Contributions of angiogenesis to inflammation, joint damage, and pain in a rat model of osteoarthritis

Metabolic regulation of skeletal cell fate and function in physiology and disease

The skeleton is diverse in its functions, which include mechanical support, movement, blood cell production, mineral storage and endocrine regulation. This multifaceted role is achieved through an interplay of osteoblasts, chondrocytes, bone marrow adipocytes and stromal cells, all generated from skeletal stem cells. Emerging evidence shows the importance of cellular metabolism in the molecular control of the skeletal system. The different skeletal cell types not only have distinct metabolic demands relating to their particular functions but also are affected by microenvironmental constraints. Specific metabolites control skeletal stem cell maintenance, direct lineage allocation and mediate cellular communication. Here, we discuss recent findings on the roles of cellular metabolism in determining skeletal stem cell fate, coordinating osteoblast and chondrocyte function, and organizing stromal support of haematopoiesis. We also consider metabolic dysregulation in skeletal ageing and degenerative diseases, and provide an outlook on how the field may evolve in the coming years.

Interaction of pain and chronic inflammation

Rheumatic diseases are characterized by chronic inflammation of synovial joints and are often associated with persistent pain and increased pain sensitivity. The inflammatory process is a complex cascade of events involving several mediators, which can lead to a chronic condition of pain. Inflammation can stimulate angiogenesis, and angiogenesis can facilitate inflammation. Inflammatory pain arises from tissue damage via the sensitization of pain receptors (nociceptors). The main peripheral mechanism underlying nociceptive pain is a change in the activity of the nociceptors located in the affected anatomical structures (joints, tendons, and ligaments), which renders them more sensitive to normally painful stimuli (hyperalgesia) or normally non-painful stimuli (allodynia). Neuroimmune interaction has been considered to play an essential role in rheumatic disease. Neurogenic inflammation, which influences normal central nervous system signaling, leads to insufficient signaling/bioavailability of various cytokines. These central mechanisms play an important role in the increased pain sensitivity following inflammation and are responsible for the development of secondary hyperalgesia in regions beyond the injured tissue. Reduction of pain in rheumatic disease requires familiarity with various pain mechanisms.

Bone Angiogenesis and Vascular Niche Remodeling in Stress, Aging, and Diseases

The bone marrow (BM) vascular niche microenvironments harbor stem and progenitor cells of various lineages. Bone angiogenesis is distinct and involves tissue-specific signals. The nurturing vascular niches in the BM are complex and heterogenous consisting of distinct vascular and perivascular cell types that provide crucial signals for the maintenance of stem and progenitor cells. Growing evidence suggests that the BM niche is highly sensitive to stress. Aging, inflammation and other stress factors induce changes in BM niche cells and their crosstalk with tissue cells leading to perturbed hematopoiesis, bone angiogenesis and bone formation. Defining vascular niche remodeling under stress conditions will improve our understanding of the BM vascular niche and its role in homeostasis and disease. Therefore, this review provides an overview of the current understanding of the BM vascular niches for hematopoietic stem cells and their malfunction during aging, bone loss diseases, arthritis and metastasis.

Non-neoplastic Disease Outside the Spine-Genicular Artery Embolization and Adhesive Capsulitis Embolization

Initial research into the treatment of pain secondary to knee osteoarthritis and shoulder adhesive capsulitis with embolization have yielded promising results. With further investigation, embolization may become a mainstay of treatment for pain from these two conditions.

Molecular Signaling Interactions and Transport at the Osteochondral Interface: A Review

Articular joints are comprised of different tissues, including cartilage and bone, with distinctive structural and mechanical properties. Joint homeostasis depends on mechanical and biological integrity of these components and signaling exchanges between them. Chondrocytes and osteocytes actively sense, integrate, and convert mechanical forces into biochemical signals in cartilage and bone, respectively. The osteochondral interface between the bone and cartilage allows these tissues to communicate with each other and exchange signaling and nutritional molecules, and by that ensure an integrated response to mechanical stimuli. It is currently not well known how molecules are transported between these tissues. Measuring molecular transport in vivo is highly desirable for tracking cartilage degeneration and osteoarthritis progression. Since transport of contrast agents, which are used for joint imaging, also depend on diffusion through the cartilage extracellular matrix, contrast agent enhanced imaging may provide a high resolution, non-invasive method for investigating molecular transport in the osteochondral unit. Only a few techniques have been developed to track molecular transport at the osteochondral interface, and there appear opportunities for development in this field. This review will describe current knowledge of the molecular interactions and transport in the osteochondral interface and discuss the potential of using contrast agents for investigating molecular transport and structural changes of the joint.

Motivating role of type H vessels in bone regeneration

Coupling between angiogenesis and osteogenesis has an important role in both normal bone injury repair and successful application of tissue‐engineered bone for bone defect repair. Type H blood vessels are specialized microvascular components that are closely related to the speed of bone healing. Interactions between type H endothelial cells and osteoblasts, and high expression of CD31 and EMCN render the environment surrounding these blood vessels rich in factors conducive to osteogenesis and promote the coupling of angiogenesis and osteogenesis. Type H vessels are mainly distributed in the metaphysis of bone and densely surrounded by Runx2⁺ and Osterix⁺ osteoprogenitors. Several other factors, including hypoxia‐inducible factor‐1α, Notch, platelet‐derived growth factor type BB, and slit guidance ligand 3 are involved in the coupling of type H vessel formation and osteogenesis. In this review, we summarize the identification and distribution of type H vessels and describe the mechanism for type H vessel‐mediated modulation of osteogenesis. Type H vessels provide new insights for detection of the molecular and cellular mechanisms that underlie the crosstalk between angiogenesis and osteogenesis. As a result, more feasible therapeutic approaches for treatment of bone defects by targeting type H vessels may be applied in the future.

Histological scoring system for subchondral bone changes in murine models of joint aging and osteoarthritis

To establish a histopathological scoring system for changes in subchondral bone in murine models of knee osteoarthritis (OA), three key parameters, subchondral bone plate (Subcho.BP) consisting of the combination of Subcho.BP.thickness (Subcho.BP.Th) and angiogenesis, bone volume (BV/TV) and osteophytes, were selected. The new grading system was tested in two mouse OA models, (1) senescence accelerated mouse (SAM)-prone 8 (SAMP8) as spontaneous OA model with SAM-resistant 1 (SAMR1) as control; (2) destabilization of the medial meniscus in C57BL/6 mice as surgical OA model. Results of the spontaneous OA model showed that Subcho.BP.Th was significantly wider, angiogenesis was greater, and BV/TV was higher in SAMP8 than SAMR1. Notably, subchondral bone score was dramatically higher in SAMP8 at 6 weeks than SAMR1, while OARSI cartilage scores became higher only at 14 weeks. In the surgical OA model, the results were similar to the spontaneous OA model, but osteophytes appeared earlier. There were strong correlations both in Subcho.BP.Th and BV/TV between this scoring system and µCT (r = 0.89, 0.84, respectively). Inter-rater reliabilities for each parameter using this system were more than 0.943. We conclude that this new histopathological scoring system is readily applicable for evaluating the early changes in aging and OA-affected murine subchondral bone.

Pathophysiological landscape of osteoarthritis

A sharp rise in osteoarthritis (OA) incidence is expected as over 25% of world population ages in the coming decade. Although OA is considered a degenerative disease, mounting evidence suggests a strong connection with chronic metabolic conditions and low-grade inflammation. OA pathology is increasingly understood as a complex interplay of multiple pathological events including oxidative stress, synovitis and immune responses revealing its intricate nature. Cellular, biochemical and molecular aspects of these pathological events along with major outcomes of the relevant research studies in this area are discussed in the present review. With reference to their published and unpublished work, the authors strongly propose synovitis as a central OA pathology and the key OA pathological events are described in connection with it. Recent research outcomes also have succeeded to establish a linkage between metabolic syndrome and OA, which has been precisely included in the present review. Impact of aging process cannot be neglected in OA. Cell senescence is an important mechanism of aging through which it facilitates development of OA like other degenerative disorders, also discussed within a frame of OA. Conclusively, the reviewers urge low-grade inflammation linked to aging and derailed immune function as a pathological platform for OA development and progression. Thus, interventions targeted to prevent inflammaging hold a promising potential in effective OA management and efforts should be invested in this direction.

Dexamethasone: chondroprotective corticosteroid or catabolic killer?

While glucocorticoids have been used for over 50 years to treat rheumatoid and osteoarthritis pain, the prescription of glucocorticoids remains controversial because of potentially harmful side effects at the molecular, cellular and tissue levels. One member of the glucocorticoid family, dexamethasone (DEX) has recently been demonstrated to rescue cartilage matrix loss and chondrocyte viability in animal studies and cartilage explant models of tissue injury and post-traumatic osteoarthritis, suggesting the possibility of DEX as a disease-modifying drug if used appropriately. However, the literature on the effects of DEX on cartilage reveals conflicting results on the drug's safety, depending on the dose and duration of DEX exposure as well as the model system used. Overall, DEX has been shown to protect against arthritis-related changes in cartilage structure and function, including matrix loss, inflammation and cartilage viability. These beneficial effects are not always observed in model systems using initially healthy cartilage or isolated chondrocytes, where many studies have reported significant increases in chondrocyte apoptosis. It is crucially important to understand under what conditions DEX may be beneficial or harmful to cartilage and other joint tissues and to determine potential for safe use of this glucocorticoid in the clinic as a disease-modifying drug.

The Pharmacology of Pain Associated With the Monoiodoacetate Model of Osteoarthritis

The high incidence of osteoarthritis (OA) in an increasingly elderly population anticipates a dramatic rise in the number of people suffering from this disease in the near future. Because pain is the main reason patients seek medical help, effective pain management-which is currently lacking-is paramount to improve the quality of life that OA sufferers desperately seek. Good animal models are, in this day and age, fundamental tools for basic research of new therapeutic pathways. Several animal models of OA have been characterized, but none of them reproduces entirely all symptoms of the disease. Choosing between different animal models depends largely on which aspect of OA one aims to study. Here, we review the current understanding of the monoiodoacetate (MIA) model of OA. MIA injection in the knee joint leads to the progressive disruption of cartilage, which, in turn, is associated with the development of pain-like behavior. There are several reasons why the MIA model of OA seems to be the most adequate to study the pharmacological effect of new drugs in pain associated with OA. First, the pathological changes induced by MIA share many common traits with those observed in human OA (Van Der Kraan et al., 1989; Guingamp et al., 1997; Guzman et al., 2003), including loss of cartilage and alterations in the subchondral bone. The model has been extensively utilized in basic research, which means that the time course of pain-related behaviors and histopathological changes, as well as pharmacological profile, namely of commonly used pain-reducing drugs, is now moderately understood. Also, the severity of the progression of pathological changes can be controlled by grading the concentration of MIA administered. Further, in contrast with other OA models, MIA offers a rapid induction of pain-related phenotypes, with the cost-saving consequence in new drug screening. This model, therefore, may be more predictive of clinical efficacy of novel pharmacological tools than other chronic or acute OA models.

Renin-angiotensin system in osteoarthritis: A new potential therapy

Osteoarthritis (OA) is one of the most common chronic joint diseases. However, the mechanism remains unclear. The traditional renin-angiotensin system (RAS) is an important system for regulating homeostasis and controlling balance. In recent years, RAS-related components have played an important role in the occurrence of OA. The purpose of this review is to summarize the research results of RAS-related components that are associated with OA. This study systematically searched e-medical databases such as PubMed, Embase, Medline, and Web of Science. The search targets included English publications describing the effects of RAS-related components in OA, including the role of renin, angiotensin-converting enzyme (ACE), Angiotensin II (Ang II), and angiotensin receptor (ATR). Additionally, this study summarizes the potential pathways for RAS-related components to intervene in OA. This study found that RAS-related components including renin, ACE, Ang II, AT1R and AT2R are involved in inflammation and chondrocyte hypertrophy in OA. RAS is involved in signaling pathways including the NF-κB, JNK, VEGFR/Tie-2, and the Axna2/Axna2R axis ones, which may be potential targets for the treatment of OA. Although there are few studies on RAS in the field of OA, the pathogenic effect of RAS-related components is still an important topic in OA treatment, and great progress may be made in this aspect in future studies.

Limiting angiogenesis to modulate scar formation

Angiogenesis, the process of new blood vessel formation from existing blood vessels, is a key aspect of virtually every repair process. During wound healing an extensive, but immature and leaky vascular plexus forms which is subsequently reduced by regression of non-functional vessels. More recent studies indicate that uncontrolled vessel growth or impaired vessel regression as a consequence of an excessive inflammatory response can impair wound healing, resulting in scarring and dysfunction. However, in order to elucidate targetable factors to promote functional tissue regeneration we need to understand the molecular and cellular underpinnings of physiological angiogenesis, ranging from induction to resolution of blood vessels. Especially for avascular tissues (e.g. cornea, tendon, ligament, cartilage, etc.), limiting rather than boosting vessel growth during wound repair potentially is beneficial to restore full tissue function and may result in favourable long-term healing outcomes.

Inflammation and Hypervascularization in a Large Animal Model of Knee Osteoarthritis: Imaging with Pathohistologic Correlation

PURPOSE

To evaluate if synovial inflammation and hypervascularization are present in a dog model of knee osteoarthritis and can be detected on conventional magnetic resonance imaging (MRI), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), contrast-enhanced magnetic resonance imaging (CE-MRI), and quantitative digital subtraction angiography (Q-DSA) imaging.

MATERIALS AND METHODS

Six dogs underwent MRI and angiography of both knees before and 12 weeks after right knee anterior cruciate ligament injury. Synovial vascularity was evaluated on CE-MRI, DCE-MRI, and Q-DSA by 2 independent observers. Synovial inflammation and vascularity were histologically scored independently. Cartilage lesions and osteophytes were analyzed macroscopically, and cartilage volumetry was analyzed by MRI. Vascularity and osteoarthritis markers on imaging were compared before and after osteoarthritis generation, and between the osteoarthritis model and the control knee, using linear mixed models accounting for within-dog correlation.

RESULTS

In all knees, baseline imaging showed no abnormalities. Control knees did not develop significant osteoarthritis changes, synovial inflammation, or hypervascularization. In osteoarthritis knees, mean synovial enhancement score on CE-MR imaging increased by 13.1 ± 0.59 (P < .0001); mean synovial inflammation variable increased from 47.33 ± 18.61 to 407.97 ± 18.61 on DCE-MR imaging (P < .0001); and area under the curve on Q-DSA increased by 1058.58 ± 199.08 (P = .0043). Synovial inflammation, hypervascularization, and osteophyte formations were present in all osteoarthritis knees. Histology scores showed strong correlation with CE-MR imaging findings (Spearman correlation coefficient [SCC] = 0.742; P = .0002) and Q-DSA findings (SCC = 0.763; P < .0001) and weak correlation with DCE-MR imaging (SCC = -0.345; P = .329). Moderate correlation was found between CE-MR imaging and DSA findings (SCC = 0.536; P = .0004).

CONCLUSIONS

In this early-stage knee osteoarthritis dog model, synovial inflammation and hypervascularization were found on imaging and confirmed by histology.

The polyadenylation inhibitor cordycepin reduces pain, inflammation and joint pathology in rodent models of osteoarthritis

Clinically, osteoarthritis (OA) pain is significantly associated with synovial inflammation. Identification of the mechanisms driving inflammation could reveal new targets to relieve this prevalent pain state. Herein, a role of polyadenylation in OA synovial samples was investigated, and the potential of the polyadenylation inhibitor cordycepin (3’ deoxyadenosine) to inhibit inflammation as well as to reduce pain and structural OA progression were studied. Joint tissues from people with OA with high or low grade inflammation and non-arthritic post-mortem controls were analysed for the polyadenylation factor CPSF4 and inflammatory markers. Effects of cordycepin on pain behavior and joint pathology were studied in models of OA (intra-articular injection of monosodium iodoacetate in rats and surgical destabilisation of the medial meniscus in mice). Human monocyte-derived macrophages and a mouse macrophage cell line were used to determine effects of cordycepin on nuclear localisation of the inflammatory transcription factor NFĸB and polyadenylation factors (WDR33 and CPSF4). CPSF4 and NFκB expression were increased in synovia from OA patients with high grade inflammation. Cordycepin reduced pain behaviour, synovial inflammation and joint pathology in both OA models. Stimulation of macrophages induced nuclear localisation of NFĸB and polyadenylation factors, effects inhibited by cordycepin. Knockdown of polyadenylation factors also prevented nuclear localisation of NFĸB. The increased expression of polyadenylation factors in OA synovia indicates a new target for analgesia treatments. This is supported by the finding that polyadenylation factors are required for inflammation in macrophages and by the fact that the polyadenylation inhibitor cordycepin attenuates pain and pathology in models of OA.

Immunoregulatory Effects of Neuropeptides on Endothelial Cells: Relevance to Dermatological Disorders

Many skin diseases, including psoriasis and atopic dermatitis, have a neurogenic component. In this regard, bidirectional interactions between components of the nervous system and multiple target cells in the skin and elsewhere have been receiving increasing attention. Neuropeptides released by sensory nerves that innervate the skin can directly modulate functions of keratinocytes, Langerhans cells, dermal dendritic cells, mast cells, dermal microvascular endothelial cells and infiltrating immune cells. As a result, neuropeptides and neuropeptide receptors participate in a complex, interdependent network of mediators that modulate the skin immune system, skin inflammation, and wound healing. In this review, we will focus on recent studies demonstrating the roles of α-melanocyte-stimulating hormone, calcitonin gene-related peptide, substance P, somatostatin, vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide, and nerve growth factor in modulating inflammation and immunity in the skin through their effects on dermal microvascular endothelial cells.

Zhuang Gu Guan Jie Wan: Reasonable Application Can Alleviate the Liver Injury for Osteoarthritis Treatment

The potential toxicity of herbal drugs, particularly drug-induced liver injury (DILI), has received extensive attention as the use of Chinese herbal medicine has rapidly increased globally. As a classic Chinese patent medicine, Zhuang Gu Guan Jie Wan (ZGGJW) has been brought into focus recently because of its satisfactory therapeutic effects on osteoarthritis (OA) as well as its unanticipated side effects. This study aimed to decipher the puzzling phenomenon of liver injury developing in response to ZGGJW that varies by the subtype of OA. Normal, anterior cruciate ligament transaction (ACLT) and partial medial meniscectomy (MMx) induced OA and ovariectomy combined with ACLT and partial MMx induced rat models were used and treated orally with ZGGJW or distilled water for 30 days. The results from histopathology, biochemistry, and immunohistochemistry showed that ZGGJW induced liver injury, increased the level of malondialdehyde (MDA), and decreased the levels of total antioxidation capability (T-AOC), superoxide dismutase (SOD), interleukin-22 (IL-22), and signal transducer and activator of transcription factor 3 (STAT3) in the liver of normal rats, while liver injury was alleviated and showed different tendencies in the above markers for ACLT and partial MMx induction rats and ovariectomy combined with ACLT and partial MMx induction rats after ZGGJW treatment. In the OA disease states, hepatic injury induced by ZGGJW could be associated with an impairment in antioxidant capacity and the high levels of IL-22 and STAT3 after ZGGJW treatment may be responsible for the slight hepatic injury of ZGGJW based on the subtype of OA. This study provides a novel approach to better understanding of the risks and limitations when using potentially toxic Chinese patent medicine in clinical applications.

Analgesic effects of the cathepsin K inhibitor L-006235 in the monosodium iodoacetate model of osteoarthritis pain

INTRODUCTION

The mounting evidence that osteoclasts play an important role in osteoarthritis (OA) pain lead us to investigate the effects of L-006235, a potent and selective inhibitor of cathepsin K, on pain behaviour and joint pathology in a model of OA pain.

METHODS

Effects of preventative (30 and 100 mg/kg) and therapeutic (100 mg/kg) oral dosing with L-006235 on weight-bearing asymmetry, hind paw withdrawal thresholds, cartilage and bone pathology, synovial inflammation, and drug exposure were studied in the monosodium iodoacetate rat model of OA pain.

RESULTS

Preventative L-006235 inhibited weight-bearing asymmetry from day 14, with this measure nearly abolished by the higher dose. In the same treatment setting, L-006235 prevented lowering of hind paw withdrawal thresholds from day 7. Exposure to L-006235 in plasma was higher for the 100 mg/kg dose, compared with 30 mg/kg. Therapeutic dosing with L-006235 from day 14 significantly inhibited weight-bearing asymmetry, compared with monosodium iodoacetate vehicle rats. Regression analysis revealed a significant interaction coefficient of the effects of L-006235 on weight-bearing asymmetry and synovitis score, but not for cartilage damage nor osteophyte scores.

CONCLUSION

Our novel finding that cathepsin K inhibition is analgesic in a clinically relevant model of OA pain provides new evidence for the therapeutic potential of this target.

Effect of Polydeoxyribonucleotide on Angiogenesis and Wound Healing in an In Vitro Model of Osteoarthritis

Osteoarthritis (OA) is degenerative disease, leading to pain and functional disability. It is reported that polydeoxyribonucleotide (PDRN) is a suitable therapy for OA. However, the therapeutic mechanisms of PDRN in OA are not fully understood. To investigate the effect of PDRN in an in vitro model of OA, interleukin (IL)-1β or phosphate-buffered saline (PBS) was used to treat a human chondrocytic cell line in hypoxic conditions for 24 h (IL-1β group or control group). PDRN was then used to treat IL-1β group cells for 24 h (PDRN group). By Label-Based Human Antibody Array 1000, angiopoietin-2 (ANG-2), platelet-derived growth factor (PDGF), angiostatin, and endostatin, which were related to angiogenesis, were chosen for further validation studies. Quantitative real-time reverse transcription polymerase chain reaction and western blot analysis validated that the levels of PDGF and ANG-2, which were related to pro-angiogenesis, were significantly increased in the PDRN group compared with those in the control group or the IL-1β group. However, the levels of endostatin and angiostatin, which were related in anti-angiogenesis, were significantly decreased in the PDRN group compared with those in the control group or the IL-1β group. In the same manner, vascular endothelial growth factor, which was a mediator of angiogenesis, was significantly increased in the PDRN group compared with those in the control group or the IL-1β group. Furthermore, wound closure was significantly increased in the PDRN group compared with the control group or the IL-1β group by in vitro scratch assay. Moreover, PDRN decreased expression of metalloproteinase 13, as a catabolic factor for OA, but increased expression of aggrecan, which was an anabolic factor for OA. These data suggest that PDRN may promote angiogenesis and wound healing via down-regulation of catabolism and up-regulation of anabolism in an in vitro model of OA.

Synovial nerve fiber density decreases with naturally-occurring osteoarthritis in horses

OBJECTIVE

To measure the nerve fiber density in synovial membranes from healthy and OA equine joints and to investigate the relationship between synovial innervation and OA severity, synovial vascularity and synovitis.

DESIGN

Twenty-five equine metacarpophalangeal joints were collected post-mortem. The joints were dissected and the macroscopic lesions of the articular cartilage were scored. Synovial membrane specimens (n = 50) were harvested, fixed, sectioned and scored histologically. Immunohistochemical staining and immunofluorescence with S-100 protein, that identifies nerve fibers, and ⍺-actin, that stains vascular smooth muscle, were also performed on site-matched specimens and the relationships between these tissues was interrogated.

RESULTS

The nerve fiber density was higher in the superficial layer (≤200 μm) of the synovium when compared to the deeper layer in control equine joints (mean difference (95% C.I.): 0.054% (0.018%, 0.11%)). In osteoarthritic joints, synovial innervation decreased in the superficial layer with increasing macroscopic OA score (β (SEM), 95% C.I.: -0.0061 (0.00021), -0.0011, -0.00017). The blood vessel density was also higher in the superficial layer of the synovium compared to the deep layer in the control (mean difference (95% C.I.): 1.1% (0.36%, 2.3%)) and OA (mean difference (95% C.I.): 0.60% (0.22%, 1.2%)) equine joints. Moreover, considering all synovial specimens, higher nerve fiber density in the deep layer positively correlated with blood vessel density (β (SEM), 95% C.I.: 0.11 (0.036), 0.035, 0.18).

CONCLUSION

The reduction in nerve fiber density with advanced cartilage degeneration suggests that peripheral neuropathy is associated with equine OA. Whether this link is associated with neuropathic pain, requires further investigation.

Effects of carrageenan induced synovitis on joint damage and pain in a rat model of knee osteoarthritis

OBJECTIVE

Knee osteoarthritis (OA) is associated with ongoing pain and joint damage that can be punctuated by acute flares of pain and inflammation. Synovitis in normal knees might resolve without long-term detriment to joint function. We hypothesised that osteoarthritis is associated with impaired resilience to inflammatory flares.

DESIGN

We induced synovitis by injecting carrageenan into rat knees with or without meniscal transection (MNX)-induced OA, and measured synovitis, weightbearing asymmetry (pain behaviour), and joint damage up to 35 days after OA induction (23 days after carrageenan-injection).

RESULTS

Carrageenan injection induced weightbearing asymmetry for 1 week, transient increase in knee diameter for 2 days, and a sustained increase in synovial macrophages, endothelial cell proliferation and vascular density compared with naive vehicle-injected controls. MNX surgery induced weightbearing asymmetry and histological evidence of OA. Carrageenan-injection in MNX-operated knees was followed for 2 days by increased weightbearing asymmetry compared either to MNX+vehicle or to sham+carrageenan groups. OA structural damage and synovitis at day 35 were greater in MNX+carrageenan compared to MNX+vehicle and sham+carrageenan groups. Carrageenan injection did not induce OA in Sham-operated knees.

CONCLUSION

Intra-articular injection of the pro-inflammatory compound carrageenan in OA and sham-operated control knees induced a short term increase in joint pain. Even though pain flares resolved in both groups and damage was not induced in sham-operated knees, carrageen injection exacerbated long-term joint damage in OA knees. OA knees display less resilience to inflammatory episodes. Preventing inflammatory flares may be particularly important in preventing symptoms and long term joint damage in OA.

Cartilage repair and inhibition of the progression of cartilage degeneration after transplantation of allogeneic chondrocyte sheets in a nontraumatic early arthritis model

Introduction

Using a rat model of nontraumatic early arthritis induced by intra-articular administration of low-dose monoiodoacetic acid (MIA), we transplanted allogeneic chondrocyte sheets and examined the effects on tissue repair.

Methods

MIA (0.2 mg/50 μl) was injected into the right knee of 20 male Wistar rats. Four weeks later, rats were randomly allocated into three groups: Group A was examined 4 weeks after administration of MIA; Group B, 8 weeks after MIA injection and chondrocyte sheet transplantation, and Group C, 8 weeks after MIA injection but without chondrocyte sheet transplantation. Allogeneic chondrocyte sheets were transplanted into the right knee of Group B rats. Pain was assessed as the weight distribution ratio of the damaged to undamaged limb. The OARSI score was used for histological scoring.

Results

The limb weight distribution ratio indicated significantly less pain in Group B. Histological scoring showed significant differences in cartilage repair and inhibition of the progression of cartilage degeneration between Groups B and C, but not between Groups A and B, or Groups A and C.

Conclusions

These findings suggest that, in this rat model of nontraumatic early arthritis induced by low-dose MIA injection, allogeneic chondrocyte sheet transplantation induces cartilage repair and suppresses cartilage degeneration.

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Therapeutic effects of allogeneic chondrocyte sheets were examined using an arthritis model of rat induced by low-dose MIA.

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Chondrocyte sheets exhibited sufficient expression of genes important to maintaining a stable cartilage matrix.

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Transplantation of chondrocyte sheets alleviated pain and induced cartilage repair and suppressed cartilage degeneration.

The effect of 12-week garlic supplementation on symptom relief in overweight or obese women with knee osteoarthritis

AIMS

Chronic joint pain and stiffness, and functional disability, are the major debilitating features of osteoarthritis (OA). The aim of this study was to assess the effect of 12-week supplementation with a garlic supplement on knee osteoarthritis outcomes in overweight or obese women.

METHODS

Seventy-six postmenopausal overweight or obese women (25≤BMI≤40 kg/m² ) with medically diagnosed knee OA participated in this randomised double-blind, placebo-controlled, parallel-design trial. After randomisation into 2 groups, patients received a daily dose of either 1000 mg odourless garlic tablet, or placebo, for 12 weeks. The total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), as well as pain, stiffness and physical function subscales, were evaluated pre- and poststudy. Anthropometric parameters and body composition (using bioelectrical impedance analysis) were also assessed.

RESULTS

Following 12-week supplementation in overweight or obese women with OA, stiffness (but not pain, function or WOMAC total score) was significantly lower in the garlic group compared with the placebo group (1.4 ± 1.6 vs 2.5 ± 1.9, P = .023). The changes in WOMAC parameters showed no statistically significant differences between the 2 groups. WOMAC total score (38.4 ± 15.9-30.6 ± 15.7, P = .004) and all the subscales, including pain (8.3 ± 3.7-7 ± 4.4, P = .026), stiffness (2.3 ± 1.6-1.4 ± 1.6, P = .013) and physical function (27.7 ± 11.9-22.2 ± 12.4, P = .001) improved significantly in the garlic group postintervention compared with pre-intervention; although pain subscale also decreased in the placebo group (9.6 ± 3.1-6.9 ± 3.7, P < .001).

CONCLUSIONS

Although pre- to postintervention knee OA symptoms were improved in overweight or obese women receiving 12 weeks garlic supplement, there was no significant difference in WOMAC changes compared with the placebo group. Further clinical trials are required to investigate the therapeutic value of garlic ingredients, and the potential role of placebo effect, in the management of OA symptoms.

Egr-1 increases angiogenesis in cartilage via binding Netrin-1 receptor DCC promoter

Background

Osteoarthritis (OA) is a joint disease characterized by degradation of cartilage. The etiology of OA is still unclear. Vascular endothelial growth factor (VEGF) plays a key role of angiogenesis in the pathogenesis of OA and contributes to the angiogenesis of NT-1/DCC. Whether or not NT-1/DCC and VEGF interact in regulating angiogenesis of OA cartilage is not known.

Methods

Histological studies for CD34, VEGF, and safranin-O staining were performed to determine angiogenesis and cartilage tissue injury. ELISA indicated the level of pro-inflammation cytokines. Immunoblotting, immunoprecipitation, and electrophoretic mobility shift assay (EMSA) were performed to assay the expression and function of NT-1/DCC-VEGF signaling pathway.

Results

Our data indicated that VEGF expression was increased in cartilage tissue from OA rats, while the chondrocytes were disorganized, and cartilage degeneration was increasing in OA rats. The inflammation factors in articular cavity fluid were higher in the OA rats than in the sham. The protein expression of NT-1, DCC, and VEGF were increased in osteoarthritic cartilage. DCC was involved in the positive regulation of osteoarthritic angiogenesis by VEGF. Egr-1 expression was higher in OA rats than in sham rats. Egr-1 is a regulator of DCC promoter activity, and the binding is higher in OA rats than in sham rats.

Conclusion

Our present study provides a mechanism by which Egr-1 induced angiogenesis via NT-1/DCC-VEGF pathway.

Therapeutic Benefit for Late, but Not Early, Passage Mesenchymal Stem Cells on Pain Behaviour in an Animal Model of Osteoarthritis

Background

Mesenchymal stem cells (MSCs) have a therapeutic potential for the treatment of osteoarthritic (OA) joint pathology and pain. The aims of this study were to determine the influence of a passage number on the effects of MSCs on pain behaviour and cartilage and bone features in a rodent model of OA.

Methods

Rats underwent either medial meniscal transection (MNX) or sham surgery under anaesthesia. Rats received intra-articular injection of either 1.5 × 10⁶ late passage MSCs labelled with 10 μg/ml SiMAG, 1.5 × 10⁶ late passage mesenchymal stem cells, the steroid Kenalog (200 μg/20 μL), 1.5 × 10⁶ early passage MSCs, or serum-free media (SFM). Sham-operated rats received intra-articular injection of SFM. Pain behaviour was quantified until day 42 postmodel induction. Magnetic resonance imaging (MRI) was used to localise the labelled cells within the knee joint.

Results

Late passage MSCs and Kenalog attenuated established pain behaviour in MNX rats, but did not alter MNX-induced joint pathology at the end of the study period. Early passage MSCs exacerbated MNX-induced pain behaviour for up to one week postinjection and did not alter joint pathology.

Conclusion

Our data demonstrate for the first time the role of a passage number in influencing the therapeutic effects of MSCs in a model of OA pain.

Do immune cells lead the way in subchondral bone disturbance in osteoarthritis?

Osteoarthritis (OA) is a whole-joint disorder, and non-cartilage articular pathologies, e.g. subchondral bone disturbance, contribute substantially to the onset and progression of the disease. In the early stage of OA, abnormal mechanical loading leads to micro-cracks or micro-fractures that trigger a reparative process with angiogenesis and inflammatory response. With the progression of disease, cystic lesion, sclerosis and osteophytosis occur at tissue level, and osteoblast dysfunction at cellular level. Osteoblasts derived from OA sclerotic bone produce increased amount of type I collagen with aberrant Col1A1/A2 ratio and poor mineralization capability. The coupling mechanism of bone resorption with formation is also impaired with elevated osteoclastic activities. All these suggest a view that OA subchondral bone presents a defective fracture repair process in a chronic course. It has been found that T and B cells, the major effectors in the adaptive immunity, take part in the hard callus formation at fracture site in addition to the initial phase of haematoma and inflammation. Infiltration of lymphocytes could interplay with osteoclasts and osteoblasts via a direct physical cell-to-cell contact. Several lines of evidence have consistently shown the involvement of T and B cells in osteoclastogenesis and bone erosion in arthritic joints. Yet the biological link between immune cells and osteoblastic function remains ambiguous. This review will discuss the current knowledge regarding the role of immune cells in bone remodelling, and address its implications in emerging basic and clinical investigations into the pathogenesis and management of subchondral bone pathologies in OA.

Formulation and in vitro/in vivo evaluation of chitosan-based film forming gel containing ketoprofen

The film forming gel, adhered to skin surfaces upon application and formed a film, has an advantage onto skin to provide protection and continuous drug release to the application site. This study aimed to prepare a chitosan-based film forming gel containing ketoprofen (CbFG) and to evaluate the CbFG and film from CbFG (CbFG-film). CbFG were prepared with chitosan, lactic acid and various skin permeation enhancers. The physicochemical characteristics were evaluated by texture analysis, viscometry, SEM, DSC, XRD and FT-IR. To identify the mechanism of skin permeation, in vitro skin permeation study was conducted with a Franz diffusion cell and excised SD-rat and hairless mouse dorsal skin. In vivo efficacy assessment in mono-iodoacetate (MIA)-induced rheumatoid arthritis animal model was also conducted. CbFG was successfully prepared and, after applying CbFG to the excised rat dorsal skin, the CbFG-film was also formed well. The physicochemical characteristics of CbFG and CbFG-film could be explained by the grafting of oleic acid onto chitosan in the absence of catalysts. In addition, CbFG containing oleic acid had a higher skin permeation rate in comparison with any other candidate enhancers. The in vivo efficacy study also confirmed significant anti-inflammatory and analgesic effects. Consequently, we report the successful preparation of chitosan-based film forming gel containing ketoprofen with excellent mechanical properties, skin permeation and anti-inflammatory and analgesic effects.

Transcatheter arterial embolization of abnormal vessels as a treatment for lateral epicondylitis refractory to conservative treatment: a pilot study with a 2-year follow-up

BACKGROUND

Abnormal vessels and accompanying nerves are possible sources of pain with lateral epicondylitis. The purpose of this study was to describe the safety and efficacy of transcatheter arterial embolization (TAE) for lateral epicondylitis resistant to conservative treatment.

METHODS

This prospective study was conducted in 24 patients with lateral epicondylitis resistant to conservative treatments for more than 3 months, with a symptom duration longer than 6 months, and with moderate to severe pain who were treated with TAE between March 2013 and October 2014. Two patients were lost to follow-up, and the remaining 22 patients were followed up for 2 years after TAE.

RESULTS

Abnormal vessels were identified in all of the patients. No major adverse events were observed. The Quick Disabilities of the Arm, Shoulder and Hand scores at baseline significantly decreased at 1, 3, 6, and 24 months after treatment (50.8 vs 23.4, 8.3, 5.3, and 2.7, respectively; all P < .001). There was a statistically significant (P < .001) change from baseline to the last observed value in all of the clinical parameters, including visual analog scale pain score, Patient-Rated Tennis Elbow Evaluation score, and pain-free grip strength. Magnetic resonance images obtained 2 years after TAE showed an improvement in tendinosis and tear scores compared with baseline, and no patients showed bone marrow necrosis, obvious cartilage loss, or muscle atrophy.

CONCLUSION

TAE could be one possible treatment option for patients with lateral epicondylitis that fails to improve with conservative treatments.

Protocol for a single-centre, parallel-arm, randomised controlled superiority trial evaluating the effects of transcatheter arterial embolisation of abnormal knee neovasculature on pain, function and quality of life in people with knee osteoarthritis

INTRODUCTION

Symptomatic knee osteoarthritis (OA) is common. Advanced knee OA is successfully treated with joint replacement surgery, but effectively managing mild to moderate knee OA can be difficult. Angiogenesis increases with OA and might contribute to pain and structural damage. Modifying angiogenesis is a potential treatment pathway for OA. The aim of the current study is to determine whether transcatheter arterial embolisation of abnormal neovasculature arising from the genicular arterial branches improves knee pain, physical function and quality of life in people with mild to moderate symptomatic knee OA.

METHODS AND ANALYSIS

The study is a single centre, parallel-arm, double-blinded (participant and assessor), randomised controlled superiority trial with 1:1 random block allocation. Eligible participants have mild to moderate symptomatic knee OA and will be randomly assigned to receive either embolisation of aberrant knee neovasculature of genicular arterial branches or a placebo intervention. Outcome measures will be collected prior to the intervention and again 1, 6 and 12 months postintervention. The primary outcome is change in knee pain between baseline and 12 month assessment as measured by the Knee Injury and Osteoarthritis Outcome Score (KOOS). Secondary outcomes include change in self-reported physical function (KOOS), self-reported quality of life (KOOS, EuroQol: EQ-5D-5L), self-reported knee joint stiffness (KOOS), self-reported global change, 6 min walk test performance, and 30 s chair-stand test performance. Intention-to-treat analysis will be performed including all participants as randomised. To detect a mean between group difference in change pain of 20% at the one year reassessment with a two-sided significance level of α=0.05 and power of 80% using a two-sample t-test, we require 29 participants per arm which allows for 20% of participants to drop out.

ETHICS AND DISSEMINATION

Barwon Health Human Research Ethics Committee, 30 May 2016, (ref:15/101). Study results will be disseminated via peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

Universal trial number U1111-1183-8503, Australian New Zealand Clinical Trials Registry, ACTRN12616001184460, approved 29 August 2016.

Efficacy of CR4056, a first-in-class imidazoline-2 analgesic drug, in comparison with naproxen in two rat models of osteoarthritis

Purpose

CR4056, (2-phenyl-6-(1H-imidazol-1yl) quinazoline), an imidazoline-2 (I2) receptor ligand, is a promising analgesic drug that has been reported to be effective in several animal models of pain. The aim of this study was to evaluate the effects of CR4056 in two well-established rat models of osteoarthritis (OA), mimicking the painful and structural components of human OA.

Methods

Knee OA was induced either by single intra-articular injection of monoiodoacetate (MIA) or by medial meniscal tear (MMT) in the right knee of male rats. In the MIA model, allodynia and hyperalgesia were measured as paw withdrawal threshold to mechanical stimulation. In the MMT model, pain behavior was analyzed as weight-bearing asymmetry (i.e. difference in hind paw weight distribution, HPWD) between the injured and the contralateral limbs.

Results

Acute oral administration of CR4056, 14 days after MIA injection, significantly and dose-dependently reduced allodynia and hyperalgesia 90 minutes after treatment, whereas acute naproxen administration significantly reduced allodynia but not hyperalgesia. After 7 days of repeated treatment, both CR4056 and naproxen showed significant anti-allodynic and anti-hyperalgesic effects in the MIA model. Rats undergoing MMT surgery developed a significant and progressive asymmetry in HPWD compared with sham-operated animals. Repeated treatment with CR4056 significantly reduced the progression of the pain behavior, whereas naproxen had no effects.

Conclusion

The data presented here show that the I2 ligand CR4056 could be a new effective treatment for OA pain. The compound is currently under Phase II clinical evaluation for this indication.

Peripheral Nerve Fibers and Their Neurotransmitters in Osteoarthritis Pathology

The importance of the nociceptive nervous system for maintaining tissue homeostasis has been known for some time, and it has also been suggested that organogenesis and tissue repair are under neuronal control. Changes in peripheral joint innervation are supposed to be partly responsible for degenerative alterations in joint tissues which contribute to development of osteoarthritis. Various resident cell types of the musculoskeletal system express receptors for sensory and sympathetic neurotransmitters, allowing response to peripheral neuronal stimuli. Among them are mesenchymal stem cells, synovial fibroblasts, bone cells and chondrocytes of different origin, which express distinct subtypes of adrenoceptors (AR), receptors for vasoactive intestinal peptide (VIP), substance P (SP) and calcitonin gene-related peptide (CGRP). Some of these cell types synthesize and secrete neuropeptides such as SP, and they are positive for tyrosine-hydroxylase (TH), the rate limiting enzyme for biosynthesis of catecholamines. Sensory and sympathetic neurotransmitters are involved in the pathology of inflammatory diseases such as rheumatoid arthritis (RA) which manifests mainly in the joints. In addition, they seem to play a role in pathogenesis of priori degenerative joint disorders such as osteoarthritis (OA). Altogether it is evident that sensory and sympathetic neurotransmitters have crucial trophic effects which are critical for joint tissue and bone homeostasis. They modulate articular cartilage, subchondral bone and synovial tissue properties in physiological and pathophysiological conditions, in addition to their classical neurological features.

Characteristics of dynamic magnetic resonance imaging of idiopathic severe frozen shoulder

BACKGROUND

The purpose of this study was to evaluate the effectiveness of current techniques for dynamic 3-dimensional magnetic resonance imaging (MRI) in the diagnosis of idiopathic severe frozen shoulder (FS).

MATERIALS AND METHODS

Subjects consisted of 5 healthy volunteers and 16 patients with idiopathic severe FS. We defined severe idiopathic FS as follows: range of motion ≤100° in forward flexion, ≤10° in external rotation, and ≤L5 in internal rotation. All patients suffered from continued global range of motion loss for at least 6 months. We evaluated the diagnostic characteristics of 3-dimensional dynamic MRI in FS patients compared with those in healthy volunteers.

RESULTS

MRI of all FS patients displayed an abnormal intake of blood flow from the acromial arterial network and the branches of circumflex humeral arteries into the axillary pouch and the rotator interval. We named this finding "burning sign." The burning sign was present at all phases of the condition. In the FS group, the patients with enhanced deposition of contrast medium in the axillary pouch in the delayed phase (n = 11) had a statistically significant score for pain during exercise, higher than that of patients with reduced deposition of contrast medium at the same site (n = 5; P = .027).

CONCLUSION

Burning sign is an abnormal finding that appears in dynamic MRI of severe FS. Hence, the burning sign may be associated with pain and inflammation in idiopathic FS.

PKCδ null mutations in a mouse model of osteoarthritis alter osteoarthritic pain independently of joint pathology by augmenting NGF/TrkA-induced axonal outgrowth

OBJECTIVES

A key clinical paradox in osteoarthritis (OA), a prevalent age-related joint disorder characterised by cartilage degeneration and debilitating pain, is that the severity of joint pain does not strictly correlate with radiographic and histological defects in joint tissues. Here, we determined whether protein kinase Cδ (PKCδ), a key mediator of cartilage degeneration, is critical to the mechanism by which OA develops from an asymptomatic joint-degenerative condition to a painful disease.

METHODS

OA was induced in 10-week-old PKCδ null (PKCδ-/-) and wild-type mice by destabilisation of the medial meniscus (DMM) followed by comprehensive examination of the histology, molecular pathways and knee-pain-related-behaviours in mice, and comparisons with human biopsies.

RESULTS

In the DMM model, the loss of PKCδ expression prevented cartilage degeneration but exacerbated OA-associated hyperalgesia. Cartilage preservation corresponded with reduced levels of inflammatory cytokines and of cartilage-degrading enzymes in the joints of PKCδ-deficient DMM mice. Hyperalgesia was associated with stimulation of nerve growth factor (NGF) by fibroblast-like synovial cells and with increased synovial angiogenesis. Results from tissue specimens of patients with symptomatic OA strikingly resembled our findings from the OA animal model. In PKCδ null mice, increases in sensory neuron distribution in knee OA synovium and activation of the NGF-tropomyosin receptor kinase (TrkA) axis in innervating dorsal root ganglia were highly correlated with knee OA hyperalgesia.

CONCLUSIONS

Increased distribution of synovial sensory neurons in the joints, and augmentation of NGF/TrkA signalling, causes OA hyperalgesia independently of cartilage preservation.

Relationship between structural pathology and pain behaviour in a model of osteoarthritis (OA)

OBJECTIVES

To address the hypothesis that different types of established osteoarthritis (OA) pain behaviours have associations with different aspects of articular pathology, we investigated the relationship between structural knee joint pathology and pain behaviour following injection of a low vs a high dose of monosodium iodoacetate (MIA) in the rat.

METHODS

Rats received a single intra-articular injection of 0.1 mg or 1 mg MIA or saline (control). Pain behaviour (hind limb weight bearing asymmetry (WB) and hindpaw withdrawal threshold (PWT) to punctate stimulation) was assessed. Cartilage and synovium were examined by macroscopic visualisation of articular surfaces and histopathology.

RESULTS

Both doses of MIA lowered PWTs, 1 mg MIA also resulted in WB asymmetry. Both doses were associated with cartilage macroscopic appearance, proteoglycan loss, abnormal chondrocyte morphology, increased numbers of vessels crossing the osteochondral junction, synovitis and macrophage infiltration into the synovium. PWTs were more strongly associated with chondrocyte morphology, synovitis and macrophage infiltration than with loss of cartilage surface integrity.

CONCLUSIONS

Both pain behaviours were associated with OA structural severity and synovitis. Differences in pain phenotype following low vs higher dose of MIA were identified despite similar structural pathology. OA structural pathology as traditionally measured only partially explains the MIA-induced pain phenotype.

Articular cartilage degeneration following anterior cruciate ligament injury: a comparison of surgical transection and noninvasive rupture as preclinical models of post-traumatic osteoarthritis

OBJECTIVE

Post-traumatic osteoarthritis (PTOA) is commonly studied using animal models. Surgical ACL transection is an established model, but noninvasive models may mimic human injury more closely. The purpose of this study was to quantify and compare changes in 3D articular cartilage (AC) morphology following noninvasive ACL rupture and surgical ACL transection.

METHODS

Thirty-six rats were randomized to uninjured control, noninvasive ACL rupture (Rupture), and surgical ACL transection (Transection), and 4 and 10 week time points (n = 6 per group). Contrast-enhanced micro-computed tomography (CE-μCT) was employed for AC imaging. Femoral and tibial AC were segmented and converted into thickness maps. Compartmental and sub-compartmental AC thickness and surface roughness (S_a) were computed. OARSI histologic scoring was performed.

RESULTS

In both injury groups, zones of adjacent thickening and thinning were evident on the medial femoral condyle, along with general thickening and roughening of femoral and tibial AC. The posterior tibia exhibited drastic thickening and surface degeneration, and this was worse in Transection. Both injury groups had increased AC thickness and S_a compared to Control at both time points, and Transection exhibited significantly higher S_a in every tibial compartment compared to Rupture. Histologic score was elevated in both groups, and the medial femur exhibited the most severe histologic degeneration.

CONCLUSIONS

This is the first 3D quantification of preclinical AC remodeling after ACL injury. Both injury models induced similar changes in AC morphology, but Transection exhibited higher tibial S_a and a greater degree of posterior tibial degeneration. We conclude that AC degeneration is a time-, compartment-, and injury-dependent cascade.

Clinical and MRI Donor Site Outcomes Following Autologous Osteochondral Transplantation for Talar Osteochondral Lesions

BACKGROUND

Autologous osteochondral transplantation (AOT) has an inherent risk of donor site morbidity (DSM). The reported rates of DSM vary from 0% to 50%, with few studies reporting clinical or imaging outcomes at the donor site as a primary outcome and even fewer report these outcomes when a biosynthetic plug backfill is employed. Although TruFit (Smith & Nephew, Andover, MA) plugs have been removed from the market for regulatory purposes, biphasic plugs (including TruFit plugs) have been used for several years and the evaluation of these is therefore pertinent.

METHODS

Thirty-nine patients who underwent forty AOT procedures of the talus, with the donor graft being taken from the ipsilateral knee, were included. Postoperative magnetic resonance imaging (MRI) was used to assess the donor site graded with magnetic resonance observation of cartilage repair tissue (MOCART) scoring. Lysholm scores were collected preoperatively, at the time of magnetic resonance imaging (MRI), and again at 24 months and at final follow-up to assess clinical outcomes. Statistical analysis was performed to establish if there was any correlation between MRI assessment of the donor site and clinical outcomes. The mean patient age was 36.2 ± 15.7 years with a mean follow-up of 41.8 ± 16.7 months.

RESULTS

All patient donor site defects were filled with OBI TruFit biphasic plugs. DSM was encountered in 12.5% of the patient cohort at 24 months, and in these patients, the Lysholm score was a mean 87.2 ± 5.0. At final follow-up, DSM was reduced to 5%. Lysholm scores for the entire cohort were 98.4 ± 4.6 and 99.4 ± 3.1 at 24 months and final follow-up, respectively. MRI of the donor sites were taken at an average of 18.1 ± 13.5 (range, 3-48) months postoperatively and the mean MOCART score was 60.0 ± 13.5. No correlation was found between the MOCART score and Lysholm outcomes at the donor knee (P = .43, r = 0.13).

CONCLUSION

Low incidence of DSM and good functional outcomes were achieved with AOT. Additionally, MRI findings did not predict clinical outcomes in our study.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Monoiodoacetic acid induces arthritis and synovitis in rats in a dose- and time-dependent manner: proposed model-specific scoring systems

OBJECTIVE

In a rat monoiodoacetic acid (MIA)-induced arthritis model, the amount of MIA commonly used was too high, resulting in rapid bone destruction. We examined the effect of MIA concentrations on articular cartilage and infrapatellar fat pad (IFP). We also established an original system for "macroscopic cartilage and bone score" and "IFP inflammation score" specific to the rat MIA-induced arthritis model.

DESIGN

Male Wistar rats received a single intra-articular injection of MIA in the knee. The amount of MIA was 0.1, 0.2, 0.5, and 1 mg respectively. Articular cartilage was evaluated at 2-12 weeks. IFP was also observed at 3-14 days.

RESULTS

Macroscopically, low MIA doses induced punctate depressions on the cartilage surface, and cartilage erosion proceeded slowly over 12 weeks, while higher MIA doses already induced cartilage erosion at 2 weeks, followed by bone destruction. MIA macroscopic cartilage and bone score, OARSI histological score, and Mankin score increased in a dose- and time-dependent manner. The IFP inflammation score peaked at 5 days in low dose groups, then decreased, while in high dose groups, the IFP score continued to increase over 14 days due to IFP fibrosis.

CONCLUSIONS

Punctate depressions, cartilage erosion, and bone destruction were observed in the MIA-induced arthritis model. The macroscopic cartilage and bone scoring enabled the quantification of cartilage degeneration and demonstrated that MIA-induced arthritis progressed in a dose- and time-dependent manner. IFP inflammation scores revealed that 0.2 mg MIA induced reversible synovitis, while 1 mg MIA induced fibrosis of the IFP body.

Knee osteoarthritis pain following medial meniscectomy in the nonhuman primate

OBJECTIVE

A number of promising compounds developed for osteoarthritic pain have failed to demonstrate clinical efficacy. To enhance preclinical translational research for osteoarthritis, a model of knee osteoarthritis pain was developed in Macaca fascicularis and the effects of two distinct pharmacological classes of drugs were tested on pain-related behavior.

DESIGN

Behavioral assessments were developed specifically for the macaque. Baseline knee pressure threshold and weight bearing were assessed prior to a unilateral medial meniscectomy (MMx). Fifteen days following MMx, macaques underwent a once daily exercise regimen for 36 days. Sixty-seven days following MMx, macaques were assigned to one of three treatment groups (n = 3/group), either non-steroidal anti-inflammatory drug (NSAID) diclofenac, NK1 receptor antagonist aprepitant or vehicle, and treated for 5 days. Animals were tested 3-4 h after p.o. dosing and testing was performed blinded. Treatment utilized a crossover design-each animal received all treatments-and a 9-day washout period was utilized between treatments.

RESULTS

Vehicle-treated macaques consistently demonstrated decreased ipsilateral pressure threshold ("hyperalgesia") and decreased weight bearing. While diclofenac increased weight bearing and pressure threshold, full attenuation of pain was not obtained. No significant improvement of either knee pressure or weight bearing was observed with aprepitant.

CONCLUSIONS

Unilateral MMx in the macaque evoked pain-related behaviors and knee joint pathology reminiscent of osteoarthritis. The behavioral endpoints were sensitive to NSAID treatment but not sensitive to NK1 receptor block, which parallel clinical findings. The current macaque osteoarthritis model could be used to test potential treatments for osteoarthritis pain.

Transient receptor potential canonical 5 (TRPC5) protects against pain and vascular inflammation in arthritis and joint inflammation

Objective

Transient receptor potential canonical 5 (TRPC5) is functionally expressed on a range of cells including fibroblast-like synoviocytes, which play an important role in arthritis. A role for TRPC5 in inflammation has not been previously shown in vivo. We investigated the contribution of TRPC5 in arthritis.

Methods

Male wild-type and TRPC5 knockout (KO) mice were used in a complete Freund's adjuvant (CFA)-induced unilateral arthritis model, assessed over 14 days. Arthritis was determined by measurement of knee joint diameter, hindlimb weightbearing asymmetry and pain behaviour. Separate studies involved chronic pharmacological antagonism of TRPC5 channels. Synovium from human postmortem control and inflammatory arthritis samples were investigated for TRPC5 gene expression.

Results

At baseline, no differences were observed. CFA-induced arthritis resulted in increased synovitis in TRPC5 KO mice assessed by histology. Additionally, TRPC5 KO mice demonstrated reduced ispilateral weightbearing and nociceptive thresholds (thermal and mechanical) following CFA-induced arthritis. This was associated with increased mRNA expression of inflammatory mediators in the ipsilateral synovium and increased concentration of cytokines in synovial lavage fluid. Chronic treatment with ML204, a TRPC5 antagonist, augmented weightbearing asymmetry, secondary hyperalgesia and cytokine concentrations in the synovial lavage fluid. Synovia from human inflammatory arthritis demonstrated a reduction in TRPC5 mRNA expression.

Conclusions

Genetic deletion or pharmacological blockade of TRPC5 results in an enhancement in joint inflammation and hyperalgesia. Our results suggest that activation of TRPC5 may be associated with an endogenous anti-inflammatory/analgesic pathway in inflammatory joint conditions.

Selective inhibition of tropomyosin-receptor-kinase A (TrkA) reduces pain and joint damage in two rat models of inflammatory arthritis

BACKGROUND

Inflammation is an essential component of arthritis pain. Nerve growth factor (NGF) plays a key role in acute and chronic pain states especially those associated with inflammation. NGF acts through tropomyosin-receptor-kinase A (TrkA). NGF blockade has reduced arthritis pain in clinical trials. We explored the mechanisms within the joint which may contribute to the analgesic effects of NGF by selectively inhibiting TrkA in carrageenan-induced or collagen-induced joint pain behaviour. The goal of the current study was to elucidate whether inflammation is central to the efficacy for NGF blockade.

METHODS

Rats were injected in their left knees with 2 % carrageenan or saline. Collagen-induced arthritis (CIA) was induced by intradermal injections of a mixture of bovine type II collagen (0.2 mg) and incomplete Freund's adjuvant (0.2 mg). Oral doses (30 mg/kg) of AR786 or vehicle control were given twice daily after arthritis induction. Ibuprofen-treated (35 mg/kg, orally, once daily) rats with CIA were used as positive analgesic controls. Pain behaviour was measured as hind-limb weight-bearing asymmetry and hind-paw withdrawal thresholds to von Frey hair stimulation (carrageenan synovitis), or withdrawal to joint compression using a Randall Selitto device (CIA). Inflammation was measured as increased knee joint diameter and by histopathological analysis.

RESULTS

Intra-articular injections of carrageenan or induction of CIA was each associated with pain behaviour and synovial inflammation. Systemic administration of the TrkA inhibitor AR786 reduced carrageenan-induced or CIA-induced pain behaviour to control values, and inhibited joint swelling and histological evidence of synovial inflammation and joint damage.

CONCLUSIONS

By using two models of varying inflammation we demonstrate for the first time that selective inhibition of TrkA may reduce carrageenan-induced or CIA-induced pain behaviour in rats, in part through potentially inhibiting synovial inflammation, although direct effects on sensory nerves are also likely. Our observations suggest that inflammatory arthritis causes pain and the presence of inflammation is fundamental to the beneficial effects (reduction in pain and pathology) of NGF blockade. Further research should determine whether TrkA inhibition may ameliorate human inflammatory arthritis.

Targeting VEGF and Its Receptors for the Treatment of Osteoarthritis and Associated Pain

Increased vascular endothelial growth factor (VEGF) levels are associated with osteoarthritis (OA) progression. Indeed, VEGF appears to be involved in OA-specific pathologies including cartilage degeneration, osteophyte formation, subchondral bone cysts and sclerosis, synovitis, and pain. Moreover, a wide range of studies suggest that inhibition of VEGF signaling reduces OA progression. This review highlights both the potential significance of VEGF in OA pathology and pain, as well as potential benefits of inhibition of VEGF and its receptors as an OA treatment. With the emergence of the clinical use of anti-VEGF therapy outside of OA, both as high-dose systemic treatments and low-dose local treatments, these particular therapies are now more widely understood. Currently, there is no established disease-modifying drug available for patients with OA, which warrants continued study of the inhibition of VEGF signaling in OA, as stand-alone or adjuvant therapy. © 2016 American Society for Bone and Mineral Research.

Anti-Inflammatory and Antiosteoarthritis Effects of Saposhnikovia divaricata ethanol Extract: In Vitro and In Vivo Studies

Saposhnikovia divaricata Schischkin has been used in traditional medicine to treat pain, inflammation, and arthritis. The aim of this study was to investigate the anti-inflammatory and antiosteoarthritis activities of Saposhnikovia divaricata extract (SDE). The anti-inflammatory effect of SDE was evaluated in vitro in lipopolysaccharide- (LPS-) treated RAW 264.7 cells. The antiosteoarthritic effect of SDE was investigated in an in vivo rat model of monosodium iodoacetate- (MIA-) induced osteoarthritis (OA) in which rats were treated orally with SDE (200 mg/kg) for 28 days. The effects of SDE were assessed in vivo by histopathological analysis and by measuring weight-bearing distribution, cytokine serum levels, and joint tissue inflammation-related gene expression. SDE showed anti-inflammatory activity by inhibiting the production of nitric oxide (NO), prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in LPS-induced RAW 264.7 cells. In addition, SDE promoted recovery of hind limb weight-bearing, inhibited the production of proinflammatory cytokines and mediators, and protected cartilage and subchondral bone tissue in the OA rat model. Therefore, SDE is a potential therapeutic agent for OA and/or associated symptoms.

OsteoRheumatology: a new discipline?

This review summarises recent evidence about the interaction between bone, the immune system and cartilage in disabling conditions such as osteoarthritis, rheumatoid arthritis and spondyloarthritis. These topics have been recently discussed at the ‘OsteoRheumatology’ conference held in Genoa in October 2014. The meeting, at its 10th edition, has been conceived to bring together distinguished international experts in the fields of rheumatic and metabolic bone diseases with the aim of discussing emerging knowledge regarding the role of the bone tissue in rheumatic diseases. Moreover, this review focuses on new treatments based on underlying the pathophysiological processes in rheumatic diseases. Although, a number of issues still remain to be clarified, it seems quite clear that in clinical practice, as well as in basic and translational research, there is a need for more knowledge of the interactions between the cartilage, the immune system and the bone. In this context, ‘OsteoRheumatology’ represents a potential new discipline providing a greater insight into this interplay, in order to face the multifactorial and complex issues underlying common and disabling rheumatic diseases.

Calcitonin gene-related peptide in the joint: contributions to pain and inflammation

Arthritis is the commonest cause of disabling chronic pain, and both osteoarthritis (OA) and rheumatoid arthritis (RA) remain major burdens on both individuals and society. Peripheral release of calcitonin gene-related peptide (CGRP) contributes to the vasodilation of acute neurogenic inflammation. Contributions of CGRP to the pain and inflammation of chronic arthritis, however, are only recently being elucidated. Animal models of arthritis are revealing the molecular and pathophysiological events that accompany and lead to progression of both arthritis and pain. Peripheral actions of CGRP in the joint might contribute to both inflammation and joint afferent sensitization. CGRP and its specific receptors are expressed in joint afferents and up-regulated following arthritis induction. Peripheral CGRP release results in activation of synovial vascular cells, through which acute vasodilatation is followed by endothelial cell proliferation and angiogenesis, key features of chronic inflammation. Local administration of CGRP to the knee also increases mechanosensitivity of joint afferents, mimicking peripheral sensitization seen in arthritic joints. Increased mechanosensitivity in OA knees and pain behaviour can be reduced by peripherally acting CGRP receptor antagonists. Effects of CGRP pathway blockade on arthritic joint afferents, but not in normal joints, suggest contributions to sensitization rather than normal joint nociception. CGRP therefore might make key contributions to the transition from normal to persistent synovitis, and the progression from nociception to sensitization. Targeting CGRP or its receptors within joint tissues to prevent these undesirable transitions during early arthritis, or suppress them in established disease, might prevent persistent inflammation and relieve arthritis pain.

In vivo three-dimensional magnetic resonance imaging of rat knee osteoarthritis model induced using meniscal transection

Background/Objective

In a rat meniscal tear model of osteoarthritis (OA), a full-thickness cut in the medial meniscus leads to joint instability and progressive development of knee OA. This study evaluated in vivo high-resolution three-dimensional magnetic resonance imaging (3D MRI) in demonstrating the knee joint structural changes of this animal model.

Methods

A left knee meniscal tear procedure was carried out on 10 rats, and sham surgery was performed on five rats. The joints were MRI scanned 44 days after surgery at 4.7 Tesla. A 3D data set was acquired using a 3D spoiled gradient echo sequence at a resolution of 59 × 117 × 234 μm³. After MRI, microscopic examination of the joints was performed.

Results

The medial meniscus tear was clearly visible with MRI. Cartilage damage was seen in all animals, with varying degrees of severities, which included a decrease of cartilage thickness and loss of cartilage in some areas, and focal neocartilage proliferation at the joint margin. Damage to the subchondral bone included local osteosclerosis, deformed tibia cortex surface, and osteophytes. The damage to the cartilage and bone was most extensive on the weight-bearing region of the medial tibial plateau. No apparent subchondral bone damage was observed in the epiphysis of the femur. In five animals, single or multiple high MR signal areas were seen within the epiphysis of the tibia, consistent with epiphyseal cyst formation. The knee interarticular space on the media side was slightly increased in two animals. Mild femur–tibia axis misalignment was seen in one animal. Changes seen on MRI were consistent with histopathological changes.

Conclusion

MRI offers in vivo information on the pathogenesis change of rat knee OA induced with menisectomy. It can serve as a supplement technique to histology, as it is particularly useful for longitudinal follow-up of OA model development.