Expression of matrix proteins in cloned fibroblasts derived from periodontal tissue under different cell growth densities

Extracellular matrix (ECM) proteins have been implicated in the attachment, migration and differentiation of cells during periodontal wound healing. This study was designed to investigate the expression of ECM proteins in gingival fibroblasts (GF) and periodontal ligament fibroblasts (PF) at different cell growth densities. Both mass-cultured and cloned cells were derived from explants of healthy human gingivae and periodontal ligament. The grown cells, in situ, were subjected to immunofluorescent staining for the expression of collagen type I (CI), III (CIII) and fibronectin (Fn), and then measured by microfluorimetry. Partial biochemical measurement of the ECM proteins secreted in the medium was done by SDS-PAGE and densitometry. These data indicated that CI, CIII and Fn were expressed in both mass-cultured and cloned GF and PF. There were variations in the expression of these ECM proteins among the clones. PF and most of its clones produced a greater amount of total cellular and ECM proteins than did GF. The expression of these proteins was found to be greater in areas of low, as opposed to high, cell density. Parallel results were also noted in limited biochemical analyses. Thus, PF differed from GF with regard to the production of cellular and matrix proteins, and protein metabolism was affected by cell growth density. These data tend to support the previous hypothesis that PF is the essential cell type contributing to periodontal regeneration.