title: Heparan sulfate mediates the proliferation and differentiation of rat mesenchymal stem cells.
abstract: The growth and differentiation of mesenchymal stem cells (MSCs) is controlled by various growth factors, the activities of which can be modulated by heparan sulfates (HSs). We have previously noted the necessity of sulfated glycosaminoglycans for the fibroblast growth factor type 2 (FGF-2)-stimulated differentiation of osteoprogenitor cells. Here we show that exogenous application of HS to cultures of primary rat MSCs stimulates their proliferation, leading to increased expression of osteogenic markers and enhanced bone nodule formation. FGF-2 can also increase the proliferation, and osteogenic differentiation of rat bone marrow stem cells (rMSCs) when applied exogenously during their linear growth. However, as opposed to exogenous HS, the continuous use of FGF-2 during in vitro differentiation completely blocked rMSC mineralization. We show that the effects of both FGF-2 and HS are mediated through FGF receptor 1 (FGFR1) and that inhibition of signaling through this receptor arrests cell growth, resulting in the cells being unable to reach the critical density necessary to induce differentiation. Blocking FGFR1 signaling in postconfluent osteogenic cultures significantly increased calcium deposition. Taken together our data suggest that FGFR1 signaling plays an important role during osteogenic differentiation, first by stimulating cell growth that is closely followed by an inhibitory effect once the cells have reached confluence. It also confirms the importance of HS as a coreceptor for the signaling of endogenous FGF-2 and suggests that purified glycosaminoglycans may be attractive alternatives to growth factors for improved ex vivo growth and differentiation of MSCs.
authors.affiliation: Stem Cells and Tissue Repair Group, Institute of Medical Biology, A*STAR, Singapore.
authors.forename: Christian
authors.initials: C
authors.lastname: Dombrowski
authors.forename: Shu Jun
authors.initials: SJ
authors.lastname: Song
authors.forename: Peiying
authors.initials: P
authors.lastname: Chuan
authors.forename: Xinhong
authors.initials: X
authors.lastname: Lim
authors.forename: Evelyn
authors.initials: E
authors.lastname: Susanto
authors.forename: Amber A
authors.initials: AA
authors.lastname: Sawyer
authors.forename: Maria A
authors.initials: MA
authors.lastname: Woodruff
authors.forename: Dietmar W
authors.initials: DW
authors.lastname: Hutmacher
authors.forename: Victor
authors.initials: V
authors.lastname: Nurcombe
authors.forename: Simon M
authors.initials: SM
authors.lastname: Cool
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006497:Heparan Sulfate / Q000494:pharmacology*; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D015415:Biomarkers; D016222:Fibroblast Growth Factor 2; D006497:Heparan Sulfate; D051496:Receptor, Fibroblast Growth Factor, Type 1