Role of Different Pre-Treatments on Composition and Rheology of Synovial Fluids

Assessment of the Substance Antioxidative Profile by Hyaluronan, Cu(II) and Ascorbate

In the minireview presented here, the authors discuss the evaluation of inhibitory effect of substances in the phases of initiation and propagation of high-molar-mass hyaluronan oxidative degradation. The experimental approach should be considered as original since on using a simple experimental assay it is possible to prove both the so-called “preventive” and “chain-breaking” antioxidant activity of investigated water-soluble endo- or exogenous substances.

Role of medial abrasion phenomenon in the pathogenesis of knee osteoarthritis

Osteoarthritis of the knee affects a large population worldwide and is associated with an extremely high economic burden largely attributable to the effects of disability, comorbid disease, and the expense of treatment. Since the initiating events that result in the cartilage degradation are poorly understood, there has been very limited success in demonstrating disease modification in clinical trials of potential therapies. Medial plica related medial abrasion phenomenon has recently been identified to have close relationship with medial compartment osteoarthritis. We hypothesized that this abrasion phenomenon will elicit lifelong interplay between pathologic medial plica and the facing medial femoral condyle and might play a role in the pathogenesis of knee osteoarthritis by both physical and chemical effects. After evaluating current evidence, we designed a study to prove that the concentrations of total protein, cartilage degrading related cytokines (tumor necrosis factor-α and interleukin-1β) and enzyme (matrix metalloproteinase-3) are higher in the medial compartment of the knee having the phenomenon of medial abrasion. The accumulating data and findings about medial abrasion phenomenon might be important for the understanding of the pathogenesis or progression of this common disease. We hope that our hypothesis will stimulate further studies verifying if medial abrasion phenomenon plays more roles in the pathogenesis of knee osteoarthritis. Further clinical observations for its appropriate treatment based on this hypothesis are also mandatory for the benefits of patients.

Mannitol Preserves the Viscoelastic Properties of Hyaluronic Acid in an In Vitro Model of Oxidative Stress

Introduction

Viscosupplementation by intra-articular injection of hyaluronic acid (HA) is a widely used treatment for lower limb osteoarthritis. However, the injected HA is rapidly degraded by reactive oxygen species (ROS), limiting its time of intra-articular residence. Optimizing clinical effectiveness of viscosupplementation by reducing HA degradation in situ, and therefore increasing the time of contact with the diseased tissue, is a challenging research approach. Mannitol, a powerful ROS scavenger, is a good candidate for this. The aim of this study was to compare in vitro the resistance to ROS-mediated degradation of two marketed viscosupplements (one linear and one cross-linked) to that of two novel viscosupplements combining HA and mannitol.

Methods

A HA viscosupplement at a concentration of 10 g/L (HA 1%), was compared to a HANOX-M, a novel viscosupplement made of a mixture of HA and mannitol. In a second experiment, Hylan G-F 20, a partially cross-linked viscosupplement, was compared to a HANOX-M-XL, a novel cross-linked viscosupplement made of a HA and mannitol (35 g/L). The four HA viscosupplements were subjected to oxidative stress generated by the addition of hydrogen peroxide (H₂O₂) and their rheological behavior (elastic moduli [G′], viscous moduli [G″], and complex viscosity [|η*|]) were compared before and after the oxidative stress exposure.

Results

The two viscosupplements not containing mannitol HA were rapidly degraded by H₂O₂, as demonstrated by the dramatic decrease of |η*|. On the other hand, the rheological properties of HA containing mannitol were not substantially modified in the presence of H₂O₂.

Conclusion

This in vitro study demonstrates that mixing mannitol with HA protects the viscosupplement from ROS-mediated degradation and might therefore increase its intra-articular residence time without substantially modifying its rheological behavior. This in vitro study has to be followed by clinical trials designed to assess whether the addition of mannitol to HA might improve the efficiency and/or the duration of action of viscosupplementation.

Electronic supplementary material

The online version of this article (doi:10.1007/s40744-014-0001-8) contains supplementary material, which is available to authorized users.

In vitro evaluation of effects of sustained anti-TNF release from MPEG-PCL-MPEG and PCL microspheres on human rheumatoid arthritis synoviocytes

Anti-tumor necrosis factor α (TNFα) drugs such as etanercept (ETN) have been mostly used in systemic treatment of rheumatoid arthritis. To eliminate the side effects in long-term treatments and to achieve a local sustained anti-inflammatory effect, a controlled drug delivery system is needed for anti-TNFα drugs. This study aims to develop novel injectable microcarriers of ETN that can provide long-term controlled release of this protein drug upon intra-articular application. In this study, poly(ε-caprolactone) (PCL) and its copolymer with poly(ethylene glycol), methoxypoly(ethylene glycol)-poly(ε-caprolactone)-methoxypoly(ethylene glycol) microspheres (MPEG-PCL-MPEG) were compared for their prospective success in rheumatoid arthritis treatment. Microspheres with smooth surface of a mean particle diameter of approximately 5 μm were prepared with both polymers. MPEG-PCL-MPEG microspheres had higher encapsulation efficiency than PCL microspheres. The activity of encapsulated ETN within MPEG-PCL-MPEG microspheres also retained while 90% of the activity of ETN within PCL microspheres could retain during 90-day release. MPEG-PCL-MPEG microspheres showed faster ETN release compared to PCL microspheres in various release media. Cumulative amounts of ETN released from both types of microspheres were significantly lower in cell culture medium and in synovial fluids than in phosphate buffered saline. This was mainly due to protein adsorption onto microspheres. Hydrophilic MPEG segment enhanced ETN release while preventing protein adsorption on microspheres compared to PCL. Sustained ETN release from microspheres resulted with a significant decrease in pro-inflammatory cytokines (TNFα, IFNγ, IL-6, IL-17) and MMP levels (MMP-3, MMP-13), while conserving viability of fibroblast-like synoviocytes compared to the free drug. Results suggest that MPEG-PCL-MPEG is a potential copolymer of PCL that can be used in development of biomedical materials for effective local treatment purposes in chronic inflammatory arthritis owing to enhanced hydrophilicity. Yet, PCL microspheres are also promising systems having good compatibility to synoviocytes and would be especially the choice for treatment approach requiring longer term and slower release.