Temporal regulation of gap junctional communication between tenocytes subjected to static tensile strain with physiological and non-physiological amplitudes.

The present study has been performed on temporal changes in gap junctional intercellular communication (GJIC) between tenocytes under static tensile strain with the magnitude of 0% (no strain), 4% (physiological magnitude) or 8% (overloading magnitude) during a 24-h culture period. Tenocytes were isolated from rabbit Achilles tendon and seeded on a stretchable microgroove substrate. GJIC was evaluated as intercellular diffusion coefficient of calcein (DGJ) using fluorescence loss in photobleaching (FLIP) protocol accompanied with a mathematical model of molecular diffusion both within the cell and between the cells. It was exhibited that the application of 4% strain for 1 h increased DGJ significantly. The increased level was maintained for 6 h, followed by returning to the pre-strain level at 24 h. This was associated with a transient increase in connexin 43 (Cx43) gene expression and protein localisation at 1 h, suggesting the increased GJIC may have involved new synthesis of gap junctions. By contrast, the application of 8% static strain reduced DGJ to the similar or lower level from 0% strain group for 6 h, associated with inhibited Cx43 gene expression. However, Cx43 protein localisation was not changed much, and thus, there seem no direct interactions among changes in GJIC, Cx43 gene expression and Cx43 localisation. The present findings highlight the differences in mechanical regulation of GJIC between physiological and non-physiological loadings, and thus the increase or the decrease in GJIC may affect tenocyte functions in different ways.

The effects of static tensile strain on the cytoskeleton of human periodontal ligament fibroblasts / 实用口腔医学杂志

Objective: To study the effects of static tensile strain on the cytoskeleton of human periodontal ligament fibroblasts (HPLFs). Methods: Tensile strain with the strain variate of 8%,12%,16% and 20% was applied in the culture of HPLFs for 1,2 and 3 d respectively with a self-devised loading apparatus. With the aid of laser scanning confocal microscope, the projected areas of each observed cell and its nuclear were calculated and the cell cytosketeton was observed. The data analysis was carried out with SPSS using Dunnett test. Results:The projected areas of the cells and nucleus incereased with the increace of loading time and tensile strain value in trial groups of 8%,12% and 16%(P