Inhibitory effect of enamel matrix derivative on osteoblastic differentiation of rat calvaria cells in culture.
OBJECTIVE
The effect of enamel matrix derivative (EMD) on bone differentiation remains unclear. Transforming growth factor beta1 (TGF-beta1) is reported to be contained in EMD. The aim of this study was to clarify the effect of EMD on osteoblastic cell differentiation and the possible role of TGF-beta1.


METHODS
Fetal rat carvarial cells were treated with 10, 50 or 100 microg/ml EMD for 5-17 days. Alkaline phosphatase (ALP) activity and bone nodule formation were measured, and mRNA expressions of bone matrix proteins and core binding factor were analysed.


RESULTS
Enamel matrix derivative inhibited ALP activity from the early stage of culture (29-44% inhibition) on days 5 and 10 and decreased bone nodule formation by 37-67% on day 17. These effects of EMD were concentration dependent. Enamel matrix derivative inhibited mRNA expression of osteocalcin and core binding factor. A high level of the active form of TGF-beta1 protein was detected in the conditioned medium treated with 100 microg/ml EMD. Treatment with TGF-beta1 antibody partly restored the inhibitory effect of EMD on ALP activity.


CONCLUSIONS
Enamel matrix derivative inhibited the osteoblastic differentiation of rat carvarial cells and this was partly mediated by an increase in the activated form of TGF-beta1, suggesting that EMD may function initially to inhibit osteoblastic differentiation to allow a predominant formation of other periodontal tissues.
Hama
Hideki
H
Department of Periodontology and Endodontology, Oral and Maxillofacial Dentistry, Division of Medico-Dental Biosciences, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima 770-8504, Japan. hama@dent.tokushima-u.ac.jp
Azuma
Hideki
H
Seto
Hiroyuki
H
Kido
Jun-ichi
J
Nagata
Toshihiko
T
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors; D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D050660:Core Binding Factors / Q000037:antagonists & inhibitors; D003746:Dental Enamel Proteins / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects*; D015675:Osteocalcin / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012886:Skull / Q000601:surgery; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology / Q000502:physiology*
D050660:Core Binding Factors; D003746:Dental Enamel Proteins; D011994:Recombinant Proteins; D053773:Transforming Growth Factor beta1; C109069:enamel matrix proteins; D015675:Osteocalcin; D000469:Alkaline Phosphatase