Transforming growth factor-beta1 supports the rapid morphogenesis of heterotopic endochondral bone initiated by human osteogenic protein-1 via the synergistic upregulation of molecular markers.
Members of the transforming growth factor-beta (TGF-beta) superfamily of proteins, the bone morphogenetic proteins (BMPs) and the TGF-beta isoforms, are involved in the coordination of cartilage and bone differentiation both in embryonic development and in postnatal life. Both osteogenic protein-1 (OP-1) and TGF-beta1 have been shown to be potent regulators and inducers of heterotopic endochondral bone induction in non-human primates. In marked contrast, TGF-beta1 does not induce heterotopic endochondral bone in rodents. In the primate, the osteogenic properties of OP-1 are synergistically enhanced by the combined administration of TGF-beta1. The binary application of OP-1 (0.1, 0.3, 1.0 and 3.0 microg) and TGF-beta1 (0.01, 0.03 and 0.1 microg) to 25 mg of guanidinium-inactivated insoluble collagenous bone matrix as carrier in the rodent heterotopic bioassay for 7, 12 and 21 days resulted in a classical synergistic, dose-dependent and temporal up-regulation of OP-1-induced endochondral bone formation. There were significant increases in alkaline phosphatase activity (day 12) and calcium content (days 12 and 21). mRNA expression of OP-1, TGF-beta1, BMP-3 and collagens type II and IV, markers of bone formation, showed an up-regulation of the genes (days 12 and 21) by the binary applications of the morphogens. Histologically, single applications of OP-1 elicited a dose dependent induction of endochondral bone formation while the binary applications resulted in a temporal acceleration of the morphogenetic cascade. The optimal ratio of OP-1/TGF-beta1 was 30:1 by weight for endochondral bone formation and expression of molecular markers. The present data provides insights to the mechanisms of synergistic molecular therapeutics for endochondral bone formation in clinical contexts.
Matsaba
T
T
Bone Research Laboratory, Medical Research Council, University of the Witwatersrand, Medical School, Johannesburg, South Africa.
Ramoshebi
L N
LN
Crooks
J
J
Ripamonti
U
U
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001681:Biological Assay; D015152:Blotting, Northern; D001846:Bone Development / Q000502:physiology; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D015854:Up-Regulation
C525819:BMP7 protein, human; C525821:Bmp7 protein, rat; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011994:Recombinant Proteins; C508960:TGFB1 protein, human; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D003094:Collagen; D000469:Alkaline Phosphatase