SPECIFIC CEMENTUM ATTACHMENT PROTEIN ENHANCES SELECTIVELY THE ATTACHMENT AND MIGRATION OF PERIODONTAL CELLS TO ROOT SURFACES

A specific cementum attachment protein (CAP) was identified in human c ementum and found to bind with high affinity to non-demineralized root surfaces, hydroxyapatite and fibronectin. Attempting to elucidate the biological function of this protein and its possible role in cementog enesis the capacity of CAP to promote selective cell migration towards and attachment of various periodontal derived cell populations to roo t surfaces in vitro was assessed. Human gingival fibroblasts (HGF), pe riodontal ligament cells (HPC), and alveolar bone cells (HABC) were la beled with [H-3]Thymidine during their exponential growth phase. Root slices, 300 mu m thick, were incubated with increasing concentrations of CAP. Untreated and fibronectin (FN) treated root slices served as n egative and positive controls, respectively. Migration was assessed by placing root slices on confluent layers of labeled cells maintained i n serum free medium and determining the number of cells migrated onto the root surface 3 days thereafter. Attachment was assessed by incubat ing root slices with labeled cell suspensions for 2 h and determining the number of attached cells. CAP promoted both cell migration and att achment dose dependently. HABC responded better than HPC and HGF to CA P treated root slices, and HPC response was higher than that of HGF. C ell attachment was dose dependently inhibited by synthetic RGD peptide s. FN did not affect the migration of HGF, barely enhanced that of HAB C, and was less potent than CAP at enhancing the migration of HPC. FN was more effective than CAP in promoting the attachment of HGF to root slices, but it was as potent as CAP in supporting the attachment of H PC and HABC. The results indicate that CAP promotes preferential migra tion towards and attachment to root surfaces of HABC and HPC as compar ed to HGF and suggests that CAP might be effective in supporting cemen togenesis.