INVITRO PHAGOCYTOSIS OF EXOGENOUS COLLAGEN BY FIBROBLASTS FROM THE PERIODONTAL-LIGAMENT - AN ELECTRON-MICROSCOPIC STUDY

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 128  (MAR) , 301-314
Abstract
Collagen degradation occurs in the rapidly remodeling periodontal ligament and is predominant during the tissue destruction associated with periodontal disease. To study the mechanism and regulation of intracellular collagen degradation and in vitro system in which fibroblast-like cells internalize exogenously added collagen was developed. Cells were cultured from explants of monkey periodontal ligament, subcultured and grown to confluence in MEM [Eagle''s minimal essential medium] plus 15% fetal calf serum plus antibiotics. Minced rat tail tendon collagen was then added to the cells, which were cultured in .alpha.MEM lacking proline, lysine, glysine and fetal calf serum for up to 7 days, after which they were processed for EM. Intracellular collagen could be seen in cells in the immediate vicinity of exogenous collagen fibrils as early as 24 h after addition of the collagen. Serial sections of such profiles demonstrated their intracellular nature. Three-dimensional reconstructions of cell-collagen interaction zones permitted the development of a novel hypothesis of the mechanism of collagen phagocytosis and intracellular degradation in vitro. Fibroblasts may cytosegregate intact collagen fibrils or segments along their length by phagocytosis, and the internalized segments of these collagen fibrils may be degraded by the action of lysosomal enzymes.