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 involve d in the formation of acellular cementum during tooth development, suggesti ng that these proteins can be used to regenerate periodontal tissues. Ename l matrix protein derived from embryonic porcine tooth germs is used clinica lly, but the mechanisms by which it promotes the formation of cementum, per iodontal ligament, and bone are not well understood. Methods: This study examined the response of osteoblasts at 3 stages of ost eogenic maturation to porcine fetal enamel matrix derivative (EMD). Prolife ration (cell number and [H-3]-thymidine incorporation), differentiation (al kaline phosphatase and osteocalcin), matrix synthesis ([S-35]-sulfate incor poration; percentage of collagen production), and local factor production ( prostaglandin E-2 [PGE(2)] and transforming growth factor-beta 1 [TGF-beta1 ]) were measured in cultures of 2T9 cells (pre-osteoblasts which exhibit os teogenesis in response to bone morphogenetic protein-2 [BMP-2]), MG63 human osteoblast-like osteosarcoma cells, and normal human osteoblasts (NHOst ce lls). Results: EMD regulated osteoblast proliferation and differentiation, but th e effects were cell-specific. In 2T9 cell cultures, EMD increased prolifera tion but had no effect on alkaline phosphatase-specific activity. EMD decre ased proliferation of MG63 cells and increased cellular alkaline phosphatas e and osteocalcin production. There was no effect on collagen synthesis, pr oteoglycan sulfation, or PGE(2) production; however, TGF-beta1 content of t he conditioned media was increased. There was a 60-fold increase in cell nu mber in third passage NHOst cells cultured for 35 days in the presence of E MD. EMD also caused a biphasic increase in alkaline phosphatase that was ma ximal at day 14. Conclusions: EMD affects early states of osteoblastic maturation by stimula ting proliferation, but as cells mature in the lineage, EMD enhances differ entiation.