Enamel factors regulate expression of genes associated with cementoblasts

Background: In order to design predictable periodontal regenerative therapi es, it is important to understand the responsiveness of cells within the lo cal environment to factors considered attractive candidates. The aim of thi s 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, pre-osteoblasts 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-da y period by cell counting; 2) gene expression using Northern blot analysis; and 3) biomineralization by von Kossa stain, in vitro and by preparing his tological 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 o steocalcin transcripts in cementoblasts and MC3T3-E1 cells and up-regulated osteopontin gene expression markedly in MC3T3-E1. cells and slightly in ce mentoblasts at day 8, In vitro, EMD decreased cementoblast-mediated biomine ralization. In contrast, mineralization was noted in implants retrieved fro m SCID mice, where cells were pretreated with EMD, Conclusion: These results indicate that EMD can influence activities of cem entoblasts and osteoblasts, and thus may be able to regulate cell activitie s at a periodontal regenerative site.