During tooth development, cells of Hertwig's epithelial root sheath secrete enamel matrix proteins. A purified enamel matrix product (Enamel Matrix Derivative, EMD) from developing porcine teeth became commercially available and has been successfully employed to restore fully functional periodontal ligament, cementum and alveolar bone. The regenerative capacity of EMD has been demonstrated in clinical and animal studies. However the biological mechanisms are not known. We hypothesize that EMD regulates some primary gene expression, which regulate osteoblast differentiation, growth and function. The objective of this project is to identify the genes regulated in the EMD treated preosteoblastic cell line MC3T3-E1 and MG63 osteoblast-like cells using DNA microarray technology. Identified interesting genes will be confirmed by northern blot analysis. Finding the common gene changes in both cell lines will help us to find which genes are involved in the interaction between EMD and osteoblasts. The difference of EMD regulated gene changes between the two cell lines will help us to understand why EMD have different effects on preosteoblasts and osteoblast-like cells. We believe that, at the completion of the proposed research, our findings will constitute sufficient data for a future R01 grant application to investigate the EMD regulated genes and the relationship of these genes with osteoblast growth and function. The results of this application will also provide foundation for identifying what molecules might be active in EMD to regulate the identified genes. The identified molecules in the EMD could be used more efficiently and conveniently for periodontal regeneration than the isolated EMD protein mixture.