Distinct Effect of TCF4 on the NFκB Pathway in Human Primary Chondrocytes and the C20/A4 Chondrocyte Cell Line

Objective: Previous studies indicated a difference in crosstalk between canonical WNT pathway and nuclear factor-κB (NFκB) signaling in human and animal chondrocytes. To assess whether the differences found were dependent on cell types used, we tested the effect of WNT modulation on NFκB signaling in human primary articular chondrocytes in comparison with the immortalized human costal chondrocyte cell line C20/A4. Design: We used gene expression analysis to study the effect of WNT modulation on IL1β-induced matrix metalloproteinase (MMP) expression as well as on WNT and NFκB target gene expression. In addition, we tested the involvement of RelA and TCF4 on activation of the WNT and NFκB pathway by TCF/LEF and NFκB reporter experiments, respectively. Results: We found an inhibitory effect of both induction and inhibition of WNT signaling on IL1β-induced MMP mRNA expression in primary chondrocytes, whereas WNT modulation did not affect MMP expression in C20/A4 cells. Furthermore, TCF/LEF and NFκB reporter activation and WNT and NFκB target gene expression were regulated differentially by TCF4 and RelA in a cell type–dependent manner. Additionally, we found significantly higher mRNA and protein expression of TCF4 and RelA in C20/A4 cells in comparison with primary chondrocytes. Conclusions: We conclude that WNT modulation of NFκB is, at least in part, cell type dependent and that the observed differences are likely because of impaired sensitivity of the NFκB pathway in C20/A4 cells to modulations in WNT signaling. This might be caused by higher basal levels of TCF4 and RelA in C20/A4 cells compared to primary chondrocytes

Requirements for a Nutrition Education Demonstrator

[Context and Motivation] Development of innovative ICT-based applications is a complex process involving collaboration of all relevant disciplines. This complexity arises due to differences in terminology, knowledge and often also the ways of working between developers in the disciplines involved. [Question/problem] Advances in each discipline bring a rich design environment of theories, models, methods and techniques. Making a selection from these makes the development of distributed applications very challenging, often requiring a holistic approach to address the needs of the disciplines involved. This paper describes early stage requirements acquisition of a mobile nutrition education demonstrator which supports overweight persons in adopting healthier dietary behaviour. [Principal idea/results] We present a novel way to combine and use known requirements acquisition methods involving a two stage user needs analysis based on scenarios which apply a theory-based model of behavioural change and are onstructed in two phases. The first phase scenarios specify an indicative description reflecting the use of the transtheoretical model of behavioural change. In the second phase, a handshake protocol adds elements of optative system-oriented descriptions to the scenarios such that the intended system can support the indicative description. [Contribution] The holistic and phased approach separates design concerns to which each of the disciplines contributes with their own expertise and domain principles. It preserves the applied domain principles in the design and it bridges gaps in terminology, knowledge and ways of working

Nanoparticle system for the local delivery of disease modifying osteoarthritic drugs

Purpose: The purpose of this study is to develop the nanoparticles that i) can be injected intra-articularly ii) target to cartilage due to an opposite charge difference with the extracellular cartilaginous matrix and iii) due to their small size can penetrate into the cartilage. In this way retention time in the joint can be prolonged. By releasing disease modifying OA drugs (DMOAD) in the vicinity of chondrocytes such materials may be beneficial for restoring cartilage tissue homeostasis. Here we demonstrate the generation of drug-containing nanoparticles for intra-articular joint therapy. Methods: We have prepared nanoparticles of biodegradable poly ethylene glycol- poly lactic acid PEG-PLA co-block polymers. The hydrophilic PEG and hydrophobic PLA ends of this polymer make it possible to generate micelles that contain drugs. The polymers are functionalized with UV-sensitive acrylate groups that can be stabilized by UV-crosslinking. These drug containing nanoparticles will be used for intra-articular joint injection and release of DMOADs. We have also established co-culture systems in vitro using MSCs and chondrocytes where the effect of these molecules and nanocarriers can be tested. Results: Micelle type nanoparticles using PEG-PLA co-block polymers were prepared. The obtained dexamethasone loaded nanoparticles had diameters of 20-80 nm. These nanoparticles are photo-crosslinked at their hydrophobic cores which provides stability to the structure and resulted in a slight decrease in average particle size . Dexamethasone was successfully encapsulated in these nanoparticles. The current release profiles show initial burst release in the first 8 hours followed by a sustained release over at least 3 days. Conclusions: We have generated nanoparticles that can serve as a carrier system to deliver clinically relevant disease modifying osteoarthritic drugs in a more effective way after intra-articular injection. We are currently investigating the retention of nanoparticles in the joint and are developing strategies to target these particles to cartilag

Pathologies vasculaires de la substance blanche

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Le choix du métier

info:eu-repo/semantics/publishe

Trophic effects of mesenchymal stem cells increase chondrocyte proliferation and matrix formation

Previous studies showed that coculture of primary chondrocytes (PCs) with various sources of multipotent cells results in a higher relative amount of cartilage matrix formation than cultures containing only chondrocytes. The aim of this study was to investigate the mechanism underlying this observation. We used coculture pellet models of human mesenchymal stem cells (hMSCs) and human PCs or bovine PCs (bPCs) and studied the fate and the contribution to cartilage formation of the individual cell populations during coculture. Enhanced cartilage matrix deposition was confirmed by histology and quantification of total glycosaminoglycan deposition. Species-specific quantitative polymerase chain reaction demonstrated that cartilage matrix gene expression was mainly from bovine origin when bPCs were used. Short tandem repeat analysis and species-specific quantitative polymerase chain reaction analysis of genomic DNA demonstrated the near-complete loss of MSCs in coculture pellets after 4 weeks of culture. In coculture pellets of immortalized MSCs and bPCs, chondrocyte proliferation was increased, which was partly mimicked using conditioned medium, and simultaneously preferential apoptosis of immortalized MSCs was induced. Taken together, our data clearly demonstrate that in pellet cocultures of MSCs and PCs, the former cells disappear over time. Increased cartilage formation in these cocultures is mainly due to a trophic role of the MSCs in stimulating chondrocyte proliferation and matrix deposition by chondrocytes rather than MSCs actively undergoing chondrogenic differentiatio