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

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

MicroRNA Levels as Prognostic Markers for the Differentiation Potential of Human Mesenchymal Stromal Cell Donors

The ability of human mesenchymal stromal/stem cells (hMSCs) to differentiate into various mesenchymal cell lineages makes them a promising cell source for the use in tissue repair strategies. Because the differentiation potential of hMSCs differs between donors, it is necessary to establish biomarkers for the identification of donors with high differentiation potential. Here, we show that microRNA (miRNA) expression levels are effective for distinguishing donors with high differentiation potential from low differentiation potential. Twenty human MSC donors were initially tested for marker expression and differentiation potential. In particular, chondrogenic differentiation potential was evaluated on the basis of histological matrix formation, mRNA expression levels of chondrogenic marker genes, and quantitative glycosaminoglycan deposition. Three donors out of twenty were identified as donors with high chondrogenic potential, whereas nine showed moderate and eight low chondrogenic potential. Expression profiles of miRNAs involved in chondrogenesis and cartilage homeostasis were used for the distinction between high-performance hMSCs and low-performance hMSCs. Global mRNA expression profiles of the donors before the onset of chondrogenic differentiation revealed minor differences in gene expression between low and high chondrogenic performers. However, analysis of miRNA expression during a seven-day differentiation period identified miR-210 and miR-630 as positive regulators of chondrogenesis. In contrast, miR-181 and miR-34a, which are negative regulators of chondrogenesis, were upregulated during differentiation in low performing donors. In conclusion, profiling of hMSC donors for a specific panel of miRNAs may have prognostic value for selecting donors with high differentiation potential to improve hMSC-based strategies for tissue regeneration

Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure.

Numerous genetic loci have been associated with systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N = 74,064) and follow-up studies (N = 48,607), we identified at genome-wide significance (P = 2.7 × 10(-8) to P = 2.3 × 10(-13)) four new PP loci (at 4q12 near CHIC2, 7q22.3 near PIK3CG, 8q24.12 in NOV and 11q24.3 near ADAMTS8), two new MAP loci (3p21.31 in MAP4 and 10q25.3 near ADRB1) and one locus associated with both of these traits (2q24.3 near FIGN) that has also recently been associated with SBP in east Asians. For three of the new PP loci, the estimated effect for SBP was opposite of that for DBP, in contrast to the majority of common SBP- and DBP-associated variants, which show concordant effects on both traits. These findings suggest new genetic pathways underlying blood pressure variation, some of which may differentially influence SBP and DBP

Investigation of the regulation of nuclear translocation of the transcription factor mesoderm induction-early response 1 (mi-er1) during embryonic development of Xenopus laevis

Temporal and spatial regulation of nuclear transport of transcription factors is important for regulating the function of many cellular and developmental processes. Here the regulation of nuclear transport of a Xenopus transcription factor, mesoderm induction-early response 1, MI-ER1, was investigated. -- It was shown that MI-ER1 is actively transported to the cell nuclei of transfected NIH 3T3 cells as well as in Xenopus embryos. The active import of MI-ER1 into the cell nuclei is dependent on the presence of an intact nuclear localization signal (NLS) located in the C-terminus of the protein. The core of this NLS consists of amino acids ⁴⁶³RPIKRQRMD⁴⁷¹ but we show that addition of amino acids flanking this region results in more efficient import into the cell nuclei. It was also shown that an additional, albeit weak, NLS is present in the N-terminus of MI-ER1. -- During embryonic development in Xenopus laevis MI-ER1 is localized in the cytoplasm by cytoplasmic retention, but localizes to the nucleus during the mid-blastula stages. Investigation into the regulation of cytoplasmic retention of MI-ER1 in Xenopus laevis embryos, showed that the NLS (ER457-475) of Ml-ER1 is able to direct β-GAL to the nucleus prematurely, which suggests that cytoplasmic retention of MI-ER1 is not dependent on NLS recognition and binding by the import machinery. -- Investigation of a phosphorylation site in the vicinity of this NLS shows, that the regulation of nuclear transport of MI-ER1 in Xenopus laevis is not regulated by phosphorylation of this cdc2 kinase/ PKA site. Furthermore, it is shown that cytoplasmic retention of MI-ER1 in embryos appears to be regulated by binding of MI-ER1 to an "anchor" molecule in the cytoplasm. It was shown that the region important for cytoplasmic retention is localized between amino acid residues 1 and 282