OSTEOBLAST-LIKE PROPERTIES OF HUMAN PERIODONTAL-LIGAMENT CELLS - AN IN-VITRO ANALYSIS

Identifying the biological properties of the cells residing within the periodontal ligament (PDL) will help in understanding the role that t hese cells play in the various functions of the periodontal ligament, and will improve the success of clinical procedures such as orthodonti c tooth movement. For this purpose, fibroblasts isolated from human pe riodontium were cultured and characterized both histochemically and bi ochemically with respect to their putative osteoblast-like properties. Histochemically, cultured PDL fibroblasts showed an intense staining for alkaline phosphatase (ALP). Biochemically, the basal ALP activity increased in culture over time. ALP levels after stimulation with 1 al pha,25-dihydroxyvitamin D-3 were significantly higher than those of co ntrol cultures. Moreover, immunofluorescence against osteocalcin (a hi ghly reliable osteoblastic marker) was strongly positive. Von Kossa st aining of the cell cultures revealed the formation of mineral-like nod ules. These results indicate that human PDL fibroblasts exhibit in vit ro phenotypic characteristics consistent with osteoblast-like cells, t hus suggesting that such cells have the potential to differentiate int o osteoblasts and/or cementoblasts.