Useful animal models for the research of osteoarthritis

Infrared Spectroscopy Can Differentiate Between Cartilage Injury Models: Implication for Assessment of Cartilage Integrity

In order to improve the ability of clinical diagnosis to differentiate articular cartilage (AC) injury of different origins, this study explores the sensitivity of mid-infrared (MIR) spectroscopy for detecting structural, compositional, and functional changes in AC resulting from two injury types. Three grooves (two in parallel in the palmar-dorsal direction and one in the mediolateral direction) were made via arthrotomy in the AC of the radial facet of the third carpal bone (middle carpal joint) and of the intermediate carpal bone (the radiocarpal joint) of nine healthy adult female Shetland ponies (age = 6.8 ± 2.6 years; range 4-13 years) using blunt and sharp tools. The defects were randomly assigned to each of the two joints. Ponies underwent a 3-week box rest followed by 8 weeks of treadmill training and 26 weeks of free pasture exercise before being euthanized for osteochondral sample collection. The osteochondral samples underwent biomechanical indentation testing, followed by MIR spectroscopic assessment. Digital densitometry was conducted afterward to estimate the tissue's proteoglycan (PG) content. Subsequently, machine learning models were developed to classify the samples to estimate their biomechanical properties and PG content based on the MIR spectra according to injury type. Results show that MIR is able to discriminate healthy from injured AC (91%) and between injury types (88%). The method can also estimate AC properties with relatively low error (thickness = 12.7% mm, equilibrium modulus = 10.7% MPa, instantaneous modulus = 11.8% MPa). These findings demonstrate the potential of MIR spectroscopy as a tool for assessment of AC integrity changes that result from injury.

Knee osteoarthritis: A review of animal models and intervention of traditional Chinese medicine

BACKGROUND

Knee osteoarthritis (KOA) characterized by degeneration of knee cartilage and subsequent bone hyperplasia is a prevalent joint condition primarily affecting aging adults. The pathophysiology of KOA remains poorly understood, as it involves complex mechanisms that result in the same outcome. Consequently, researchers are interested in studying KOA and require appropriate animal models for basic research. Chinese herbal compounds, which consist of multiple herbs with diverse pharmacological properties, possess characteristics such as multicomponent, multipathway, and multitarget effects. The potential benefits in the treatment of KOA continue to attract attention.

PURPOSE

This study aims to provide a comprehensive overview of the advantages, limitations, and specific considerations in selecting different species and methods for KOA animal models. This will help researchers make informed decisions when choosing an animal model.

METHODS

Online academic databases (e.g., PubMed, Google Scholar, Web of Science, and CNKI) were searched using the search terms "knee osteoarthritis," "animal models," "traditional Chinese medicine," and their combinations, primarily including KOA studies published from 2010 to 2023.

RESULTS

Based on literature retrieval, this review provides a comprehensive overview of the methods of establishing KOA animal models; introduces the current status of advantages and disadvantages of various animal models, including mice, rats, rabbits, dogs, and sheep/goats; and presents the current status of methods used to establish KOA animal models.

CONCLUSION

This study provides a review of the animal models used in recent KOA research, discusses the common modeling methods, and emphasizes the role of traditional Chinese medicine compounds in the treatment of KOA.

Neuroinflammation in osteoarthritis: From pain to mood disorders

Osteoarthritis (OA) is the most common form of musculoskeletal disease, and its prevalence is increasing due to the aging of the population. Chronic pain is the most burdensome symptom of OA that significantly lowers patients' quality of life, also due to its frequent association with emotional comorbidities, such as anxiety and depression. In recent years, both chronic pain and mood alterations have been linked to the development of neuroinflammation in the peripheral nervous system, spinal cord and supraspinal brain areas. Thus, mechanisms at the basis of the development of the neuroinflammatory process may indicate promising targets for novel treatment for pain and affective comorbidities that accompany OA. In order to assess the key role of neuroinflammation in the maintenance of chronic pain and its potential involvement in development of psychiatric components, the monoiodoacetate (MIA) model of OA in rodents has been used and validated. In the present commentary article, we aim to summarize up-to-date results achieved in this experimental model of OA, focusing on glia activation and cytokine production in the sciatic nerve, dorsal root ganglia (DRGs), spinal cord and brain areas. The association of a neuroinflammatory state with the development of pain and anxiety- and depression-like behaviors are discussed. Results suggest that cells and molecules involved in neuroinflammation may represent novel targets for innovative pharmacological treatments of OA pain and mood comorbidities.

The dysregulated autophagy in osteoarthritis: Revisiting molecular profile

The risk factors of osteoarthritis (OA) are different and obesity, lifestyle, inflammation, cell death mechanisms and diabetes mellitus are among them. The changes in the biological mechanisms are considered as main regulators of OA pathogenesis. The dysregulation of autophagy is observed in different human diseases. During the pathogenesis of OA, the autophagy levels (induction or inhibition) change. The supportive and pro-survival function of autophagy can retard the progression of OA. The protective autophagy prevents the cartilage degeneration. Moreover, autophagy demonstrates interactions with cell death mechanisms and through inhibition of apoptosis and necroptosis, it improves OA. The non-coding RNA molecules can regulate autophagy and through direct and indirect control of autophagy, they dually delay/increase OA pathogenesis. The mitochondrial integrity can be regulated by autophagy to alleviate OA. Furthermore, therapeutic compounds, especially phytochemicals, stimulate protective autophagy in chondrocytes to prevent cell death. The protective autophagy has ability of reducing inflammation and oxidative damage, as two key players in the pathogenesis of OA.

Enlarged colony housing promotes linear progression of subchondral bone remodeling in joint instability rat models

Objective: Osteoarthritis (OA) is a disease with high prevalence and an unmet medical need for disease modifying treatments. In rat models, OA-like subchondral bone and cartilage changes can be induced by instability surgery with different severity levels. Factors which determine structural changes additionally comprise the study duration and activity-impacted joint loading. Methods: A medial meniscal tear (MMT) or anterior cruciate ligament transection with partial meniscectomy (ACLT+pMx) was induced unilaterally in rats housed in a rat colony cage (RCC), allowing high activity levels including jumping and stair climbing. In parallel, ACLT+pMx rats were housed in Type IV cages. The time course of OA-related changes was investigated at 4, 8, 12, and 16 weeks after surgery by micro-CT, gait analysis and joint diameter measurements. Results: Gait disturbance was observed after 2 weeks and to a similar extend in all models. The increase in ipsilateral joint diameters peaked after 2 weeks and were more pronounced after ACLT+pMx compared to MMT-surgery, but independent of housing. Micro-CT analysis revealed that increases in osseous tibial width were most distinct after ACLT+pMx in RCC and progressed continuously until week sixteen. In contrast, osseous tibial width of ipsilateral joints in MMT RCC and ACLT+pMx Type IV groups did not increase further after week twelve. In contralateral joints, this parameter was not affected, regardless of the model or caging. However, a significant increase in bone volume fraction and trabecular thickness was observed over time in the femur and tibia of both ipsilateral and contralateral knees. Here, the medial tibial compartment of the operated joint was most affected and linear changes were most pronounced in the ACLT+pMx RCC group. Conclusion: Increased movement of animals in colony cages leads to robust structural changes in subchondral bone after surgically induced joint instability over time, while in regular Type IV housing maximal changes are reached in week twelve. The new insights into the differentiation of the models, particularly with respect to the linear progression of bone changes in ACLT+pMx in the RCC, may be useful for the design of chronic OA-studies within a longer lifespan and therefore supporting the development of novel therapies.

Establishment of an image evaluation grading criteria for experimental stifle joint osteoarthritis in dogs: an X-ray and CT imaging study

BACKGROUND

This study aimed to establish an image evaluation grading criteria for experimental stifle joint osteoarthritis (OA) in anterior cruciate ligament transection induced OA beagle dog models. The severity of OA was assessed using X-ray and computed tomography (CT) imaging.

RESULTS

A total of 32 dogs (8 controls and 24 OA-induced dogs) were included in the study. The OA-induced group showed significantly higher manual joint palpation, gait analysis, and OA severity scores than the control group. Based on these two results, we calculated correlation coefficients. There was a strong positive correlation between manual joint palpation scores and OA severity on diagnostic imaging and between gait analysis scores and OA severity.

CONCLUSIONS

The developed grading criteria based on radiographic evaluation correlated with clinical assessments. The study also employed CT imaging to enhance the accuracy and sensitivity of early-stage OA change detection in the stifle joint. However, further studies with larger sample sizes and multiple evaluators are recommended for the validation and generalizability of this grading system. These established image evaluation grading criteria can help evaluate and monitor the efficacy of interventions and changes in OA lesions in canine models.

Hyaluronic acid/diminazene aceturate combination ameliorates osteoarthritic anomalies in a rodent model: a role of the ACE2/Ang1-7/MasR axis

The implication of the tissue-localized renin-angiotensin system (RAS) in the pathogenesis of osteoarthritis (OA) has been documented in the last decades. A combination of intraarticular (IA) corticosteroid and hyaluronic acid (HYAL) is approved for pain relief in patients with mild to moderate OA. Combining HYAL with an activator of angiotensin-converting enzyme 2, diminazen aceturate (DIZE), was evaluated in this study for its therapeutic potential. Monosodium iodoacetate was used to induce OA. The effects of daily administration of DIZE versus once-per-week IA injection of HYAL and a combination of both drugs for 21 days on OA deformities in rats' knees were observed. Evaluation of motor activities, pain, and inflammatory response was done using rotarod, knee bend, and knee swelling tests. RAS components, inflammatory biomarkers, and oxidative stress mediators were measured in the knee joint. X-ray radiological examination and histopathological investigations were used to assess joint degeneration and regeneration. Levels of both inflammatory and oxidative markers in knee joint homogenate of OA rats rose, and these increments were mostly improved by the three therapies with a more prominent effect of the drug combination, an effect that was also reflected in the behavioral tests. RAS markers have shown better responsiveness to the combination therapy over both drugs individually, showing a pronounced increase in the angiotensin 1-7 amount. Both radiological and histopathology investigations came to confirm the biochemical results, nominating a combination of HYAL and DIZE as a possible therapeutic option for OA.

Face and Predictive Validity of MI-RAT (Montreal Induction of Rat Arthritis Testing), a Surgical Model of Osteoarthritis Pain in Rodents Combined with Calibrated Exercise

Validating animal pain models is crucial to enhancing translational research and response to pharmacological treatment. This study investigated the effects of a calibrated slight exercise protocol alone or combined with multimodal analgesia on sensory sensitivity, neuroproteomics, and joint structural components in the MI-RAT model. Joint instability was induced surgically on day (D) 0 in female rats (N = 48) distributed into sedentary-placebo, exercise-placebo, sedentary-positive analgesic (PA), and exercise-PA groups. Daily analgesic treatment (D3-D56) included pregabalin and carprofen. Quantitative sensory testing was achieved temporally (D-1, D7, D21, D56), while cartilage alteration (modified Mankin's score (mMs)) and targeted spinal pain neuropeptide were quantified upon sacrifice. Compared with the sedentary-placebo (presenting allodynia from D7), the exercise-placebo group showed an increase in sensitivity threshold (p < 0.04 on D7, D21, and D56). PA treatment was efficient on D56 (p = 0.001) and presented a synergic anti-allodynic effect with exercise from D21 to D56 (p < 0.0001). Histological assessment demonstrated a detrimental influence of exercise (mMs = 33.3%) compared with sedentary counterparts (mMs = 12.0%; p < 0.001), with more mature transformations. Spinal neuropeptide concentration was correlated with sensory sensitization and modulation sites (inflammation and endogenous inhibitory control) of the forced mobility effect. The surgical MI-RAT OA model coupled with calibrated slight exercise demonstrated face and predictive validity, an assurance of higher clinical translatability.

Potential of thermoresponsive hydrogel as an alternative therapy for rat knee osteoarthritis

Osteoarthritis is a degenerative condition that is highly prevalent and primarily affects the joints. The knee is the most commonly affected site, impacting the lives of over 300 million individuals worldwide. This study presents a potential solution to address the unmet need for a minimally invasive technique in the treatment of osteoarthritis: a biocompatible, injectable, and thermoresponsive hydrogel. In comparison to commercially available products such as lyophilized platelets, dextrose, and triamcinolone, the thermoresponsive hydrogel exhibits significantly superior performance in dynamic behaviors, including print area, stability, and step cycle, when tested on rats with knee osteoarthritis. However, it demonstrates similar treatment efficacy to these products in static behaviors, as observed through histopathological and immunohistochemical analysis. Therefore, the thermoresponsive hydrogel holds promise as an effective alternative therapy for osteoarthritis. Moreover, by blending the hydrogel with drugs, controlled and sustained release can be achieved, thereby facilitating the long-term management of osteoarthritis symptoms.

Tizoxanide as a novel theraputic candidate for osteoarthritis

Osteoarthritis (OA) is a frequently seen degenerative joint disease in the elderly. Its pathogenesis is highly related to the local inflammatory reaction and autophagy. Tizoxanide (Tiz), the main active metabolite of nitazoxanide, has proved its anti-inflammatory properties in several diseases. However, the exact role of Tiz in OA remains to explore. In this study, we investigated the anti-arthritic effects and the underlying molecular mechanisms of Tiz on rat OA. The results showed that Tiz could attenuate the IL-1β-induced inflammatory disorders, cartilage matrix damage and autophagy reduction in rat chondrocytes. Moreover, employment of autophagy inhibitor 3-methyladenine (3-MA) could antagonize the protective effects of Tiz in IL-1β-treated rat chondrocytes. Additionally, Tiz also inhibited the IL-1β-induced PI3K/AKT/mTOR and P38/JNK phosphorylation in chondrocytes. In vivo, intra-articular injection of Tiz could significantly alleviate the progression of cartilage damage in rat OA model. Briefly, our study demonstrated the therapeutic potential of Tiz in OA, suggesting that Tiz administration might serve as a promising strategy in OA therapy.

Two Amnion-Derived Mesenchymal Stem-Cells Injections to Osteoarthritic Elbows in Dogs-Pilot Study

The aim of the study was to investigate the potential of cell-based regenerative therapy for elbow joints affected by osteoarthritis. Interest was focused on two intra-articular applications of amnion-derived mesenchymal stem cells (A-MSCs) to a group of different breeds of dogs with elbow osteoarthritis (13 joints). Two injections were performed 14 days apart. We evaluated synovial fluid biomarkers, such as IFN-γ, IL-6, IL-15, IL-10, MCP-1, TNF-α, and GM-CSF, by multiplex fluorescent micro-bead immunoassay in the treated group of elbows (n = 13) (day 0, day 14, and day 28) and in the control group of elbows (n = 9). Kinematic gait analysis determined the joint range of motion (ROM) before and after each A-MSCs application. Kinematic gait analysis was performed on day 0, day 14, and day 28. Kinematic gait analysis pointed out improvement in the average range of motion of elbow joints from day 0 (38.45 ± 5.74°), day 14 (41.7 ± 6.04°), and day 28 (44.78 ± 4.69°) with statistical significance (p < 0.05) in nine elbows. Correlation analyses proved statistical significance (p < 0.05) in associations between ROM (day 0, day 14, and day 28) and IFN-γ, IL-6, IL-15, MCP-1, TNF-α, and GM-CSF concentrations (day 0, day 14, and day 28). IFN-γ, IL-6, IL-15, MCP-1, GM-CSF, and TNF- α showed negative correlation with ROM at day 0, day 14, and day 28, while IL-10 demonstrated positive correlation with ROM. As a consequence of A-MSC application to the elbow joint, we detected a statistically significant (p < 0.05) decrease in concentration levels between day 0 and day 28 for IFN-γ, IL-6, and TNF-α and statistically significant increase for IL-10. Statistical significance (p < 0.05) was detected in TNF-α, IFN-γ, and GM-CSF concentrations between day 14 and the control group as well as at day 28 and the control group. IL-6 concentrations showed statistical significance (p < 0.05) between day 14 and the control group.

Therapeutic Effect of Acupotomy at Sanheyang for Cartilage Collagen Damage in Moderate Knee Osteoarthritis: A Rabbit Model

Objective

Acupotomy based on the meridian-sinew theory of traditional Chinese medicine has benefits in treating knee osteoarthritis (KOA). The current study aims to prove that acupotomy at the sinew points of Sanheyang protect the knee joint and alleviate the progression of moderate KOA by evaluating KOA symptoms, cartilage structure, and analyzing the changes of cytokines in rabbit cartilage.

Methods

The model used was mono-iodoacetate-induced moderate KOA in the rabbit's right leg. Rabbits were divided into the model group, the acupotomy group, and the control group, with each group receiving two parts of treatment for 2 weeks and 4 weeks. We evaluated pain in the knee joint and range of motion. The articular cartilage sections were stained with Safranin O/Fast Green and Masson. We used immunohistochemistry and real-time PCR to detect the protein and mRNA expressions of collagen prototype II (COL-II), matrix metalloproteinase 13 (MMP13), and integrin-β1 (ITG-β1).

Results

Compared with the model group, the acupotomy group had higher body weight, lower pain score, higher range of motion, lower Mankin score, and significantly lower protein and mRNA expression of MMP13. After 4 weeks of treatment, Col-II expression in the acupotomy group was significantly higher than that in the model group and the expression of ITG-β1 in the model group was abnormally increased.

Conclusion

Acupotomy at Sanheyang improved the pain symptoms and range of joint motion in rabbits with moderate KOA, and could protect Col-II by regulating MMP13, which may be related to ITG-β1-mediated mechanical force transmission, thus reducing the damage to cartilage structure and delaying the progression of moderate KOA.

Mesenchymal stem/stromal cells-derived extracellular vesicles as a potentially more beneficial therapeutic strategy than MSC-based treatment in a mild metabolic osteoarthritis model

BACKGROUND

Mesenchymal stromal/stem cells (MSCs) and MSC-derived extracellular vesicles (MSC-EVs) hold promise as a disease modifying treatment in osteoarthritis (OA). Obesity, and its associated inflammation, contribute to OA development and metabolic OA represents a specific and significant group of the OA patient population. Given their immunomodulatory properties, MSC and MSC-EVs are especially interesting for this group of patients as a therapeutic option. Here, we were the first to compare the therapeutic efficacy of MSCs and MSC-EVs in a mild OA model taking these metabolic aspects into consideration.

METHODS

Male Wistar-Han rats (Crl:WI(Han) (n = 36) were fed a high fat diet for 24 weeks, with unilateral induction of OA by groove surgery after 12 weeks. Eight days after surgery rats were randomized in three treatment groups receiving MSCs, MSC-EVs or vehicle injection. Pain-associated behavior, joint degeneration, and local and systemic inflammation were measured.

RESULTS

We demonstrated that despite not having a significant therapeutic effect, MSC-EV treatment results in lower cartilage degeneration, less pain behaviour, osteophytosis and joint inflammation, than MSC treatment. Suggesting that MSC-EVs could be a more promising therapeutic strategy than MSCs in this mild metabolic OA model.

CONCLUSION

In summary, we find that MSC treatment has negative effects on the joint in metabolic mild OA. This is an essential finding for the significant group of patients with metabolic OA phenotype, and might help to understand why clinical translation of MSC treatment shows varying therapeutic efficacy thus far. Our results also suggest that MSC-EV-based treatment might be a promising option for these patients, however MSC-EV therapeutic efficacy will need improvement.

Integrin αVβ3 Signaling in the Progression of Osteoarthritis Induced by Excessive Mechanical Stress

Osteoarthritis (OA) is believed to be linked with cartilage degeneration, subchondral bone sclerosis, and synovial inflammation that lead to joint failure, and yet treatment that can effectively reverse the pathological process of the disease still not exists. Recent evidence suggests excessive mechanical stress (eMS) as an essential role in the pathogenesis of OA. Increased levels of integrin αVβ3 have been detected in osteoarthritic cartilage and were previously implicated in OA pathogenesis. However, the role of integrin αVβ3 in the process of eMS-induced OA remains unclear. Here, histologic and proteomic analyses of osteoarthritic cartilage in a rat destabilization of the medial meniscus model demonstrated elevated expression of integrin αVβ3 as well as more serious cartilage degeneration in the medial weight-bearing area. Furthermore, results of in vitro study demonstrated that eMS led to a significant increase of integrin αVβ3 expression and phosphorylation of downstream signaling molecules such as FAK and ERK, as well as upregulated expressions of inflammatory and degradative mediators. In addition, we found that inhibition of integrin αVβ3 could alleviate chondrocyte inflammation triggered by eMS both in vivo and in vitro. Our findings suggest a central role for upregulation of integrin αVβ3 signaling in OA pathogenesis and demonstrate that activation of integrin αVβ3 signaling in cartilage contributes to inflammation and joint destruction in eMS-induced OA. Taken together, our data presented here provide a possibility for targeting integrin αVβ3 signaling pathway as a disease-modifying therapy.

Crocus sativus Extract as a Biological Agent for Disease-Modifying Therapy of Collagenase-Induced Mouse Model of Osteoarthritis

Objectives: Osteoarthritis (OA) is an age-related joint disease that involves the degeneration of cartilage and is the most prevalent form of arthritis, affecting a large part of the population. OA is a multifactorial disorder, and no single etiological mechanism has been found to be common to all forms of the disease. Currently used therapies for control of the disease are mainly nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroid medications. The aim of this study was to investigate the extract from Crocus sativus as a biological disease-suppressing therapy agent. Methods: Balb/c mice were injected intra-articularly with Clostridium histolyticum type IA for induction of osteoarthritis. The mice were randomized to five groups: control group, I group (CIOA untreated), II group (CIOA + 100 mg/kg/daily saffron), III group (CIOA + 50 mg/kg/daily saffron), IV group (CIOA + 25 mg/kg/daily saffron). Flow-cytometry analysis was used to study the splenocytes’ phenotype isolated from the treated animals. The serum levels of inflammatory and anti-inflammatory cytokines were analyzed with ELISA. The histological assessment was used to analyze the saffron extract effect on histopathological alterations. Results: Saffron treatment significantly decreased osteoarthritis-associated joint histological manifestations and decreased serum TNFα levels. The flow-cytometry analysis showed a decrease in pro-inflammatory immune cell subtypes in the spleen. Conclusions: The results obtained suggest that saffron affected the disease progression and could be a potential therapeutic approach in osteoarthritic patients’ therapy.

Development, optimization, and invitro evaluation of novel fast dissolving oral films (FDOF's) of Uncaria tomentosa extract to treat osteoarthritis

Fast dissolving oral films(FDOF's) are the popular dosage forms when placed in the oral cavity, disintegrate rapidly and dissolve to release the medication for improving oral absorption. Traditionally Uncaria tomentosa plant is used in the treatment of rheumatoid arthritis as Non-steroidal Anti-inflammatory agent along with analgesic properties. The plant extract is reported to be used in low dose as analgesic and anti-inflammatory agent in Rheumatoid Arthritis. No scientific data was reported on Uncaria plant formulation as FDOF's for treating osteoarthritis. This study aims to formulate fast oral dissolving film(FDOFs) Uncaria tomentosa bark extract and evaluate using Invitro studies for osteoarthritis. About 14 formulations were prepared using standard Box Behnken design protocol for optimization using the natural film formers, synthetic polymers, super disintegrants, plasticizers as independent variables with folding endurance and disintegration time as dependent variables by solvent casting method. Further the formulation characteristics including physical and mechanical behavior of films and drug release behavior was evaluated. The 3D countour plots and response curves suing the design expert software were investigated which proved that the optimized oral dissolving films of extract with Pullalan gum, HPMC (polymers), Propylene glycol, PEG 400 (Co-solvents) and Croscarmellose sodium (super Disintegrant) are stable and uniform with formulation characteristics. The drug release rates prove that F5 and F13 formulations showed 99.90% drug release within 30 min following first order kinetics with satisfactory mechanical properties. The study results suggest that the fast dissolving oral films of Uncaria tomentosa extract is novel, attractive and alternative to the available marketed products resulting in improved patient adherence in treatment of osteoarthritis.

Protective effects of Pudilan Tablets against osteoarthritis in mice induced by monosodium iodoacetate

Osteoarthritis (OA) is a complicated disorder that is the most prevalent chronic degenerative joint disease nowadays. Pudilan Tablets (PDL) is a prominent traditional Chinese medicine formula used in clinical settings to treat chronic inflammatory illnesses. However, there is currently minimal fundamental research on PDL in the therapy of joint diseases. As a result, this study looked at the anti-inflammatory and anti-OA properties of PDL in vitro and in vivo, as well as the mechanism of PDL in the treatment of OA. We investigated the anti-OA properties of PDL in OA mice that were generated by monosodium iodoacetate (MIA). All animals were administered PDL (2 g/kg or 4 g/kg) or the positive control drug, indomethacin (150 mg/kg), once daily for a total of 28 days starting on the day of MIA injection. The CCK-8 assay was used to test the vitality of PDL-treated RAW264.7 cells in vitro. RAW264.7 cells that had been activated with lipopolysaccharide (LPS) were used to assess the anti-inflammatory properties of PDL. In the MIA-induced OA model mice, PDL reduced pain, decreased OA-induced cartilage damages and degradation, decreased production of pro-inflammatory cytokines in serum, and suppressed IL-1β, IL-6, and TNF-α mRNA expression levels in tibiofemoral joint. In RAW264.7 cells, PDL treatment prevented LPS-induced activation of the ERK/Akt signaling pathway and significantly decreased the levels of inflammatory cytokines, such as IL-1β, IL-6, and TNF-α. In conclusion, these results suggest that PDL is involved in combating the development and progression of OA, exerts a powerful anti-inflammatory effect on the knee joint, and may be a promising candidate for the treatment of OA.

Autophagy in the pathogenesis and therapeutic potential of post-traumatic osteoarthritis

Autophagy, as a fundamental mechanism for cellular homeostasis, is generally involved in the occurrence and progression of various diseases. Osteoarthritis (OA) is the most common musculoskeletal disease that often leads to pain, disability and economic loss in patients. Post-traumatic OA (PTOA) is a subtype of OA, accounting for >12% of the overall burden of OA. PTOA is often caused by joint injuries including anterior cruciate ligament rupture, meniscus tear and intra-articular fracture. Although a variety of methods have been developed to treat acute joint injury, the current measures have limited success in effectively reducing the incidence and delaying the progression of PTOA. Therefore, the pathogenesis and intervention strategy of PTOA need further study. In the past decade, the roles and mechanisms of autophagy in PTOA have aroused great interest in the field. It was revealed that autophagy could maintain the homeostasis of chondrocytes, reduce joint inflammatory level, prevent chondrocyte death and matrix degradation, which accordingly improved joint symptoms and delayed the progression of PTOA. Moreover, many strategies that target PTOA have been revealed to promote autophagy. In this review,  we summarize the roles and mechanisms of autophagy in PTOA and the current strategies for PTOA treatment that depend on autophagy regulation, which may be beneficial for PTOA patients in the future.

Mechanism of action of genicular artery embolization in a rabbit model of knee osteoarthritis

OBJECTIVES

To establish a rabbit osteoarthritis model for genicular artery embolization (GAE) experiments and to investigate the cellular mechanism of action of this novel procedure for interventional radiologists.

METHODS

Rabbit knee osteoarthritis was surgically modeled by anterior cruciate ligament transection and medial partial meniscectomy of the bilateral hindlimbs followed by 10 weeks of incubation. Rabbits exhibiting synovitis on magnetic resonance imaging were randomly divided into two groups: the bilateral GAE group and the control (sham procedure) group. Four weeks later, the rabbits' mobility (moving time, sec/10 min) and the histopathological features of each knee were assessed, and inter-group differences were evaluated using Student's t-test and ordinal/linear logistic models with generalized estimating equations.

RESULTS

Osteoarthritis modeling and endovascular procedures were successful in 15 of 20 rabbits (8 and 7 in the GAE and control groups, respectively). There was no significant difference in moving times between the two groups (p = .958). The degree of structural cartilage damage was similar in both groups (p = .780). However, the synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) scores were significantly lower in the GAE group than in the control group. The CD3+ cell density (p = .018) and CD3 + cell-infiltrated area (p = .019) were also significantly lower in the GAE group than in the control group.

CONCLUSION

GAE can limit inflammatory processes in the synovium of osteoarthritis-affected knees.

KEY POINTS

Surgical transection of the anterior cruciate ligament and medial partial meniscectomy of rabbit knees provides a useful animal model for research of genicular artery embolization. Osteoarthritic knees treated by genicular artery embolization showed milder synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) than the untreated knees. Osteoarthritic knees treated by genicular artery embolization presented lower CD3+ cell density (p = .018) and CD3+ cell-infiltrated area (p = .019) in the synovium than the untreated knees.

Therapeutic exercise interventions in rat models of arthritis

Arthritis is the leading cause of musculoskeletal pain and disability worldwide. Nearly 50% of individuals over the age of 65 have arthritis, which contributes to limited function, articular pain, physical inactivity, and diminished quality of life. Therapeutic exercise is often recommended in clinical settings for patients experiencing arthritic pain, however, there is little practical guidance regarding the use of therapeutic exercise to alleviate arthritic musculoskeletal pain. Rodent models of arthritis allow researchers to control experimental variables, which cannot be done with human participants, providing an opportunity to test therapeutic approaches in preclinical models. This literature review provides a summary of published findings in therapeutic exercise interventions in rat models of arthritis as well as gaps in the existing literature. We reveal that preclinical research in this field has yet to adequately investigate the impact of experimental variables in therapeutic exercise including their modality, intensity, duration, and frequency on joint pathophysiology and pain outcomes.

Development and Analysis of Mouse Medial Meniscus Posterior Root Tear Model

Medial meniscus posterior root tears (MMPRT) are often associated with osteoarthritis (OA) progression and subchondral bone insufficiency fractures. This study aimed to develop the first MMPRT mouse model. The MMPRT model was created by sectioning the medial meniscus posterior root of 12-week-old CL57BL/6J male mice under stereomicroscopic observation. The sham operation and the destabilization of the medial meniscus (DMM) model groups were also created. OA progression and subchondral bone changes were evaluated histologically using the Osteoarthritis Research Society International (OARSI) subchondral bone scoring system at 2, 4, 8, and 12 weeks after surgery. Microcomputed tomography (µCT) was performed to evaluate the presence of insufficient fractures. OA progression and medial meniscus extrusion were observed in the MMPRT and DMM models 12 weeks after surgery. OA progressed in both models during the time course, without a significant difference in the OARSI score between the two groups. The subchondral bone score was significantly higher at 12 weeks than at 2 and 4 weeks in the MMPRT group, while no significant difference was found between the two groups. In the µCT analysis, destruction of the medial tibial plateau was observed in 4/40 knees, while none were observed in the DMM group. Of the four knees, destruction of the medial femoral condyle was also observed in three knees. Characteristic pathological changes were observed in the mouse MMPRT model. The mouse MMPRT model may be useful for investigating pathological changes after MMPRT.

Collagenase-Induced Mouse Model of Osteoarthritis-A Thorough Flow Cytometry Analysis

OBJECTIVES

Osteoarthritis (OA) is a chronic degenerative disorder of the joint characterized by cartilage breakdown and synovial inflammation. A number of different cells of innate and adaptive immunity contribute to joint pathology during OA inflammation. The interaction between the local synovial and systemic inflammatory cellular response and the structural changes in the joint is still unknown. The objective of this study was to investigate the role of the different types of immune cells in the development of OA.

METHODS

Collagenase-induced osteoarthritis was induced in Balb/c mice; flow cytometry analysis; and histopathological damages were assessed in histological sections stained with H&E, Toluidine blue, and Safranin O.

RESULTS

Flow cytometry analysis showed B lymphocyte infiltration in the active phase of inflammation and an increase in the effector T cell population into the synovium. An increased activation state of cytotoxic T cells and of NK cell populations in the spleen and synovium was also found. The differentiation of NK cells from a cytotoxic phenotype in early OA to cells with an effector phenotype in the chronic phase of the disease followed.

CONCLUSIONS

A number of different cells contribute to inflammatory processes in OA. The correlation between their phenotype and the inflammatory pathophysiology could result in the development of novel approaches to suppress destructive changes in the joint.

Effect of cells on spatial quantification of proteoglycans in articular cartilage of small animals

OBJECTIVE

Histochemical characterization of proteoglycan content in articular cartilage is important for the understanding of osteoarthritis pathogenesis. However, cartilage cells may interfere with the measurement of matrix proteoglycan content in small animal models (e.g. mice and rats) due to the high cell volume fraction (38%) in mice compared to human tissue (~1%). We investigated whether excluding the cells from image analysis affects the histochemically measured proteoglycan content of rat knee joint cartilage and assessed the effectiveness of a deep learning algorithm-based tool named U-Net in cell segmentation.

DESIGN

Histological sections were stained with Safranin-O, after which optical densities were measured using digital densitometry to estimate proteoglycan content. U-Net was trained with 600 annotated Safranin-O cartilage images for exclusion of cells from the cartilage extracellular matrix. Optical densities of the ECM with and without cells were compared as a function of normalized tissue depth.

RESULTS

U-Net cell segmentation was accurate, with the measured cell area fraction following largely that of ground-truth images (average difference: 4.3%). Cell area fraction varied as a function of tissue depth and took up 8-21% of the tissue area. The exclusion of cells from the analysis led to an increase in the analyzed depth-dependent optical density of cartilage by approximately 0.6-1.8% (p < 0.01).

CONCLUSIONS

Although the effect of cells on the analyzed proteoglycan content is small, it should be considered for improved sensitivity, especially at the onset of the disease during which cells may proliferate in small animals.

Senescence-accelerated mice prone 8 (SAMP8) in male as a spontaneous osteoarthritis model

BACKGROUND

Animal models of spontaneous osteoarthritis (OA) are sparse and not well characterized. The purpose of the present study is to examine OA-related changes and mechanisms in senescence-accelerated mouse prone 8 (SAMP8) that displays a phenotype of accelerated aging.  METHODS: Knees of male SAMP8 and SAM-resistant 1 (SAMR1) mice as control from 6 to 33 weeks of age were evaluated by histological grading systems for joint tissues (cartilage, meniscus, synovium, and subchondral bone), and µCT analysis. Gene expression patterns in articular cartilage were analyzed by real-time PCR. Immunohistochemistry was performed for OA-related factors, senescence markers, and apoptosis.

RESULTS

Starting at 14 weeks of age, SAMP8 exhibited mild OA-like changes such as proteoglycan loss and cartilage fibrillation. From 18 to 33 weeks of age, SAMP8 progressed to partial or full-thickness defects with exposure of subchondral bone on the medial tibia and exhibited synovitis. Histological scoring indicated significantly more severe OA in SAMP8 compared with SAMR1 from 14 weeks [median (interquartile range): SAMR1: 0.89 (0.56-1.81) vs SAMP8: 1.78 (1.35-4.62)] to 33 weeks of age [SAMR1: 1.67 (1.61-1.04) vs SAMP8: 13.03 (12.26-13.57)]. Subchondral bone sclerosis in the medial tibia, bone mineral density (BMD) loss of femoral metaphysis, and meniscus degeneration occurred much earlier than the onset of cartilage degeneration in SAMP8 at 14 weeks of age.

CONCLUSIONS

SAMP8 are a spontaneous OA model that is useful for investigating the pathogenesis of primary OA and evaluating therapeutic interventions.

Mesenchymal stem cells-derived microvesicles versus platelet-rich plasma in the treatment of monoiodoacetate-induced temporomandibular joint osteoarthritis in Albino rats

Temporomandibular joint osteoarthritis (TMJ-OA) is a serious disease, designated by severe joint pain and dysfunction. Limitations of current therapeutics have led to an increased interest in regenerative strategies. Recently, the non-surgical treatment of OA has seen increased use of biologic injectable therapies like mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP). Although these biotherapies represent an admirable effort, more studies are necessary to determine their efficacy. Thus, the aim of this study was to assess the curative potential of a single intra-articular injection of bone marrow MSCs-derived microvesicles (BM-MSCs-MVs) versus a single intra-articular injection of PRP in monoiodoacetate (MIA)-induced TMJ-OA model in Albino rats. Forty-eight male rats were used. A single intra-articular unilateral MIA injection was utilized to induce TMJ-OA. One week post induction, rats were sorted into 3 groups (16 rats each): group (I): received no treatment, groups (II) & (III): received BM-MSCs-MVs and PRP respectively. Scarification was done at 2 and 4 weeks from onset of treatment. Histological changes of the condylar TMJ were examined with H&E staining. Expression of IL-1β, TNF-α, NF-κB, MMP-13, MMP-3, and collagen ΙΙ markers was detected using real-time PCR. Histologically, the osteoarthritic group exhibited degenerated condylar tissues which were aggravated at 4 weeks. Oppositely, a marked improvement in the condylar TMJ histology was noticed in both the BM-MSCs-MVs-and PRP-treated groups at both time intervals. Additionally, the treated groups showed a decrease in IL-1β, TNF-α, NF-κB, MMP-13 and MMP-3 and an increase in collagen ΙΙ genes expression in contrast to the untreated group. Moreover, this difference was significant in the BM-MSCs-MVs group as compared to the PRP-treated group. Our results concluded that BM-MSCs-MVs as well as PRP treatments were able to target the key pathological features in OA, mainly inflammation and matrix degradation, and helped in restoring condylar structure in TMJ-OA rat model. However, BM-MSCs-MVs treatment exhibited more efficient therapeutic potential as compared to PRP treatment.

Assessment of the Efficacy of Bone Marrow-Derived Mesenchymal Stem Cells against a Monoiodoacetate-Induced Osteoarthritis Model in Wistar Rats

Osteoarthritis (OA) of the knee is a debilitating condition that can severely limit an individual's mobility and quality of life. This study was designed to evaluate the efficacy of bone marrow-derived mesenchymal stem cell (BM-MSC) treatment in cartilage repair using a rat model of monoiodoacetate- (MIA-) induced knee OA. OA was induced in the knee joint of rats by an intracapsular injection of MIA (2 mg/50 μL) on day zero. The rats were divided into three groups (n = 6): a normal control group, an osteoarthritic control group, and an osteoarthritic group receiving a single intra-articular injection of BM-MSCs (5 × 10⁶ cells/rat). The knee diameter was recorded once per week. By the end of the performed experiment, X-ray imaging and enzyme-linked immunosorbent assay analysis of serum inflammatory cytokines interleukin-1beta (IL-β), IL-6, and tumor necrosis factor-α (TNF-α) and anti-inflammatory cytokines interleukin-10 and transforming growth factor-beta (TGF-β) were carried out. In addition, RT-PCR was used to measure nuclear factor-kappa B (NF-κB), inducible nitric oxide synthase (iNOS), and type II collagen mRNA levels and Western blot analysis was used to determine caspase-3 protein levels in all treated groups. Finally, hematoxylin/and eosin stains were used for histopathological investigation. Administration of BM-MSCs significantly downregulated knee joint swelling and MIA-induced (IL-1β, IL-6, and TNF-α) and upregulated IL-10 and TGF-β as well. Moreover, BM-MSC-treated osteoarthritic rats exhibited decreased expression of NF-κB, iNOS, and apoptotic mediator (caspase-3) and increased expression of type II collagen when compared to rats treated with MIA alone. The hematoxylin/eosin-stained sections revealed that BM-MSC administration ameliorated the knee joint alterations in MIA-injected rats. BM-MSCs could be an effective treatment for inflamed knee joints in the MIA-treated rat model of osteoarthritis, and the effect may be mediated via its anti-inflammatory and antioxidant potential.

Monosodium iodoacetate-induced subchondral bone microstructure and inflammatory changes in an animal model of osteoarthritis

The monosodium iodoacetate (MIA)-induced osteoarthritis (OA) may lead to cartilage degeneration and histopathological lesions. However, the correlation between inflammatory reaction and subchondral bone remodeling in a rodent osteoarthritic model is ambiguous. In this study, intra-articular injection of MIA was performed in 36 four-week-old specific pathogen-free male Wistar rats to induce OA. After 4 weeks of intervention, changes in intrinsic structural properties of the subchondral bones were measured, and the histological evaluation, as well as biochemical analysis, was conducted. We found that intra-articular injection of MIA increased chondrocyte apoptosis and promoted cartilage matrix degradation, such as cartilage surface defects and shallow or disappearing staining. MIA also induced inflammation, improved the expression of IL-1β, TNF-α, and matrix metalloproteinase, and decreased the expression of cartilage-specific proteins with the extension of modeling time. Meanwhile, the MIA also significantly accelerated the subchondral bone remodeling, as shown by the decreased subchondral bone density, thinning of trabeculae, disordered cartilage structure, and morphology. In conclusion, we have shown that MIA-induced rodent osteoarthritic model would cause decreased subchondral bone density, sparse trabecular bone, and other manifestations of osteoporosis accompanied by an inflammatory response, which would worsen with the progression of modeling time. Our results suggest that different phases of MIA-induced OA are associated with the changes in subchondral bone microstructure and the progression of local inflammation.

Transporting Hydrogel via Chinese Acupuncture Needles for Lesion Positioning Therapy

Lesion positioning therapy optimizes medical treatment by directly targeting lesions. However, strong physical barriers greatly hinder its wide use. Here, the Chinese acupuncture needles (CA-needles) with a screw-thread structure at the tip (ST-needle) and the hydrogel with the function of adhesive metal and loaded drug sustained-release structure are designed, through the minimally invasive and precise positioning of lesions by ST-needles, the dry-wet conversion of hydrogel with absorbing fluids and swelling, and the rotation back of ST-needles, the hydrogel is precisely positioned in the subchondral bone with physical barrier to achieve precise positioning therapy for lesions. In vitro experiments show that the ST-needle penetrates the physical barrier of cartilage and enters the subchondral bone. Simultaneously, the hydrogel transfer efficiency of the ST-needle (73.25%) is significantly higher than that of the CA-needle (29.92%) due to the protective effect of the screw-thread structure. In vivo experiments demonstrate that precise positioning in subchondral bone in osteoarthritis rats with ST-needles effectively inhibits abnormal subchondral bone remodeling, alleviating the degeneration and degradation of cartilage. Therefore, ST-needles achieve lesion positioning therapy through minimally invasive penetration of physical barriers, precisely positioning within lesions, and delivering hydrogel to release drugs.

Animal Models of Temporomandibular Joint Osteoarthritis: Classification and Selection

Temporomandibular joint osteoarthritis (TMJOA) is a common degenerative joint disease that can cause severe pain and dysfunction. It has a serious impact on the quality of lives of patients. Since mechanism underlying the pathogenesis of TMJOA is not fully understood, the development of effective tools for early diagnosis and disease-modifying therapies has been hindered. Animal models play a key role in understanding the pathological process of diseases and evaluating new therapeutic interventions. Although some similarities in disease processes between animals and humans are known, no one animal model is sufficient for studying all characteristics of TMJOA, as each model has different translatability to human clinical conditions. For the past 4 decades, TMJOA animal models have been studied by numerous researchers and can be broadly divided into induced, naturally occurring, and genetically modified models. The induced models can be divided into invasive models (intra-articular injection and surgical induction) or non-invasive models (mechanical loading, high-fat diet, and sleep deprivation). Different types of animal models simulate different pathological expressions of TMJOA and have their unique characteristics. Currently, mice, rats, and rabbits are commonly used in the study of TMJOA. This review sought to provide a general description of current experimental models of TMJOA and assist researchers in selecting the most appropriate models for different kinds of research.

Automatic Detection of Medial and Lateral Compartments from Histological Sections of Mouse Knee Joints Using the Single-Shot Multibox Detector Algorithm

OBJECTIVE

Although mouse osteoarthritis (OA) models are widely used, their histological analysis may be susceptible to arbitrariness and inter-examiner variability in conventional methods. Therefore, a method for the unbiased scoring of OA histology is needed. In this study, as the first step for establishing this system, we developed a computer-vision algorithm that automatically detects the medial and lateral compartments of mouse knee sections in a rigorous and unbiased manner.

DESIGN

A total of 706 images of coronal sections of mouse knee joints stained by hematoxylin and eosin, safranin O, or toluidine blue were randomly divided into training and validation images at a ratio of 80:20. A model to detect both compartments automatically was built by machine learning using a single-shot multibox detector (SSD) algorithm with training images. The model was tested to determine whether it could accurately detect both compartments by analyzing the validation images and 52 images of sections stained with Picrosirius red, a method not used for the training images.

RESULTS

The trained model accurately detected both medial and lateral compartments of all 140 validation images regardless of the staining method employed, severity of articular cartilage defects, and the anatomical positions and conditions of the sections. Our model also correctly detected both compartments of 50 of 52 Picrosirius red-stained images.

CONCLUSIONS

By applying deep learning based on the SSD algorithm, we successfully developed a model that detects the locations of the medial and lateral compartments of tissue sections of mouse knee joints with high accuracy.

Osteoarthritis Pain

Joint pain is the hallmark symptom of osteoarthritis (OA) and the main reason for patients to seek medical assistance. OA pain greatly contributes to functional limitations of joints and reduced quality of life. Although several pain-relieving medications are available for OA treatment, the current intervention strategy for OA pain cannot provide satisfactory pain relief, and the chronic use of the drugs for pain management is often associated with significant side effects and toxicities. These observations suggest that the mechanisms of OA-related pain remain undefined. The current review mainly focuses on the characteristics and mechanisms of OA pain. We evaluate pathways associated with OA pain, such as nerve growth factor (NGF)/tropomyosin receptor kinase A (TrkA), calcitonin gene-related peptide (CGRP), C–C motif chemokine ligands 2 (CCL2)/chemokine receptor 2 (CCR2) and tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), the NOD-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3) inflammasome, and the Wnt/β-catenin signaling pathway. In addition, animal models currently used for OA pain studies and emerging preclinical studies are discussed. Understanding the multifactorial components contributing to OA pain could provide novel insights into the development of more specific and effective drugs for OA pain management.

Hedgehog signalling in bone and osteoarthritis: the role of Smoothened and cholesterol

Hedgehog signalling is essential for development, crucial for normal anatomical arrangement and activated during tissue damage repair. Dysregulation of hedgehog signalling is associated with cancer, developmental disorders and other diseases including osteoarthritis (OA). The hedgehog gene was first discovered in Drosophila melanogaster, and the pathway is evolutionarily conserved in most animals. Although there are several hedgehog ligands with different protein expression patterns, they share a common plasma membrane receptor, Patched1 and hedgehog signalling pathway activation is transduced through the G-protein-coupled receptor-like protein Smoothened (SMO) and downstream effectors. Functional assays revealed that activation of SMO is dependent on sterol binding, and cholesterol was observed bound to SMO in crystallography experiments. In vertebrates, hedgehog signalling coordinates endochondral ossification and balances osteoblast and osteoclast activation to maintain homeostasis. A recently discovered mutation of SMO in humans (SMO^R173C ) is predicted to alter cholesterol binding and is associated with a higher risk of hip OA. Functional studies in mice and human tissue analysis provide evidence that hedgehog signalling is pathologically activated in chondrocytes of osteoarthritic cartilage.

Ligamentous injury-induced ankle instability causing posttraumatic osteoarthritis in a mouse model

BACKGROUND

This study aims to explore the relationship between surgically-induced ankle instability and posttraumatic osteoarthritis (PTOA) in a mouse model, and to provide reference for clinical practice.

RESULTS

Ligamentectomy was performed on 24 eight-week-old male C57BL/6 J mice, which were divided into three groups. Both the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) were severed in the CFL + ATFL group, while only the CFL was removed in the CFL group. The SHAM group was set as the blank control group. A wheel-running device was used to accelerate the development of ankle osteoarthritis (OA). Balance measurement, footprint analysis, and histological analysis were used to assess the degree of ankle instability and OA. According to the balance test results, the CFL + ATFL group demonstrated the highest number of slips and the longest crossing beam time at 8 weeks postoperatively. The results of gait analysis exhibited that the CFL + ATFL group had the most significant asymmetry in stride length, stance length, and foot base width compared to the CFL and SHAM groups. The OARSI score of the CFL + ATFL group (16.7 ± 2.18) was also much higher than those of the CFL group (5.1 ± 0.96) and the SHAM group (1.6 ± 1.14).

CONCLUSION

Based on the mouse model, the findings indicate that severe ankle instability has nearly three times the chance to develop into ankle OA compared to moderate ankle instability.

Synovial fluid proteome profile of surgical versus chemical induced osteoarthritis in rabbits

BACKGROUND

Animal models are significant for understanding human osteoarthritis (OA). This study compared the synovial fluid proteomics changes in surgical and chemical induced OA models.

METHODS

Thirty rabbits either had anterior cruciate ligament transection (ACLT) procedure or injected intra-articularly with monosodium iodoacetate (MIA, 8 mg) into the right knee. The joints were anatomically assessed, and the synovial fluid proteins analyzed using two-dimensional polyacrylamide gel electrophoresis (2DGE) and MALDI TOF/TOF mass spectrometry analysis at 4, 8 and 12 weeks. The proteins' upregulation and downregulation were compared with control healthy knees.

RESULTS

Seven proteins (histidine-rich glycoprotein, beta-actin-like protein 2 isoform X1, retinol-binding protein-4, alpha-1-antiproteinase, gelsolin isoform, serotransferrin, immunoglobulin kappa-b4 chain-C-region) were significantly expressed by the surgical induction. They characterized cellular process (27%), organization of cellular components or biogenesis (27%), localization (27%) and biological regulation (18%), which related to synovitis, increased cellularity, and subsequently cartilage damage. Three proteins (apolipoprotein I-IV precursor, serpin peptidase inhibitor and haptoglobin precursor) were significantly modified by the chemical induction. They characterized stimulus responses (23%), immune responses (15%), biological regulations (15%), metabolism (15%), organization of cellular components or biogenesis (8%), cellular process (8%), biological adhesions (8%) and localization (8%), which related to chondrocytes glycolysis/death, neovascularization, subchondral bone necrosis/collapse and inflammation.

CONCLUSIONS

The surgical induced OA model showed a wider range of protein changes, which were most upregulated at week 12. The biological process proteins expressions showed the chemical induced joints had slower OA progression compared to surgical induced joints. The chemical induced OA joints showed early inflammatory changes, which later decreased.

In vivo methodologies to assist preclinical development of topical fixed-dose combinations for pain management

The combination in a fixed dose of two or more active pharmaceutical ingredients in the same pharmaceutical dosage form is an approach that has been used successfully in the treatment of several pathologies, including pain. In the preclinical development of a topical fixed-dose combination product with analgesic and anti-inflammatory activities for pain management, the main objective is to establish the nature of the interaction between the different active pharmaceutical ingredients while obtaining data on the medicinal product safety and efficacy. Despite the improvement of in vitro assays, animal models remain a fundamental strategy to characterise the interaction, efficacy and safety of active pharmaceutical ingredients at the physiological level, which cannot be reached by in vitro assays. Thus, the main goal of this review is to systematise the available animal models to evaluate the efficacy and safety of a new fixed-dose combination product for topical administration indicated for pain management. Particular emphasis is given to animal models that are accepted for regulatory purposes.

Mouse Models of Osteoarthritis: A Summary of Models and Outcomes Assessment

Osteoarthritis (OA) is a multidimensional health problem and a common chronic disease. It has a substantial impact onpatient quality of life and is a common cause of pain and mobility issues in older adults. The functional limitations, lack of curative treatments, and cost to society all demonstrate the need for translational and clinical research. The use of OA models in mice is important for achieving a better understanding of the disease. Models with clinical relevance are needed to achieve 2 main goals: to assess the impact of the OA disease (pain and function) and to study the efficacy of potential treatments. However, few OA models include practical strategies for functional assessment of the mice. OA signs in mice incorporate complex interrelations between pain and dysfunction. The current review provides a comprehensive compilation of mousemodels of OA and animal evaluations that include static and dynamic clinical assessment of the mice, merging evaluationof pain and function by using automatic and noninvasive techniques. These new techniques allow simultaneous recordingof spontaneous activity from thousands of home cages and also monitor environment conditions. Technologies such as videographyand computational approaches can also be used to improve pain assessment in rodents but these new tools must first be validated experimentally. An example of a new tool is the digital ventilated cage, which is an automated home-cage monitor that records spontaneous activity in the cages.

Development of a novel model of intervertebral disc degeneration by the intradiscal application of monosodium iodoacetate (MIA) in rat

BACKGROUND CONTEXT

Low back pain is one of the most common musculoskeletal disorders. Although, the pathology of intervertebral disc (IVD) degeneration has been modeled using various biological methods, these models are inadequate for simulating similar pathologic states in humans.

PURPOSE

This study investigated whether monosodium iodoacetate (MIA) injection into the IVD of rats could generate a reliable model of IVD degeneration.

STUDY DESIGN/SETTINGS

In vivo animal study.

METHODS

MIA was injected into two-disc spaces (L4-5 and L5-6) of Sprague-Dawley rats. Their behaviors were examined by measuring weight load shifts from hind to forefoot, rearing, and von Frey tests. We examined the inhibition of pain behavior through intraperitoneal morphine injection and measured cyclooxygenase-2 (COX-2) and transcription factor nuclear factor-kappa B (NF-κB) levels in the IVD and dorsal root ganglion (DRG) by Western blot. Bone alterations were assessed by microfocus computed tomography (micro-CT), and IVD and/or cartilage changes were evaluated by hematoxylin and eosin and safranin-O staining and inducible nitric oxide synthase (iNOS) immunohistochemistry. The other authors declare no conflicts of interest. This project funded by the Memorial Fund and the National Research Foundation of Korea (NRF).

RESULTS

We observed increased weight load shifts to the forefoot and decreased rearing. Morphine-injected rats showed reduced pain. NF-κB and COX-2 expression increased in the IVD and left and/or right DRG. Micro-CT analyses suggested progressive bone deformation. Histologic examination showed decreased IVD width and nucleus pulposus area. Cartilaginous changes indicated epiphyseal growth plate loss. Finally, iNOS expression was increased in the subchondral endplate.

CONCLUSIONS

These results suggest that low back pain (LBP) models can be developed by MIA injection into the IVDs of rats and that an animal model is useful for exploring degenerative alterations in the affected discs. Therefore, MIA injection may be a useful model for the study of changes in the IVD to elucidate the mechanisms underlying clinical symptoms, such as LBP, in patients with IVD degeneration.

CLINICAL SIGNIFICANCE

This model in which MIA was injected into the disc better represented the human histologic and behavioral characteristics than the existing puncture model.

Imaging Study on Acupuncture Inhibiting Inflammation and Bone Destruction in Knee Osteoarthritis Induced by Monosodium Iodoacetate in Rat Model

Objective

We aim to explore whether acupuncture inhibits inflammation and bone destruction in rat model monosodium iodoacetate (MIA)-induced knee osteoarthritis (KOA) by 18F-fluorodeoxyglucose (18F-FDG) small-animal positron emission tomography (PET) and micro-computed tomography (CT) imaging.

Methods

KOA was induced in rats by intra-articular injection MIA (2 mg/50 μL) through the right knee of the rats. Forty male Sprague Dawley rats weighing 280 to 340 g (12 weeks old) were randomly divided into four groups including Control group, KOA group, KOA plus manual acupuncture group (KOA+MA), KOA plus sham acupuncture group (KOA+SA). The acupuncture treatment lasted for three weeks (one-day rest after six days of treatment). Paw withdrawal threshold test and open-field test were used to assess mechanical allodynia and locomotor activity respectively for once a week. Hematoxylin and eosin (H&E) staining was used to assess the damage of the cartilage, synovium and infrapatellar fat pad (IFP). 18F-FDG PET was performed to quantify joint inflammation. The influence on the subchondral bone in these rats was confirmed by micro-CT.

Results

Mechanical hyperalgesia, joint inflammation, and obvious bone destruction were observed in the KOA group. H&E staining of the knee joint found that manual acupuncture played a protective effect in cartilage, synovium and IFP destruction. However, compared with KOA group, the results in sham acupuncture had no significant difference. After manual acupuncture treatment in KOA rats, inflammation was significantly suppressed shown by 18F-FDG PET imaging. Micro-CT analysis of the knee joint revealed that manual acupuncture protected bone by inhibiting osteophyte development and subchondral bone remodeling.

Conclusion

The results of 18F-FDG PET and micro-CT showed that manual acupuncture inhibited inflammation and bone destruction, which provides reliable evidence for the effectiveness of acupuncture in hindering development of KOA, and provides reliable evidence for clinical application of acupuncture.

A rabbit model to investigate temporomandibular joint osteochondral regeneration

OBJECTIVE

The objective of this study was 2-fold: (1) to describe the rabbit temporomandibular joint (TMJ) anatomy and (2) to provide a detailed, step-by-step description of a minimally invasive approach to perform a standard osteochondral TMJ defect that can be used to investigate the regenerative potential of biomaterials.

STUDY DESIGN

This study was performed in 2 steps. In the first, a total of 8 rabbit carcasses (n = 16 joints) were used to study the normal TMJ anatomy and histology to develop a minimally invasive approach to access the articulating surface of the condyle to perform a standard osteochondral defect. In the second, the surgical procedure was performed in 10 live animals to evaluate the feasibility of the model and to evaluate the regenerative potential of a biodegradable light-cured hydrogel seeded with stem cells (results not shown).

RESULTS

The cartilage of the mandibular condyle showed 4 layers: fibrous, proliferative, hypertrophic, and a zone of calcified cartilage. Positive safranin O staining was observed in the cartilage. The mean duration of the procedure (from incision to last stitch) was 35.5 (±9.21) minutes. All animals survived the procedures without any major complications.

CONCLUSIONS

This animal model represents an easy and nonmorbid surgical approach to rabbit TMJ.

Evaluation of Different Intraarticular Injection Therapies with Gait Analysis in a Rat Osteoarthritis Model

OBJECTIVE

Osteoarthritis (OA) is a degenerative disease that causes serious damage to joints, especially in elderly patients. The aim of study was to demonstrate the effectiveness of intraarticular therapies that are currently used or recently popularized in the treatment of OA.

DESIGN

The baseline values were determined by walking the rats on the CatWalk system. Afterwards, a monosodium iodoacetate (MIA)-induced knee OA model was created with intraarticular MIA, and the rats were walked again on the CatWalk system and post-OA values were recorded. At this stage, the rats were divided into 4 groups, and intraarticular astaxanthin, intraarticular corticosteroid, intraarticular hyaluronic acid, and intraarticular astaxanthin + hyaluronic acid were applied to the groups, respectively. The rats were walked once more and posttreatment values were obtained. Nine different dynamic gait parameters were used in the comparison.

RESULTS

Significant changes were measured in 6 of the 9 dynamic gait parameters after the MIA-induced knee OA model. While the best improvement was observed in run duration (P = 0.0022), stride length (P < 0.0001), and swing speed (P = 0.0355) in the astaxanthin group, the results closest to basal values in paw print length (P < 0.0001), paw print width (P = 0.0101), and paw print area (P = 0.0277) were seen in the astaxanthin + hyaluronic acid group.

CONCLUSION

Astaxanthin gave better outcomes than corticosteroid and hyaluronic acid in both dynamic gait parameters and histological examinations. Intraarticular astaxanthin therapy can be a good alternative to corticosteroid and hyaluronic acid currently used in intraarticular therapy to treat OA.

Analysis of Serum Metabolomics in Rats with Osteoarthritis by Mass Spectrometry

Osteoarthritis is a common multifactorial chronic disease that occurs in articular cartilage, subchondral bone, and periarticular tissue. The pathogenesis of OA is still unclear. To investigate the differences in serum metabolites between OA and the control group, liquid chromatography/mass spectrometry (LC/MS)-based metabolomics was used. To reveal the pathogenesis of OA, 12 SD male rats were randomly divided into control and OA groups using collagenase to induce OA for modeling, and serum was collected 7 days after modeling for testing. The OA group was distinguished from the control group by principal component analysis and orthogonal partial least squares-discriminant analysis, and six biomarkers were finally identified. These biomarkers were metabolized through tryptophan metabolism, glutamate metabolism, nitrogen metabolism, spermidine metabolism, and fatty acid metabolism pathways. The study identified metabolites that may be altered in OA, suggesting a role in OA through relevant metabolic pathways. Metabolomics, as an important tool for studying disease mechanisms, provides useful information for studying the metabolic mechanisms of OA.

A New Method to Develop the Primate Model of Knee Osteoarthritis With Focal Cartilage Defect

Objective: Osteoarthritis (OA) is a common degenerative joint disease, and animal models have proven pivotal in investigating this disease. This study aimed to develop a primate model of OA that may be more relevant to research studies on OA in humans.

Method: Twelve female rhesus macaques were randomly divided into three groups. Four animals were untreated (Control group); four were subjected to the modified Hulth method, involving cutting of the anterior and posterior cruciate ligaments, and transecting the meniscus (Hulth group); and four were subjected to the modified Hulth method combined with cartilage defect (MHCD group). Each primate was subjected to motor ability tests, and underwent arthroscopic, radiographic, morphological, and pathological observation of the knee joints at various times for up to 180 days.

Results: Motor ability on Day 180 was significantly lower in the MHCD group than in the Control (p＜0.01) and Hulth (p＜0.05) groups. Radiographic and morphological examination showed that the severity of knee joint deformity and articular cartilage injury were greater in the MHCD group than in the other groups. Pathological examination showed that cartilage thickness was significantly lower in the MHCD group than in the other groups at the same time points. The Mankin score on Day 180 was markedly higher in the MHCD group than in the Hulth (p＜0.05) and Control (p＜0.001) groups.

Conclusion: The MHCD model of OA closely resembles the pathophysiological processes of spontaneous knee OA in humans. The time required to develop knee OA is shorter using the MHCD model than using the Hulth method.

Models of Osteoarthritis: Relevance and New Insights

Osteoarthritis (OA) is a progressive and disabling musculoskeletal disease affecting millions of people and resulting in major healthcare costs worldwide. It is the most common form of arthritis, characterised by degradation of the articular cartilage, formation of osteophytes, subchondral sclerosis, synovial inflammation and ultimate loss of joint function. Understanding the pathogenesis of OA and its multifactorial aetiology will lead to the development of effective treatments, which are currently lacking. Two-dimensional (2D) in vitro tissue models of OA allow affordable, high-throughput analysis and stringent control over specific variables. However, they are linear in fashion and are not representative of physiological conditions. Recent in vitro studies have adopted three-dimensional (3D) tissue models of OA, which retain the advantages of 2D models and are able to mimic physiological conditions, thereby allowing investigation of additional variables including interactions between the cells and their surrounding extracellular matrix. Numerous spontaneous and induced animal models are used to reproduce the onset and monitor the progression of OA based on the aetiology under investigation. This therefore allows elucidation of the pathogenesis of OA and will ultimately enable the development of novel and specific therapeutic interventions. This review summarises the current understanding of in vitro and in vivo OA models in the context of disease pathophysiology, classification and relevance, thus providing new insights and directions for OA research.

Regenerative Engineering Animal Models for Knee Osteoarthritis

Abstract

Osteoarthritis (OA) of the knee is the most common synovial joint disorder worldwide, with a growing incidence due to increasing rates of obesity and an aging population. A significant amount of research is currently being conducted to further our understanding of the pathophysiology of knee osteoarthritis to design less invasive and more effective treatment options once conservative management has failed. Regenerative engineering techniques have shown promising preclinical results in treating OA due to their innovative approaches and have emerged as a popular area of study. To investigate these therapeutics, animal models of OA have been used in preclinical trials. There are various mechanisms by which OA can be induced in the knee/stifle of animals that are classified by the etiology of the OA that they are designed to recapitulate. Thus, it is essential to utilize the correct animal model in studies that are investigating regenerative engineering techniques for proper translation of efficacy into clinical trials. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering trials and the corresponding classification system.

Lay Summary

Osteoarthritis (OA) of the knee is the most common synovial joint disease worldwide, with high rates of occurrence due to an increase in obesity and an aging population. A great deal of research is currently underway to further our understanding of the causes of osteoarthritis, to design more effective treatments. The emergence of regenerative engineering has provided physicians and investigators with unique opportunities to join ideas in tackling human diseases such as OA. Once the concept is proven to work, the initial procedure for the evaluation of a treatment solution begins with an animal model. Thus, it is essential to utilize a suitable animal model that reflects the particular ailment in regenerative engineering studies for proper translation to human patients as each model has associated advantages and disadvantages. There are various ways by which OA can occur in the knee joint, which are classified according to the particular cause of the OA. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering investigations and the corresponding classification system.

Reduction of knee joint load suppresses cartilage degeneration, osteophyte formation, and synovitis in early-stage osteoarthritis using a post-traumatic rat model

The purpose of this study was to clarify the histological effect of reducing the loading to knee on cartilage degeneration, osteophyte formation, and synovitis in early-stage osteoarthritis (OA) using a post-traumatic rat model. Ten male rats were randomly allocated into two experimental groups: OA induction by surgical destabilization of medial meniscus (DMM, OA group) and hindlimb suspension after OA induction by DMM (OAHS group). The articular cartilage, osteophyte formation, and synovial membrane in the medial tibiofemoral joint were analyzed histologically and histomorphometrically at 2 and 4 weeks after surgery. The histological scores and changes in articular cartilage and osteophyte formation were significantly milder and slower in the OAHS group than in the OA group. At 2 and 4 weeks, there were no significant differences in cartilage thickness and matrix staining intensity between both the groups, but chondrocytes density was significantly lower in the OA group. Synovitis was milder in OAHS group than in OA group at 2 weeks. Reducing knee joint loading inhibited histological OA changes in articular cartilage, osteophyte formation, and synovial inflammation. This result supports the latest clinical guidelines for OA treatment. Further studies using biochemical and mechanical analyses are necessary to elucidate the mechanism underlying delayed OA progression caused by joint-load reduction.

A network pharmacology strategy to investigate the anti-osteoarthritis mechanism of main lignans components of Schisandrae Fructus

Osteoarthritis (OA) is a chronic age-related progressive joint disorder. Degradation of the cartilage extracellular matrix (ECM) is considered a hallmark of OA and may be a target for new therapeutic methods. Schisandrae Fructus (SF) has been shown to be effective in treating OA. The major active components of SF are lignans. However, the targets of SF and the pharmacological mechanisms underlying the effects of SF lignans in the treatment of OA have not been elucidated. Therefore, based on network pharmacology, this research predicted the treatment targets of six lignans in SF, constructed a protein-protein interaction network and identified 15 hub genes in the OA-target protein-protein interaction network. Through Gene Ontology function and pathway analyses, the gene functions of lignans in the treatment of OA were determined. Finally, the anti-OA effects of lignans and underlying mechanisms identified in the network pharmacology analysis were verified by molecular docking, real-time PCR and western blotting in vitro. The biological processes of the genes and proteins targeted by lignans in the treatment of OA included the immune response, inflammatory response, cell signal transduction and phospholipid metabolism. Moreover, 20 metabolic pathways were enriched. Network pharmacology, molecular docking and in vitro and in vivo experimental results revealed that SF, schisanhenol and gamma-schisandrin inhibited EGFR and MAPK14 gene expression by inhibiting SRC gene expression and activity and then decreased MMP 13 and collagen II protein and gene expression. This research provides a basis for further study of the anti-OA effects and mechanisms of SF, schisanhenol and gamma-schisandrin.

Glucosamine and Chondroitin Sulfate: Is There Any Scientific Evidence for Their Effectiveness as Disease-Modifying Drugs in Knee Osteoarthritis Preclinical Studies?-A Systematic Review from 2000 to 2021

Simple Summary

Osteoarthritis is the most common progressive joint disease diagnosed in companion animals and its management continues to be a significant challenge. Nutraceuticals have been widely investigated over the years in the treatment of osteoarthritis and among them, glucosamine and chondroitin sulfate treatments are probably the most common therapies used in veterinary management. However, heterogeneous results were obtained among animal studies and the evidence of their efficacy is still controversial. Animal models have a crucial role in studying the histological changes and evaluating the therapy efficacy of different drugs. Consequently, we consider it may be of interest to evaluate the effectiveness of the most representative nutraceuticals in experimental animal studies of osteoarthritis. In this systematic review, we found a large inconsistency among the experimental protocols, but a positive cartilage response and biochemical modulation were observed in half of the evaluated articles, mainly associated with pre-emptive administrations and with some therapies’ combinations. Even though some of these results were promising, additional data are needed to draw solid conclusions, and further studies evaluating their efficacy in the long term and focusing on other synovial components may be needed to clarify their function.

Abstract

Glucosamine and chondroitin sulfate have been proposed due to their physiological and functional benefits in the management of osteoarthritis in companion animals. However, the scientific evidence for their use is still controversial. The purpose of this review was to critically elucidate the efficacy of these nutraceutical therapies in delaying the progression of osteoarthritis, evaluating their impact on the synovial knee joint tissues and biochemical markers in preclinical studies by systematically reviewing the last two decades of peer-reviewed publications on experimental osteoarthritis. Three databases (PubMed, Scopus and, Web of Science) were screened for eligible studies. Twenty-two articles were included in the review. Preclinical studies showed a great heterogeneity among the experimental designs and their outcomes. Generally, the evaluated nutraceuticals, alone or in combination, did not seem to prevent the subchondral bone changes, the synovial inflammation or the osteophyte formation. However, further experimental studies may be needed to evaluate their effect at those levels. Regarding the cartilage status and biomarkers, positive responses were identified in approximately half of the evaluated articles. Furthermore, beneficial effects were associated with the pre-emptive administrations, higher doses and, multimodality approaches with some combined therapies. However, additional studies in the long term and with good quality and systematic design are required.

Microbiome and osteoarthritis: New insights from animal and human studies

Osteoarthritis (OA) is a common cause of disability, especially among the elderly. With an ageing and increasingly obese population, OA will become more prevalent. Obesity and metabolic syndrome are risk factors for OA and have been implicated in its pathogenesis. The gut microbiome may shed light on this possible common pathogenesis. Recent animal and human studies have gained important insights into the relationship between OA, obesity, and the gut microbiome. Animal studies have demonstrated links between obesity and increased severity of OA and altered gut microbial DNA profile. Use of prebiotics and probiotics in animal trials provides proof-of-concept that interventional options to the gut microbiome can modulate the progression of OA favorably. Current evidence in human studies is limited. Shifts in gut microbial profile and reduced gut microbial diversity have been associated with people with OA, as well as blood and synovial fluid lipopolysaccharide endotoxemia. Linkages between microbiome dysbiosis and host responses may help in the understanding of OA pathogenesis and the discovery of therapeutic targets. This narrative review provides a summary of up-to-date animal and human studies on the gut microbiome and its link with OA.

Sodium Monoiodoacetate Dose-Dependent Changes in Matrix Metalloproteinases and Inflammatory Components as Prognostic Factors for the Progression of Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease that primarily affects people over 65 years old. During OA progression irreversible cartilage, synovial membrane and subchondral bone degradation is observed, which results in the development of difficult-to-treat chronic pain. One of the most important factors in OA progression is joint inflammation. Both proinflammatory and anti-inflammatory factors, as well as extracellular matrix degradation enzymes (matrix metalloproteinases (MMPs), play an important role in disease development. One of the most widely used animal OA models involves an intra-articular injection of sodium monoiodoacetate (MIA) directly into the joint capsule, which results in glycolysis inhibition in chondrocytes and cartilage degeneration. This model mimics the degenerative changes observed in OA patients. However, the dose of MIA varies in the literature, ranging from 0.5 to 4.8 mg. The aim of our study was to characterize grading changes after injection of 1, 2 or 3 mg of MIA at the behavioral and molecular levels over a 28-day period. In the behavioral studies, MIA injection at all doses resulted in a gradual increase in tactile allodynia and resulted in abnormal weight bearing during free walking sequences. At several days post-OA induction, cartilage, synovial membrane and synovial fluid samples were collected, and qPCR and Western blot analyses were performed. We observed significant dose- and time-dependent changes in both gene expression and protein secretion levels. Inflammatory factors (CCL2, CXCL1, IL-1β, COMP) increased at the beginning of the experiment, indicating a transient inflammatory state connected to the MIA injection and, in more severe OA, also in the advanced stages of the disease. Overall, the results in the 1 mg MIA group were not consistently clear, indicating that the lowest tested dose may not be sufficient to induce long-lasting OA-like changes at the molecular level. In the 2 mg MIA group, significant alterations in the measured factors were observed. In the 3 mg MIA group, MMP-2, MMP-3, MMP-9, and MMP-13 levels showed very strong upregulation, which may cause overly strong reactions in animals. Therefore, a dose of 2 mg appears optimal, as it induces significant but not excessive OA-like changes in a rat model.