ABSTRACT
Objective To explore the combined effects of mechanical stretch and interleukin-1β (IL-1β) on gene expression of extracellular matrix in rabbit corneal fibroblasts. Methods Isolated rabbit corneal fibroblasts were subjected to 15% equibiaxial stretch at frequency of 0.1 Hz for 12 h, 24 h and 36 h, respectively, in presence of IL-1β. The gene expressions of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases 1 (TIMP-1) and collagen type I alpha 1 (Collagen Iα1) were detected by real-time quantitative PCR. Results The mRNA levels of MMP-1, MMP-3 and MMP-9 could be up-regulated by IL-1β alone. However, MMP-1 and MMP-3 mRNA levels decreased with time, while MMP-9, TIMP-1 and collagen Iα1 increased with time. Compared with corresponding IL-1β treatment with mechanical stretch groups, the mRNA levels of MMP-1, MMP-3 and MMP-9 were increased and the mRNA levels of TIMP-1 and collagen Iα1 were decreased in a time-dependent manner. The mRNA level of Collagen Iα1 was decreased by loading mechanical stretch alone, and would further decrease time-dependently in combination with IL-1β treatment. Conclusions Mechanical stretch combined with IL-1β may facilitate the corneal tissue damage, thereby contribute to the development of keratectasia.
ABSTRACT
As a new technique of determining the viscoelasticity of soft biomaterials and cell cytoplasm in living cells, particle tracking microrheology (PTM) is mainly applied in the biomechanical research field, such as cell movement, embryo development, laminopathies. PTM has many advantages over the conventional detection methods in cell mechanics. Using this technique, the Brownian motion of probe particles embedded in the medium could be measured by the video-microscopy, and the movement trajectories of the probe could be mathematically transformed into the mean squared displacements (MSDs) thus to extract the parameters such as the frequency-dependent viscoelastic modulus or the creep compliance from the time dependent MSDs of the probes. The basic principles of PTM technique and its application in biomechanics will be reviewed in this paper.