Short-term effect of the combination of hyaluronic acid, chondroitin sulfate, and keratin matrix on early symptomatic knee osteoarthritis

Differences between soluble and insoluble undenatured type II collagen in improving osteoarthritis in rats and their potential mechanisms

Our previous research showed that soluble (SC II) and insoluble (IC II) undenatured type II collagen had significant differences during gastrointestinal digestion in vitro, and SC II exposed more type II collagen with triple helix structure. However, the differences in their in vivo digestive characteristics, improvement on osteoarthritis (OA), and possible mechanisms have not been elucidated. The aim of this study was to explore these issues. After oral administration of SC II and IC II, the joint swelling of OA rats significantly reduced, and the weight bearing ratio of right hind limb significantly increased, especially in SC II group (raised to 48%). The Mankin and OARSI scores decreased by 35% and 48% in SC II group, respectively. SC II and IC II increased the mRNA expression of anti-inflammatory factors and the proportion of regulatory T cells (Treg). Importantly, type II collagen released by IC II during in vivo gastrointestinal digestion was far less than SC II, which explained the higher ability of SC II to induce immune tolerance in small intestine than IC II. Bioinformatics analysis showed that the differential genes between model and control were significantly enriched in PI3K/AKT, PPAR and AMPK signalling pathways, and 24 hub genes were analyzed. SC II significantly down-regulated the mRNA expression of Il6, Ccl7, NF-κB, AKT and up-regulated the mRNA expression of Scd1. These results showed that SC II was superior to IC II in improving OA by inducing immune tolerance and could regulate key biomarkers and signalling pathways in OA rats.

Undenatured type II collagen and its role in improving osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease, affecting 32.5 million US adults or 242 million people worldwide. There is no cure for OA. Many animal and clinical trials showed that oral administration of undenatured type II collagen could significantly reduce the incidence of OA or alleviate the symptoms of articular cartilage. Type II collagen is an important component of cartilage matrix. This article reviewed research progress of undenatured type II collagen including its methods of extraction and preparation, structure and characterization, solubility, thermal stability, gastrointestinal digestive stability, its role in improving OA, and the mechanism of its action in improving OA. Type II collagen has been extensively explored for its potential in improving arthritis. Methods of extraction of type II collagen are inefficient and tedious. The method of limited enzymatic hydrolysis is mainly used to prepare soluble undenatured type II collagen (SC II). The solubility, thermal and gastrointestinal digestive stability of SC II are affected by the sources of raw material, pH, salt ions, and temperature. Oral administration of undenatured type II collagen improves OA, whereas its activity is affected by the sources, degree of denaturalization, intervention methods and doses. However, the influence of the structure of undenatured type II collagen on its activity and the mechanism are unclear. The findings in this review support that undenatured type II collagen can be used in the intervention or auxiliary intervention of patients with OA.

Natural Compounds: Potential Therapeutics for the Inhibition of Cartilage Matrix Degradation in Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease characterized by enzymatic degradation of the cartilage extracellular matrix (ECM) causing joint pain and disability. There is no disease-modifying drug available for the treatment of OA. An ideal drug is expected to stop cartilage ECM degradation and restore the degenerated ECM. The ECM primarily contains type II collagen and aggrecan but also has minor quantities of other collagen fibers and proteoglycans. In OA joints, the components of the cartilage ECM are degraded by matrix-degrading proteases and hydrolases which are produced by chondrocytes and synoviocytes. Matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS5) are the major collagenase and aggrecanase, respectively, which are highly expressed in OA cartilage and promote cartilage ECM degradation. Current studies using various in vitro and in vivo approaches show that natural compounds inhibit the expression and activity of MMP-13, ADAMTS4, and ADAMTS5 and increase the expression of ECM components. In this review, we have summarized recent advancements in OA research with a focus on natural compounds as potential therapeutics for the treatment of OA with emphasis on the prevention of cartilage ECM degradation and improvement of joint health.

The Booster Effect of a Single Quarterly Dose of Hyaluronic Acid in Knee Osteoarthritis: Five-Year Results of a Registry-Based Study

Objective

Viscosupplementation by hyaluronic acid (HA) is well established non-surgical treatment of knee osteoarthritis (KOA). This registry-based study investigated the booster effect of a quarterly intra-articular single knee injection (30mg/2ml) for five years.

Methods

Sixty patients, including 29 males and 31 females, with a mean ± SD age 61.07 ± 9.15 with Kellgren-Lawrence grade I-III KOA, have been selected from a registry of interventional treatments for musculoskeletal pain conditions. To be eligible, patients had to be treated with a single quarterly intraarticular injection of HA with a follow-up of at least five years and assessed with Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Numeric Rating Scale (NRS) at baseline and after each HA injection in the first 24 months and at 36, 48, and 60 months.

Results

Sixty of 63 patients enrolled in this study completed the 60 months of follow-up. Patients had a marked improvement in knee function and pain, expressed by the significant reduction in WOMAC (T0 48.62±8.95 vs. T11 10.75±4.36; p<0.0001) and NRS scores (6.38±1.06 vs. T11 0.95±0.89 p<0.0001) from the baseline to the end of the follow-up period.

Conclusion

A quarterly injection of HA provides a rapid, safe, and stable long-term reduction of pain and improvement of function in elderly people with mild to moderate knee osteoarthritis along a five-year period of treatment and follow-up. Further investigations are necessary to confirm these findings.

New Hyaluronic Acid from Plant Origin to Improve Joint Protection—An In Vitro Study

Background: In recent decades, hyaluronic acid (HA) has attracted great attention as a new treatment option for osteoarthritis. Classical therapies are not able to stop the cartilage degeneration process nor do they favor tissue repair. Nowadays, it is accepted that high molecular weight HA can reduce inflammation by promoting tissue regeneration; therefore, the aim of this study was to verify the efficacy of a new high molecular weight HA of plant origin (called GreenIuronic®) in maintaining joint homeostasis and preventing the harmful processes of osteoarthritis. Methods: The bioavailability of GreenIuronic® was investigated in a 3D intestinal barrier model that mimics human oral intake while excluding damage to the intestinal barrier. Furthermore, the chemical significance and biological properties of GreenIuronic® were investigated in conditions that simulate osteoarthritis. Results: Our data demonstrated that GreenIuronic® crosses the intestinal barrier without side effects as it has a chemical–biological profile, which could be responsible for many specific chondrocyte functions. Furthermore, in the osteoarthritis model, GreenIuronic® can modulate the molecular mechanism responsible for preventing and restoring the degradation of cartilage. Conclusion: According to our results, this new form of HA appears to be well absorbed and distributed to chondrocytes, preserving their biological activities. Therefore, the oral administration of GreenIuronic® in humans can be considered a valid strategy to obtain beneficial therapeutic effects during osteoarthritis.

Intra-Articular Injection of a Novel DVS Cross-Linked Hyaluronic Acid Manufactured by Biological Fermentation (YYD302) in Patients With Knee Osteoarthritis: A Double-Blind, Randomized, Multicenter, Noninferiority Study

PURPOSE

This double-blind, randomized, Phase III clinical trial was conducted to assess the efficacy and safety of the novel divinyl sulfone cross-linked hyaluronate (YYD302) compared with the 1,4-butanediol diglycidyl ether cross-linked hyaluronate (Synovian) in patients with knee osteoarthritis.

METHODS

A total of 184 patients with osteoarthritis (Kellgren-Lawrence grade I-III) were randomized to 1 of 2 study groups (YYD302 group, n = 95; Synovian group, n = 89). A single injection of YYD302 or Synovian was given to both groups, and 182 participants completed the study (YYD302 group, n = 95; Synovian group, n = 87). The primary end point was the change in weight-bearing pain (WBP) at 12 weeks after the primary single injection. Secondary end points included the Knee Injury and Osteoarthritis Outcome Score; the Western Ontario and McMaster Universities Osteoarthritis Index score; the Patient Global Assessment and Investigator Global Assessment; the range of motion, swelling, and tenderness of the target knee; OMERACT-OARSI responder rate; WBP responder rate (the proportion of patients achieving at least 20 mm or 40% decrease in WBP); and rate of rescue medicine use and its total consumption at weeks 2, 4, and 12. Based on the efficacy results at week 12, the responders were administered an additional single injection of the same study drug at week 24, and safety and efficacy were additionally assessed at week 36.

FINDINGS

Mean changes of WBP at 12 weeks after the primary injection were -31.76 mm with YYD302 and -29.74 mm with Synovian, proving noninferiority of the YYD302 group to the Synovian group as the lower bound of the 95% CI (-4.3 to 8.3) was well above the predefined margin (-10 mm). At week 2, the Knee Injury and Osteoarthritis Outcome Score (total, pain, activities of daily living, and sports/recreation) and Western Ontario and McMaster Universities Osteoarthritis Index scores (total, stiffness) were significantly better in the YYD302 group than in the Synovian group. There were no significant differences between the groups in all other end points. Local overall adverse events (pain, heat, erythema, or swelling) at the injection site were observed in 48.4% of the YYD302 group and in 47.7% of the Synovian group. No serious reactions were reported. There was no statistically significant difference between the 2 groups regarding re-injected patients (YYD302 group, n = 54; Synovian group, n = 46) in any of the efficacy outcomes at week 36.

IMPLICATIONS

The results of this study support that YYD302 is comparable to Synovian in terms of the efficacy and safety of the intra-articular injection treatment for osteoarthritis of the knee joint. Furthermore, YYD302 provided faster improvements in some efficacy assessments compared with Synovian. ClinicalTrials.gov identifier: NCT03561779.

Safety Aspects of the Use of Isolated Piperine Ingested as a Bolus

Piperine is a natural ingredient of Piper nigrum (black pepper) and some other Piper species. Compared to the use of pepper for food seasoning, piperine is used in food supplements in an isolated, concentrated form and ingested as a bolus. The present review focuses on the assessment of the possible critical health effects regarding the use of isolated piperine as a single ingredient in food supplements. In human and animal studies with single or short-term bolus application of isolated piperine, interactions with several drugs, in most cases resulting in increased drug bioavailability, were observed. Depending on the drug and extent of the interaction, such interactions may carry the risk of unintended deleteriously increased or adverse drug effects. Animal studies with higher daily piperine bolus doses than in human interaction studies provide indications of disturbance of spermatogenesis and of maternal reproductive and embryotoxic effects. Although the available human studies rarely reported effects that were regarded as being adverse, their suitability for detailed risk assessment is limited due to an insufficient focus on safety parameters apart from drug interactions, as well as due to the lack of investigation of the potentially adverse effects observed in animal studies and/or combined administration of piperine with other substances. Taken together, it appears advisable to consider the potential health risks related to intake of isolated piperine in bolus form, e.g., when using certain food supplements.

Non-Inferiority of a Single Injection of Sodium Hyaluronate Plus Sorbitol to Hylan G-F20: A 6-Month Randomized Controlled Trial

Introduction

Several viscosupplement treatments are available for patients suffering from painful osteoarthritis (OA) of the knee, but few comparative clinical trials have been conducted. The primary objective of the trial was to demonstrate the non-inferiority of Synolis VA (80 mg hyaluronic acid and 160 mg sorbitol) (Group HA1) to Synvisc-One (48 mg hylan GF-20) (Group HA2) at Day 168 in terms of pain relief efficacy in patients with knee OA (Kellgren and Lawrence radiological stage II or III) in whom oral treatment with analgesics, NSAIDs or weak opioids provided insufficient clinical responses or were poorly tolerated.

Methods

This was a prospective, multicentre, comparative, randomized, double-blinded trial comparing the two previously indicated viscosupplements, HA1 and HA2. The average VAS pain score (1–100) was 62.5 at baseline (Day 0). The patients were randomized into two parallel groups at Day 0 and followed until Day 168. They received one injection of either HA1 or HA2. The primary end point was the evolution of the Western Ontario and McMaster University (WOMAC) pain index at D168 in the groups. One of the secondary end points was the daily assessment of this index by the patient for 7 days following the injection and thereafter at Day 14. The other secondary end points were the WOMAC pain, stiffness, function and total scores assessed at Day 28, Day 84 and Day 168. At Day 168, efficacy and satisfaction were assessed by the evaluator and by the patient using a Likert scale (7 points). Moreover, the number of strict responders in each group was evaluated according to the The Osteoarthritis Research Society International (OARSI) Standing Committee for Clinical Trials Response Criteria Initiative and the Outcome Measures in Rheumatology (OMERACT) criteria (OMERACT-OARSI). The per protocol (PP) population was used for the primary analysis.

Results

A total of 202 patients were randomized. The patients were predominantly female (66%). The median age of the whole population was 65 years, and the median body mass index was 27.4 kg/m². No statistically significant differences between the two treatment groups were observed for any of the demographic criteria. At Day 168, 197 had had no protocol violations (94 in the HA1 group and 103 in the HA2 group). The WOMAC pain score decreased in the two groups: − 29.2 ± 24.1 (SD) in the HA1 group and − 31.6 ± 25.5 (SD) in the HA2 group, confirming the non-inferiority of Synolis VA (P = 0.57 for the difference between groups). Regarding the secondary end points, no significant difference was observed at Day 14, Day 28, Day 84 or Day 168 for all the outcomes except stiffness at Day 28 (P = in favour of treatment received in HA2). The rate of responders was comparable between the two groups: 79% for HA1 and 77% for HA2. Both products were well tolerated. Serious adverse events were reported by four patients in the HA1 group and 3 in the HA2 group.

Conclusion

In this trial, we confirmed the non-inferiority of Synolis VA compared to Synvisc-One at Day 168 according to the WOMAC pain score. Safety was satisfying and comparable in the two groups.

Trial Registration

2017-A00034-49.

Clinical therapy of platelet-rich plasma vs hyaluronic acid injections in patients with knee osteoarthritis: A systematic review and meta-analysis of randomized double-blind controlled trials

OBJECTIVE:

Knee osteoarthritis (KOA) is the most common degenerative disease of the joints caused by articular cartilage injury, degeneration of joint edges and hyperplasia of subchondral bone. The purpose of this study is to investigate the efficacy and safety of clinical therapy of platelet-rich plasma vs hyaluronic acid injections in patients with KOA.

METHODS:

We systematically investigated Pubmed, Embase, and the Cochrane Library for all related articles published through May 2020. Any study was included that compared the effect of platelet-rich plasma (PRP) and hyaluronic acid (HA) in patients with KOA. The search terms included “platelet-rich plasma,” “PRP,” “hyaluronic acid,” “HA,” “knee,” “osteoarthritis,” “arthritis,” “KOA”. Review Manager 5.3 was used to analyze and calculate data regarding these outcome indicators.

RESULTS:

In this study, 1. Six randomized double-blind controlled trials were included, including 338 patients in the PRP group and 323 patients in the HA group. 2. Meta-analysis results showed that the Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) Total Score was differed significantly between the PRP and HA groups at the 1, 6, 12 months follow-up (MD = 3.39, 95% CI: 2.85–3.92, P < .05). In a comparison of Physical function scores at the 12 months follow-up, PRP improved knee function scores more than HA (MD = 3.28; 95% CI: 2.13–4.43; P < .05). However, International Knee Documentation Committee (IKDC), Tegner Activity scores, EuroQol visual analogue scale (EQ-VAS), and Adverse Events (AEs) were all not significantly different (P > .05). 3. Results showed that compared with HA, PRP had significant advantages in relevant improving knee function and quality of life.

CONCLUSION:

In improving knee function and quality of life, PRP showed superiority over HA in long-term follow-up from well-designed double-blind trials, but a large number of high-quality multi-center studies are still needed to provide more sufficient evidence.

A Randomized, Double-Blind, Placebo-Controlled, Prospective Clinical Trial Evaluating Water-Soluble Chicken Eggshell Membrane for Improvement in Joint Health in Adults with Knee Osteoarthritis

Osteoarthritis (OA) is a chronic condition that impacts quality of life and functionality for which consumers often seek dietary supplements to provide some relief. The purpose of this double-blind, placebo-controlled clinical trial was to assess the safety and efficacy of a water-soluble chicken eggshell membrane hydrosylate (WSEM) dietary supplement (BiovaFlex^®) 450 mg daily on knee function, mobility, and general health and well-being in 88 adults with OA randomized into intervention (n = 44) or placebo (n = 44) groups. Outcomes were assessed periodically over 12 weeks, including the Western Ontario McMaster Osteoarthritis Index (WOMAC), the six-minute walk test (6MWT), knee range of motion (ROM) testing, and safety. Normalized analysis (improvement over baseline) showed that the poorest initial performers benefited the greatest from the WSEM by day 5 in the 6MWT, with the rest of the population showing significant improvement over placebo by week 12. The normalized WOMAC Stiffness score was also significantly improved over placebo by day 5 (P < .05). Without normalization, no statistically significant improvements were seen in WOMAC, 6MWT, and ROM testing. The Product was also found to be safe in this study. In conclusion, daily consumption of WSEM significantly enhanced average individual physical capacity (walking distance and ability), reduced stiffness by the fifth day of supplementation with the greatest benefit seen by the most compromised individuals, and was maintained over 12 weeks. A WSEM dietary supplement may offer a safe option for relief from symptoms and increased mobility for those with OA.

Methods for producing microstructured hydrogels for targeted applications in biology

Hydrogels have been broadly studied for applications in clinically motivated fields such as tissue regeneration, drug delivery, and wound healing, as well as in a wide variety of consumer and industry uses. While the control of mechanical properties and network structures are important in all of these applications, for regenerative medicine applications in particular, matching the chemical, topographical and mechanical properties for the target use/tissue is critical. There have been multiple alternatives developed for fabricating materials with microstructures with goals of controlling the spatial location, phenotypic evolution, and signaling of cells. The commonly employed polymers such as poly(ethylene glycol) (PEG), polypeptides, and polysaccharides (as well as others) can be processed by various methods in order to control material heterogeneity and microscale structures. We review here the more commonly used polymers, chemistries, and methods for generating microstructures in biomaterials, highlighting the range of possible morphologies that can be produced, and the limitations of each method. With a focus in liquid-liquid phase separation, methods and chemistries well suited for stabilizing the interface and arresting the phase separation are covered. As the microstructures can affect cell behavior, examples of such effects are reviewed as well. STATEMENT OF SIGNIFICANCE: Heterogeneous hydrogels with enhanced matrix complexity have been studied for a variety of biomimetic materials. A range of materials based on poly(ethylene glycol), polypeptides, proteins, and/or polysaccharides, have been employed in the studies of materials that by virtue of their microstructure, can control the behaviors of cells. Methods including microfluidics, photolithography, gelation in the presence of porogens, and liquid-liquid phase separation, are presented as possible strategies for producing materials, and their relative advantages and disadvantages are discussed. We also describe in more detail the various processes involved in LLPS, and how they can be manipulated to alter the kinetics of phase separation and to yield different microstructured materials.

Clinical and radiographic comparison of a single LP-PRP injection, a single hyaluronic acid injection and daily NSAID administration with a 52-week follow-up: a randomized controlled trial

Background

Knee osteoarthritis (OA) is a disease with a high prevalence in the adult population. Nonsteroidal anti-inflammatory drugs (NSAID) or intra-articular injections [hyaluronic acid (HA) or platelet-rich plasma (PRP)] can provide clinical benefit. Magnetic resonance imaging (MRI) has proven to be useful for the evaluation of cartilage volume and thickness in knee osteoarthritis. The purpose of this study was to evaluate the benefit provided by PRP injection in comparison with hyaluronic acid and NSAID in knee OA patients and to compare the radiographic evolution at the 52-week follow-up.

Methods

One hundred and six patients were enrolled and randomized according to the Spanish Rheumatology Society knee osteoarthritis diagnosis criteria. Ninety-eight patients completed the study (33 received NSAID treatment, 32 a single hyaluronic acid injection and 33 a single PRP injection). Patients were prospectively evaluated at baseline, 26 and 52 weeks using the Western Ontario McMaster Universities osteoarthritis index (WOMAC) and the visual analogue scale (VAS), and at baseline and 52 weeks with X-ray and MRI.

Results

A 20% decrease in WOMAC pain and increase in physical function was found in 30 and 24%, respectively, of those patients who received PRP treatment, at the 52-week follow-up. WOMAC pain and VAS improved in the hyaluronic acid and NSAID groups. However, better results were obtained in the PRP group compared to hyaluronic acid and NSAIDs (P < 0.05). No differences in Kellgren–Lawrence or cartilage thickness progression were found.

Conclusions

Leukocyte-poor platelet-rich plasma (LP-PRP) injections are better in terms of clinical improvement with respect to HA injections or oral NSAID treatment in knee osteoarthritis patients at the 52-week follow-up. Moreover, a single LP-PRP injection is effective. However, LP-PRP has no influence on cartilage progression.

Level of evidence

Level II.

Engineering S. equi subsp. zooepidemicus towards concurrent production of hyaluronic acid and chondroitin biopolymers of biomedical interest

Glycosaminoglycans, such as hyaluronic acid and chondroitin sulphate, are not only more and more required as main ingredients in cosmeceutical and nutraceutical preparations, but also as active principles in medical devices and pharmaceutical products. However, while biotechnological production of hyaluronic acid is industrially established through fermentation of Streptococcus spp. and recently Bacillus subtilis, biotechnological chondroitin is not yet on the market. A non-hemolytic and hyaluronidase negative S. equi subsp. zooepidemicus mutant strain was engineered in this work by the addition of two E. coli K4 genes, namely kfoA and kfoC, involved in the biosynthesis of chondroitin-like polysaccharide. Chondroitin is the precursor of chondroitin sulphate, a nutraceutical present on the market as anti-arthritic drug, that is lately being studied for its intrinsic bioactivity. In small scale bioreactor batch experiments the production of about 1.46 ± 0.38 g/L hyaluronic acid and 300 ± 28 mg/L of chondroitin with an average molecular weight of 1750 and 25 kDa, respectively, was demonstrated, providing an approach to the concurrent production of both biopolymers in a single fermentation.

Efficacy and safety of single injection of cross-linked sodium hyaluronate vs. three injections of high molecular weight sodium hyaluronate for osteoarthritis of the knee: a double-blind, randomized, multi-center, non-inferiority study

BACKGROUND

This randomized, double-blind, multi-center, non-inferiority trial was conducted to assess the efficacy and safety of a cross-linked hyaluronate (XLHA, single injection form) compared with a linear high molecular hyaluronate (HMWHA, thrice injection form) in patients with symptomatic knee osteoarthritis.

METHODS

Two hundred eighty seven patients with osteoarthritis (Kellgren-Lawrence grade I to III) were randomized to each group. Three weekly injections were given in both groups but two times of saline injections preceded XLHA injection to maintain double-blindness. Primary endpoint was the change of weight-bearing pain (WBP) at 12 weeks after the last injection. Secondary endpoints included Western Ontario and McMaster Universities Osteoarthritis index; patient's and investigator's global assessment; pain at rest, at night, or in motion; OMERACT-OARSI responder rate; proportion of patients achieving at least 20 mm or 40% decrease in WBP; and rate of rescue medicine use and its total consumption.

RESULTS

Mean changes of WBP at 12 weeks after the last injection were -33.3 mm with XLHA and -29.2 mm with HMWHA, proving non-inferiority of XLHA to HMWHA as the lower bound of 95% CI (-1.9 mm, 10.1 mm) was well above the predefined margin (-10 mm). There were no significant between-group differences in all secondary endpoints. Injection site pain was the most common adverse event and no remarkable safety issue was identified.

CONCLUSIONS

This study demonstrated that a single injection of XLHA was non-inferior to three weekly injections of HMWHA in terms of WBP reduction, and supports XLHA as an effective and safe treatment for knee osteoarthritis.

TRIAL REGISTRATION

ClinicalTrials.gov ( NCT01510535 ). This trial was registered on January 6, 2012.

Adelmidrol, in combination with hyaluronic acid, displays increased anti-inflammatory and analgesic effects against monosodium iodoacetate-induced osteoarthritis in rats

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease produced by a cascade of events that can ultimately lead to joint damage. The aim of this study was to evaluate the effect of adelmidrol, a synthetic palmitoylethanolamide analogue, combined with hyaluronic acid on pain severity and modulation of the inflammatory response in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis.

METHODS

OA was induced by intra-articular injection of MIA in the knee joint. On day 21 post-MIA administration, the knee joint was analyzed. Rats subjected to OA were treated by intra-articular injection of adelmidrol in combination with sodium hyaluronate at different doses and time points after MIA induction. Limb nociception was assessed by the paw withdrawal latency and threshold measurement. Samples were examined macroscopically, histologically, and by immunohistochemistry.

RESULTS

At day 21 post-MIA injection, the MIA + solvent and MIA + 1.0% sodium hyaluronate groups showed irregularities and fibrillation in the surface layer, a decrease in blood cells and multilayering in transition and radial zones, no pannus formation, and modified Mankin scores significantly higher than sham knees. The combination of hyaluronic acid and adelmidrol dose-dependently (adelmidrol 0.6% + 1.0% sodium hyaluronate and adelmidrol 2% + 1.0% sodium hyaluronate) reduced the histological alterations induced by MIA. Moreover, degeneration of articular cartilage, mast cell infiltration, and pro-inflammatory cytokine and chemokine plasma levels were significantly downregulated by treatment with a combination of hyaluronic acid and adelmidrol at the above doses.

CONCLUSIONS

Our results clearly demonstrate that the combination of hyaluronic acid and adelmidrol improves the signs of OA induced by MIA.