Efficacy of zoledronic acid in treatment of teoarthritis is dependent on the disease progression stage in rat medial meniscal tear model

Temporal progression of subchondral bone alterations in OA models involving induction of compromised meniscus integrity in mice and rats: A scoping review

OBJECTIVE

To categorize the temporal progression of subchondral bone alterations induced by compromising meniscus integrity in mouse and rat models of knee osteoarthritis (OA).

METHOD

Scoping review of investigations reporting subchondral bone changes with appropriate negative controls in the different mouse and rat models of OA induced by compromising meniscus integrity.

RESULTS

The available literature provides appropriate temporal detail on subchondral changes in these models, covering the entire spectrum of OA with an emphasis on early and mid-term time points. Microstructural changes of the subarticular spongiosa are comprehensively described; those of the subchondral bone plate are not. In mouse models, global subchondral bone alterations are unidirectional, involving an advancing sclerosis of the trabecular structure over time. In rats, biphasic subchondral bone alterations begin with an osteopenic degeneration and loss of subchondral trabeculae, progressing to a late sclerosis of the entire subchondral bone. Rat models, independently from the applied technique, relatively faithfully mirror the early bone loss detected in larger animals, and the late subchondral bone sclerosis observed in human advanced OA.

CONCLUSION

Mice and rats allow us to study the microstructural consequences of compromising meniscus integrity at high temporal detail. Thickening of the subchondral bone plate, an early loss of thinner subarticular trabecular elements, followed by a subsequent sclerosis of the entire subchondral bone are all important and reliable hallmarks that occur in parallel with the advancing articular cartilage degeneration. Thoughtful decisions on the study design, laterality, selection of controls and volumes of interest are crucial to obtain meaningful data.

Daily low-intensity pulsed ultrasound stimulation mitigates joint degradation and pain in a post-traumatic osteoarthritis rat model

Objectives

The aim of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) in a post-traumatic osteoarthritis (OA) rat model and in vitro.

Methods

Thirty-eight male, four-month-old Sprague Dawley rats were randomly assigned to Sham, Sham ​+ ​US, OA, and OA ​+ ​US. Sham surgery was performed to serve as a negative control, and anterior cruciate ligament transection was used to induce OA. Three days after the surgical procedures, Sham ​+ ​US and OA ​+ ​US animals received daily LIPUS treatment, while the rest of the groups received sham ultrasound (US) signals. Behavioral pain tests were performed at baseline and every week thereafter. After 31 days, the tissues were collected, and histological analyses were performed on knees and innervated dorsal root ganglia (DRG) neurons traced by retrograde labeling. Furthermore, to assess the activation of osteoclasts by LIPUS treatment, RAW264.7 ​cells were differentiated into osteoclasts and treated with LIPUS.

Results

Joint degradation in cartilage and bone microarchitecture were mitigated in OA ​+ ​US compared to OA. OA ​+ ​US showed improvements in behavioral pain tests. A significant increase of large soma-sized DRG neurons was located in OA compared to Sham. In addition, a greater percentage of large soma-sized innervated neurons were calcitonin gene-related peptide-positive. Daily LIPUS treatment suppressed osteoclastogenesis in vitro, which was confirmed via histological analyses and mRNA expression. Finally, lower expression of netrin-1, a sensory innervation-related protein, was found in the LIPUS treated cells.

Conclusion

Our findings demonstrate that early intervention using LIPUS treatment has protective effects from the progression of knee OA, including reduced tissue degradation, mitigated pain characteristics, improved subchondral bone microarchitecture, and less sensory innervation. Furthermore, daily LIPUS treatment has a suppressive effect on osteoclastogenesis, which may be linked to the suppression of sensory innervation in OA.

The translational potential of this article

This study presents a new potential for early intervention in treating OA symptoms through the use of LIPUS, which involves the suppression of osteoclastogenesis and the alteration of DRG profiles. This intervention aims to delay joint degradation and reduce pain.

OA foundations - experimental models of osteoarthritis

Osteoarthritis (OA) is increasingly recognised as a disease of diverse phenotypes with variable clinical presentation, progression, and response to therapeutic intervention. This same diversity is readily apparent in the many animal models of OA. However, model selection, study design, and interpretation of resultant findings, are not routinely done in the context of the target human (or veterinary) patient OA sub-population or phenotype. This review discusses the selection and use of animal models of OA in discovery and therapeutic-development research. Beyond evaluation of the different animal models on offer, this review suggests focussing the approach to OA-animal model selection on study objective(s), alignment of available models with OA-patient sub-types, and the resources available to achieve valid and translatable results. How this approach impacts model selection is discussed and an experimental design checklist for selecting the optimal model(s) is proposed. This approach should act as a guide to new researchers and a reminder to those already in the field, as to issues that need to be considered before embarking on in vivo pre-clinical research. The ultimate purpose of using an OA animal model is to provide the best possible evidence if, how, when and where a molecule, pathway, cell or process is important in clinical disease. By definition this requires both model and study outcomes to align with and be predictive of outcomes in patients. Keeping this at the forefront of research using pre-clinical OA models, will go a long way to improving the quality of evidence and its translational value.

Bisphosphonates as a treatment modality in osteoarthritis

Osteoarthritis (OA) is affecting large proportions of the population worldwide. So far, no effective disease modifying drug has been developed for this disease, limiting the therapeutic options to pain medications, physiotherapy and ultimately surgical approaches, mainly joint implant surgery. In vitro and animal studies have demonstrated that bisphosphonates have the potential to become effective modalities for the treatment of OA. This group of pharmacological agents modulates crucial aspects of OA pathogenesis (subchondral bone turnover and loss, bone marrow edema formation, cartilage degeneration and synovitis), and have shown clear efficacy in animal models of OA. Human studies have, however, so far been disappointing with only one of six clinical studies showing clear short-term efficacy. Possible reasons for these discrepancies will be discussed.

No Effect of Long-Term Risedronate Use on Cartilage and Subchondral Bone in an Experimental Rabbit Model of Osteoarthritis

Osteoarthritis (OA) is the most prevalent degenerative joint disease in animals and humans. It is characterized by pain, articular cartilage damage and joint stiffness. It has been suggested that the status of the subchondral bone compartment plays an important role in the initiation and progression of OA. Bisphosphonates have been proposed as a potential disease-modifying treatment for OA, however their effectiveness is not yet clear. Twenty-four male adult New Zealand rabbits were used to evaluate the effects of risedronate on the subchondral bone quality and cartilage degradation in a long-term model of experimentally induced OA. Animals underwent an anterior cruciate ligament transection and partial medial meniscectomy or sham operation in only one knee, which was randomly chosen, using the contralateral as healthy control. Animals were divided into three groups (n = 8): untreated control group and sham surgery control group; both groups received only vehicle; and risedronate group, treated with 2.5 mg orally weekly for 24 weeks. Stifle joints were harvested and scanned using a high-resolution micro-CT to evaluate the subchondral plate and trabecular bone changes. The macroscopic evaluation and histological analysis were determined using an adapted Osteoarthritis Research Society International scoring scheme to assess the cartilage degeneration. The lateral and medial femoral condyle and tibial plateau were evaluated. Additionally, the histological synovial membrane assessment was carried out. Sample analysis showed that the experimental model induced osteoarthritic changes in the operated joints, whereas in sham-operated rabbits, almost no histological changes were observed on articular cartilage surfaces. In terms of macroscopic and histological analyses, risedronate-treated animals did not show improved cartilage health compared with untreated operated rabbits, but a slightly anti-inflammatory activity was observed in the synovial membrane. Risedronate administration showed a slight tendency to increase subchondral bone plate thickness in lateral compartments but, it did not show conservation of periarticular bone and was not be able to suppress the osteophyte formation. In conclusion, long-term risedronate use did not demonstrate a positive effect on reducing the cartilage damage, and failed to prevent the subchondral bone changes and osteophytogenesis in an experimental rabbit model of OA.

Understanding the Molecular Mechanisms Underlying the Pathogenesis of Arthritis Pain Using Animal Models

Arthritis, including osteoarthritis (OA) and rheumatoid arthritis (RA), is the leading cause of years lived with disability (YLD) worldwide. Although pain is the cardinal symptom of arthritis, which is directly related to function and quality of life, the elucidation of the mechanism underlying the pathogenesis of pain in arthritis has lagged behind other areas, such as inflammation control and regulation of autoimmunity. The lack of therapeutics for optimal pain management is partially responsible for the current epidemic of opioid and narcotic abuse. Recent advances in animal experimentation and molecular biology have led to significant progress in our understanding of arthritis pain. Despite the inherent problems in the extrapolation of data gained from animal pain studies to arthritis in human patients, the critical assessment of molecular mediators and translational studies would help to define the relevance of novel therapeutic targets for the treatment of arthritis pain. This review discusses biological and molecular mechanisms underlying the pathogenesis of arthritis pain determined in animal models of OA and RA, along with the methodologies used.

Pharmacology of bisphosphonates in pain

The treatment of pain, in particular, chronic pain, remains a clinical challenge. This is particularly true for pain associated with severe or rare conditions, such as bone cancer pain, vulvodynia, or complex regional pain syndrome. Over the recent years, there is an increasing interest in the potential of bisphosphonates in the treatment of pain, although there are few papers describing antinociceptive and anti-hypersensitizing effects of bisphosphonates in various animal models of pain. There is also increasing evidence for clinical efficacy of bisphosphonates in chronic pain states, although the number of well-controlled studies is still limited. However, the mechanisms underlying the analgesic effects of bisphosphonates are still largely elusive. This review provides an overview of preclinical and clinical studies of bisphosphonates in pain and discusses various pharmacological mechanisms that have been postulated to explain their analgesic effects. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

Subchondral bone fragility with meniscal tear accelerates and parathyroid hormone decelerates articular cartilage degeneration in rat osteoarthritis model

The aims of this study were to investigate the influence of subchondral bone fragility (SBF) on the progression of the knee osteoarthritis by using a novel rat model, and to examine the preventive effect of parathyroid hormone (PTH) on cartilage degeneration. First, 40 rats were assigned to the following four groups: Sham, SBF, Medial meniscal tear (MMT), and MMT + SBF groups. In SBF and MMT + SBF groups, we induced SBF by microdrilling the subchondral bone. Second, 10 additional rats were randomly assigned to the following two groups: MMT + SBF + saline and MMT + SBF + PTH groups. Osteoarthritic changes in the articular cartilage and subchondral bone were evaluated using safranin-O/fast green staining, matrix metalloproteinase-13 (MMP-13), and type X collagen immunohistochemistry, toluidine blue staining, and micro-CT scanning. The combination of SBF and meniscal tear increased the number of mast cells in the subchondral bone, and led to the abnormal subchondral bone microarchitecture, such as abnormally decreased trabecular number and increased trabecular thickness, compared with meniscal tear alone. Moreover, SBF with meniscal tear enhanced articular cartilage degeneration and increased the expression of MMP-13 and type X collagen, compared with meniscal tear alone. The administration of PTH decreased the number of mast cells in the subchondral bone and improved the microstructural parameters of the subchondral bone, and delayed the progression of articular cartilage degeneration. These results suggest that SBF is one of the factors underlying the osteoarthritis development, especially in knees with traumatic osteoarthritis, and that the administration of PTH is a potential therapeutic treatment for preventing OA progression. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1959-1968, 2018.

Characterization and comparison of rat monosodium iodoacetate and medial meniscal tear models of osteoarthritic pain

Osteoarthritis (OA) is a degenerative form of arthritis that can result in loss of joint function and chronic pain. The pathological pain state that develops with OA disease involves plastic changes in the peripheral and central nervous systems, however, the cellular mechanisms underlying OA are not fully understood. We characterized the medial meniscal tear (MMT) surgical model and the intra-articular injection of monosodium iodoacetate (MIA) chemical model of OA in rats. Both models produced histological changes in the knee joint and associated bones consistent with OA pathology. Both models also increased p38 activation in the L3, but not L4 dorsal root ganglia (DRG), increased tyrosine hydroxylase immunostaining in the L3 DRG indicating sympathetic sprouting, and increased phosphorylated (p)CREB in thalamic neurons. In MIA-OA, but not MMT-OA rats, p38 and pERK were increased in the spinal cord, and pCREB was enhanced in the prefrontal cortex. Using in vivo electrophysiology, elevated spontaneous activity and increased responsiveness of wide dynamic range neurons to stimulation of the knee was found in both models. However, a more widespread sensitization was observed in the MIA-OA rats as neurons with paw receptive fields spontaneously fired at a greater rate in MIA-OA than MMT-OA rats. Taken together, the MIA and MMT models of OA share several common features associated with histopathology and sensitization of primary somatosensory pathways, but, observed differences between the models highlights unique consequences of the related specific injuries, and these differences should be considered when choosing an OA model and when interpreting data outcomes. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Considerations for the design and execution of protocols for animal research and treatment to improve reproducibility and standardization: "DEPART well-prepared and ARRIVE safely"

OBJECTIVE

To review the factors in experimental design that contribute to poor translation of pre-clinical research to therapies for patients with osteoarthritis (OA) and how this might be improved.

METHODS

Narrative review of the literature, and evaluation of the different stages of design conduct and analysis of studies using animal models of OA to define specific issues that might reduce quality of evidence and how this can be minimised.

RESULTS

Preventing bias and improving experimental rigour and reporting are important modifiable factors to improve translation from pre-clinical animal models to successful clinical trials of therapeutic agents. Despite publication and adoption by many journals of guidelines such as Animals in Research: Reporting In Vivo Experiments (ARRIVE), experimental animal studies published in leading rheumatology journals are still deficient in their reporting. In part, this may be caused by researchers first consulting these guidelines after the completion of experiments, at the time of publication. This review discusses factors that can (1) bias the outcome of experimental studies using animal models of osteoarthritis or (2) alter the quality of evidence for translation. We propose a checklist to consult prior to starting experiments; in the Design and Execution of Protocols for Animal Research and Treatment (DEPART).

CONCLUSIONS

Following DEPART during the design phase will enable completion of the ARRIVE checklist at the time of publication, and thus improve the quality of evidence for inclusion of experimental animal research in meta-analyses and systematic reviews: "DEPART well-prepared and ARRIVE safely".

Measuring and realizing the translational significance of preclinical in vivo studies of painful osteoarthritis

In this communication, we discuss some key issues surrounding the translation of preclinical efficacy studies in models of painful osteoarthritis (OA) to the clinical arena. We highlight potential pitfalls which could negatively impact successful translation. These include lack of alignment between a model + endpoint and the intended clinical population, employing testing strategies in animals that are not appropriate for the targeted human population such as pre-emptive treatment and lastly, underestimating the magnitude of the efficacy signal in animals that may be needed to see an effect in the clinical population. Through careful analysis, we highlight the importance of each pitfall by providing relevant examples that will hopefully improve future chances of optimizing translation in the area of OA pain research. We advocate advancing publications directed at comparing methods, outcomes and conclusions between preclinical and clinical studies, regardless of whether the findings are positive or negative, are important for improving the potential for a desired successful translation from the bench to bedside.

Dynamic Alterations in Microarchitecture, Mineralization and Mechanical Property of Subchondral Bone in Rat Medial Meniscal Tear Model of Osteoarthritis

Background:

The properties of subchondral bone influence the integrity of articular cartilage in the pathogenesis of osteoarthritis (OA). However, the characteristics of subchondral bone alterations remain unresolved. The present study aimed to observe the dynamic alterations in the microarchitecture, mineralization, and mechanical properties of subchondral bone during the progression of OA.

Methods:

A medial meniscal tear (MMT) operation was performed in 128 adult Sprague Dawley rats to induce OA. At 2, 4, 8, and 12 weeks following the MMT operation, cartilage degeneration was evaluated using toluidine blue O staining, whereas changes in the microarchitecture indices and tissue mineral density (TMD), mineral-to-collagen ratio, and intrinsic mechanical properties of subchondral bone plates (BPs) and trabecular bones (Tbs) were measured using micro-computed tomography scanning, confocal Raman microspectroscopy and nanoindentation testing, respectively.

Results:

Cartilage degeneration occurred and worsened progressively from 2 to 12 weeks after OA induction. Microarchitecture analysis revealed that the subchondral bone shifted from bone resorption early (reduced trabecular BV/TV, trabecular number, connectivity density and trabecular thickness [Tb.Th], and increased trabecular spacing (Tb.Sp) at 2 and 4 weeks) to bone accretion late (increased BV/TV, Tb.Th and thickness of subchondral bone plate, and reduced Tb.Sp at 8 and 12 weeks). The TMD of both the BP and Tb displayed no significant changes at 2 and 4 weeks but decreased at 8 and 12 weeks. The mineral-to-collagen ratio showed a significant decrease from 4 weeks for the Tb and from 8 weeks for the BP after OA induction. Both the elastic modulus and hardness of the Tb showed a significant decrease from 4 weeks after OA induction. The BP showed a significant decrease in its elastic modulus from 8 weeks and its hardness from 4 weeks.

Conclusion:

The microarchitecture, mineralization and mechanical properties of subchondral bone changed in a time-dependent manner as OA progressed.

Therapeutic effects of an anti-ADAMTS-5 antibody on joint damage and mechanical allodynia in a murine model of osteoarthritis

OBJECTIVE

The primary goal of this study was to test the disease-modifying effect of blocking a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5 with a neutralizing monoclonal antibody (mAb) starting 4 weeks after destabilization of the medial meniscus (DMM) in the mouse. We also investigated whether ADAMTS-5 blockade reversed mechanical allodynia and decreased monocyte chemoattractant protein (MCP)-1 production by dorsal root ganglia (DRG) cells.

METHODS

Ten-week old male C57BL/6 mice underwent DMM surgery and were either left untreated or treated with anti-ADAMTS-5 mAb or IgG2c isotype control mAb starting 4 weeks after surgery. Knees were collected for histopathology 4 or 12 weeks later. Mechanical allodynia was monitored biweekly in the ipsilateral hind paw through 16 weeks. DRG were collected and cultured 8 weeks after DMM for analysis of MCP-1 production.

RESULTS

By 4 weeks after DMM, mild cartilage degeneration was evident in the medial compartment, small osteophytes were present, and subchondral bone sclerosis was established. By 16 weeks after surgery, significant cartilage deterioration was apparent on the medial tibial plateaux and medial femoral condyles, osteophyte size had increased, and subchondral bone sclerosis was maintained. Treatment with ADAMTS-5 mAb from week 4 to 16 after surgery slowed cartilage degeneration and osteophyte growth but did not affect subchondral bone sclerosis. Moreover, ADAMTS-5 blockade resulted in temporary reversal of mechanical allodynia, which correlated with decreased MCP-1 production by cultured DRG cells.

CONCLUSIONS

This study suggests therapeutic efficacy of an ADAMTS-5 mAb in the DMM model, when therapy starts early in disease.

Effect of antiresorptive and anabolic bone therapy on development of osteoarthritis in a posttraumatic rat model of OA

Introduction

Osteoarthritis (OA) is a leading cause of disability, but despite the high unmet clinical need and extensive research seeking dependable therapeutic interventions, no proven disease-modifying treatment for OA is currently available. Due to the close interaction and interplay between the articular cartilage and the subchondral bone plate, it has been hypothesized that antiresorptive drugs can also reduce cartilage degradation, inhibit excessive turnover of the subchondral bone plate, prevent osteophyte formation, and/or that bone anabolic drugs might also stimulate cartilage synthesis by chondrocytes and preserve cartilage integrity. The benefit of intensive zoledronate (Zol) and parathyroid hormone (PTH) therapy for bone and cartilage metabolism was evaluated in a rat model of OA.

Methods

Medial meniscectomy (MM) was used to induce OA in male Lewis rats. Therapy with Zol and human PTH was initiated immediately after surgery. A dynamic weight-bearing (DWB) system was deployed to evaluate the weight-bearing capacity of the front and hind legs. At the end of the 10-week study, the rats were euthanized and the cartilage pathology was evaluated by contrast (Hexabrix)-enhanced μCT imaging and traditional histology. Bone tissue was evaluated at the tibial metaphysis and epiphysis, including the subchondral bone. Histological techniques and dynamic histomorphometry were used to evaluate cartilage morphology and bone mineralization.

Results

The results of this study highlight the complex changes in bone metabolism in different bone compartments influenced by local factors, including inflammation, pain and mechanical loads. Surgery caused severe and extensive deterioration of the articular cartilage at the medial tibial plateau, as evidenced by contrast-enhanced μCT and histology. The study results showed the negative impact of MM surgery on the weight-bearing capacity of the operated limb, which was not corrected by treatment. Although both Zol and PTH improved subchondral bone mass and Zol reduced serum CTX-II level, both treatments failed to prevent or correct cartilage deterioration, osteophyte formation and mechanical incapacity.

Conclusions

The various methods utilized in this study showed that aggressive treatment with Zol and PTH did not have the capacity to prevent or correct the deterioration of the hyaline cartilage, thickening of the subchondral bone plate, osteophyte formation or the mechanical incapacity of the osteoarthritic knee.

Investigational drugs for the treatment of osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a common joint disease with multiple pathophysiological processes, affecting the whole joint. Current therapeutic options such as NSAIDs can provide a palliative effect on symptoms but have limited effect on disease progression. New drugs targeting OA structures may retard disease progression at an earlier stage and delay the need for joint replacement.

AREAS COVERED

Some drugs have entered into clinical trials and a few, such as strontium ranelate, do have improvements in both pain and structure changes. However, most of them have failed in clinical trials largely due to increased side effects or the failure to identify the right OA phenotype for the right drug in clinical design. This review describes various investigational drugs developed for the treatment of OA covering those at stages from preclinical experiments to early phase clinical trials. They include drugs for slowing cartilage degradation, regulating cartilage metabolism, targeting subchondral bone, controlling inflammation and relieving pain.

EXPERT OPINION

Treatment options for OA remain limited. However, with the emergence of sensitive tools to detect early disease progression and identification of different OA phenotypes, disease-modifying anti-OA drugs with increased benefit and reduced risks will become available for OA treatment in the near future.

On the predictive utility of animal models of osteoarthritis

Animal models of osteoarthritis are extensively used for investigating disease pathways and for preclinical testing of novel therapies. Their predictive utility, however, has often been questioned, mainly because preclinical efficacy of novel therapeutics is poorly translated in clinical trials. In the current narrative review, we consider the preclinical models that were used to support undertaking clinical trials for disease-modifying osteoarthritis drugs, and compare outcomes between clinical and preclinical studies. We discuss this in light of the 1999 Food and Drug Administration draft guidelines for industry for use in the development of drugs, devices, and biological products intended for the treatment of osteoarthritis, which raised five considerations on the usefulness of osteoarthritis models. We systematically discuss what has been learnt regarding these five points since 1999, with emphasis on replicating distinct risk factors and subtypes of human osteoarthritis, and on comprehensive evaluation of the disease in animals, including pathology of all joint tissues, biomarker analysis, and assessment of pain and joint function. Finally, we discuss lessons learnt and propose some recommendations for how the evidence from preclinical research might be strengthened with a view to improving success in clinical translation.

Effect of alendronate on post-traumatic osteoarthritis induced by anterior cruciate ligament rupture in mice

Introduction

Previous studies in animal models of osteoarthritis suggest that alendronate (ALN) has antiresorptive and chondroprotective effects, and can reduce osteophyte formation. However, these studies used non-physiologic injury methods, and did not investigate early time points during which bone is rapidly remodeled prior to cartilage degeneration. The current study utilized a non-invasive model of knee injury in mice to investigate the effect of ALN treatment on subchondral bone changes, articular cartilage degeneration, and osteophyte formation following injury.

Methods

Non-invasive knee injury via tibial compression overload or sham injury was performed on a total of 90 mice. Mice were treated with twice weekly subcutaneous injections of low-dose ALN (40 μg/kg/dose), high-dose ALN (1,000 μg/kg/dose), or vehicle, starting immediately after injury until sacrifice at 7, 14 or 56 days. Trabecular bone of the femoral epiphysis, subchondral cortical bone, and osteophyte volume were quantified using micro-computed tomography (μCT). Whole-joint histology was performed at all time points to analyze articular cartilage and joint degeneration. Blood was collected at sacrifice, and serum was analyzed for biomarkers of bone formation and resorption.

Results

μCT analysis revealed significant loss of trabecular bone from the femoral epiphysis 7 and 14 days post-injury, which was effectively prevented by high-dose ALN treatment. High-dose ALN treatment was also able to reduce subchondral bone thickening 56 days post-injury, and was able to partially preserve articular cartilage 14 days post-injury. However, ALN treatment was not able to reduce osteophyte formation at 56 days post-injury, nor was it able to prevent articular cartilage and joint degeneration at this time point. Analysis of serum biomarkers revealed an increase in bone resorption at 7 and 14 days post-injury, with no change in bone formation at any time points.

Conclusions

High-dose ALN treatment was able to prevent early trabecular bone loss and cartilage degeneration following non-invasive knee injury, but was not able to mitigate long-term joint degeneration. These data contribute to understanding the effect of bisphosphonates on the development of osteoarthritis, and may support the use of anti-resorptive drugs to prevent joint degeneration following injury, although further investigation is warranted.

Chondroprotective effect of high-dose zoledronic acid: An experimental study in a rabbit model of osteoarthritis

To address the need to impact the subchondral bone-articular cartilage interaction for the treatment of degenerative osteoarthritis (OA), bisphosphonates may be used as a means to inhibit the subchondral bone resorption. The purpose of the present study is to evaluate the chondroprotective effect of zoledronic acid (ZOL) in a model of OA. Eighteen adult male rabbits underwent an anterior cruciate ligament transection and were separated into two groups: ZOL group (n=10) received 0.6 mg/kg intravenous injection of ZOL on day 1, 15, and 29 and placebo group (n=8) received saline. The animals were euthanized at 8 weeks. Macroscopically, the ZOL group had significantly milder ulcerations, cartilage softening and fibrillation compared to the placebo group. Microscopically, morphology of the articular cartilage was better in the ZOL treated group compared with the placebo group, without complete disorganization in any section of the ZOL group. Furthermore, the chondrocytes in the ZOL treated group were mainly cloning, indicating cartilage repairing and regeneration process, while in the placebo group hypocellularity predominated. Additionally, subchondral necrosis was evident in some specimens of the placebo group. Zoledronic acid, in a high-dose regimen, proved to be chondroprotective in a well-established animal model of OA.

Low magnitude high frequency vibration accelerated cartilage degeneration but improved epiphyseal bone formation in anterior cruciate ligament transect induced osteoarthritis rat model

OBJECTIVES

To evaluate the effects of low-magnitude high-frequency vibration (LMHFV) on degenerated articular cartilage and subchondral bone in anterior cruciate ligament transection (ACLT) induced osteoarthritis (OA) rat model.

METHODS

6 months old female Sprague-Dawley rats received ACLT on right knee and randomly divided into treatment and control groups. OA developed 12 weeks after surgery. LMHFV (35 Hz, 0.3 g) treatment was given 20 min/day and 5 days/week. After 6, 12 and 18 weeks, six rats of each group were sacrificed at each time point and the right knees were harvested. OA grading score, distal femur cartilage volume (CV), subchondral bone morphology, elastic modulus of cartilage and functional changes between groups were analyzed.

RESULTS

Increased cartilage degradation (higher OA grading score) and worse functional results (lower duty cycle, regular index and higher limb idleness index) were observed after LMHFV treatment (P = 0.011, 0.020, 0.012 and 0.005, respectively). CV increased after LMHFV treatment (P = 0.019). Subchondral bone density increased with OA progress (P < 0.01). Increased BV/TV, Tb.N and decreased Tb.Sp were observed in distal femur epiphysis in LMHFV treatment group (P = 0.006, 0.018 and 0.011, respectively).

CONCLUSION

LMHFV accelerated cartilage degeneration and caused further functional deterioration of OA affected limb in ACLT-induced OA rat model. In contrast, LMHFV promoted bone formation in OA affected distal femur epiphysis, but did not reverse OA progression.

The coupling of bone and cartilage turnover in osteoarthritis: opportunities for bone antiresorptives and anabolics as potential treatments?

Osteoarthritis (OA) is the most common form of arthritic disease, and a major cause of disability and impaired quality of life in the elderly. OA is a complex disease of the entire joint, affecting bone, cartilage and synovium that thereby presents multiple targets for treatment. This manuscript will summarise emerging observations from cell biology, preclinical and preliminary clinical trials that elucidate interactions between the bone and cartilage components in particular. Bone and cartilage health are tightly associated. Ample evidence has been found for bone changes during progression of OA including, but not limited to, increased turnover in the subchondral bone, undermineralisation of the trabecular structure, osteophyte formation, bone marrow lesions and sclerosis of the subchondral plate. Meanwhile, a range of investigations has shown positive effects on cartilage health when bone resorption is suppressed, or deterioration of the cartilage when resorption is increased. Known bone therapies, namely oestrogens, selective oestrogen receptor modifiers (SERMs), bisphosphonates, strontium ranelate, calcitonin and parathyroid hormone, might prove useful for treating two critical tissue components of the OA joint, the bone and the cartilage. An optimal treatment for OA likely targets at least these two tissue components. The patient subgroups for whom these therapies are most appropriate have yet to be fully defined but would likely include, at a minimum, those with high bone turnover.

The inhibition of subchondral bone lesions significantly reversed the weight-bearing deficit and the overexpression of CGRP in DRG neurons, GFAP and Iba-1 in the spinal dorsal horn in the monosodium iodoacetate induced model of osteoarthritis pain

BACKGROUND

Chronic pain is the most prominent and disabling symptom of osteoarthritis (OA). Clinical data suggest that subchondral bone lesions contribute to the occurrence of joint pain. The present study investigated the effect of the inhibition of subchondral bone lesions on joint pain.

METHODS

Osteoarthritic pain was induced by an injection of monosodium iodoacetate (MIA) into the rat knee joint. Zoledronic acid (ZOL), a third generation of bisphosphonate, was used to inhibit subchondral bone lesions. Joint histomorphology was evaluated using X-ray micro computed tomography scanning and hematoxylin-eosin staining. The activity of osteoclast in subchondral bone was evaluated using tartrate-resistant acid phosphatase staining. Joint pain was evaluated using weight-bearing asymmetry, the expression of calcitonin gene-related peptide (CGRP) in the dorsal root ganglion (DRG), and spinal glial activation status using glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) immunofluorescence. Afferent neurons in the DRGs that innervated the joints were identified using retrograde fluorogold labeling.

RESULTS

MIA injections induced significant histomorphological alterations and joint pain. The inhibition of subchondral bone lesions by ZOL significantly reduced the MIA-induced weight-bearing deficit and overexpression of CGRP in DRG neurons, GFAP and Iba-1 in the spinal dorsal horn at 3 and 6 weeks after MIA injection; however, joint swelling and synovial reaction were unaffected.

CONCLUSIONS

The inhibition of subchondral bone lesions alleviated joint pain. Subchondral bone lesions should be a key target in the management of osteoarthritic joint pain.

An OA phenotype may obtain major benefit from bone-acting agents

BACKGROUND

Osteoarthritis (OA) joints display relevant microstructure alterations associated to an increase in remodeling at subchondral bone, which supports its crucial role in OA pathogenesis. Despite this, the treatment of knee OA patients with antiresorptive drugs has given discordant results, suggesting the existence of a particular patient subset with good response to halting high subchondral remodeling.

OBJECTIVE

To identify an OA phenotype that may obtain major benefit from therapy with bone-acting agents.

METHODS

A systematic review of the literature was performed by searching the Medline and PubMed databases from 1990 to April 2013 using the following keywords: subchondral bone, articular cartilage, and osteoarthritis in various combinations with bone agents, bone mineral density, and scintigraphy.

RESULTS

Early animal and human studies provided the rationale for the beneficial use of bone agents on OA cartilage damage. Several bone-acting agents have reduced low back pain and likely spondylosis progression. Recently, strontium ranelate has been reported to exert both structural and clinical benefits in knee OA patients with radiological progression. However, other antiresorptives have shown divergent results. Human studies suggest that these contradictory results may be due to the lack of well-defined OA phenotypes and an accurate methodology to recruit and follow up these patients.

CONCLUSIONS

A particular subset of postmenopausal patients with high remodeling and/or low subchondral bone density may benefit from the treatment with bone-acting agents hindering OA progression. This OA population could be identified with the simultaneous use of subchondral bone dual-energy X-ray absorptiometry and scintigraphy.

A commentary on modelling osteoarthritis pain in small animals

OBJECTIVE

To describe the currently used animal models for the study of osteoarthritis (OA) pain, with an emphasis on small animals (predominantly mice and rats).

OUTLINE

Narrative review summarizing the opportunities and limitations of the most commonly used small animal models for the study of pain and pain pathways associated with OA, and discussing currently used methods for pain assessment. Involvement of neural degeneration in OA is briefly discussed. A list of considerations when studying pain-related behaviours and pathways in animal models of OA is proposed.

CONCLUSIONS

Animal models offer great potential to unravel the complex pathophysiology of OA pain, its molecular and temporal regulation. They constitute a critical pathway for developing and testing disease-specific symptom-modifying therapeutic interventions. However, a number of issues remain to be resolved in order to standardize pre-clinical OA pain research and to optimize translation to clinical trials and patient therapies.

Disease modification: promising targets and impediments to success

Osteoarthritis (OA) is a significant and growing concern to a large segment of the population. Effective treatments for slowing or stopping the progression of the disease are not available despite a great deal of investment-backed effort on the part of academia, government, and the pharmaceutical industry. Target selection has been problematic. Progress may also have been hindered to some extent by the prevalent cartilage-centric view of OA. Significant clinical development challenges remain for novel therapeutics in this area. This review elaborates on the challenges of disease-modifying OA drug development and points out specific therapeutic intervention strategies recently tried or currently being pursued.

Strontium ranelate reduces cartilage degeneration and subchondral bone remodeling in rat osteoarthritis model

AIM

To investigate whether strontium ranelate (SR), a new antiosteoporotic agent, could attenuate cartilage degeneration and subchondral bone remodeling in osteoarthritis (OA).

METHODS

Medial meniscal tear (MMT) operation was performed in adult SD rats to induce OA. SR (625 or 1800 mg·kg(-1)·d(-1)) was administered via gavage for 3 or 6 weeks. After the animals were sacrificed, articular cartilage degeneration was evaluated using toluidine blue O staining, SOX9 immunohistochemistry and TUNEL assay. The changes in microarchitecture indices and tissue mineral density (TMD), chemical composition (mineral-to-collagen ratio), and intrinsic mechanical properties of the subchondral bones were measured using micro-CT scanning, confocal Raman microspectroscopy and nanoindentation testing, respectively.

RESULTS

The high-dose SR significantly attenuated cartilage matrix and chondrocyte loss at 6 weeks, and decreased chondrocyte apoptosis, improved the expression of SOX9, a critical transcription factor responsible for the expression of anabolic genes type II collagen and aggrecan, at both 3 and 6 weeks. Meanwhile, the high-dose SR also significantly attenuated the subchondral bone remodeling at both 3 and 6 weeks, as shown by the improved microarchitecture indices, TMD, mineral-to-collagen ratio and intrinsic mechanical properties. In contrast, the low-dose SR did not significantly change all the detection indices of cartilage and bone at both 3 and 6 weeks.

CONCLUSION

The high-dose SR treatment can reduce articular cartilage degeneration and subchondral bone remodeling in the rat MMT model of OA.