FUNCTIONAL-CHARACTERISTICS OF GINGIVAL AND PERIODONTAL-LIGAMENT FIBROBLASTS

In periodontal surgery, healing after Guided Tissue Regeneration (GTR) may be explained by differences in functional activities of gingival and periodontal ligament fibroblasts (GF and PDLF). Several studies in vitro have supported this hypothesis, but much remains to be defined. In the present work, gingi val and periodontal ligament fibroblasts d erived from five healthy subjects were isolated and compared in ville. The morphology of the cells was observed under scanning electron micr oscopy (SEM). Several extracellular matrix components (ECM) were studi ed to compare the effects on fibroblast attachment, proliferation, and protein synthesis. Several biochemical markers were examined in both cellular extract (CE) and conditioned medium (CM). We also examined th e muscle differentiation markers alpha-smooth muscle actin, desmin, an d smooth-muscle myosin. Finally, we studied the effects of epithelial cells on the proliferation and protein synthesis of the two types of f ibroblasts. GF and PDLF appeared identical under the SEM. All ECM comp onents enhanced attachment; however, while collagen types I and IV pro moted the attachment of GF, gelatin laminin, and vitronectin promoted that of PDLF. Most ECM components increased the proliferation rate of GF and the biosynthetic activity of PDLF. The biochemical markers were similarly distributed between the two cell types, except for alkaline phosphatase, which was detected only in the CE of PDLF. Both GF and P DLF strongly expressed alpha-smooth-muscle actin and were negative for desmin; only PDLF were positive for smooth-muscle myosin. Epithelial cells increased the proliferation of both GF and PDLF but had no effec t on their biosynthetic activity. These in vitro results may better ex plain the in vivo functional differences between GF and PDLF.