Cells with osteoblastic phenotypes can be explanted from human gingiva and periodontal ligament

Considerable phenotypic heterogeneity has been reported in gingival fibroblasts. Similarly, cells from the periodontal ligament (PDL) can be isolated with different phenotypes. Although it has been suggested that cells from the gingiva do not contribute to the formation of hard tissue, it is theoretically possible that under appropriate stimuli, immature mesenchymal cells in gingiva could differentiate along an osteoblastic pathway. Differentiation of immature mesenchymal cells into osteoblasts following stimulation with osteoinductive factors has been demonstrated in muscle. We undertook experiments to establish whether cells with osteoblastic characteristics could be identified from human gingiva as well as from human periodontal ligament. Some cell populations from each of these tissues were found to have high basal alkaline phosphatase activity, to release osteocalcin in response to 1,25(OH)2 VitD3, and to form a mineralized matrix. Thus, cells can be isolated from the gingiva and PDL that exhibit phenotypic markers, which taken together are characteristic of osteoblastic cells. Other cell populations derived from the PDL and gingival connective tissue were isolated that had fibroblastic characteristics. These studies support the concept that gingival tissue can give rise to cells which may differentiate along either a fibroblastic or an osteoblastic pathway.