title: Association between in vivo bone formation and ex vivo migratory capacity of human bone marrow stromal cells.
abstract: BACKGROUND
  There is a clinical need for developing systemic transplantation protocols for use of human skeletal stem cells (also known bone marrow stromal stem cells) (hBMSC) in tissue regeneration. In systemic transplantation studies, only a limited number of hBMSC home to injured tissues suggesting that only a subpopulation of hBMSC possesses "homing" capacity. Thus, we tested the hypothesis that a subpopulation of hBMSC defined by ability to form heterotopic bone in vivo, is capable of homing to injured bone.
  
  
  METHODS
  We tested ex vivo and in vivo homing capacity of a number of clonal cell populations derived from telomerized hBMSC (hBMSC-TERT) with variable ability to form heterotopic bone when implanted subcutaneously in immune deficient mice. In vitro transwell migration assay was used and the in vivo homing ability of transplanted hBMSC to bone fractures in mice was visualized by bioluminescence imaging (BLI). In order to identify the molecular phenotype associated with enhanced migration, we carried out comparative DNA microarray analysis of gene expression of hBMSC-derived high bone forming (HBF) clones versus low bone forming (LBF) clones.
  
  
  RESULTS
  HBF clones were exhibited higher ex vivo transwell migration and following intravenous injection, better in vivo homing ability to bone fracture when compared to LBF clones. Comparative microarray analysis of HBF versus LBF clones identified enrichment of gene categories of chemo-attraction, adhesion and migration associated genes. Among these, platelet-derived growth factor receptor (PDGFR) α and β were highly expressed in HBF clones. Follow up studies showed that the chemoattractant effects of PDGF in vitro was more enhanced in HBF compared to LBF clones and this effect was reduced in presence of a PDGFRβ-specific inhibitor: SU-16 f. Also, PDGF exerted greater chemoattractant effect on PDGFRβ(+) cells sorted from LBF clones compared to PDGFRβ(-) cells.
  
  
  CONCLUSIONS
  Our data demonstrate phenotypic and molecular association between in vivo bone forming ability and migratory capacity of hBMSC. PDGFRβ can be used as a potential marker for the prospective selection of hBMSC populations with high migration and bone formation capacities suitable for clinical trials for enhancing bone regeneration.
authors.affiliation: Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark. rka@biomed.au.dk.
authors.forename: Rikke K
authors.initials: RK
authors.lastname: Andersen
authors.affiliation: Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark. wzaher@health.sdu.dk.|Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University, Riyadh, Saudi Arabia. wzaher@health.sdu.dk.
authors.forename: Walid
authors.initials: W
authors.lastname: Zaher
authors.affiliation: Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark. khaubergs@gmail.com.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Larsen
authors.affiliation: Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark. nditzel@health.sdu.dk.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Ditzel
authors.affiliation: Department of Vertebrate Genomics, Molecular Embryology and Aging Group, Max Planck Institute for Molecular Genetics, Berlin, Germany. katharina_drews@gmx.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Drews
authors.affiliation: Research and Regenerative Medicine, Faculty of Medicine, Heinrich Heine University, Duesseldorf, Germany. Wasco.Wruck@med.uni-duesseldorf.de.
authors.forename: Wasco
authors.initials: W
authors.lastname: Wruck
authors.affiliation: Department of Vertebrate Genomics, Molecular Embryology and Aging Group, Max Planck Institute for Molecular Genetics, Berlin, Germany. james.adjaye@med.uni-duesseldorf.de.|Research and Regenerative Medicine, Faculty of Medicine, Heinrich Heine University, Duesseldorf, Germany. james.adjaye@med.uni-duesseldorf.de.
authors.forename: James
authors.initials: J
authors.lastname: Adjaye
authors.affiliation: Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark. babdallah@health.sdu.dk.|Faculty of Science, Helwan University, Cairo, Egypt. babdallah@health.sdu.dk.
authors.forename: Basem M
authors.initials: BM
authors.lastname: Abdallah
authors.affiliation: Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark. mkassem@health.sdu.dk.|Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University, Riyadh, Saudi Arabia. mkassem@health.sdu.dk.|Danish Stem Cell Center (DanStem), Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. mkassem@health.sdu.dk.
authors.forename: Moustapha
authors.initials: M
authors.lastname: Kassem
mesh_terms: D017667:Adipocytes / Q000502:physiology; D000818:Animals; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D010012:Osteogenesis; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism
chemical_list: D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta