title: Glycosaminoglycan composition changes with MG-63 osteosarcoma osteogenesis in vitro and induces human mesenchymal stem cell aggregation.
abstract: Osteogenic differentiation is coordinated by the exposure of cells to temporal changes in a combination of growth factors and elements within the extracellular matrix (ECM). Many of the key proteins that drive these changes share the property of being dependent on ECM glycosaminoglycans (GAGs) for their activity. Here, we examined whether GAGs isolated from proliferating, differentiating and mineralizing MG-63 osteosarcoma cells differed in their physical properties, and thus in their capacities to coordinate the osteogenic cascade both in human MG-63 osteosarcoma cells and primary human mesenchymal stem cells (hMSCs). Our results show that the size distribution of GAGs, the expression of GAG-carrying proteoglycan cores and the expression of enzymes involved in their modification systematically change as MG-63 cells mature in culture. When dosed back onto cells exogenously in soluble form, GAGs regulated MG-63 survival and growth in a dose-dependent manner, but not differentiation in either cell type. In contrast, hMSCs aggregated into distinct colonies when grown on GAG-coated substrates, while MG-63 cells did not. Heparin-coated substrates improved hMSC viability without inducing aggregation. These results suggest a complex role for GAGs in coordinating the emergence of the osteoblast phenotype, and provide further evidence for the use of heparans in bone tissue repair applications.
authors.affiliation: Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Kumarasuriyar
authors.forename: S
authors.initials: S
authors.lastname: Murali
authors.forename: V
authors.initials: V
authors.lastname: Nurcombe
authors.forename: S M
authors.initials: SM
authors.lastname: Cool
mesh_terms: D002449:Cell Aggregation; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D048430:Cell Shape; D002470:Cell Survival; D002809:Chondroitin Sulfates / Q000378:metabolism; D003871:Dermatan Sulfate / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D006025:Glycosaminoglycans / Q000737:chemistry* / Q000302:isolation & purification; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D010012:Osteogenesis; D012516:Osteosarcoma / Q000378:metabolism* / Q000473:pathology*; D010641:Phenotype; D011485:Protein Binding; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D006025:Glycosaminoglycans; D019812:Heparan Sulfate Proteoglycans; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D003871:Dermatan Sulfate; D006493:Heparin; D002809:Chondroitin Sulfates