The induction of bone formation by the recombinant human transforming growth factor-β3.
Implantation of recombinant human transforming growth factor-β3 (hTGF-β3) with coral-derived calcium carbonate-based macroporous bioreactors with limited conversion to hydroxyapatite (7% HA/CC) in the rectus abdominis muscle of the non-human primate Chacma baboon Papio ursinus induces endochondral bone formation. The exact mechanisms by which hTGF-β3 signalling induces bone in heterotopic sites of P. ursinus are not known. Coral-derived 7% HA/CC bioreactors with and without 125 μg hTGF-β3 were implanted in triplicate in the rectus abdominis muscle of 6 adult baboons. 7% HA/CC bioreactors either with or without hTGF-β3 were loaded with 125 μg of recombinant human Noggin (hNoggin), a bone morphogenetic proteins (BMPs) antagonist. Tissues on day 15, 60 and 90 were analysed by histomorphometry and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Down-regulation of BMP-2 characterized 7% HA/CC constructs preloaded with 125 μg hNoggin with Noggin down-regulated on day 60 and 90 together with lack of TGF-β3 expression. Down-regulation of BMP-2 correlated with minimal bone formation by induction. hTGF-β3/hNoggin pre-treated bioreactors up-regulated BMP-2 but only on day 90 together with a significant down-regulation of Noggin on day 60 and 90, correlating with the induction of bone formation, albeit limited, on day 90 at the periphery of the macroporous bioreactors only. hTGF-β3 treated bioreactors significantly down-regulated BMP-2 on day 15 whilst up-regulating BMP-2 on day 60 and 90, together with down-regulation of Noggin on day 60 and 90 correlating with the prominent induction of bone formation. hTGF-β3 significantly up-regulated RUNX-2 and Osteocalcin expression on day 15 controlling the differentiation of progenitor stem cells into the osteoblastic lineage. The induction of bone as initiated by hTGF-β3 in the rectus abdominis muscle of P. ursinus is via the BMPs pathway with hTGF-β3 controlling the induction of bone formation by regulating the expression of BMPs via Noggin expression. These results unequivocally demonstrate that hTGF-β3 elicits bone induction by up-regulation of endogenous BMP-2 and is blocked by hNoggin.
Bone Research Laboratory, School of Physiology, Faculty of Health Sciences, Medical School, University of the Witwatersrand, Parktown, Johannesburg 2193 South Africa.
Roland M
RM
Klar
Department of Internal Medicine, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, South Africa.
Raquel
R
Duarte
Department of Internal Medicine, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, South Africa.
Therese
T
Dix-Peek
Bone Research Laboratory, School of Physiology, Faculty of Health Sciences, Medical School, University of the Witwatersrand, Parktown, Johannesburg 2193 South Africa. Electronic address: ugo.ripamonti@wits.ac.za.
Ugo
U
Ripamonti
D000818:Animals; D019149:Bioreactors; D002119:Calcium Carbonate / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D017886:Durapatite / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D009024:Morphogenesis / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects*; D048549:Papio ursinus; D016062:Porosity; D019919:Prosthesis Implantation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053782:Transforming Growth Factor beta3 / Q000494:pharmacology*; D000099176:Noggin Protein
D002119:Calcium Carbonate; D002352:Carrier Proteins; D017886:Durapatite; D053782:Transforming Growth Factor beta3; D000099176:Noggin Protein; C509044:TGFB3 protein, human
Bone morphogenetic proteins; Noggin; Primates; Tissue induction; Transforming growth factor-β(3); qRT-PCR