Porcine fetal enamel matrix derivative stimulates proliferation but not differentiation of pre-osteoblastic 2T9 cells, inhibits proliferation and stimulates differentiation of osteoblast-like MG63 cells, and increases proliferation and differentiation of normal human osteoblast NHOst cells.
BACKGROUND
Embryonic enamel matrix proteins are hypothesized to be involved in the formation of acellular cementum during tooth development, suggesting that these proteins can be used to regenerate periodontal tissues. Enamel matrix protein derived from embryonic porcine tooth germs is used clinically, but the mechanisms by which it promotes the formation of cementum, periodontal ligament, and bone are not well understood.


METHODS
This study examined the response of osteoblasts at 3 stages of osteogenic maturation to porcine fetal enamel matrix derivative (EMD). Proliferation (cell number and [3H]-thymidine incorporation), differentiation (alkaline phosphatase and osteocalcin), matrix synthesis ([35S]-sulfate incorporation; percentage of collagen production), and local factor production (prostaglandin E2 [PGE2] and transforming growth factor-beta 1 [TGF-beta1]) were measured in cultures of 2T9 cells (pre-osteoblasts which exhibit osteogenesis in response to bone morphogenetic protein-2 [BMP-2]), MG63 human osteoblast-like osteosarcoma cells, and normal human osteoblasts (NHOst cells).


RESULTS
EMD regulated osteoblast proliferation and differentiation, but the effects were cell-specific. In 2T9 cell cultures, EMD increased proliferation but had no effect on alkaline phosphatase-specific activity. EMD decreased proliferation of MG63 cells and increased cellular alkaline phosphatase and osteocalcin production. There was no effect on collagen synthesis, proteoglycan sulfation, or PGE2 production; however, TGF-beta1 content of the conditioned media was increased. There was a 60-fold increase in cell number in third passage NHOst cells cultured for 35 days in the presence of EMD. EMD also caused a biphasic increase in alkaline phosphatase that was maximal at day 14.


CONCLUSIONS
EMD affects early states of osteoblastic maturation by stimulating proliferation, but as cells mature in the lineage, EMD enhances differentiation.
Schwartz
Z
Z
Department of Orthopaedics, University of Texas Health Science Center, San Antonio 78229-3900, USA.
Carnes
D L
DL
Pulliam
R
R
Lohmann
C H
CH
Sylvia
V L
VL
Liu
Y
Y
Dean
D D
DD
Cochran
D L
DL
Boyan
B D
BD
D000469:Alkaline Phosphatase / Q000187:drug effects; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D019070:Cell Lineage; D003094:Collagen / Q000378:metabolism; D017077:Culture Media, Conditioned; D003746:Dental Enamel Proteins / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects*; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D012516:Osteosarcoma / Q000473:pathology* / Q000503:physiopathology; D019275:Radiopharmaceuticals; D013462:Sulfur Radioisotopes; D013552:Swine; D013936:Thymidine / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology; D014316:Tritium; D014407:Tumor Cells, Cultured
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D017077:Culture Media, Conditioned; D003746:Dental Enamel Proteins; D019275:Radiopharmaceuticals; D013462:Sulfur Radioisotopes; D016212:Transforming Growth Factor beta; C109069:enamel matrix proteins; D014316:Tritium; D015675:Osteocalcin; D003094:Collagen; D000469:Alkaline Phosphatase; D015232:Dinoprostone; D013936:Thymidine