Kurzfassung

The cellular basis of posttraumatic joint contracture has not been evaluated in detail. Myofibroblasts (MFs) have been considered a major pathogenetic factor in joint stiffness due to the increase of their numbers after injury and their ability to contract the extracellular matrix (ECM). To better understand the regulation of MFs on molecular level we investigated the impact of different cytokines and agents on proliferation and contractile function of these cells.
MF-cultures were isolated...The cellular basis of posttraumatic joint contracture has not been evaluated in detail. Myofibroblasts (MFs) have been considered a major pathogenetic factor in joint stiffness due to the increase of their numbers after injury and their ability to contract the extracellular matrix (ECM). To better understand the regulation of MFs on molecular level we investigated the impact of different cytokines and agents on proliferation and contractile function of these cells.
MF-cultures were isolated from human joint capsules. The effect of the cytokines TGF-β1, TNF-α, PDGF, VEGF as well as of the agents dexamethasone, and diclofenac on MF´s function was analysed using a 3D-collagen gel-contraction model. Cell proliferation was measured using the well established MTT-test. The contractile forces exerted by MFs were quantified using the ImageJ image analysis software. Gene expression of the MF marker α-smooth muscle actin (αSMA) was quantified using quantitative RT-PCR.
Cell proliferation of MFs was significantly increased by TGF-β1, TNF-α, PDGF, and VEGF. The contraction of collagen gels was also significantly increased by TGF-β1, PDGF, VEGF (1ng/ml) and Diclofenac (10µg/ml) in a dose-dependent manner. Gene expression of αSMA was up-regulated by PDGF (5ng/ml), VEGF (50ng/ml), and Diclofenac (10µg/ml). In clear contrast, cell proliferation, ECM-contraction, and α-SMA-expression were significantly inhibited by dexamethasone. Furthermore, TNF-α also caused a significant inhibition of ECM-contraction and α-SMA-gene expression. The inhibitory effects of TNF-α were blocked by the COX-inhibitor diclofenac.
The results of this study clearly demonstrate that cell function parameters MF are strictly regulated by different growth factors that may provide promising targets for new pharmacological strategies to prevent and treat posttraumatic joint contractures. Specific cytokine inhibitors or antiproliferative agents (e.g. dexamethasone) can be considered as potential therapeutic substances» weiterlesen» einklappen