title: The effect of timing in the administration of hepatocyte growth factor to modulate BMP-2-induced osteoblast differentiation.
abstract: Development of bone morphogenetic protein (BMP) signaling modulators may provide useful therapeutic options for the treatment of large bony defects in clinical settings. Controversy remains over whether hepatocyte growth factor (HGF) is a positive or negative modulator of BMP-induced osteogenesis. This study analyzed osteogenic properties of HGF, particularly during BMP-2-induced bone formation. Using a mouse model of ectopic bone formation, HGF-impregnated gelatin sponges displayed significantly reduced bone formation induced by BMP-2, both radiologically and histologically. Abrogation of endogenous HGF production by knockdown of HGF mRNA resulted in upregulation of BMP-2-induced ALP activity for C2C12 myoblasts in vitro. In contrast, addition of exogenous HGF inhibited BMP-2-induced ALP activity and osteocalcin production by mouse embryonic fibroblasts (MEFs) through HGF-c-Met interactions. Inhibition of ALP activity by HGF was rescued by U0126, a MEK1/2 inhibitor, indicating that HGF suppresses the BMP-2-Smad axis via activation of ERK1/2. Importantly, treatment with HGF prior to administration of BMP-2 induced cellular proliferation of MEFs and did not influence subsequent osteoblast differentiation induced by BMP-2. The effects of HGF may differ according to the differentiation stage of mesenchymal stem cells, which would explain the inconsistencies seen in osteogenic properties of HGF in previous reports. The timing of HGF treatment is critical and should be carefully determined for successful induction of bone formation by BMPs.
authors.affiliation: Department of Orthopaedic Surgery, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Niki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Keisuke
authors.initials: K
authors.lastname: Horiuchi
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Mamoru
authors.initials: M
authors.lastname: Aizawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D004357:Drug Synergism; D017228:Hepatocyte Growth Factor / Q000008:administration & dosage*; D051379:Mice; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects*; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D017228:Hepatocyte Growth Factor