Enamel factors regulate expression of genes associated with cementoblasts.

BACKGROUND: In order to design predictable periodontal regenerative therapies, it is important to understand the responsiveness of cells within the local environment to factors considered attractive candidates. The aim of this study was to determine the effect of an enamel matrix derivative (EMD) on cementoblast behavior in vitro and in vivo.
METHODS: Osteocalcin (OC) promoter SV40 transgenic mice were used to obtain cementoblasts. For comparison, preosteoblasts from these mice, as well as another murine pre-osteoblast cell line, MC3T3-E1 cells, were used. Cells exposed to EMD were evaluated for changes in: 1) proliferation over an 8-day period by cell counting; 2) gene expression using Northern blot analysis; and 3) biomineralization by von Kossa stain, in vitro and by preparing histological samples from implants retrieved from immunodeficient (SCID) mice, where cementoblasts were treated with EMD prior to implantation.
RESULTS: EMD promoted proliferation of all cell types. EMD down-regulated osteocalcin transcripts in cementoblasts and MC3T3-E1 cells and up-regulated osteopontin gene expression markedly in MC3T3-E1 cells and slightly in cementoblasts at day 8. In vitro, EMD decreased cementoblast-mediated biomineralization. In contrast, mineralization was noted in implants retrieved from SCID mice, where cells were pretreated with EMD.
CONCLUSION: These results indicate that EMD can influence activities of cementoblasts and osteoblasts, and thus may be able to regulate cell activities at a periodontal regenerative site.