Favorable effect of myofibroblasts on collagen synthesis and osteocalcin production in the periodontal ligament.

In this study, we aimed to explore the expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the periodontal ligament (PDL) under orthodontic loading, and to investigate the effect of myofibroblasts on collagen synthesis and osteocalcin production. The teeth in the right maxillae of the rats were orthodontically loaded while the contralateral teeth remained unloaded as controls. The total 30 rats were divided into 5 groups, with each group corresponding to a treatment duration (0, 3, 5, 7, or 14 days, respectively). The expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the tension area of the PDL over time were analyzed by immunochemistry staining. For the in-vitro study, the expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the myofibroblasts and human osteoblast-like cells (MG63) coculture and PDL cells-MG63 coculture systems were examined by Western blot and real-time polymerase chain reaction. Enhanced expression of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the tension area of the PDL under orthodontic loading were observed in vivo, and increased expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the myofibroblasts-MG63 coculture system were observed compared with the controls. Expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin are up-regulated in the PDL under orthodontic tensile loading. Myofibroblasts have a more positive effect on collagen synthesis and osteocalcin expression than do PDL cells.