Stretching modulates oxytalan fibers in human periodontal ligament cells

Background and Objective: Oxytalan fibers, as well as collagen fibers, are the structural components of periodontal ligaments. Periodontal ligaments are continuously exposed to various functional forces. However, the behavior of oxytalan fibers under mechanical strain has not been investigated. We hypothesized that strain would alter the amount and appearance of oxytalan fibers in terms of positivity for their major components, fibrillin-1 and fibrillin-2. Material and Methods: We subjected periodontal ligament fibroblasts to stretching strain to examine the effects on their formation of oxytalan fibers in cell/matrix layers. Results: Stretching increased the levels of fibrillin-1 and fibrillin-2 by 25% relative to the control, but did not affect the gene expression level of either type of fibrillin. Immunofluorescence and immunogold electron microscopy analysis revealed that bundles of oxytalan fibers became thicker under stretching conditions. Conclusion: These results suggest that tension strain functionally regulates microfibril assembly in periodontal ligament fibroblasts and thus may contribute to the homeostasis of oxytalan fibers in periodontal ligaments.