Hyaluronan suppressed nitric oxide production in the meniscus and synovium of rabbit osteoarthritis model

Different molecular weights of hyaluronan research in knee osteoarthritis: A state-of-the-art review

Osteoarthritis (OA), the most common form of arthritis, is characterized by progressive cartilage destruction, concomitant adaptive osteogenesis, and loss of joint function. The progression of OA with aging is associated with a decrease in native hyaluronan (HA, hyaluronate or hyaluronic acid) with a high molecular weight (HMW) in synovial fluid and a subsequent increase in lower MW HA and fragments. As HMW HA possesses numerous biochemical and biological properties, we review new molecular insights into the potential of HA to modify OA processes. Different MWs in the formulation of products appear to have varying effects on knee OA (KOA) pain relief, improved function, and postponing surgery. In addition to the safety profile, more evidence indicates that intraarticular (IA) HA administration may be an effective option to treat KOA, with a particular emphasis on the use of HA with fewer injections of higher MW, including potential applications of HA of very HMW. We also analyzed published systemic reviews and meta-analyses of IA HA in treating KOA in order to discuss their conclusions and consensus statements. According to its MW, HA may offer a simple way to refine therapeutic information in selective KOA.

Low molecular weight hyaluronates: biological action, efficacy, safety and clinical experience in the treatment of musculoskeletal pain syndromes (literature review and clinical observations)

Hyaluronic acid (HA) drugs are ingrained in complex treatment of osteoarthritis (OA). They have not only lubricant, but also anti-inflammatory properties, and ability to slow down the progression of OA. The article summarizes current data on the efficacy and safety of low molecular weight HA. The possibilities of using it both intra-articularly (i/a) and for the treatment of tendinopathies are considered. The authors present their own clinical experience in the treatment of patients with musculoskeletal (MS) pain syndromes.It has been shown that i/a administration of HA can effectively reduce the intensity of pain and improve joint function, and when injected into the synovial sheaths of tendons, it can also relieve pain of extra-articular localization. The peculiarities of the surgical technique, preparing for manipulation and post-injection period management are described.The existing evidence base indicates the expediency of active use of HA drugs not only for OA treatment, but also for various extra-articular musculoskeletal pain syndromes.

Immunomodulatory biomaterials and their application in therapies for chronic inflammation-related diseases

The degree of tissue injuries such as the level of scarring or organ dysfunction, and the immune response against them primarily determine the outcome and speed of healing process. The successful regeneration of functional tissues requires proper modulation of inflammation-producing immune cells and bioactive factors existing in the damaged microenvironment. In the tissue repair and regeneration processes, different types of biomaterials are implanted either alone or by combined with other bioactive factors, which will interact with the immune systems including immune cells, cytokines and chemokines etc. to achieve different results highly depending on this interplay. In this review article, the influences of different types of biomaterials such as nanoparticles, hydrogels and scaffolds on the immune cells and the modification of immune-responsive factors such as reactive oxygen species (ROS), cytokines, chemokines, enzymes, and metalloproteinases in tissue microenvironment are summarized. In addition, the recent advances of immune-responsive biomaterials in therapy of inflammation-associated diseases such as myocardial infarction, spinal cord injury, osteoarthritis, inflammatory bowel disease and diabetic ulcer are discussed.

An animal model study on the gene expression profile of meniscal degeneration

Meniscal degeneration is a very common condition in elderly individuals, but the underlying mechanisms of its occurrence are not completely clear. This study examines the molecular mechanisms of meniscal degeneration. The anterior cruciate ligament (ACL) and lateral collateral ligament (LCL) of the right rear limbs of seven Wuzhishan mini-pigs were resected (meniscal degeneration group), and the left rear legs were sham-operated (control group). After 6 months, samples were taken for gene chip analysis, including differentially expressed gene (DEG) analysis, gene ontology (GO) analysis, clustering analysis, and pathway analysis. The selected 12 DEGs were validated by real time reverse transcription-polymerase chain reaction (RT-PCR). The two groups showed specific and highly clustered DEGs. A total of 893 DEGs were found, in which 537 are upregulated, and 356 are downregulated. The GO analysis showed that the significantly affected biological processes include nitric oxide metabolic process, male sex differentiation, and mesenchymal morphogenesis, the significantly affected cellular components include the endoplasmic reticulum membrane, and the significantly affected molecular functions include transition metal ion binding and iron ion binding. The pathway analysis showed that the significantly affected pathways include type II diabetes mellitus, inflammatory mediator regulation of TRP channels, and AMPK signaling pathway. The results of RT-PCR indicate that the microarray data accurately reflects the gene expression patterns. These findings indicate that several molecular mechanisms are involved in the development of meniscal degeneration, thus improving our understanding of meniscal degeneration and provide molecular therapeutic targets in the future.

Hyaluronic Acid: Molecular Mechanisms and Therapeutic Trajectory

Hyaluronic acid (also known as hyaluronan or hyaluronate) is naturally found in many tissues and fluids, but more abundantly in articular cartilage and synovial fluid (SF). Hyaluronic acid (HA) content varies widely in different joints and species. HA is a non-sulfated, naturally occurring non-protein glycosaminoglycan (GAG), with distinct physico-chemical properties, produced by synoviocytes, fibroblasts, and chondrocytes. HA has an important role in the biomechanics of normal SF, where it is partially responsible for lubrication and viscoelasticity of the SF. The concentration of HA and its molecular weight (MW) decline as osteoarthritis (OA) progresses with aging. For that reason, HA has been used for more than four decades in the treatment of OA in dogs, horses and humans. HA produces anti-arthritic effects via multiple mechanisms involving receptors, enzymes and other metabolic pathways. HA is also used in the treatment of ophthalmic, dermal, burns, wound repair, and other health conditions. The MW of HA appears to play a critical role in the formulation of the products used in the treatment of diseases. This review provides a mechanism-based rationale for the use of HA in some disease conditions with special reference to OA.

Are the Biological and Biomechanical Properties of Meniscal Scaffolds Reflected in Clinical Practice? A Systematic Review of the Literature

The aim of this PRISMA review was to assess whether the CMI and Actifit scaffolds, when used in clinical practice, improve clinical outcomes and demonstrate the ideal biological and biomechanical properties of scaffolds: being chondroprotective, porous, resorbable, able to mature and promote regeneration of tissue. This was done by only including studies that assessed clinical outcome and used a scale to assess both integrity of the scaffold and its effects on articular cartilage via MRI. A search was performed on PubMed, EMBASE, Scopus and clinicaltrials.gov. 2457 articles were screened, from which eight studies were selected: four used Actifit, three used CMI and one compared the two. All studies reported significant improvement in at least one clinical outcome compared to baseline. Some studies suggested that the scaffolds appeared to show porosity, mature, resorb and/or have possible chondroprotective effects, as assessed by MRI. The evidence for clinical translation is limited by differences in study methodology and small sample sizes, but is promising in terms of improving clinical outcomes in the short to mid-term. Higher level evidence, with MRI and histological evaluation of the scaffold and articular cartilage, is now needed to further determine whether these scaffolds exhibit these useful properties.

Anti-Inflammatory Effects of Intra-Articular Hyaluronic Acid: A Systematic Review

OBJECTIVE

Osteoarthritis (OA) is one of the leading causes of disability in the adult population. Common nonoperative treatment options include nonsteroidal anti-inflammatory drugs (NSAIDs), intra-articular corticosteroids, and intra-articular injections of hyaluronic acid (HA). HA is found intrinsically within the knee joint providing viscoelastic properties to the synovial fluid. HA therapy provides anti-inflammatory relief through a number of different pathways, including the suppression of pro-inflammatory cytokines and chemokines.

METHODS

We conducted a systematic review to summarize the published literature on the anti-inflammatory properties of hyaluronic acid in osteoarthritis. Included articles were categorized based on the primary anti-inflammatory responses described within them, by the immediate cell surface receptor protein assessed within the article, or based on the primary theme of the article. Key findings aimed to describe the macromolecules and inflammatory-mediated responses associated with the cell transmembrane receptors.

RESULTS

Forty-eight articles were included in this systematic review that focused on the general anti-inflammatory effects of HA in knee OA, mediated through receptor-binding relationships with cluster determinant 44 (CD44), toll-like receptor 2 (TLR-2) and 4 (TLR-4), intercellular adhesion molecule-1 (ICAM-1), and layilin (LAYN) cell surface receptors. Higher molecular weight HA (HMWHA) promotes anti-inflammatory responses, whereas short HA oligosaccharides produce inflammatory reactions.

CONCLUSIONS

Intra-articular HA is a viable therapeutic option in treating knee OA and suppressing inflammatory responses. HMWHA is effective in suppressing the key macromolecules that elicit the inflammatory response by short HA oligosaccharides.

Platelet-Rich Plasma and Hyaluronic Acid Are Not Synergistic When Used as Biological Adjuncts with Autologous Osteochondral Transplantation

Introduction Autologous osteochondral transplantation (AOT) is a treatment for osteochondral lesions with known concerns, including histological degradation of the graft and poor cartilage integration. Platelet-rich plasma (PRP) and hyaluronic acid (HA) have been described has having the potential to improve results. The aim of this study was to evaluate the effect of PRP and HA on AOT in a rabbit model. Methods Thirty-six rabbits underwent bilateral knee AOT treated with either the biological adjunct (PRP, n = 12; HA, n = 12; PRP + HA, n = 12) or saline (control). PRP and HA were administered as an intra-articular injection. The rabbits were euthanized at 3, 6, or 12 weeks postoperatively. The graft sections were assessed using the modified International Cartilage Repair Society (ICRS) scoring system. The results from the PRP alone group is from previously published data. Results The mean modified ICRS histological score for the PRP-treated group was higher than its control ( P = 0.002). The mean modified ICRS histological score for the HA-treated group showed no difference compared with its control ( P = 0.142). The mean modified ICRS histological score for the PRP + HA-treated group was higher than its control ( P = 0.006). There was no difference between the mean modified ICRS scores of the PRP- and the PRP + HA-treated grafts ( P = 0.445). Conclusion PRP may decrease graft degradation and improve chondral integration in an animal model. In this model, the addition of HA was not synergistic for the parameters assessed.

LEVEL OF EVIDENCE

Basic science, Level V.

CLINICAL RELEVANCE

PRP can be used as an adjunct to AOT, which may decrease graft degeneration and improve clinical outcomes. HA may not influence AOT.

Polysaccharides As Viscosupplementation Agents: Structural Molecular Characteristics but Not Rheology Appear Crucial to the Therapeutic Response

Introduction

Most clinical studies and basic research document viscosupplementation (VS) in terms of effectiveness and safety, but only a few highlight its molecular mechanisms of action. Besides, there is generally focus on hyaluronic acid (HA) as being the most relevant polysaccharide to reach the clinical endpoints, attributing its effect mainly to its unique viscoelastic properties, related to a high-molecular weight and gel formulation. Usually, studies do not approach the possible biological pathways where HA may interfere, and there is a lack of reports on other biocompatible polysaccharides that could be of use in VS.

Aim

We briefly review the main proposed mechanisms of action of intra-articular hyaluronic acid (IA-HA) treatment and discuss its effectiveness focusing on the role of rheological and intrinsic structural molecular properties of polysaccharides in providing a therapeutic effect.

Methods

We conducted a literature search using PubMed database to find articles dealing with the mechanisms of action of IA-HA treatment and/or emphasizing how the structural properties of the polysaccharide used influenced the clinical outcomes.

Discussion/conclusion

HA is involved in numerous biochemical interactions that may explain the clinical benefits of VS, most of them resulting from HA–cluster of differentiation 44 receptor interaction. There are other important aspects apart from the molecular size or the colloidal state of the IA-HA involved in VS efficiency that still need to be consolidated. Indeed, it seems that clinical response may be dependent on the intrinsic properties of the polysaccharide, regardless of being HA, rather than to rheology, posing some controversy to previous beliefs.

Effects of a viscosupplementation therapy on rabbit menisci in an anterior cruciate ligament transection model of osteoarthritis

The aim of this study was to evaluate the morphological, microstructural, and mechanical effects of a viscosupplementation therapy on rabbit menisci at an early stage of osteoarthritis (OA). Anterior cruciate ligament transection (ACLT) was performed in twelve male New-Zealand White rabbits on the right knee joint. Six of these twelve rabbits received a mono intra-articular injection of high molecular weight hyaluronic acid (HA) two weeks after ACLT. Six additional healthy rabbits served as controls. Medial menisci were removed from all right knees (n=18) six weeks after ACLT and were graded macroscopically. Indentation-relaxation tests were performed in the anterior and posterior regions of the menisci. Collagen fiber organization and glycosaminoglycan (GAG) content were assessed by biphotonic confocal microscopy and histology, respectively. Viscosupplementation significantly (p=0.002) improved the surface integrity of the medial menisci compared to the operated non-treated group. Moreover, the injection seems to have an effect on the GAG distribution in the anterior region of the menisci. However, the viscoelastic properties of both operated groups were similar and significantly lower than those of the healthy group, which was explained by their modified collagen fiber organization. They displayed disruption of the tie fibers due to structural alterations of the superficial layers from which they emanate, leading to modifications in the deep zone. To conclude, the viscosupplementation therapy prevents macroscopic lesions of the menisci, but it fails to restore their collagen fiber organization and their viscoelastic properties. This finding supports the role of this treatment in improving the lubrication over the knee.

The effect of sodium hyaluronate-chondroitin sulfate combined solution on cartilage formation in osteochondral defects of the rabbit knee: an experimental study

Objective

In focal cartilage lesions, multipotent mesenchymal stem cells in bone marrow are aimed to be moved into the defect area using subchondral drilling or microfracture method. However, repaired tissue insufficiently fills the defect area or cannot meet natural hyaline tissue functions, due to fibrous structure. We investigated the effect of a combined solution of sodium hyaluronate + chondroitin sulfate (HA+CS) administered intra-articularly after subchondral drilling on newly formed cartilage in rabbits with focal osteochondral defects.

Materials and methods

A total of 32 New Zealand White mature rabbits, whose weights ranged from 2.5 to 3 kg, were randomly divided into four groups. Full-thickness osteochondral defect was formed in the left-knee medial femur condyles of all rabbits. Subchondral drilling was then performed. The following treatment protocol was administered intra-articularly on knee joints on days 7, 14, and 21 after surgery: group 1, 0.3 mL combined solution of HA+CS (20 mg CS combined with 16 mg HA/mL); group 2, 0.3 mL HA (16 mg/mL); group 3, 0.3 mL CS (20 mg/mL); and group 4 (control group), 0.3 mL saline solution. In the sixth week, all animals were killed and then evaluated histopathologically and biochemically.

Results

There was significant articular cartilage formation in the HA+CS group compared to the HA, CS, and control groups. Hyaline cartilage formation was observed only in the HA+CS group. Cartilage-surface continuity and smoothness were significantly higher in the HA+CS and HA groups compared to the other groups. Normal cartilage mineralization was found to be significantly higher in the HA+CS group compared to the other groups. Increased levels of VEGFA and IL-1β in synovial fluid were observed in the HA+CS group.

Conclusion

After subchondral drilling, intra-articular HA-CS combination therapy is a good choice to promote better quality new cartilage-tissue formation in the treatment of focal osteochondral defects.

No Effects of Early Viscosupplementation After Arthroscopic Partial Meniscectomy: A Randomized Controlled Trial

BACKGROUND

The management of the postoperative period after knee arthroscopic surgery may be challenging because surgical trauma deeply alters the joint microenvironment, causing the release of several catabolic molecules and proinflammatory factors that might slow down functional recovery. The possibility of using hyaluronic acid (HA) to promote postoperative pain relief and expedite functional improvement seems attractive, considering its biological properties.

PURPOSE

The aim of the present double-blind randomized controlled trial was to evaluate the effects, in terms of pain control and functional recovery, provided by a single HA injection performed at the end of arthroscopic meniscectomy.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 90 patients, 18 to 55 years old, were included according to the following criteria: (1) chronic, symptomatic meniscal tears requiring partial resection; (2) a healthy contralateral knee; (3) no previous surgery on the index knee; and (4) no other concurrent articular lesions requiring surgical treatment (eg, cartilage or ligament injuries). Patients were randomized into 2 treatment groups: one underwent meniscectomy alone, whereas the other also received an injection of 3 mL HA at the end of the procedure. All patients were evaluated at baseline and then at 15, 30, 60, and 180 days using the following tools: International Knee Documentation Committee (IKDC) subjective, Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, VAS for general health status, and Tegner scores. The transpatellar circumference and active and passive ranges of motion were also recorded during the follow-up evaluations.

RESULTS

No major adverse events were reported using HA postoperatively. A statistically significant increase in all the clinical scores was reported in both treatment groups, but no significant intergroup difference was documented at any follow-up evaluation. No difference was observed also in the objective measurements. The mean time to return to full sports activity was not different between groups, and a comparable satisfaction rate was recorded in both treatment groups.

CONCLUSION

Early postoperative viscosupplementation did not provide significant clinical benefits after arthroscopic meniscectomy. Despite the lack of major adverse events, the administration of a single HA injection at the end of the surgical procedure is not a successful strategy to provide either faster functional recovery or symptomatic improvement after meniscectomy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02629380.

[Muscle, tendon and joint injections : What is the evidence?]

Injections at tendon insertions, in muscles and in joints are an important instrument in the conservative treatment of musculoskeletal diseases, for acute injuries as well as for chronic degenerative diseases. Local anesthetic agents and glucocorticoids are well-established medications; however, severe side effects, such as chondrolysis have sometimes been reported, particularly for local anesthetic agents. In addition platelet rich plasma (PRP) and hyaluronic acid are also widely used; however, the clinical effectiveness has not always been proven. This article gives an overview on the most commonly used medications for injections and the mechanisms of action. The indications for treatment and the evidence for the clinical adminstration of muscle, tendon and joint injections are described based on the currently available literature.

Effects of corticosteroids and their combinations with hyaluronanon on the biochemical properties of porcine cartilage explants

Background

Intra-articular injection of corticosteroids is used to treat the inflammatory pain of arthritis and osteoarthritis (OA), but our previous study found a deleterious effect of these steroids on chondrocyte cells. Hyaluronic acid (HA) injection has been suggested as a means to counteract negative side effects through replenishment of synovial fluid that can decrease pain in affected joints. To better understand the effects of corticosteroids on these processes, dexamethasone (Dex) and prednisolone (Pred) were administered to porcine cartilage explants at several concentrations with and without HA. We examined corticoid effects by determining sulfate-glycosaminoglycan (s-GAG) and uronic acid (UA) content of the explant media, and safranin-O staining of the cells. Analysis of lactate dehydrogenase (LDH) activity was conducted to assess cell cytotoxicity.

Results

Dex treatment significantly reduced cellular cytotoxicity compared to the other treatment groups, especially with regards to the release of s-GAG, and protects against superficial proteoglycan damage. However, there was no difference between Pred and Dex, with and without HA, in the UA content remaining in porcine cartilage explants.

Conclusions

The data suggest that combinations of Dex and Pred with HA did not have a significant effect on protection or enhancement of the articular cartilage matrix under the current conditions.

The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review

BACKGROUND

Knee osteoarthritis (OA) is one of the leading causes of disability within the adult population. Current treatment options for OA of the knee include intra-articular (IA) hyaluronic acid (HA), a molecule found intrinsically within the knee joint that provides viscoelastic properties to the synovial fluid. A variety of mechanisms in which HA is thought to combat knee OA are reported in the current basic literature.

METHODS

We conducted a comprehensive literature search to identify currently available primary non-clinical basic science articles focussing on the mechanism of action of IA-HA treatment. Included articles were assessed and categorized based on the mechanism of action described within them. The key findings and conclusions from each included article were obtained and analyzed in aggregate with studies of the same categorical assignment.

RESULTS

Chondroprotection was the most frequent mechanism reported within the included articles, followed by proteoglycan and glycosaminoglycan synthesis, anti-inflammatory, mechanical, subchondral, and analgesic actions. HA-cluster of differentiation 44 (CD44) receptor binding was the most frequently reported biological cause of the mechanisms presented. High molecular weight HA was seen to be superior to lower molecular weight HA products. HA derived through a biological fermentation process is also described as having favorable safety outcomes over avian-derived HA products.

CONCLUSIONS

The non-clinical basic science literature provides evidence for numerous mechanisms in which HA acts on joint structures and function. These actions provide support for the purported clinical benefit of IA-HA in OA of the knee. Future research should not only focus on the pain relief provided by IA-HA treatment, but the disease modification properties that this treatment modality possesses as well.

Knee osteoarthritis: Clinical connections to articular cartilage structure and function

Articular cartilage is a unique biphasic material that supports a lifetime of compressive and shear forces across joints. When articular cartilage deteriorates, whether due to injury, wear and tear or normal aging, osteoarthritis and resultant pain can ensue. Understanding the basic science of the structure and biomechanics of articular cartilage can help clinicians guide their patients to appropriate activity and loading choices. The purpose of this article is to examine how articular cartilage structure and mechanics, may interact with risk factors to contribute to OA and how this interaction provides guidelines for intervention choices This paper will review the microstructure of articular cartilage, its mechanical properties and link this information to clinical decision making.

Pharmacological effects of novel cross-linked hyaluronate, Gel-200, in experimental animal models of osteoarthritis and human cell lines

OBJECTIVE

To study the pharmacological effects of Gel-200, cross-linked hyaluronate.

EXPERIMENTAL DESIGN

We examined the chondroprotective, anti-inflammatory and analgesic effects of Gel-200 in experimental animal models for osteoarthritis (OA) and in a human synovial sarcoma cell line and normal human articular chondrocytes.

RESULTS

In the OA model, a single-dose intra-articular (IA) injection of Gel-200 significantly suppressed cartilage degeneration and reduced synovitis of the knee joint. In the joint pain model, Gel-200 significantly suppressed pain responses for 4 weeks after injection. The residual property of Gel-200 in the knee joint tissue was investigated in rabbits. The mean residual ratio of injected Gel-200 in the synovium was 3.3% (95% confidence interval [CI], 2.4-4.2) at 28 days after the injection. The long-lasting analgesic effect of Gel-200 might be explained by its high residual ratio in the joint. In addition, we investigated the mechanism of action of Gel-200 in a human synovial sarcoma cell line and normal human articular chondrocytes. Gel-200 inhibited IL-1β-induced production of MMP-1, 3 and 13 in human chondrocytes and production of prostaglandin E2 in human synoviocytes in a concentration-dependent manner, respectively.

CONCLUSION

A single-dose IA injection of Gel-200 exerts chondroprotective and anti-inflammatory effects in the experimental OA model, and long-lasting analgesia in the joint pain model, suggesting the beneficial multimodal function of Gel-200 against symptomatic OA patients.

Intra-articular administration of hyaluronic acid increases the volume of the hyaline cartilage regenerated in a large osteochondral defect by implantation of a double-network gel

Implantation of PAMPS/PDMAAm double-network (DN) gel can induce hyaline cartilage regeneration in the osteochondral defect. However, it is a problem that the volume of the regenerated cartilage tissue is gradually reduced at 12 weeks. This study investigated whether intra-articular administration of hyaluronic acid (HA) increases the volume of the cartilage regenerated with the DN gel at 12 weeks. A total of 48 rabbits were used in this study. A cylindrical osteochondral defect created in the bilateral femoral trochlea was treated with DN gel (Group DN) or left without any implantation (Group C). In both Groups, we injected 1.0 mL of HA in the left knee, and 1.0 mL of saline solution in the right knee. Quantitative histological evaluations were performed at 2, 4, and 12 weeks, and PCR analysis was performed at 2 and 4 weeks after surgery. In Group DN, the proteoglycan-rich area was significantly greater in the HA-injected knees than in the saline-injected knees at 12 weeks (P = 0.0247), and expression of type 2 collagen, aggrecan, and Sox9 mRNAs was significantly greater in the HA-injected knees than in the saline-injected knees at 2 weeks (P = 0.0475, P = 0.0257, P = 0.0222, respectively). The intra-articular administration of HA significantly enhanced these gene expression at 2 weeks and significantly increased the volume of the hyaline cartilage regenerated by implantation of a DN gel at 12 weeks. This information is important to develop an additional method to increase the volume of the hyaline cartilage tissue in a potential cartilage regeneration strategy using the DN gel.

Pain treatment for patients with osteoarthritis and central sensitization

Osteoarthritis is one of the most frequent, disabling, and costly pathologies of modern society. Among the main aims of osteoarthritis management are pain control and functional ability improvement. The exact cause of osteoarthritis pain remains unclear. In addition to the pathological changes in articular structures, changes in central pain processing or central sensitization appear to be involved in osteoarthritis pain. The latter calls for a broader approach to the management of patients with osteoarthritis. Yet, the scientific literature offers scant information addressing the treatment of central sensitization, specifically in patients with osteoarthritis. Interventions such as cognitive-behavioral therapy and neuroscience education potentially target cognitive-emotional sensitization (and descending facilitation), and centrally acting drugs and exercise therapy can improve endogenous analgesia (descending inhibition) in patients with osteoarthritis. Future studies should assess these new treatment avenues.

Therapeutic effects of mesenchymal stem cells and hyaluronic Acid injection on osteochondral defects in rabbits' knees

Purpose

To evaluate the treatment results of intraarticular injection according to the frequency of hyaluronic acid with mesenchymal stem cells on the osteochondral defect of rabbits' medial femoral condyles.

Materials and Methods

A 5 mm diameter and 4 mm depth osteochondral defect was made on the medial femoral condyles of 18 rabbits, divided into six groups. One week after osteochondral defect, group B was injected intraarticularly with hyaluronic acid (HA), group C with mesenchymal stem cells (MSCs), and group D, E and F with both HA and MSCs. Group E and F received second HA injection a week after. Further, group F received third HA injection in the third week.

Results

In a macroscopic evaluation, groups B (6; range, 5-8), C (6; range, 6-7), D (7; range, 6-7), E (6.5; range, 6-8) and F (7.5; range, 6-8) showed statistically significant improvements in osteochondral defect healing, compared with that of group A (4; range, 3-5) (p=0.002). In histological evaluation, groups B (11.5; range, 11-13), C (13; range, 12-18), D (16; range, 13-18), E (17.5; range, 13-20), and F (19.5; range, 12-22) showed statistically significant differences in osteochondral defect healing, compared with group A (8; range, 6-9) (p=0.006).

Conclusions

The intraarticular injections of MSCs or HA can play an effective role during the healing osteochondral defects in rabbits.

Combined effect of subchondral drilling and hyaluronic acid with/without diacerein in full-thickness articular cartilage lesion in rabbits

The osteochondral healing potential of hyaluronic acid (HA) plus diacerein was evaluated in subchondral-drilling- (SCD-) induced fibrocartilage generation in rabbits. A full-thickness chondral defect was created along the patellar groove of both knees and then SCD was subsequently performed only in the left knee. A week later, the rabbits were allocated into 3 groups to receive weekly intra-articular (IA) injection for 5 weeks with normal saline solution (NSS) (group 1) or with HA (group 2 and group 3). Starting at the first IA injection, rabbits were also gavaged daily for 9 weeks with NSS (group 1 and group 2) or with diacerein (group 3). The animals were then sacrificed for evaluation. The newly formed tissue in SCD lesions showed significantly better histological grading scale and had higher content of type II collagen in HA-treated group compared to NSS control. In addition, adding oral diacerein to HA injection enhanced healing potential of HA.

Hyaluronan modulates accumulation of hypoxia-inducible factor-1 alpha, inducible nitric oxide synthase, and matrix metalloproteinase-3 in the synovium of rat adjuvant-induced arthritis model

Introduction

Hypoxia is a feature of the inflamed synovium in rheumatoid arthritis (RA). Intra-articular injection of hyaluronan (HA) may be considered a potential way to treat RA. However, the exact molecular mechanism of HA on decreased cellular responses to hypoxic environment is unclear. The present study has been designed to use the adjuvant-induced arthritis model to examine the effects of HA on the changes of immunohistochemical expressions of hypoxia-inducible factor-1alpha (HIF-1alpha), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase-3 (MMP3) in the synovial tissues at the early phase of arthritic inflammation.

Methods

Monoarthritis was induced in adult male Sprague-Dawley (250-300 g) via intraarticular injection of complete Freund's adjuvant (CFA) into the tibiotarsal joint. The CFA-induction arthritis animals were divided into three groups: treatment (intraarticular injection of HA), placebo (intraarticular injection of saline) and controls (no treatments). Functional evaluations of edema and pain behavior, histology, and HIF-1alpha, iNOS, and MMP3 immunohistochemistry were performed before, after the first injection, three injections, and on the follow-up injection of the treatments.

Results

Intra-articular injection of HA also significantly suppressed the mechanical allodynia (p < 0.001) and overexpressions of HIF-1alpha (p < 0.001), iNOS (p = 0.004) and MMP3 (p < 0.001) immunoreactivity in synovium.

Conclusions

This study demonstrated that early intervention of HA is an effective protection against accumulation of inflammation-induced HIF-1alpha, iNOS, and MMP3 to limit erosive damage in CFA-induced model of arthritis.

Correlation of changes in pain intensity with synovial fluid adenosine triphosphate levels after treatment of patients with osteoarthritis of the knee with high-molecular-weight hyaluronic acid

We sought to determine whether a clinical association exists between osteoarthritis (OA)-associated knee pain and adenosine triphosphate (ATP) levels in synovial fluid (SF). A total of 28 patients with 28 primary OA knees were included. They routinely received intra-articular injection of high-molecular-weight hyaluronic acid (HA) once weekly for 5 weeks (treated group). Eight patients without knee pain who had undergone an operation for anterior or posterior cruciate ligament reconstruction 2 years ago were also examined (control group). SF and blood ATP concentrations, total amount of ATP, total SF volume, and Visual Analogue Scale (VAS) scores in all patients were measured and we compared pre-treatment values with those 1 week after the final treatment. We evaluated the correlation of change in total ATP (ΔATP) and change in VAS score (ΔVAS), ΔVAS and change in SF volume (ΔSF), and ATP concentration in SF and blood. In the treated group, SF ATP concentration, total amount of ATP, SF volume, and VAS score were all significantly lower post-treatment than pre-treatment (p = 0.0005, 0.0003, 0.0022, and < 0.0001, respectively). In treated group, ΔVAS was significantly associated with ΔATP (r = 0.56, p = 0.0032), ΔSF was significantly associated with ΔVAS (r = 0.78, p < 0.0001), and total amount of SF ATP and SF volume at pre-treatment were significantly higher than the control group (p < 0.0001, p < 0.0001) We demonstrated an association between SF ATP level changes and OA knee pain, which should facilitate a further understanding of OA pain mechanisms.

Interactions of meniscal cells with extracellular matrix molecules: towards the generation of tissue engineered menisci

Menisci are one of the most commonly injured parts of the knee. Conventional surgical interventions are often associated with a long-term increased risk of osteoarthritis. Meniscal tissue engineering utilizes natural or synthetic matrices as a scaffold to guide tissue repair or regeneration in three dimensions. Studies have shown that a diverse cellular response can be triggered depending on the composition of the surrounding extracellular matrix (ECM) components. As such, attempts have been made to replace or repair meniscus defects using tissue grafts or reconstituted ECM components prepared from a multitude of tissues. This commentary summarizes the most recent data on the response of meniscal cells to ECM components, both in vivo and in vitro, and focuses on their potential roles in meniscal repair and regeneration. We also discuss our recent investigations into the interactions of meniscal cells and a self assembled biomimetic surface composed of meniscal ECM molecules. The biological effects conferred by the biomimetic surface, in terms of cell adhesion, proliferation, gene expression profiles and matrix synthesis, were evaluated. Finally, some suggested directions for future research in this field are outlined.

Intra-articular injection of hyaluronan restores the aberrant expression of matrix metalloproteinase-13 in osteoarthritic subchondral bone

Subchondral bone is a candidate for treatment of osteoarthritis (OA). We investigated the effects of intra-articular injection of hyaluronan (IAI-HA) on subchondral bone in rabbit OA model. OA was induced by anterior cruciate ligament transection, with some rabbits receiving IAI-HA. OA was graded morphologically, and expression of mRNA was assessed by real-time RT-PCR. Tissue sections were stained with hyaluronan-binding protein, and penetration of fluorescent hyaluronan was assessed. The in vitro inhibitory effect of hyaluronan on MMP-13 was analyzed in human osteoarthritic subchondral bone osteoblasts (OA Ob) by real-time RT-PCR and ELISA. Binding of hyaluronan to OA Ob via CD44 was assessed by immunofluorescence cytochemistry. Expression of MMP-13 and IL-6 mRNA in cartilage and subchondral bone, and morphological OA grade, increased over time. IAI-HA ameliorated the OA grade and selectively suppressed MMP-13 mRNA in subchondral bone. IAI-HA enhanced the hyaluronan staining of subchondral bone marrow cells and osteocyte lacunae. Fluorescence was observed in the subchondral bone marrow space. In OA Ob, hyaluronan reduced the expression and production of MMP-13, and anti-CD44 antibody blocked hyaluronan binding to OA Ob. These findings indicate that regulation of MMP-13 in subchondral bone may be a critical mechanism during IAI-HA.

Brain activity for chronic knee osteoarthritis: dissociating evoked pain from spontaneous pain

Chronic pain is a hallmark of osteoarthritis (OA), yet little is known about its properties and representation in the brain. Here we use fMRI combined with psychophysics to study knee pain in fourteen OA patients and nine healthy controls. Mechanical painful pressure stimuli were applied to the knee in both groups and ratings of evoked pain and related brain activity examined. We observe that psychophysical properties and brain activation patterns of evoked pain are essentially the same between OA patients and healthy subjects, and between worse and better OA knees. In OA patients, stimulus-related brain activity could be distinguished from brain activity associated with spontaneous pain. The former activated brain regions commonly observed for acute painful stimuli in healthy subjects, while the spontaneous pain of OA engaged prefrontal-limbic regions closely corresponding to areas observed for spontaneous pain in other chronic pain conditions, such as chronic back pain and post-herpetic neuralgia. Arthritis-related clinical characteristics of knee OA also mapped to prefrontal-limbic regions. In a subgroup of patients (n=6) we examined brain activity changes for a 2-week, repeat measure, cyclooxygenase-2 inhibitor (valdecoxib) therapy. Treatment decreased spontaneous pain for the worse knee and clinical characteristics of OA, and increased blood and csf levels of the drug which correlated positively with prefrontal-limbic brain activity. These findings indicate dissociation between mechanically induced and spontaneous OA knee pain, the latter engaging brain regions involved in emotional assessment of the self, and challenge the standard clinical view regarding the nature of OA pain.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the rabbit

AIM

The primary goal of this body of work is to suggest a standardized system for histopathological assessment of experimental surgical instability models of osteoarthritis (OA) in rabbits, building on past experience, to achieve comparability of studies from different centres. An additional objective is to review methodologies that have been employed in the past for assessing OA in rabbits with particular reference to the surgical anterior cruciate ligament transection (ACLT) model.

METHODS

A panel of scientists and clinician-scientists with recognized expertise in assessing rabbit models of OA reviewed the literature to provide a critical appraisal of the methods that have been employed to assess both macroscopic and microscopic changes occurring in rabbit joint tissues in experimental OA. In addition, a validation of the proposed histologic histochemical grading system was performed.

RESULTS

The ACLT variant of the surgical instability model in skeletally mature rabbits is the variation most capable of reproducing the entire range of cartilage, synovial and bone lesions recognized to be associated with OA. These lesions can be semiquantitatively graded using macroscopic and microscopic techniques. Further, as well as cartilage lesions, this ACLT model can produce synovial and bone lesions similar to that of human OA.

CONCLUSIONS

The ACLT variant of the surgical instability model in rabbits is a reproducible and effective model of OA. The cartilage lesions in this model and their response to therapy can be graded according to an adapted histological and histochemical grading system, though also this system is to some extent subjective and, thus, neither objective nor entirely reproducible.

Hyaluronic acid inhibits nitric oxide-induced apoptosis and dedifferentiation of articular chondrocytes in vitro

OBJECTIVE

Nitric oxide is an important mediator in Osteoarthritis (OA), and causes apoptosis and dedifferentiation in articular chondrocytes. Protein kinase Calpha is involved in modulating apoptosis and dedifferentiation of articular chondrocytes induced by nitric oxide. Hyaluronic acid is widely used in the treatment of osteoarthritis and exerts significant chondroprotective effects. The exact mechanisms of its chondroprotective action are not yet fully elucidated. The present study was performed to investigate the effects and mechanisms of hyaluronic acid in NO-induced apoptosis and dedifferentiation of chondrocytes.

METHODS

The ratio of apoptotic cell and cell viability was surveyed by TUNEL, MTT assay and flow cytometry. The expression of aggrecan, type II collagen, and PKCalpha were determined by real-time PCR and Western blot. The expression changes of caspase-3 and bcl-2 was detected by Western blot. The mitochondrial membrane potential (DeltaPsim) was evaluated by Rhodamine-123 fluorescence.

RESULTS

HA reduces the TUNEL positive cell, nuclei fragment and the impairment of DeltaPsim. NO-induced chondrocyte dedifferentiation was blocked by HA, which restores expression of aggrecan and type II collagen of chondrocytes and cell viability. HA can block inhibition of PKC-alpha by NO.

CONCLUSION

Our results show that HA blocks NO-induced apoptosis and dedifferentiation of articular chondrocytes by modulation of DeltaPsim and PKCalpha.

Analysing the role of endogenous matrix molecules in the development of osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis worldwide. In this condition, damage to the extracellular matrix (ECM) of cartilage occurs, resulting in joint destruction. Factors mediating cartilage damage include mechanical injury, cytokine and superoxide release on a background of genetic susceptibility and obesity. Studies of arthritic cartilage show increased production of ECM molecules including type II collagen, cartilage oligomeric matrix protein, fibronectin (FN) and fibromodulin. Recent reports suggest that ECM proteins may become endogenous catabolic factors during joint damage. Activation of pro-inflammatory pathways by ECM proteins has led to their description as damage-associated molecular patterns (DAMPs). The ECM proteins involved include fibromodulin, which activates the complement pathway and may promote the persistence of joint inflammation. Fragmentation of type II collagen, FN and hyaluronan reveals cryptic epitopes that stimulate proteolytic enzymes including matrix metalloproteinases and aggrecanases (ADAMTSs - a disintegrin and metalloproteinase with thrombospondin type 1 motifs). Proteolytic fragments also stimulate the release of nitric oxide, chemokines and cytokines and activation of the MAP kinases. Reports are emerging that the receptors for the fragments described involve interaction with integrins and toll-like receptors. In this review the contribution of endogenous ECM molecules to joint destruction will be discussed. A deeper understanding of the pathways stimulated by endogenous ligands could offer potential avenues for novel therapies in the future.

Hylan G-F 20 has better pain relief and cost-effectiveness than sodium hyaluronate in treating early osteoarthritic knees in Taiwan

BACKGROUND/PURPOSE

Intra-articular injection of hyaluronan (hyaluronic acid; HA) products is available to treat early osteoarthritis (OA) of the knee in Taiwan. We tested whether HA products with different molecular weights have significantly different effects on clinical efficacy and cost-effectiveness.

METHODS

Thirty-seven patients with mild to moderate OA of both knees underwent five weekly intra-articular injections of sodium hyaluronate (Artz) in one knee and three weekly intra-articular injections of chemically cross-linked Hylan G-F 20 (Synvisc) in the other. Visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lequesne's index, and Hospital for Special Surgery (HSS) knee scores were compared initially and at the last injection, and at 8, 12, 16, 20, and 26 weeks after the first injection.

RESULTS

VAS, WOMAC, WOMAC-A1 (pain when walking on a flat surface) scores before week 16, HSS scores before week 12, and Lequesne's index scores except at week 26 all showed that HA significantly improved the scores time-dependently. In VAS scores, Synvisc showed better improvement before week 20, while this effect appeared at week 12 for the WOMAC-A1 scores. The incremental cost-effectiveness ratio of the Taiwan National Health Insurance Program, of the patient, and both of these was lower for Synvisc, which also reduced the number of additional hospital visits for injections by two.

CONCLUSION

Synvisc possesses better symptom-modifying ability and cost-utility in treating early OA of the knee in Taiwan.

Effects of hyaluronan on vascular endothelial growth factor and receptor-2 expression in a rabbit osteoarthritis model

BACKGROUND

Little is known about the expression of vascular endothelial growth factor (VEGF) and its receptor-2 (VEGFR-2) mRNA in the cartilage of a rabbit osteoarthritis model or the influence of intraarticular injection of hyaluronan (HA) on the expression of VEGF and VEGFR-2 in cartilage during the process of osteoarthritis (OA). The therapeutic mechanism of HA is not completely understood, and we hypothesize that the mechanism is through the effects of VEGF and VEGFR2. In this study, we determined the VEGF and VEGFR-2 mRNA expression in a rabbit OA model and assessed the therapeutic mechanism of HA against OA.

METHODS

We carried out this study at the Center Laboratory of Renmin Hospital at Wuhan University and the Key Laboratory of Respiratory Disease of the Ministry of Public Health, Huazhong University of Science and Technology. Between October 2006 and April 2008 a total of 24 mature New Zealand white rabbits were divided into three groups: normal controls, a no-HA group, and an HA group. The no-HA and HA groups underwent unilateral anterior cruciate ligament transection. At 4 weeks after the operation, animals in the HA group received intraarticular injections of 1% sodium hyaluronate (HA) once a week for 5 weeks as per the clinical treatment presently utilized. The no-HA rabbits were not given HA. At death, 11 weeks following surgery, cartilage was harvested and total RNA was extracted. VEGF and VEGFR mRNAs were analyzed using the reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR for each group.

RESULTS

Cartilage damage (both extent and grade) was less severe in the HA group than in the no-HA group. VEGF and VEGFR-2 mRNA expression was enhanced in the cartilage of the OA model. Intraarticular 1% sodium hyaluronate injection inhibited VEGFR-2 expression but had no effect on reducing the VEGF mRNA expression in cartilage.

CONCLUSIONS

These results suggested that VEGF and VEGFR-2 may be involved in the progression of OA and in the therapeutic mechanism of HA at least partly through the influence of VEGFR-2 expression during the development of OA.

A preliminary fMRI study of analgesic treatment in chronic back pain and knee osteoarthritis

The effects of an analgesic treatment (lidocaine patches) on brain activity in chronic low back pain (CBP) and in knee osteoarthritis (OA) were investigated using serial fMRI (contrasting fMRI between before and after two weeks of treatment). Prior to treatment brain activity was distinct between the two groups: CBP spontaneous pain was associated mainly with activity in medial prefrontal cortex, while OA painful mechanical knee stimulation was associated with bilateral activity in the thalamus, secondary somatosensory, insular, and cingulate cortices, and unilateral activity in the putamen and amygdala. After 5% lidocaine patches were applied to the painful body part for two weeks, CBP patients exhibited a significant decrease in clinical pain measures, while in OA clinical questionnaire based outcomes showed no treatment effect but stimulus evoked pain showed a borderline decrease. The lidocaine treatment resulted in significantly decreased brain activity in both patient groups with distinct brain regions responding in each group, and sub-regions within these areas were correlated with pain ratings specifically for each group (medial prefrontal cortex in CBP and thalamus in OA). We conclude that the two chronic pain conditions involve distinct brain regions, with OA pain engaging many brain regions commonly observed in acute pain. Moreover, lidocaine patch treatment modulates distinct brain circuitry in each condition, yet in OA we observe divergent results with fMRI and with questionnaire based instruments.

Influence of sodium hyaluronate on iNOS expression in synovium and NO content in synovial fluid of rabbits with traumatic osteoarthritis

OBJECTIVE

To observe the influence of intra-articular injection of sodium hyaluronate (SH) on the expression of inducible nitric oxide synthase (iNOS) in the synovium and nitric oxide (NO) content in synovial fluid of rabbits with traumatic osteoarthritis (OA).

METHODS

Sixteen white rabbits underwent unilateral anterior cruciate ligament transection and were randomly divided into 2 groups 5 weeks after the operation. Rabbits in the experimental group received intra-articular injection of 0.3 ml of 1% SH, once a week for 5 weeks. Animals in the control group were treated under the same conditions using physiological saline. All the animals were sacrificed at the 10th week after surgery. The mRNA expression of iNOS in the synovium was analyzed using reverse transcription-polymerase chain reaction. The content of NO in the synovial fluid was assayed.

RESULTS

The level of iNOS expression of the synovium in the experimental group was lower than that in control group (0.47+/-0.09 vs. 0.65+/-0.12, t equal to 3.45, P less than 0.01). Compared with control group, the content of NO decreased significantly in synovial fluid of SH injection group (134.11 micromolar/L +/- 12.47 micromolar/L vs. 152.17 micromolar/L +/- 15.69 micromolar/L, t equal to 2.55, P less than 0.05).

CONCLUSIONS

SH significantly decreases the content of NO in the synovial fluid of rabbits with traumatic OA. SH may exert the effect on synovial fluid NO level as a result of the suppression of iNOS expression in the synovium. It may be one of the mechanisms of the therapeutic effect of SH on early traumatic OA.

Significant synovial pathology in a meniscectomy model of osteoarthritis: modification by intra-articular hyaluronan therapy

Objective. IA therapy with hyaluronan (HA) is reported to provide symptomatic relief and disease modification in OA. This study assessed the pathological changes in the synovium of an ovine model of OA and evaluated the effects of two HA preparations on this pathology.

Methods. Eighteen sheep had bilateral lateral meniscectomy to induce OA. Four months post-surgery animals received IA saline or HA (Hyalgan®) weekly for 5 weeks or three injections of an amide derivative of HA (HYADD®4-G) every 2 weeks (n = 6 per group). Six months after meniscectomy, sheep were killed, knee joint synovium processed, scored for pathological change and compared with synovium from non-operated animals. Sections of synovium from normal and treated joints were also immunostained for TNF-α, HSP-47, TGF-β, CD44, connective tissue growth factor (CTGF) or iNOS. HA synthesis by synovial fibroblasts isolated from each OA joint was quantified.

Results. Aggregate scores of pathological change were higher in OA joint synovia compared with controls, with individual measures of subintimal fibrosis and vascularity predominantly affected. Depth of intimal fibrosis was also significantly higher in meniscectomized joints. IA treatment with Hyalgan® decreased aggregate score, vascularity and depth of fibrosis. HYADD®4-G treatment decreased vascularity, intimal hyperplasia and increased high-molecular weight HA synthesis by synovial fibroblasts. CD44, CTGF or iNOS expression was increased in the synovial lining of OA joints compared with normal, but there was no significant modulation of this increase by either HA preparation.

Conclusion. Increased fibrosis and vascularity are hallmarks of pathological change in synovium in this meniscectomy model of OA. Both the IA HA and an amide derivative of HA reduced aspects of this pathology thus providing a potential mechanism for improving joint mobility and function in OA.

Effects of different molecular weight hyaluronan products on the expression of urokinase plasminogen activator and inhibitor and gelatinases during the early stage of osteoarthritis

Hyaluronan or hyaluronic acid (HA) has been used to treat osteoarthritic knees for more than 30 years. Here, we tested the hypothesis that HA with high molecular weight (MW) would have greater effects than HA with low MW on the expression of the plasminogen activator (PA)/plasmin system and gelatinases [matrix metalloproteinase (MMP)-2 and MMP-9] during early development of osteoarthritis (OA). We compared the levels of MMP-2, MMP-9, urokinase-type PA (u-PA), and PA inhibitor-1 (PAI-1) in a series of chondral, meniscal, and synovial cultures of early OA after treatment with or without three different MW HA products (Hyalgan and Artz with low MW, and Synvisc with high MW). Gelatin zymography revealed that three different HA products could decrease the secretion of MMP-2 in all tissue cultures and MMP-9 in meniscal and synovial cultures time-dependently. Enzyme-linked immunosorbent assay showed that Artz and Synvisc had significant inhibition on u-PA and PAI-1 levels after 24 h, but Hyalgan did at 96 h. Compared with Hyalgan and Artz, Synvisc provided the greatest ability to inhibit MMP-2, MMP-9, u-PA, and PAI-1 expression. Our studies clearly demonstrate that the therapeutic effects of using HA to treat early OA may be partially dependant on downregulation of the PA/plasmin system and gelatinases expression, which delay the structural progression of the disease. HA with high MW might have a greater ability than that with low MW to offer effective protection for articular cartilage.

Hyaluronan in Breast Cancer: Correlations With Nitric Oxide Synthases and Tyrosine Nitrosylation

Reactive oxygen species (ROS), including nitric oxide (NO•), are associated with all steps of carcinogenesis. Hyaluronan (HA), a high-molecular-mass glycosaminoglycan over-expressed in a variety of human malignancies also has ROS-scavenging properties. We histochemically studied the level of HA in breast carcinoma cells and their stroma and compared it with the expression of NO• synthases (NOSs), major antioxidant enzymes, and nitrotyrosine. We also assessed whether the level of HA correlates with traditional prognostic factors of breast cancer and survival. Stromal HA level was moderate or high in all the samples studied ( n=185), and 84% of the lesions showed HA-positive carcinoma cells. Intense stromal HA signal was associated with high neuronal NOS expression ( p=0.009), whereas tumor-cell associated HA was inversely correlated with nitrotyrosine expression ( p=0.027). Of the traditional prognostic factors, tumor cell-associated HA was correlated with poor differentiation ( p=0.011), and high stromal HA levels were associated with aggressive features of the carcinomas such as large primary tumor ( p=0.002), poor differentiation ( p=0.019), and estrogen ( p=0.012) and progesterone receptor negativity ( p=0.009). High stromal HA level also significantly predicted poorer survival. The strong positive correlation between neuronal NOS and stromal HA could reflect NO•-stimulated synthesis of HA, an extracellular matrix alteration that favors breast cancer progression. Furthermore, it is suggested that, while acting as a scavenger of NO•-derived radicals, cell-associated HA undergoes partial fragmentation, release from receptors, and further degradation in lysosomes, and thus becomes undetectable in histological sections.

The effects of glucosamine hydrochloride on subchondral bone changes in an animal model of osteoarthritis

OBJECTIVE

To quantify periarticular subchondral bone changes in a rabbit model of experimental osteoarthritis (OA), and to determine the effects of continuous administration of a clinically relevant dose of glucosamine HCl on subchondral bone changes in this model.

METHODS

Anterior cruciate ligament transection (ACLT) was performed on the left femorotibial joints of 16 rabbits to induce OA. Ten rabbits that did not undergo ACLT served as unoperated controls. Eight rabbits that underwent ACLT and 6 control rabbits were treated with 100 mg of glucosamine daily, and the others were given a placebo. The articular cartilage was evaluated macroscopically and graded at the time of necropsy, 8 weeks after ACLT. Bone mineral density (BMD) was measured using dual-energy x-ray absorptiometry on the dissected distal femur and proximal tibia. Subchondral trabecular bone turnover, architecture, and connectivity, as well as subchondral plate thickness and mineralization were studied on the undecalcified tibia sections from each animal.

RESULTS

Eight weeks after ACLT, most of the operated joints had various degrees of cartilage damage and fibrillation. Compared with the control group, the ACLT group had significantly increased subchondral bone turnover and lower BMD, bone volume, connectivity, and bone mineralization. The high bone turnover was significantly reduced in glucosamine-treated animals that underwent ACLT. In fact, there were no significant differences between the ACLT/glucosamine group and the control/glucosamine group in most of the bone parameters studied.

CONCLUSION

This study shows that subchondral bone turnover, structure, and mineralization are significantly altered in the early stages of experimental OA, and that these changes are attenuated by glucosamine treatment.

Different effects of high molecular weight sodium hyaluronate and NSAID on the progression of the cartilage degeneration in rabbit OA model

OBJECTIVE

We examined the effects of nonsteroidal anti-inflammatory drug (NSAID) and intra-articular injections of sodium hyaluronate (HA) on cartilage degeneration in rabbit knee osteoarthritis (OA) model induced by partial meniscectomy.

METHODS

Loxoprofen sodium (LOX) was used as the NSAID, administered p.o. once daily for 14 days at a dose of 4 mg/kg, starting from the day of meniscectomy. Suvenyl(SVE) was used as the high molecular weight HA, injected intra-articularly into injured knee every 3 days from the day of surgery. The effect on pain was assessed by an Incapacitance Tester, and the damage of cartilage was evaluated by visual assessment and histopathology at 14 days after the surgery.

RESULTS

Hind paw weight bearing on the injured paw decreased time-dependently in the control group. In other three groups, the decrease of hind paw weight distribution was suppressed, demonstrating an analgesic effect. Visible damage and histopathological findings of cartilage degeneration were evident in the cartilages of the control group at day 14. In the SVE group, the damaged cartilage area decreased and cartilage degeneration was ameliorated. In contrast, in the LOX group, the cartilage degeneration was augmented compared with the control group. And, this exacerbated cartilage degeneration induced by LOX was reversed by the concomitant use of SVE.

CONCLUSION

Our data show that the treatment with high molecular weight HA from earlier stage is strongly recommended to preserve the structure of cartilage.

Analgesic activity of a polysaccharide in experimental osteoarthritis in rats

Viscosupplementation efficacy has been related to the high molecular weight of hyaluronic acid-like compounds, as well as to gel formulation. We evaluated the effect of a galactomannan polysaccharide derived from Guar gum (GG) in joint pain in an osteoarthritis (OA) model. Wistar rats (six animals/group) were subjected to anterior cruciate ligament transection (ACLT-OA group). The OA group was compared to a false-operated group (sham). Joint pain was recorded daily, using the articular incapacitation test, until 7 days after ACLT. Solutions or gel preparations of GG (100 microg) or Hylan G-F 20 (100 microg), used as a comparator, were given intraarticularly (i.a.) at day 4 after ACLT. Controls received saline i.a. The OA group had significantly increased joint pain as compared to sham (P<0.001). GG, either as a gel or solution, significantly inhibited joint pain similar to the inhibition achieved with Hylan G-F20. This is the first demonstration that a galactomannan derived from GG reduces joint pain in experimental OA. This analgesia is independent of the colloidal state. We propose that the analgesic benefit of viscosupplementation may be due to an intrinsic carbohydrate-mediated mechanism rather than to the rheologic properties of the material.

Inflammatory and immunological responses to hyaluronan preparations. Study of a murine biocompatibility model

BACKGROUND

Intra-articular injection of hyaluronan preparations is a popular treatment for osteoarthritis of the knee. Recently, clinical reports have described acute inflammatory reactions in joints following these injections. The purpose of this study was to use a murine pouch model to study the local inflammatory and possibly immunological effects of three commercially available hyaluronan-derived products.

METHODS

Each of three different hyaluronan products (Synvisc, Hyalgan, and Supartz) was injected into air pouches established in groups of BALB/c mice. A positive control group (with particle-induced inflammation) and a negative control group (injected with saline solution) were also included. After fourteen days, the mice were killed and the air pouches were explanted and prepared for histological evaluation of the local inflammatory reaction. The antibody response was measured with use of ELISA (enzyme-linked immunosorbent assay) of serum samples obtained after the mice were killed.

RESULTS

Histological analysis revealed a significant increase in total membrane cellularity (p < 0.001 to p < 0.03) after the use of all hyaluronan preparations. The increased cellularity was attributed to an inflammatory cell influx, rather than accumulation of fibroblasts, and elevated lymphocyte counts were observed in membranes stimulated by Synvisc (hylan G-F 20). The ELISA data revealed an antibody response to the Synvisc preparation. This immunological response was directed against a non-hyaluronan portion of the product, as indicated by the lack of cross-reactivity with the other hyaluronan products.

CONCLUSIONS

These findings demonstrate that all three hyaluronan preparations, as currently manufactured, can cause an inflammatory soft-tissue reaction, but only the non-hyaluronan portion of the Synvisc product created an immunological response. It appears likely that this component may be the target of adverse responses in patients.

Effects of hyaluronan on nitric oxide levels and superoxide dismutase activities in synovial fluid in knee osteoarthritis

The aim of the present study was to evaluate the effects of hyaluronan (HA) on nitric oxide (NO) levels and superoxide dismutase (SOD) enzyme activities in synovial fluid (SF) in the treatment of patients with knee osteoarthritis (OA). SF samples were aspirated from OA patients before the commencement of the treatment (n=23) and 6 weeks after they were treated with HA products. NO levels and SOD activities were compared between the pre- and post-treatment of OA patients and of the control group (n=10). SF NO levels were significantly higher in patients with OA before the commencement of the treatment compared with the post-treatment (p<0.001) and the control groups. The SF SOD activity of patients before the commencement of the treatment was lower than the values in the controls and post-treatment (p<0.001). There is no significant correlation between SF NO and SOD levels and the radiographic changes of the OA knee according to Kellgren-Lawrence grading (p>0.05). Also, the Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) pain scores and physical function scores were gradually improved. These findings made us think that SF NO was a potent mediator in cartilage damage in OA, whereas SOD was an antioxidant mediator in the same process. Exogenous HA injections might reduce the NO levels and increase SOD activities in synovial fluid. These effects also do not seem to be dependent on the radiographic grading of the OA knee. More comprehensive studies are needed to clarify a possible clinical significance of this topic, and we suggest that this is an important area for further research into new treatment options.

Biochemical effects of two different hyaluronic acid products in a co-culture model of osteoarthritis

OBJECTIVES

To compare the effects of two hyaluronic acid (HA) formulations on mediators of matrix turnover and inflammation in an IL-1-treated cartilage-synovium co-culture model with the aim of elucidating mechanisms by which viscosupplementation exerts beneficial effects in osteoarthritic joints.

DESIGN

A co-culture model (100 ng/ml interleukin-1beta (IL-1beta) added to canine synovial and cartilage explants) was used to investigate the effects of HA on cartilage-synovium interactions. Three concentrations (1x, 0.5x, and 0.1x) of two commercial sources of HA (A: Synvisc [hylan G-F 20]; B: Hyalgan [sodium hyaluronate]) were used. Co-cultures without IL-1beta (negative) or with IL-1beta (positive) but neither HA product served as controls. The liquid media were collected every 3 days and explants of cartilage and synovium were collected on days 3, 6, and 20. Media and explants were analyzed histologically, biochemically, and immunohistochemically.

RESULTS

Glycosaminoglycan (GAG) content was measured in cartilage explants. GAG content in explants was higher in both HA groups at the beginning and the conclusion of the study compared to the IL-1beta-treated group. GAG content of the media was significantly (P<0.05) lower in the Synvisc group than all other groups early. The Hyalgan group demonstrated progressively less GAG release later in the study. The addition of Synvisc did not decrease the matrix metalloproteinase (MMP)-3 concentrations at any point. MMP-3 concentrations were significantly (P<0.05) lower among the 1x and 0.5x Hyalgan groups on day 20 compared to the IL-1beta-treated group. On day 3, prostaglandin E(2) concentrations were significantly (P<0.05) higher in the IL-1beta-treated group compared to other groups. Both HA groups had less nitric oxide production than the control groups throughout the study.

CONCLUSIONS

This study supports two potential mechanisms for viscosupplementation: a biosynthetic-chondroprotective mechanism, with a possible delay in onset depending on the form of HA; and an anti-inflammatory mechanism.