Anterior Cruciate Ligament Transection Model Research Articles

Assessment of osteoarthritis functional outcomes and intra-articular injection volume in the rat anterior cruciate ligament transection model.

The rat surgical anterior cruciate ligament transection (ACLT) model is commonly used to investigate intra-articular osteoarthritis (OA) therapies,and histological assessment is often the primary outcome measure. However, histological changes do not always correlate well with clinical outcomes. Therefore, this study evaluated functional outcomes in the rat surgical ACLT model and compared intra-articular injection volumes ranging from 20 to 50 μl. Unilateral ACLT was surgically inducedand static weight-bearing, mechanical allodynia, motor function, and gait were assessed in four groups of male, Sprague-Dawley rats (n = 6 per group). Intra-articular injections of 20 µl Dulbecco's phosphate-buffered saline (DPBS), 50 µl DPBS, or 50 µl of synthetic biomimetic boundary lubricant were administered once weekly for 3 weeks postoperatively. Structural changes were evaluated histologically at 20 weeks. Rat cadaver knees were injected with 20, 30, 40, or 50 µl of gadolinium solutions and were imaged using magnetic resonance imaging (MRI). Static weight-bearing, mechanical allodynia, and gait parameters in ACLT groups revealed differences from baseline and naïve controls for 4 weeks post-ACLT; however, these differences did not persist beyond 6 weeks. Different intra-articular DPBS injection volumes did not result in functional or histological changes; however, peri-articular leakage was documented via MRI following 50, 40, and 30 µl but not 20 µl gadolinium injections.Statement of clinical significance:Differences in functional parameters were predominantly restricted to early, postoperative changes in the rat surgical ACLT model despite evidence of moderate histologic OA at 20 weeks. Injection volumes of 20-30 µl are more appropriate for investigating intra-articular therapies in the rat knee.

Abrine promotes cell proliferation and inhibits apoptosis of interleukin-1β-stimulated chondrocytes via PIM2/VEGF signalling in osteoarthritis

BackgroundOsteoarthritis (OA), a common joint disorder with an increasing incidence worldwide, severely affects the quality of life of patients. In Chinese herbal medicine, Abrus cantoniensis Hance is considered to exert protective effects on the liver and to have beneficial effects on the gallbladder; additionally, it has antibacterial and anti-inflammatory properties, as well as the ability to enhance immunity, scavenge free radicals, regulate smooth muscle function, and improve endurance. Abrine extracted from A. cantoniensis Hance has been reported as a main functional compound capable of treating chronic inflammation. PurposeIn this study, we explored the effect of abrine on OA progression. Study DesignBioinformatics analysis was performed on abrine and its potential targets in OA, using the Comparative Toxicogenomics Database, GSE1919 dataset from the Gene Expression Omnibus database, Gene Set Enrichment Analysis, and docking interaction analysis. MethodsThe effect of abrine in vitro was analysed by Cell Counting Kit 8 assays, colony formation assays, enzyme-linked immunosorbent assay, flow cytometry analysis, quantitative real-time PCR, and western blotting using human transformed chondrocyte cell line C28/I2. The effect of abrine was evaluated in vivo using the anterior cruciate ligament transection (ACLT) Sprague-Dawley rat OA model. ResultsAbrine enhanced the proliferation of interleukin (IL)-1β-stimulated C28/I2 cells in a dose-dependant manner. Expression of pro-inflammatory cytokines was induced by IL-1β treatment, whereas abrine treatment repressed the induction of C28/I2 cells in a dose dependant manner (p < 0.05). Abrine induced cell proliferation and inhibited apoptosis in IL-1β-stimulated C28/I2 cells (p < 0.05). Abrine also inhibited Proviral Integrations of Moloney virus 2 (PIM2) expression in IL-1β-stimulated C28/I2 cells (p < 0.05). The expression of vascular endothelial growth factor (VEGF), p-VEGFR2, and p-eNOS was induced by IL-1β treatment in C28/I2 cells, while abrine inhibited this induction in a dose dependant manner. Treatment with abrine decreased the expression levels of PIM2 and VEGF in IL-1β-stimulated C28/I2 cells (p < 0.05). Overexpression of PIM2 induced cell proliferation and inhibited apoptosis in IL-1β-stimulated C28/I2 cells, while VEGF silencing reversed this effect (p < 0.05). Finally, abrine prevented cartilage degradation in the ACLT model. ConclusionWe demonstrated that abrine promoted cell proliferation and inhibited apoptosis in IL-1β-stimulated C28/I2 cells through PIM2/VEGF signalling. These findings indicate PIM2 to be a potential drug target. Moreover, abrine has potential applicability as a therapeutic agent against OA.

The difference in joint instability affects the onset of cartilage degeneration or subchondral bone changes

It has been debated whether the onset of knee osteoarthritis is initiated in cartilage or subchondral bone. The purpose of this study was to clarify the effects of increasing or decreasing joint instability on cartilage degeneration and subchondral bone changes in knee OA by comparing different models of joint instability. We used the anterior cruciate ligament transection (ACL-T) model and the destabilization of the medial meniscus (DMM) model. In addition, we created a controlled abnormal tibial translation (CATT) model and a controlled abnormal tibial rotation (CATR) model. We performed joint instability analysis, micro-computed tomography analysis, histological and immunohistological analysis in 4 and 6 weeks. The CATT group suppressed joint instability in the ACL-T group (6 weeks; P=0.032), and the CATR group suppressed joint instability in the DMM group (6 weeks; P=0.032). Chondrocyte hypertrophy in the ACL-T and DMM groups was increased compared to the Sham group (6 weeks; [ACL-T vs Sham], P=0.002, 95%CI [5.983-33.025]; [DMM vs Sham], P=0.022, 95%CI [1.691-28.733]). In the subchondral bone, the BV/TV in the DMM and CATR groups was increased compared to the ACL-T and CATT groups (6 weeks; [DMM vs ACL-T], P=0.002, 95%CI [7.404-37.582]; [DMM vs CATT], P=0.014, 95%CI [2.881-33.059]; [CATR vs ACL-T], P=0.006, 95%CI [4.615-34.793]; [CATR vs CATT], P=0.048, 95%CI [0.092-30.270]). This study showed that joint instability promotes chondrocyte hypertrophy, but subchondral bone changes were influenced by differences in ACL and meniscus function.

Quantification of Cartilage Surface Degeneration by Curvature Analysis Using 3D Scanning in a Rabbit Model.

Accurate analysis to quantify cartilage morphology is critical for evaluating degenerative conditions in osteoarthritis (OA). Three-dimensional (3D) optical scanning provides 3D data for the entire cartilage surface; however, there is no consensus on how to quantify it. Our purpose was to validate a 3D method for evaluating spatiotemporal alterations in degenerative cartilages in a rabbit OA model by analyzing their curvatures at various stages of progression. Twelve rabbits underwent anterior cruciate ligament transection (ACLT) unilaterally and were divided into 4 groups: 4 weeks control, 4 weeks OA, 8 weeks control, and 8 weeks OA. 3D scanning, India ink staining, and histological assessments were performed in all groups. In 3D curvature visualization, the surfaces of the condyles were divided into 8 areas. The standard deviations (SD) of mean curvatures from all vertices of condylar surfaces and subareas were calculated. Regarding the site of OA change, curvature analysis was consistent with India ink scoring. The SD of mean curvature correlated strongly with the India ink Osteoarthritis Research Society International (OARSI) score. In curvature histograms, the curvature distribution in OA was more scattered than in control. Of the 8 areas, significant OA progression in the posterolateral part of the lateral condyle (L-PL) was observed at 4 weeks. The histology result was consistent with the 3D evaluation in terms of representative section. This study demonstrated that 3D scanning with curvature analysis can quantify the severity of cartilage degeneration objectively. Furthermore, the L-PL was found to be the initial area where OA degeneration occurred in the rabbit ACLT model.

Low-Molecular-Weight Collagen Peptide Ameliorates Osteoarthritis Progression through Promoting Extracellular Matrix Synthesis by Chondrocytes in a Rabbit Anterior Cruciate Ligament Transection Model.

This study examined whether the oral administration of low-molecular-weight collagen peptide (LMCP) containing 3% Gly-Pro-Hyp with >15% tripeptide (Gly-X-Y) content could ameliorate osteoarthritis (OA) progression using a rabbit anterior cruciate ligament transection (ACLT) model of induced OA and chondrocytes isolated from a patient with OA. Oral LMCP administration (100 or 200 mg/kg/day) for 12 weeks ameliorated cartilage damage and reduced the loss of proteoglycan compared to the findings in the ACLT control group, resulting in dose-dependent (p < 0.05) improvements of the OARSI score in hematoxylin & eosin (H&E) and Safranin O staining. In microcomputed tomography analysis, LMCP also significantly (p < 0.05) suppressed the deterioration of the microstructure in tibial subchondral bone during OA progression. The elevation of IL-1βand IL-6 concentrations in synovial fluid following OA induction was dose-dependently (p < 0.05) reduced by LMCP treatment. Furthermore, immunohistochemistry illustrated that LMCP significantly (p < 0.05) upregulated type II collagen and downregulated matrix metalloproteinase-13 in cartilage tissue. Consistent with the in vivo results, LMCP significantly (p < 0.05) increased the mRNA expression of COL2A1 and ACAN in chondrocytes isolated from a patient with OA regardless of the conditions for IL-1βinduction. These findings suggest that LMCP has potential as a therapeutic treatment for OA that stimulates cartilage regeneration.

A low dose cell therapy system for treating osteoarthritis: In vivo study and in vitro mechanistic investigations

Mesenchymal stem cells (MSCs) can be effective in alleviating the progression of osteoarthritis (OA). However, low MSC retention and survival at the injection site frequently require high doses of cells and/or repeated injections, which are not economically viable and create additional risks of complications. In this study, we produced MSC-laden microcarriers in spinner flask culture as cell delivery vehicles. These microcarriers containing a low initial dose of MSCs administered through a single injection in a rat anterior cruciate ligament (ACL) transection model of OA achieved similar reparative effects as repeated high doses of MSCs, as evaluated through imaging and histological analyses. Mechanistic investigations were conducted using a co-culture model involving human primary chondrocytes grown in monolayer, together with MSCs grown either within 3D constructs or as a monolayer. Co-culture supernatants subjected to secretome analysis showed significant decrease of inflammatory factors in the 3D group. RNA-seq of co-cultured MSCs and chondrocytes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed processes relating to early chondrogenesis and increased extracellular matrix interactions in MSCs of the 3D group, as well as phenotypic maintenance in the co-cultured chondrocytes. The cell delivery platform we investigated may be effective in reducing the cell dose and injection frequency required for therapeutic applications.

Differences in the progression of articular cartilage and subchondral bone degeneration between two mouse models

Purpose: Osteoarthritis (OA) of the knee is a common cause of chronic pain and restriction in performing activities of daily living. Whether OA arises from articular cartilage degeneration or subchondral bone degeneration remains unclear. Currently, the anterior cruciate ligament transection (ACL-T) model and the destabilization of the medial meniscus (DMM) model are used as animal models of OA. Studies have shown that OA progresses more slowly in the DMM model than in the ACL-T model. There are few reports directly comparing the two models and no consensus exists about the mechanism of OA in the two models.

Bridge-Enhanced Anterior Cruciate Ligament Repair Leads to Greater Limb Asymmetry and Less Cartilage Damage Than Untreated ACL Transection or ACL Reconstruction in the Porcine Model

Background: The extent of posttraumatic osteoarthritis (PTOA) in the porcine anterior cruciate ligament (ACL) transection model is dependent on the surgical treatment selected. In a previous study, animals treated with bridge-enhanced ACL repair using a tissue-engineered implant developed less PTOA than those treated with ACL reconstruction (ACLR). Alterations in gait, including asymmetric weightbearing and shorter stance times, have been noted in clinical studies of subjects with osteoarthritis. Hypothesis: Animals receiving a surgical treatment that results in less PTOA (ie, bridge-enhanced ACL repair) would exhibit fewer longitudinal postoperative gait asymmetries over a 1-year period when compared with treatments that result in greater PTOA (ie, ACLR and ACL transection). Study Design: Controlled laboratory study. Methods: Thirty-six Yucatan minipigs underwent ACL transection and were randomized to receive (1) no further treatment, (2) ACLR, or (3) bridge-enhanced ACL repair. Gait analyses were performed preoperatively, and at 4, 12, 26, and 52 weeks postoperatively. Macroscopic cartilage assessments were performed at 52 weeks. Results: Knees treated with bridge-enhanced ACL repair had less macroscopic damage in the medial tibial plateau than those treated with ACLR or ACL transection (adjusted P = .03 for both comparisons). The knees treated with bridge-enhanced ACL repair had greater asymmetry in hindlimb maximum force and impulse loading at 52 weeks than the knees treated with ACL transection (adjusted P < .05 for both comparisons). Although not significant, there was a trend that knees treated with bridge-enhanced ACL repair had greater asymmetry in hindlimb maximum force and impulse loading (adjusted P < .10 for both comparisons) compared with ACLR. Conclusion: Contrary to our hypothesis, the surgical treatment resulting in less macroscopic cartilage damage (ie, bridge-enhanced ACL repair) exhibited greater asymmetry in load-related gait parameters than the other surgical groups. This finding suggests that increased offloading of the surgical knee may be associated with a slower rate of PTOA development. Clinical Relevance: Less cartilage damage at 52 weeks was found in the surgical group that continued to protect the limb from full body weight during gait. This finding suggests that protection of the knee from maximum stresses may be important in minimizing the development of PTOA in the ACL-injured knee within 1 year.

Regulation of inflammatory and catabolic responses to IL-1β in rat articular chondrocytes by microRNAs miR-122 and miR-451

miR-122 stimulates proliferation of growth plate chondrocytes whereas miR-451 stimulates terminal differentiation and matrix turnover. Here, we examined the potential of these microRNA as regulators of articular chondrocytes using an in vitro model of osteoarthritis. miR-122 and miR-451 presence in rat articular cartilage was assessed using the anterior cruciate ligament transection model of OA. In vitro testing used first passage rat articular chondrocytes (rArCs) that were transfected with lipofectamine (Lipo) and miR-122 or miR-451 for 24-h, then treated with 10ng/mL IL-1β in order to mimic an osteoarthritic environment. Conditioned media were collected and MMP13, PGE2 and OA-related cytokines were measured. Matrix vesicles were collected from cell layer lysates using ultra-centrifugation. Cells were treated with miR-122 or miR-451 inhibitors to verify miR-specific effects. Both miR-122 and miR-451 were increased in the OA articular cartilage compared to healthy tissue; rArCs expressed both microRNAs in MVs. miR-122 prevented IL-1β-dependent increases in MMP-13 and PGE2, whereas miR-451 significantly increased the IL-1β effect. Multiplex data indicated that miR-122 reduced the stimulatory effect of IL-1β on IL-1α, IL-2, Il-4, IL-6, GM-CSF, MIP-1A, RANTES and VEGF. In contrast, IL-2, IL-4, IL-6, GM-CSF, and MIP-1A were increased by miR-451 while VEGF was decreased. Inhibiting miR-122 exacerbated the response to IL-1β indicating endogenous levels of miR-122 were present. There were no differences in MMP-13 or PGE2 with miR-451 Locked Nucleic Acid (LNA) inhibitor treatment. Both miRs were elevated in OA in a rat bilateral anterior cruciate ligament transection (ACLT) model. miR-122 prevented, while miR-451 exacerbated the effects of IL-1β on rArCs.

Experimental animal models of post-traumatic osteoarthritis of the knee.

Due to the complex and dynamic nature of osteoarthritis (OA) and post-traumatic osteoarthritis (PTOA), animal models have been used to investigate the progression and pathogenesis of the disease. Researchers have used different experimental models to study OA and PTOA. With an emphasis on the knee joint, this review will compare and contrast the existing body of knowledge from anterior cruciate ligament transection models, meniscectomy models, combination models, as well as impact models in large animals to see how tissues respond to these different approaches to induce experimental OA and PTOA. The tissues discussed will include articular cartilage and the meniscus, with a focus on morphological, mechanical and histological assessments. The goal of this review is to demonstrate the progressive nature of OA by indicating the strong correlation between progressive tissue degeneration, change of mechanical properties, and loss of biochemical integrity and to highlight key differences between the most commonly used experimental animal models.

Disturbances in Metabolic Pathways and the Identification of a Potential Biomarker Panel for Early Cartilage Degeneration in a Rabbit Anterior Cruciate Ligament Transection Model.

This study aimed to assess the association between synovial fluid (SF) metabolites and magnetic resonance imaging (MRI) measurements of cartilage biochemical composition to identify potential SF biomarkers for detecting the early onset of cartilage degeneration in a rabbit model. Both knees of 12 New Zealand White rabbits were used. The anterior cruciate ligament transection (ACLT) model was performed on right knees, and the sham surgery on left knees. MRI UTE-T2* scanning and SF sample collection were performed on ACLT knees at 4 and 8 weeks postsurgery and on sham surgery knees at 4 weeks postsurgery. Ultra-performance liquid chromatography-mass spectrometry and multivariate statistical analysis were used to distinguish samples in three groups. Pathway and receiver operating characteristic analyses were utilized to identify potential metabolite biomarkers. There were 12 knees in sham surgery models, 11 in ACLT models at 4 weeks postsurgery, and 10 in ACLT models at 8 weeks postsurgery. UTE-T2* values for the lateral tibia cartilage showed significant decreases over the study period. Levels of 103 identified metabolites in SF were markedly different among three groups. Furthermore, 24 metabolites were inversely correlated with UTE-T2* values of the lateral tibia cartilage, while hippuric acid was positively correlated with UTE-T2* values of the lateral tibia cartilage. Among 25 potential markers, N1-acetylspermidine, 2-amino-1,3,4-octadecanetriol, l-phenylalanine, 5-hydroxy-l-tryptophan, and l-tryptophan were identified as potential biomarkers with high area under the curve values and Pearson correlation coefficients. Five differential metabolites in SF were found as potential biomarkers for the early detection of cartilage degeneration in the rabbit ACLT model.

Deep learning-based segmentation from histology allows for automated quantification of calcified cartilage morphology in a rabbit model of post-traumatic osteoarthritis

Purpose: Calcified cartilage (CC) undergoes constant remodeling due to two competing events: 1) mineralization of the deep non-calcified cartilage that advances the tidemark, and 2) new bone formation through endochondral ossification that advances the cement line. However, CC modifications in the presence of osteoarthritis (OA) progression are not well understood. In this study, we investigate CC morphology during OA progression and aging in the rabbit anterior cruciate ligament transection (ACLT) model.

Effect of joint instability on bone-cartilage degeneration in destabilization of the medial meniscus model

Purpose: Osteoarthritis (OA) of the knee is a common cause of chronic pain and restriction in performing activities of daily living. Globally, OA affects more than 100 million people. Although the cause of OA is still unclear, mechanical stress and joint instability are the main causes of OA. Currently, anterior cruciate ligament transection (ACLT) model and destabilization of the medial meniscus (DMM) model are used as OA animal models. In addition, our laboratory has established the controlled abnormal joint movement (CAJM) model that suppresses abnormal joint movement in rat and mouse ACLT models (Kokubun et al.

Impact of controlling abnormal joint movement on the effectiveness of subsequent exercise intervention in mouse model of early knee osteoarthritis

Purpose: Moderate mechanical stress is necessary for preserving the cartilage. Recent evidence from animal models of surgically induced OA indicates that the progression of cartilage degeneration can be delayed by moderate exercise. On the other hand, joint instability induces excessive mechanical stress contributes to OA onset and progression. The anterior cruciate ligament transection (ACL-T) model, which is a commonly used animal model of surgically induced OA. In contrast, the controlled abnormal joint movement (CAJM) model, proposed by (Murata et al. 2017) and (Onitsuka et al. 2018) involves ACL-T followed by another surgical procedure to re-stabilize the joint and reduce joint instability. In the CAJM model, the expression of inflammatory factors and cartilage matrix degrading factors is suppressed, joint instability is reduced, and progression to OA is slower. We hypothesized that exercise intervention is more effective at preventing the degeneration of articular cartilage in knee OA if joint instability is controlled. Methods: This study used 28 adults (12-week-old) ICR male mice. The mice were divided into 4 experimental groups: ACL-T without exercise intervention, CAJM without exercise intervention, ACL-T with exercise intervention (ACL-T/Ex), and CAJM with exercise intervention (CAJM/Ex). For mice assigned to CAJM groups, a 25-gauge needle was used to create bone tunnels in the anterior portion of the proximal tibia and in the posterior portion of the femoral condyle in order to decrease the anterior translation of the tibia onto the femur. Subsequently, 4-0 nylon thread was passed through the bone tunnels to compensate for ACL function and help control the anterior translation of the tibia. To assess knee joint instability, the anterior drawer test was performed using a constant force spring (0.05 kgf; Sanko Spring Co., Ltd., Fukuoka, Japan) and a soft X-ray device (M-60; Softex Co., Ltd., Kanagawa, Japan). Mice allocated to the exercise groups (ACL-T/Ex and CAJM/Ex) were exercised on a rodent treadmill, were exercised on the treadmill at a constant speed of 18 m/min for 30 min/d, 3 d/wk, for 4 weeks. Thin sections (7 μm) were cut in the sagittal plane, stained with safranin-O/fast green, and subjected to histology evaluation to estimate the degree of cartilage damage. Two independent observers (T Kano and KO) per- formed OARSI scoring on a scale of 8 stages (0, 0.5, 1-6), and the average value was retained. To evaluate the expression of IL-1βand MMP-13, we performed immuno- histochemical staining using the avidin-biotinylated enzyme complex method. For analysis, we calculated the ratio between the number of IL-1β- or MMP-13-positive cells and the number of chondrocytes in an articular cartilage area of 10000 μm2 (100 μm × 100 μm). Results: Joint instability was quantified using X-ray radiography with the anterior drawer test (Fig. 1A).Compared with the ACL-T and ACL-T/Ex groups, the CAJM and CAJM/Ex groups had significantly lower anterior displacement of the tibia (p<0.05) (Fig. 1B).In the ACL-T/Ex group, marked surface fibrillation and reduction in cartilage thickness were noted in the posterior part of the articular cartilage, together with a significantly higher OARSI score than that noted for the other 3 groups (p<0.001) (Fig. 2). With regard to inflammation, IL-1β-positive cells were confirmed from the cartilage surface layer to the deep layer in the ACL-T, CAJM, and ACL-T/Ex groups but not in the CAJM/Ex group (Fig. 3A). The percentage of IL-1β- positive cells in the anterior part of the cartilage was significantly higher in the ACL-T and ACL-T/Ex groups than in the CAJM/Ex group, the percentage of IL-1β-positive cells in the posterior part of the cartilage was significantly higher for the ACL-T and ACL-T/Ex groups than for the CAJM/Ex group (p<0.05) (Fig. 3B). Similarly, MMP-13-positive cells were confirmed in the ACL-T and ACL-T/Ex groups, compared with very weak MMP-13 expression in the CAJM and CAJM/Ex groups (Fig. 3A). However, while no significant difference among the four groups was noted in terms of the percentage of MMP-13-positive cells in the anterior part of the cartilage, the percentage of MMP-13-positive cells in the posterior part of the cartilage was significantly higher for the ACL-T/Ex group than for the CAJM/Ex group (p=0.02) (Fig. 3C). Conclusions: Previous studies reported that exercise alone could delay the progress of OA. However, our present Results indicate that the internal environment of the joint strongly modulates the effect of exercise, sometimes completely canceling the benefit. In other words, when prescribing exercise, we need to consider the internal environment of the knee joint.In the clinical setting, these findings may trans- late in the need to consider an intervention to correct abnormal joint movement before prescribing physical exercise in the treatment of OA.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Shea Nut Oil Extracts Enhance the Intra-Articular Sodium Hyaluronate Effectiveness on Surgically Induced OA Progression in Rats.

Osteoarthritis (OA) progression is associated with joint pain and stiffness. Intra-articular hyaluronic acid (IAHA) injection in knee OA restores the viscoelasticity of the joint and prevents cartilage damage. Shea nut oil extract (SNO) was shown to provide chondroprotection on surgically-induced OA progression in rats. Here we aim to examine IAHA injection supplemented with SNO diet for a synergetic evaluation on the disease progression in OA rats. We employed an anterior cruciate ligament transection plus medial meniscectomy-induced knee OA rat model with up to 12 weeks of sign/behavior observation (knee width, weight-bearing) and histological assessments of joint damage. We found both IAHA and SNO alone significantly attenuated histological changes of cartilage degeneration and synovial reactions in these knee OA rats. Nonetheless, oral SNO alone mitigated OA pain and inflammation while IAHA alone had no significant impact on the weight-bearing test and knee joint swelling. Moreover, with IAHA-treated rats fed with oral SNO diet, additional anti-inflammatory and anti-nociceptive effects were found, which further enhanced and maintained IAHA protection. Given the differential phenotype of oral SNO vs. IAHA, a regimen of IAHA coupled with SNO supplement provides a long-term effect of IAHA treatment. Taken together, the SNO supplement can be safely used as an adjuvant diet for chronic symptomatic relief of OA coupled with IAHA management.

Comparison between two rabbit models of posttraumatic osteoarthritis: A longitudinal tear in the medial meniscus and anterior cruciate ligament transection

Animal osteoarthritis (OA) models have been developed to understand OA progression and evaluate new OA therapies. However, individual variations in joint lesions remain a critical problem in most current OA models. We established a novel rabbit model by creating a longitudinal tear in the medial meniscus body that was reproducible and similar to posttraumatic biomechanical disturbances in human OA. New Zealand rabbits underwent surgery and were assessed for 9 weeks. The rabbits were randomized into the sham control, medial meniscal tear (MMT), and anterior cruciate ligament transection (ACLT) groups. The animals were sacrificed at 4, 6, and 9 weeks posttreatment. The knee joints were harvested for histological and gene expression assessments. Both the MMT and ACLT procedures led to time-dependent degenerative changes in the femoral condyle cartilage. At each time point, the MMT group cartilage showed more severe degenerative changes than did the ACLT group cartilage. Consistently, inflammatory cytokine and catabolic gene expression were significantly higher, and anabolic gene expression was significantly lower in the MMT group than in the ACLT group. MMT treatment caused more severe structural damage to the cartilage and higher catabolic gene expression levels than the ACLT model at each time point. The MMT model may be highly beneficial in investigating posttraumatic OA (PTOA) development, especially PTOA from a meniscal injury. The MMT model replicated key features of human PTOA, including meniscal lesions, inflammatory responses, and the progression to osteoarthritic cartilage degeneration, thereby providing an exciting new avenue for translating promising treatments to clinical practice.

Chondro-protective effects of celastrol on osteoarthritis through autophagy activation and NF-κB signaling pathway inhibition.

Osteoarthritis (OA) is a degenerative articular cartilage disease accompanied by superfluous apoptosis of chondrocytes in the elderly. Celastrol is a potent bioactive medicine which can exert anti-inflammatory and anti-oxidative effects in various diseases. This study aimed to elucidate the possible role of celastrol in OA as well as the specific mechanism of celastrol in vitro and in vivo. Autophagy-related biomarkers and apoptotic molecules were evaluated by PCR, Western blot and immunofluorescence staining. The level of autophagy was assessed by MDC staining and transmission electron microscopy. To study the downstream signaling pathway, nuclear factor kappa B (NF-κB) signaling pathway-related proteins were examined by Western blot. Moreover, an anterior cruciate ligament transection (ACLT) rat model was established to observe the protective effect of celastrol on rat cartilage. We found celastrol ameliorated IL-1β-induced chondrocyte apoptosis and increased the expression of LC3-II and Beclin-1. In addition, the suppression of celastrol-induced autophagy by 3-methyladenine (3MA) prevented the protective effect of celastrol in chondrocytes. Moreover, celastrol decreased the IL-1β-stimulated phosphorylation degree of IκBα and P65. We also found PDTC (a known NF-κB pathway inhibitor) can promote the activation of autophagy and attenuate the apoptosis of chondrocytes. Meanwhile, the results of rat ACLT model revealed the same effect as in vitro experiments. In summary, celastrol protected against chondrocyte apoptosis by promoting autophagy and inhibiting NF-κB signaling pathway in vitro and in vivo.

Increasing Concentration of Sinovial: Effect on Cartilage Protection in a Rabbit ACLT Model.

This study aimed to test the hypothesis that administration of increasing doses of Sinovial (hyaluronic acid [HA]), would exhibit a dose-dependent effect on the prevention of cartilage degradation, without local and systemic toxicity. Twenty-seven adult rabbits were subjected to anterior cruciate ligament transection (ACLT). Two Sinovial products containing HA concentrations of 1.6% and 2.4% were used as active treatment, and 0.9% saline was used as control and injected intra-articularly 7 days post ACLT. Radiographs were taken prior to surgery, at injection and sacrifice times. After euthanasia, 8 weeks postsurgery, knee joints were observed macroscopically using India ink staining with OARSI (Osteoarthritis Research Society International) scoring and histologically using modified Mankin scoring. The synovial membranes were analyzed using Cake classification. No intraoperative complications were observed. One week postinjection, 4 animals in the HA 2.4% group developed subcutaneous nodules that disappeared spontaneously. No inflammation of the synovial membrane was ever observed. The control group exhibited the maximum uptake of India ink 2.22 ± 0.14. HA groups exhibited a dose-dependent (P = 0.02) reduction in India ink uptake: 1.75 ± 0.17 for HA 1.6% and 1.58 ± 0.14 for HA 2.4%. The most marked dose-dependent effect of this study was a reduction of modified Mankin score for HA groups, with the 2.4% treatment achieving a statistically significant improvement as compared with the control group (7.19 ± 0.85 for saline, 4.65 ± 0.66 for HA 1.6%, and 3.53 ± 0.59 for HA 2.4%; P = 0.005). A dose-dependent protective effect on cartilage was observed after injection of both HA solutions.

Effect of Lubricin Mimetics on the Inhibition of Osteoarthritis in a Rat Anterior Cruciate Ligament Transection Model

Background: Lubricin, a mucinous glycoprotein, plays a chondroprotective role as a constituent of synovial fluid. Structural analogs have been synthesized to mimic the structure and function of native lubricin in an effort to recapitulate this effect with the goal of delaying progression of osteoarthritis (OA). Purpose: To investigate the efficacy of intra-articular injections of lubricin mimetics in slowing or preventing the progression of posttraumatic OA by using a rat anterior cruciate ligament transection model. Study Design: Controlled laboratory design. Methods: Four lubricin mimetics were investigated, differing from one another in their binding orientations and steric interactions. Eighty skeletally mature Sprague-Dawley rats underwent bilateral anterior cruciate ligament transections and were randomly allocated to receive intra-articular injections (50 µL/injection) of 1 of the 4 mimetics in the right knee and equal volumes of saline injection in the contralateral knee (control). All rats were euthanized 8 weeks postoperatively and assessed via biomechanical analysis, which evaluated comparative friction coefficients across the 4 groups, and histological evaluation of articular cartilage, osteophytes, and synovitis. The Osteoarthritis Research Society International (OARSI) histopathological assessment system was used to evaluate the degree of articular cartilage degeneration and osteophytes, while synovitis was assessed through a semiquantitative scoring system. Binding efficacy of the 4 mimetics was assessed in vitro and in vivo through the immunohistochemical localization of polyethylene glycol. Articular cartilage degeneration and synovitis scoring data analyses were performed with generalized estimating equation modeling. Results: Injection of the group 3 mimetic (random 24 + 400 + 30) directly correlated with improved OARSI scores for femoral articular cartilage degeneration when compared with saline-injected contralateral control knees (P = .0410). No lubricin mimetic group demonstrated statistically significant differences in OARSI scores for tibial articular cartilage degeneration. Injection of the group 4 mimetic (AB 24 + 400 + 30) led to a statistically significant difference in osteophyte OARSI score (P = .0019). None of the 4 lubricin mimetics injections incited an additive synovial inflammatory response. Immunohistochemical staining substantiated the binding capacity of all 4 mimetics, while in vivo experimentation revealed that the group 1 and 3 mimetics were still retained within the joint 4 weeks after injection. There were no differences in friction coefficients between any pair of groups and no significant trends based on lubricin mimetic structure. Conclusion: We demonstrated that the tribosupplementation of a traumatically injured knee with a specific lubricin structural analog may attenuate the natural progression of OA. Clinical Relevance: The current lack of efficacious clinical options to counter the onset and subsequent development of OA suggests that further investigation into the synthesis and behavior of lubricin analogs could yield novel translational applications.

Increased elastic modulus of the synovial membrane in a rat ACLT model of osteoarthritis revealed by atomic force microscopy.

This study aimed to explore changes in nanoscale elastic modulus of the synovium using atomic force microscopy (AFM) in addition to investigate changes in synovial histomorphology and secretory function in osteoarthritis (OA) in a rat anterior cruciate ligament transection (ACLT) model. Sprague-Dawley rats were randomly assigned to sham control and ACLT OA groups. All right knee joints were harvested at 4, 8, or 12 weeks (W) after surgery for histological assessment of cartilage damage and synovitis in both the anterior and posterior capsules. AFM imaging and nanoscale biomechanical testing were conducted to measure the elastic modulus of the synovial collagen fibrils. Immunohistochemistry was used to visualize the expression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase-3 (MMP-3) in the synovium. The OA groups exhibited progressive development of disease in the cartilage and synovium. Histopathological scores of the synovium in the OA groups increased gradually. Significant differences were observed between all OA groups except for the posterior 4W group. The synovial fibril arrangement in all OA groups was significantly disordered. The synovial fibrils in all ACLT OA groups at each time point were stiffer than those in the sham controls. OA rats displayed a significantly higher expression of IL-1β and MMP3 in the anterior capsule. In summary, synovial stiffening was closely associated with joint degeneration and might be a factor contributing to synovitis and increased production of proinflammatory mediators. Our data provided insights into the role of synovitis, particularly stiffening of the synovium, in OA pathogenesis.