title: Biomimetic coating with phosphoserine-tethered poly(epsilon-lysine) dendrons on titanium surfaces enhances Wnt and osteoblastic differentiation.
abstract: OBJECTIVE
  Phosphoserine-based functionalization has been proposed as a tool to improve integration of endosseous implants by promoting osteoblast adhesion and differentiation in vitro. The present work investigates whether phosphoserine-tethered poly(epsilon-lysine) dendrons, when applied as a film to titanium surfaces, enhance the differentiation of osteoblastic cells and the activation of Wnt/β-catenin signaling.
  
  
  METHODS
  These films were tested in a murine model of calvaria-derived MC3T3 osteoblastic cells, primary bone marrow cells and mesenchymal, undifferentiated C2C12 cells. Gene expression was assayed by Real Time PCR, and activation of Wnt signaling pathway was measured with a reporter assay.
  
  
  RESULTS
  Dendrons increased expression of alkaline phosphatase and osteocalcin, two osteoblastic markers, in both murine osteoblastic MC3T3 cells and primary bone marrow cells. The expression of osteoprotegerin, a protein opposing osteoclastogenesis was also significantly higher in cells growing on dendron-coated substrates both at 3 and 6 days of culture. Similarly, the mRNA levels of Wisp-2 and of β-catenin, two Wnt target genes, were also markedly increased in this group at day 6. The activation of this signaling pathway in cells growing on the dendron-coated surfaces was confirmed by use of a TCF/β-catenin reporter system in the C2C12 cell line.
  
  
  CONCLUSIONS
  The findings of the present study show that phosphoserine-tethered poly(epsilon-lysine) dendron films act as stimuli for the activation of specific signal cascades and promote the differentiation of adhering progenitor cells into an osteoblastic phenotype.
authors.affiliation: Department of Biotechnology, Biomedical and Translational Sciences, University of Parma, Parma, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Galli
authors.forename: Marilina
authors.initials: M
authors.lastname: Piemontese
authors.forename: Steven T
authors.initials: ST
authors.lastname: Meikle
authors.forename: Matteo
authors.initials: M
authors.lastname: Santin
authors.forename: Guido M
authors.initials: GM
authors.lastname: Macaluso
authors.forename: Giovanni
authors.initials: G
authors.lastname: Passeri
mesh_terms: D000134:Acid Etching, Dental; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D032701:Biomimetics; D002448:Cell Adhesion; D002454:Cell Differentiation; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D020099:Coated Materials, Biocompatible; D050091:Dendrimers / Q000494:pharmacology*; D008239:Lysine / Q000494:pharmacology*; D013058:Mass Spectrometry; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010006:Osteoblasts / Q000502:physiology*; D015675:Osteocalcin / Q000378:metabolism; D010768:Phosphoserine / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D013499:Surface Properties; D014025:Titanium / Q000494:pharmacology*; D060449:Wnt Signaling Pathway / Q000502:physiology*
chemical_list: D015415:Biomarkers; D020099:Coated Materials, Biocompatible; D050091:Dendrimers; D015675:Osteocalcin; D010768:Phosphoserine; D014025:Titanium; D000469:Alkaline Phosphatase; D008239:Lysine