BioProject

Introduction: 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. More...

Introduction: 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 possess “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 in vivo homing ability 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: In this study, clonal cell populations forming in vivo bone were shown to exhibit higher ex vivo transwell migration and following intravenous infusion, enhanced in vivo homing ability to bone fractures. Comparative microarray analysis of LBF versus HBF clones identified a significant enrichment of gene categories of cell chemo-attraction, adhesion and migration. Among these genes, platelet-derived growth factor receptor (PDGF-R) α and β were highly expressed in HBF clones. Further studies showed that the chemoattractive effects of PDGF in vitro was more enhanced in HBF clones compared to LBF clones and this effect was abolished in presence of a PDGFR-β-specific inhibitor: SU-16f. Sorted PDGFR-β+ cells from LBF clones showed that the PDGFR-β+ enriched cell population exhibited strong chemoattractance towards PDGF. Conclusion: Our data demonstrate phenotypic and molecular association between in vivo bone formation and migratory capacity of hBMSC. PDGFR-β 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. Overall design: Total RNA obtained from telomerized human bone marrow derived mesenchymal stromal cells (T4P38a) with high in vivo bone forming capacity and (T4P74a) with low bone forming capacity and three single cell clones with high bone forming capacities (DD8, AD10 and BB10) and three clones with low bone forming capacities (CF1, CB4 and CD4). All cells were cultured under standard conditions and RNAs were isolated at baseline with no induction. each sample was represented in doublicate as a and b. Less...