Extensive osteolysis adjacent to orthopedic implants is often associated with wear particles of prosthetic material. The activation of the RANKL/RANK/OPG system is considered to be a likely cause of periprosthetic osteolysis leading to implant failure. The aim of this study was to examine the possible correlation between the clinical extent of osteolysis, the number of wear particles and expression of the osteoclastic mediator RANKL (receptor activator of nuclear factor kappa B ligand) in the tissues aro und aseptically loosened cemented and non-cemented total hip replacements. Periprosthetic tissues were harvested from 59 patients undergoing revision of hip replacement for aseptic loosening. We observed RANKL-positive cells in 23 of our 59 patients, their presence was noted predominantly in tissues with a loosened cemented endoprosthesis. We have found that RANKL is present only in tissues with a large amount of wear debris and predominantly in cases involving loosened cemented implants., D. Veigl, J. Niederlová, O. Kryštůfková., and Obsahuje bibliografii a bibliografické odkazy
Materials on the basis of cycloolefin copolymers (COC) are suitable for subchondral defect repairs. The objective of this study was to evaluate the influence of surface modification of COC and COC/LLDPE blends on the viability and gene expression of chondrocytes. Human chondrocytes were incubated on the surface of the studied materials. Half of the materials were plasmatically modified with a subsequent type II collagen application. The gene expression of matrix metalloproteinases (MMP-1,-3,-13), pro-inflammatory cytokines (IL-1, TNF-alpha) and apoptotic molecules (BAX, Bcl-2) was evaluated using quantitative Taq-Man PCR after 48 h incubation. Chondrocyte viability was evaluated by the MTT test after 2, 4 and 8 days of incubation. The synthesis of MMPs was measured by ELISA assay in cell culture medium after 48 h of incubation. Chondrocytes incubated on plasmatically modified in contrast to unmodified materials demonstrated significantly increased gene expression of IL-1 (p<0.05), MMP-1 and MMP-3 (p<0.05 for both comparisons) as well as MMP-13 (p<0.001). Increased gene expression was confirmed by significantly increased production of active forms of particular MMPs into the cell culture medium. Unlike surface unmodified polymers, the modified materials showed timedependent reduction of chondrocyte viability. The gene expression of TNF-α and apoptotic molecules by chondrocytes was not significantly changed by different materials. Cycloolefin copolymers and their blends may represent suitable materials for tissue engineering, however, their surface modification followed by collagen type II application may, at least under in vitro conditions, reduce the viability of chondrocytes and induce their pro-destructive behavior. The potential benefit or disadvantage of surface modifications of materials for osteochondral defect repairs needs to be further elucidated., M. Polanská ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy