initials: J
authors.lastname: Ziebart
authors.forename: Marc O
authors.initials: MO
authors.lastname: Klein
authors.forename: Bilal
authors.initials: B
authors.lastname: Al-Nawas
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D002452:Cell Count; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D048430:Cell Shape; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D045662:Dental Etching / Q000379:methods; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry*; D042783:Endothelial Cells / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology*; D005353:Fibronectins / Q000737:chemistry; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D052247:Nitric Oxide Synthase Type II / Q000032:analysis; D052250:Nitric Oxide Synthase Type III / Q000032:analysis; D016348:Osseointegration / Q000502:physiology; D010641:Phenotype; D011137:Polystyrenes / Q000737:chemistry; D013234:Stem Cells / Q000502:physiology*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis
chemical_list: D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D003764:Dental Materials; D005353:Fibronectins; D011137:Polystyrenes; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D014025:Titanium; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III