Low dose fibroblast growth factor-2 (FGF-2) enhances bone morphogenetic protein-2 (BMP-2)-induced ectopic bone formation in mice.
To examine how fibroblast growth factor-2 (FGF-2) affects the BMP signaling pathway during bone morphogenetic protein-2 (BMP-2)-induced ectopic bone formation, we implanted type I collagen disks containing constant amounts of BMP-2 (5 micrograms) and varying amounts of FGF-2 onto the back muscles of adult male mice. We then performed histological analyses and histomorphometry, and measured bone mineral density and radiopaque area on the discs 1, 2, and 3 weeks after implantation. We also determined the expression profiles of several genes involved in bone formation and the BMP signaling pathway in the muscle that had been adjacent to the implanted disc and in muscle-derived primary culture cells that had similarly been treated with a constant concentration of BMP-2 and a varying concentration of FGF-2. In the presence of a constant amount of BMP-2, we confirmed that low doses of FGF-2 increased ectopic bone formation in vivo and high doses inhibited bone formation. Northern and/or Western blots of recovered muscle from the in vivo experiment and treated muscle-derived primary culture cells from the in vitro experiment revealed that low doses of FGF-2, but not high doses, increased the expression BMP receptor (BMPR)-1B, phosphorylated Smad1, Noggin, and Osteocalcin. Our results indicate that low-dose FGF-2 may facilitate BMP-2-induced ectopic bone formation by altering the expression of BMPRs on the surface of bone forming progenitor cells. They also indicate that the inhibitory effect of high-dose FGF-2 is not mediated via increased expression of the BMP inhibitor Noggin.
Nakamura
Yukio
Y
Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan.
Tensho
Keiji
K
Nakaya
Hiroyuki
H
Nawata
Masashi
M
Okabe
Takahiro
T
Wakitani
Shigeyuki
S
D000818:Animals; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D004357:Drug Synergism; D016222:Fibroblast Growth Factor 2 / Q000008:administration & dosage*; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009999:Ossification, Heterotopic / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*
C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2