title: Heparin affects human bone marrow stromal cell fate: Promoting osteogenic and reducing adipogenic differentiation and conversion.
abstract: Heparins are broadly used for the prevention and treatment of thrombosis and embolism. Yet, osteoporosis is considered to be a severe side effect in up to one third of all patients on long-term treatment. However, the mechanisms underlying this clinical problem are only partially understood. To investigate if heparin affects differentiation of skeletal precursors, we examined the effects of heparin on the osteogenic and adipogenic lineage commitment and differentiation of primary human bone marrow stromal cells (hBMSCs). Due to the known inverse relationship between adipogenesis and osteogenesis and the capacity of pre-differentiated cells to convert into the respective other lineage, we also determined heparin effects on osteogenic conversion and adipogenic differentiation/conversion. Interestingly, heparin did not only significantly increase mRNA expression and enzyme activity of the osteogenic marker alkaline phosphatase (ALP), but it also promoted mineralization during osteogenic differentiation and conversion. Furthermore, the mRNA expression of the osteogenic marker bone morphogenic protein 4 (BMP4) was enhanced. In addition, heparin administration partly prevented adipogenic differentiation and conversion demonstrated by reduced lipid droplet formation along with a decreased expression of adipogenic markers. Moreover, luciferase reporter assays, inhibitor experiments and gene expression analyses revealed that heparin had putative permissive effects on osteogenic signaling via the BMP pathway and reduced the mRNA expression of the Wnt pathway inhibitors dickkopf 1 (DKK1) and sclerostin (SOST). Taken together, our data show a rather supportive than inhibitory effect of heparin on osteogenic hBMSC differentiation and conversion in vitro. Further studies will have to investigate the net effects of heparin administration on bone formation versus bone resorption in vivo to unravel the molecular mechanisms of heparin-associated osteoporosis and reconcile conflicting experimental data with clinical observations.
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany. Electronic address: m-simann.klh@uni-wuerzburg.de.
authors.forename: Meike
authors.initials: M
authors.lastname: Simann
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Schneider
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Solange
authors.initials: S
authors.lastname: Le Blanc
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Dotterweich
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Viola
authors.initials: V
authors.lastname: Zehe
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Krug
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Jakob
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Schilling
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Department of Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Schütze
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017667:Adipocytes / Q000166:cytology; D050156:Adipogenesis; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000737:chemistry; D001854:Bone Marrow Cells / Q000166:cytology*; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D005260:Female; D005819:Genetic Markers; D006493:Heparin / Q000737:chemistry*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D008875:Middle Aged; D010011:Osteocytes / Q000166:cytology; D010012:Osteogenesis; D010024:Osteoporosis / Q000209:etiology / Q000503:physiopathology*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000925:Anticoagulants; C525809:BMP4 protein, human; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; C501126:DKK1 protein, human; D005819:Genetic Markers; D036341:Intercellular Signaling Peptides and Proteins; D008055:Lipids; D012333:RNA, Messenger; D011994:Recombinant Proteins; C422903:SOST protein, human; D051153:Wnt Proteins; D006493:Heparin
keywords: Adipogenic differentiation; Conversion; Heparin; Human bone marrow stromal cell (hBMSC); Osteogenic differentiation; Osteoporosis