A new model of osteoarthritis in rabbits. I. Development of knee joint pathology following lateral meniscectomy and section of the fibular collateral and sesamoid ligaments

High-resolution magnetic resonance imaging can predict osteoarthritic progression after medial meniscus posterior root injury: randomized in vivo experimental study in a rabbit model

IMPORTANCE

The field of meniscal root preservation has undergone significant advancement over the past decades; however, the challenge remains to fully understand whether meniscal root repair can ultimately arrest or delay osteoarthritic changes.

OBJECTIVE

To assess longitudinal changes in articular cartilage, subchondral bone, and progression to meniscal extrusion (ME) using high-resolution magnetic resonance imaging (MRI).

METHODS

Medial meniscus posterior root tear was surgically induced in 39 New Zealand white rabbits. Animals were randomly assigned into three experimental groups: partial meniscectomy after root tear (PM, n ​= ​13); root tear left in situ (CT, n ​= ​13); and transtibial root repair (RR, n ​= ​13). Contralateral limbs were used as healthy controls. High resolution 4.7 Tesla MRI of the knee joint was performed at baseline, after 2-, and 4-months of post-surgery. Cartilage thickness was calculated in medial and lateral compartments. In addition, the evaluation of ME, subchondral bone edema and healing potential after root repair were assessed too.

RESULTS

Progressive cartilage thinning, ME, and subchondral bone edema were evident in all 3 study groups after 4-months of follow-up. The mean cartilage thickness in the PM group was 0.53 ​mm (±0.050), 0.57 ​mm (±0.05) in the CT group, and 0.60 ​mm (±0.08) in the RR group. The PM group exhibited significantly higher cartilage loss when compared to the CT and RR groups (p ​< ​0.001). Moreover, progressive ME and subchondral bone edema were associated with a more severe cartilage loss at the final follow-up.

CONCLUSION

Meniscal root repair did not halt but rather reduced the progression of osteoarthritis (OA). Degenerative changes worsened at a rapid rate in the PM group compared to the RR and CT groups. Early cartilage swelling, persistent subchondral edema, and progressive ME predicted a more severe progression to knee OA in the CT and RR groups.

LEVEL OF EVIDENCE

II.

Comparison of Resorption in Autogenous Dorsal Onlay Cartilage Grafts: An Experimental Study

OBJECTIVES

The present study was designed to compare the graft resorption characteristics of autogenous cartilage from the septum, auricle, and costal in the superficial muscular aponeurotic system of the nasal dorsum of the rabbit model.

METHODS

Equal-sized perichondrium-free septal, auricular, and costal cartilage grafts were collected from fifteen New Zealand white rabbits. Cartilage grafts were taken at the scale of two grafts from each animal's ear, two from its costal part, and one from its septum. Costal cartilage grafts that were shaped with a micro-motor device and monopolar electrocautery, elastic cartilage grafts that were shaped with a micro-motor device and monopolar electrocautery, and septal cartilage grafts that were shaped with a scalpel were all implanted into the dorsum of rabbit's noses to create five groups. All autogenous cartilage tissues were removed 3 months later. Cartilages were evaluated for histological features, graft mass, and chondrocyte density resorption.

RESULTS

The elastic cartilage group, where electrocautery was used to shape the cartilage, had a higher resorption score than the other groups. The costal cartilage graft shaped with a micro-motor was also observed to have the best cartilage regeneration score.

CONCLUSION

We observed that the resorption of costal cartilage was lower than that of ear and septum cartilage. It was determined that micro-motor application for the shaping process caused less resorption and stimulated more regeneration than cautery application.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Medial Meniscus Posterior Root Repair Reduces but Does Not Avoid Histologic Progression of Osteoarthritis: Randomized In Vivo Experimental Study in a Rabbit Model

BACKGROUND

The optimal treatment option for meniscus root tears is still challenging, and whether the meniscus root repair ultimately can arrest or delay osteoarthritic changes is still a concern.

PURPOSE/HYPOTHESIS

The purpose of this study was 2-fold: (1) to describe and compare histopathologic findings of 3 different therapeutic options for medial meniscus posterior root tear: nonoperative management, partial meniscectomy, and meniscus root repair; and (2) to test the hypothesis that meniscus root tears treated nonoperatively predispose to a lower risk of osteoarthritic progression compared with partial meniscectomy.

STUDY DESIGN

Controlled laboratory study.

METHODS

Posteromedial meniscus root tears were carried out in 39 New Zealand White rabbits. Animals were randomly assigned into 3 experimental groups: partial meniscectomy after root tear (PM; n = 13), root tears treated conservatively (CT; n = 13), and transtibial root repair (RR; n = 13). Contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro- and microscopic assessment to detect signs of early osteoarthritis (OA). Each sample was histopathologically assessed using the Osteoarthritis Research Society International grading and staging system.

RESULTS

Osteoarthritic changes were the hallmark in all 3 experimental groups. The RR group had the lowest scores for cartilage damage (mean, 2.5; range, 2-3), and the PM group exhibited higher and more severe signs of OA (mean, 16; range, 9-16) compared with the CT group (mean, 5; range, 4-6). The between-group comparison revealed significant differences, as the PM group showed a significantly higher rate of macro- and microscopic osteoarthritic changes compared with the RR (P < .001) and CT (P < .001) groups. The weightbearing area of the medial femoral condyle was the most severely affected, and tidemark disruption was evident in all tissue samples.

CONCLUSION

Meniscus root repair cannot completely arrest the histopathologic progression of knee OA but leads to significantly less severe degenerative changes than partial meniscectomy and nonoperative treatment. Partial meniscectomy leads to the most severe osteoarthritic progression, while stable radial tears left in situ have lower progression compared with partial meniscectomy.

CLINICAL RELEVANCE

Histologic assessment is an essential tool and metric for guiding and understanding osteoarthritic features, providing insight into the disease development and progression. This study provides histopathologic evidence on osteoarthritic progression after medial meniscus posterior root repair. This knowledge can help to set more realistic expectations and can lead to the future development of augmented techniques.

Synergistic prevention and reparative effects of sesquiterpene farnesol in a rabbit model of surgical resection-induced osteoarthritis

Articular cartilage may regenerate poorly after injury or during aging. In vitro, farnesol can modulate extracellular matrix synthesis and restore chondrocyte phenotypes by increasing type II collagen (COL II) and glycosaminoglycan (GAG) production. Here, we evaluated farnesol's preventive and reparative effects against osteoarthritis (OA) in vivo. We induced OA in rabbits through resection of the lateral collateral ligament and meniscus. After 2 weeks, the affected limb was treated with 0.5 ml of 0.4 mM farnesol, hyaluronan (HA) nanoparticle-encapsulated 0.8 mM farnesol (Farn/HA), or HA nanoparticles intra-articularly. After 2 and 6 treatment weeks, synovial inflammatory cytokine levels were analyzed. We also removed the entire joint cartilage from lateral femoral condyles for histological investigation. The half-maximum inhibitory concentration of farnesol was 0.5 mM. Farn/HA had relatively low cytotoxicity showing cells remained viable after being treated with 1 mM a concentration Farn/HA. Untreated lateral condyle exhibited extensive wear. By contrast, 0.4 mM farnesol or 0.8 mM Farn/HA led to a relatively transparent and bright appearance. After 2 and 6 treatment weeks, farnesol, particularly 0.8 mM Farn/HA, reduced matrix metalloproteinase 1 and 13 levels considerably. Therefore, 0.8 mM Farn/HA, which enabled slow drug release, demonstrated the highest anti-inflammatory and OA preventive effects. After 6 treatment weeks, farnesol also promoted COL II and GAG synthesis and, thus, aided healing.

Which part of the blood in the knee joint is responsible for its detrimental effects? (An experimental study on the knee joint in rabbits)

AIM

This study aims to determine the potential causative elements which are responsible for the cartilage damage in case of frequent intra-articular bleeding and to evaluate the effects of intra-articular free iron and chelation of iron in the knee joint.

METHODS

Thirty-five New Zealand rabbits were randomly divided into five groups according to substances injected into their knee joints. Plasma (group I) and cellular components (group II) of the blood harvested from the rabbits, iron (ferric hydroxide sucrose) (group III), iron&chelator (group IV) and only chelator (deferoxamine mesylate) (group V) were injected into their right knees three times a week for 12 weeks. The joint surface was examined histologically according to the classification system modified from Colombo et al. The changes in the synovial tissue were evaluated according to the scoring system modified from Madhok et al.

RESULTS

Cartilage and synovial abnormality scores were significantly higher in all study groups when compared to their own controls (p < 0.0001). Cartilage scores of groups I and V were significantly lower when compared to groups III and IV (p = 0.002 for group I and p = 0.003 for group V). Synovial abnormality score of group I was significantly lower than scores of groups III and IV (p = 0.001); and of group V lower than groups III and IV (p = 0.003 and p = 0.001, respectively).

CONCLUSIONS

All substances tested in this study caused a certain amount of damage in the cartilage tissue and led to synovial abnormalities. Both iron and iron&chelator caused more damage in the cartilage and led to more advanced synovial changes when compared to the plasma component of blood and chelator itself. Influence of iron and iron&chelators were found to be similar showing that chelation was inadequate in antagonizing the detrimental effects of iron.

Developing an experimental model of early knee osteoarthritis after medial meniscus posterior root release: an in vivo study

Purpose

To develop a predictable and reproducible model of knee osteoarthritis after medial meniscus posterior root release.

Methods

Posteromedial meniscal root tears were created in 12 White New Zealand rabbit knees. The contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro and microscopic analyses to detect signs of early degeneration. Clinical evaluation of the weight-bearing status on the affected knee was conducted at 0-, 4-, 8-, and 16-weeks postoperatively.

Results

Early and severe osteoarthritic changes were the hallmark and the main findings after 16-weeks post-surgery. Macroscopically, extensive osteoarthritic changes were observed across the femoral condyle and tibial plateau. Microscopic finding included ulcerations, fissures, fibrillations, pitting, and loss of the superficial layer. Cellularity was diminished, the normal pattern of distribution in columns was lost, and subchondral bone exposure was also evident.

Conclusions

This study describes a novel model of knee osteoarthritis that may guide the development of tailored interventions to delay or prevent knee osteoarthritis. This knowledge could shift the current treatment paradigm toward more conservative and knee salvageable treatment options and increase surgeons’ awareness of this injury pattern. Such considerations may have a positive impact on clinical decision-making and subsequent patient-reported clinical outcomes.

Design

Controlled laboratory study.

Level of evidence

II.

Beneficial effects of Vigna angularis extract in osteoporosis and osteoarthritis

In Asia, Vigna angularis (azuki bean) has been used as a traditional medicine to treat various diseases because of its biological properties. Osteoarthritis (OA) and osteoporosis (OP) are common regenerative bone diseases that are characterized by deterioration of joint and bone structure. In this study, we evaluated the effects of Vigna angularis extract (VAE) on monosodium iodoacetate (MIA)-induced OA and ovariectomy (OVX)-induced OP models. In the MIA-induced OA results, severe OA was alleviated by the administration of VAE. Extensive local damage in the cartilage and hemorrhagic and edematous of surrounding tissues were decreased by VAE treatment. Articular cartilage was almost intact except for a focal mild abrasion, and the surface was glistening, similar to that of the normal joint. In the OVX-induced OP results, bone mineral content (BMC) and bone mineral density (BMD) were recovered by VAE treatment, and it improved the microstructures of bone. These results show that VAE could inhibit OA and OP symptoms.

Chondroprotective and antiarthritic effects of Daphnetin used in vitro and in vivo osteoarthritis models

AIMS

Daphnetin (DAP) is a traditional Chinese drug usually used to treat cardiovascular diseases. Studies have confirmed the anti-inflammatory, antioxidant, anti-bacterial and insecticidal, anti-tumor and neuro-protective effects of DAP. However, its anti-arthritic potential remains unexplored. The aim of this study is to investigate the in vitro and in vivo chondroprotective effects of DAP.

MAIN METHODS

The effect of DAP on primary rabbit chondrocytes was examined using recombinant human IL-1β for 24 h. For the in vivo studies, rabbits were randomly divided into groups: a normal control group and osteoarthritis (OA) groups. The OA groups received three different doses of DAP for 4 or 8 weeks. The anti-arthritic effect of DAP was assessed using histopathological examinations, qRT-PCR, western blotting and immunohistochemical analysis.

KEY FINDINGS

Both in vitro and in vivo results indicate that DAP exerts a protective effect against IL-1β in chondrocytes. In vitro, DAP inhibits the expression of IL-6, IL-12, MMP-3, MMP-9 and MMP-13, induced by IL-1β in rabbit chondrocytes, and stimulates the production of IL-10. The inhibitory effect of DAP on the MMPs is partially regulated by the inhibition of the PI3K/AKT, MAPK and NF-κB signaling pathways. The effect of DAP on OA may be attributed to the suppression of inflammatory factor secretion, chondrocyte apoptosis observed by the decrease in pro-apoptotic Caspase-3 and BAX, and the activation of anti-apoptotic BCL-2.

SIGNIFICANCE

DAP has a broad range of prospects in the treatment of OA, which provides a novel therapeutic strategy for OA.

Vitamin D in the Prevention and Treatment of Osteoarthritis: From Clinical Interventions to Cellular Evidence

Older adults are recommended vitamin D to prevent fractures. Though this population is also at risk of osteoarthritis (OA), the effect of vitamin D on OA is unclear and may differ by disease state. The relationship between vitamin D and OA during OA initiation and progression were considered in this narrative review of in vivo and in vitro studies. Regarding OA initiation in humans, the small number of published observational studies suggest a lack of association between induction of OA and vitamin D status. Most randomized controlled trials were performed in White OA patients with relatively high vitamin D status (>50 nmol/L). These studies found no benefit of vitamin D supplementation on OA progression. However, subset analyses and one randomized controlled pilot trial indicated that vitamin D supplementation may alleviate joint pain in OA patients with low vitamin D status (<50 nmol/L). As the etiology of OA is recently being more fully uncovered, better animal and cell models are needed. According to currently available clinical results, evidence is lacking to set a vitamin D level to prevent OA, and increasing vitamin D status above 50 nmol/L does not seem to benefit OA patients.

Chondroprotective Effects of a Standardized Extract (KBH-JP-040) from Kalopanax pictus, Hericium erinaceus, and Astragalus membranaceus in Experimentally Induced In Vitro and In Vivo Osteoarthritis Models

The aim of this study was to investigate the chondroprotective effect of a standardized extract (KBH-JP-040) of the Korean traditional herbs Kalopanax pictus Castor-Aralia, Hericium erinaceus (Bull.) Persoon, and Astragalus membranaceus Schischkin on in vivo and in vitro osteoarthritis (OA) models. Cultured rat chondrocytes were pre-treated with KBH-JP-040 (50, 100 and 200 μg/mL) for 1 h, then recombinant human IL-1α (rhIL-1α) for 24 h. For the in vivo model, rabbits (n = 60) were equally divided into experimental groups: normal control (NC), a collagenase-induced OA group, and OA groups treated with KBH-JP-040 (75, 100, and 150 mg/kg body weight) and celecoxib (Cx, 100 mg/kg) orally for 28 days. Treatment with KBH-JP-040 significantly attenuated inflammatory cytokines and matrix metalloproteinases (MMPs), suppressed the expression of IκBα, NF-κB, and JNK/p38 mitogen-activated protein (MAP) kinase, and upregulated aggrecan and collagen type-II expression in rhIL-1α-stimulated chondrocytes. Furthermore, the serum and synovial levels of inflammatory cytokines of rabbits also decreased in the treatment groups when compared with the OA group. Improved magnetic resonance imaging and histopathological findings further confirmed the therapeutic efficacy of KBH-JP-040 against OA. In conclusion, these results indicate that KBH-JP-040 possesses chondroprotective effects, suppressing inflammation and MMPs, and downregulating IκBα, NF-κB, and JNK/p38 MAP kinase-signaling pathways. This might be a potential therapeutic candidate for OA treatment.

Toxicology Evaluation of Drugs Administered via Uncommon Routes: Intranasal, Intraocular, Intrathecal/Intraspinal, and Intra-Articular

As the need for nasal, ocular, spinal, and articular therapeutic compounds increases, toxicology assessments of drugs administered via these routes play an important role in human safety. This symposium outlined the local and systemic evaluation to support safety during the development of these drugs in nonclinical models with some case studies. Discussions included selection of appropriate species for the intended route; conducting nonclinical studies that closely mimic the intended use with adequate duration; functional assessment, if deemed necessary; evaluation of local tissues with special histological staining procedure; and evaluations of safety margins based on local and systemic toxicity.

Repair of Torn Avascular Meniscal Cartilage Using Undifferentiated Autologous Mesenchymal Stem Cells: From In Vitro Optimization to a First-in-Human Study

Meniscal cartilage tears are common and predispose to osteoarthritis (OA). Most occur in the avascular portion of the meniscus where current repair techniques usually fail. We described previously the use of undifferentiated autologous mesenchymal stem cells (MSCs) seeded onto a collagen scaffold (MSC/collagen‐scaffold) to integrate meniscal tissues in vitro. Our objective was to translate this method into a cell therapy for patients with torn meniscus, with the long‐term goal of delaying or preventing the onset of OA. After in vitro optimization, we tested an ovine‐MSC/collagen‐scaffold in a sheep meniscal cartilage tear model with promising results after 13 weeks, although repair was not sustained over 6 months. We then conducted a single center, prospective, open‐label first‐in‐human safety study of patients with an avascular meniscal tear. Autologous MSCs were isolated from an iliac crest bone marrow biopsy, expanded and seeded into the collagen scaffold. The resulting human‐MSC/collagen‐scaffold implant was placed into the meniscal tear prior to repair with vertical mattress sutures and the patients were followed for 2 years. Five patients were treated and there was significant clinical improvement on repeated measures analysis. Three were asymptomatic at 24 months with no magnetic resonance imaging evidence of recurrent tear and clinical improvement in knee function scores. Two required subsequent meniscectomy due to retear or nonhealing of the meniscal tear at approximately 15 months after implantation. No other adverse events occurred. We conclude that undifferentiated MSCs could provide a safe way to augment avascular meniscal repair in some patients. Registration: EU Clinical Trials Register, 2010‐024162‐22. Stem Cells Translational Medicine2017;6:1237–1248

Early in situ changes in chondrocyte biomechanical responses due to a partial meniscectomy in the lateral compartment of the mature rabbit knee joint

We determined the biomechanical responses of chondrocytes to indentation at specific locations within the superficial zone of cartilage (i.e. patellar, femoral groove, femoral condylar and tibial plateau sites) taken from female New Zealand white rabbits three days after a partial meniscectomy in the lateral compartment of a knee joint. Confocal laser scanning microscopy combined with a custom indentation system was utilized to image chondrocyte responses at sites taken from ten contralateral and experimental knee joints. Cell volume, height, width and depth changes, global, local axial and transverse strains and Young׳s moduli were determined. Histological assessment was performed and proteoglycan content from the superficial zone of each site was determined. Relative to contralateral group cells, patellar, femoral groove and lateral femoral condyle cells in the experimental group underwent greater volume decreases (p < 0.05), due to smaller lateral expansions (with greater decreases in cell height only for the lateral femoral condyle cells; p < 0.05) whereas medial femoral and medial tibial plateau cells underwent smaller volume decreases (p < 0.05), due to less deformation in cell height (p < 0.05). Proteoglycan content was reduced in the patellar (p > 0.05), femoral groove, medial femoral condyle and medial tibial plateau experimental sites (p < 0.05). The findings suggest: (i) cell biomechanical responses to cartilage loading in the rabbit knee joint can become altered as early as 3 days after a partial meniscectomy, (ii) are site-specific, and (iii) occur before alterations in tissue mechanics or changes detectable with histology.

Safety Studies for Use of Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells in a Rabbit Model for Osteoarthritis to Support a Phase I Clinical Trial

Adipose‐derived mesenchymal stem cells (AMSCs) offer potential as a therapeutic option for clinical applications in musculoskeletal regenerative medicine because of their immunomodulatory functions and capacity for trilineage differentiation. In preparation for a phase I clinical trial using AMSCs to treat patients with osteoarthritis, we carried out preclinical studies to assess the safety of human AMSCs within the intra‐articular joint space. Culture‐expanded human AMSCs grown in human platelet‐lysate were delivered via intra‐articular injections into normal healthy rabbit knees and knees at risk for the development of osteoarthritis after bilateral medial anterior hemimeniscectomy. Treatment outcomes and safety were evaluated by assessing the general health, function, and behavior of the animals. Joint tissues were analyzed by x‐ray, magnetic resonance imaging, and histopathology. Intra‐articular AMSC therapy was well tolerated in this study. We did not observe adverse systemic reactions, nor did we find evidence of damage to intra‐articular joint tissues. Thus, the data generated in this study show a favorable safety profile for AMSCs within the joint space in support of a phase I clinical trial evaluating the clinical utility of AMSCs to treat osteoarthritis. Stem Cells Translational Medicine2017;6:910–922

Efficacy study of two novel hyaluronic acid-based formulations for viscosupplementation therapy in an early osteoarthrosic rabbit model

Viscosupplementation (VS) is a therapy for osteoarthrosis (OA) consisting of repetitive intra-articular injections of hyaluronic acid (HA). It is known to be clinically effective in relieving pain and increasing joint mobility by restoring joint homeostasis. In this study, the effects of two novel HA-based VS hydrogel formulations were assessed and challenged against a pure HA commercial formulation for the first time and this in a rabbit model of early OA induced by anterior cruciate ligament transection (ACLT). The first formulation tested was a hybrid hydrogel composed of HA and reacetylated chitosan, a biopolymer considered to be chondroprotective, assembled thanks to an ionic shielding. The second formulation consisted of a novel HA polymer grafted with antioxidant molecules (HA-4AR) aiming at decreasing OA oxidative stress and increasing HA retention time in the articulation. ACLT was performed on rabbits in order to cause structural changes comparable to traumatic osteoarthrosis. The protective effects of the different formulations were observed on the early phase of the pathology in a full randomized and blinded manner. The cartilage, synovial membrane, and subchondral bone were evaluated by complementary investigation techniques such as gross morphological scoring, scanning electron microscopy, histological scoring, and micro-computed tomography were used. In this study, ACLT was proven to successfully reproduce early OA articular characteristics found in humans. HA and HA-4AR hydrogels were found to be moderately protective for cartilage as highlighted by μCT. The HA-4AR was the only formulation able to decrease synovial membrane hypertrophy occurring in OA. Finally, the hybrid HA-reacetylated chitosan hydrogel surprisingly led to increased subchondral bone remodeling and cartilage defect formation. This study shows significant effects of two innovative HA modification strategies in an OA rabbit model, which warrant further studies toward more effective viscosupplementation formulations.

Alterative effects of an oral alginate extract on experimental rabbit osteoarthritis

Background

Osteoarthritis (OA) is a common joint disease that causes disabilities in elderly. However, few agents with high efficacy and low side effects have been developed to treat OA. In this study, we evaluated the effects of the alginate extract named CTX in OA cell and rabbit models.

Results

CTX was formulated by hydrolyzing sodium alginate polymers with alginate lyase and then mixing with pectin. HPLC was used to analyze the CTX content. Human chondrosarcoma SW1353 cells treated with interleukin-1β were used as OA model cells to investigate the effects of CTX on chondrocyte inflammation and anabolism. CTX at concentrations up to 1000 μg/ml exerted low cytotoxicity. It inhibited the gene expression of proinflammatory matrix metalloproteinases (MMPs) including MMP1, MMP3 and MMP13 in a dose-dependent manner and increased the mRNA level of aggrecan, the major proteoglycan in articular cartilage, at 1000 μg/ml. Thirteen-week-old New Zealand White rabbits underwent a surgical anterior cruciate ligament transection and were orally treated with normal saline, glucosamine or CTX for up to 7 weeks. Examinations of the rabbit femur and tibia samples demonstrated that the rabbits taking oral CTX at a dosage of 30 mg/kg/day suffered lesser degrees of articular stiffness and histological cartilage damage than the control rabbits.

Conclusions

The gene expression profiles in the cell and the examinations done on the rabbit cartilage suggest that the alginate extract CTX is a pharmaco-therapeutic agent applicable for OA therapy.

Cartilage Protective and Chondrogenic Capacity of WIN-34B, a New Herbal Agent, in the Collagenase-Induced Osteoarthritis Rabbit Model and in Progenitor Cells from Subchondral Bone

We sought to determine the cartilage repair capacity of WIN-34B in the collagenase-induced osteoarthritis rabbit model and in progenitor cells from subchondral bone. The cartilage protective effect of WIN-34B was measured by clinical and histological scores, cartilage area, and proteoglycan and collagen contents in the collagenase-induced osteoarthritis rabbit model. The efficacy of chondrogenic differentiation of WIN-34B was assessed by expression of CD105, CD73, type II collagen, and aggrecan in vivo and was analyzed by the surface markers of progenitor cells, the mRNA levels of chondrogenic marker genes, and the level of proteoglycan, GAG, and type II collagen in vitro. Oral administration of WIN-34B significantly increased cartilage area, and this was associated with the recovery of proteoglycan and collagen content. Moreover, WIN-34B at 200 mg/kg significantly increased the expression of CD105, CD73, type II collagen, and aggrecan compared to the vehicle group. WIN-34B markedly enhanced the chondrogenic differentiation of CD105 and type II collagen in the progenitor cells from subchondral bone. Also, we confirmed that treatment with WIN-34B strongly increased the number of SH-2(CD105) cells and expression type II collagen in subchondral progenitor cells. Moreover, WIN-34B significantly increased proteoglycan, as measured by alcian blue staining; the mRNA level of type II α 1 collagen, cartilage link protein, and aggrecan; and the inhibition of cartilage matrix molecules, such as GAG and type II collagen, in IL-1 β -treated progenitor cells. These findings suggest that WIN-34B could be a potential candidate for effective anti-osteoarthritic therapy with cartilage repair as well as cartilage protection via enhancement of chondrogenic differentiation in the collagenase-induced osteoarthritis rabbit model and progenitor cells from subchondral bone.

Calcitonin delays the progress of early-stage mechanically induced osteoarthritis. In vivo, prospective study

BACKGROUND/RATIONALE

Introducing new or testing existing drugs in an attempt to modify the progress of osteoarthritis (OA) is of paramount importance.

QUESTIONS/PURPOSES

This study aims to determine the effect exerted by Calcitonin on the progress of early-stage osteoarthritic lesions.

METHODS

We used 18, skeletally mature, white, female, New Zealand rabbits. OA was operatively induced in the right knee of each animal by the complete dissection of the anterior cruciate ligament, complete medial meniscectomy and partial dissection of the medial collateral ligament. Postoperatively, animals were divided into two groups. Starting on the ninth postoperative day and daily thereafter, group A animals (n = 9) received 10 IU oculus dexter (o.d.) of synthetic Calcitonin IntraMuscularly (I.M.); group B animals (n = 9) received equal volume of saline o.d. Three animals from each group were sacrificed at 1, 2 and 3 months following treatment's initiation. The extent and the grade of OA were assessed macroscopically, histologically and by radiographs, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)-scans. The Osteoarthritis Research Society International (OARSI) score, incorporating histological and macroscopic information, was calculated for each knee.

RESULTS

Osteoarthritic changes in group A animals were less severe and progressed less rapidly when compared with those of group B animals (sham). This difference was statistically significant in the first and second month (P = 0.05), but not in the third month (P = 0.513).

CONCLUSIONS

I.M. administration of Calcitonin seems to delay the progress of early-stage osteoarthritic lesions induced by mechanical instability in a rabbit experimental model.

Animal models for meniscus repair and regeneration

The meniscus plays an important role in knee function and mechanics. Meniscal lesions, however, are common phenomena and this tissue is not able to achieve spontaneous successful repair, particularly in the inner avascular zone. Several animal models have been studied and proposed for testing different reparative approaches, as well as for studying regenerative methods aiming to restore the original shape and function of this structure. This review summarizes the gross anatomy, function, ultrastructure and biochemical composition of the knee meniscus in several animal models in comparison with the human meniscus. The relevance of the models is discussed from the point of view of basic research as well as of clinical translation for meniscal repair, substitution and regeneration. Finally, the advantages and disadvantages of each model for various research directions are critically discussed.

Injectable hyaluronic-acid-doxycycline hydrogel therapy in experimental rabbit osteoarthritis

Background

Osteoarthritis (OA) is a common joint disease that causes disabilities in elderly adults. However, few long-lasting pharmacotherapeutic agents with low side effects have been developed to treat OA. We evaluated the therapeutic effects of intra-articular injections of hydrogels containing hyaluronic acid (HA) and doxycycline (DOX) in a rabbit OA model.

Results

Thirteen week old New Zealand White rabbits undergone a partial meniscectomy and unilateral fibular ligament transection were administered with either normal saline (NT), HA, DOX or HA-DOX hydrogels on day 0, 3, 6, 9 and 12; animals were also examined the pain assessment in every three days. The joint samples were taken at day 14 post-surgery for further histopathological evaluation. The degree of pain was significantly attenuated after day 7 post-treatment with both HA and HA-DOX hydrogels. In macroscopic appearance, HA-DOX hydrogel group showed a smoother cartilage surface, no or minimal signs of ulceration, smaller osteophytes, and less fissure formation in compare to HA or DOX treatment alone. In the areas with slight OA changes, HA-DOX hydrogel group exhibited normal distribution of chondrocytes, indicating the existence of cartilage regeneration. In addition, HA-DOX hydrogels also ameliorated the progression of OA by protecting the injury of articular cartilage layer and restoring the elastoviscosity.

Conclusion

Overall, from both macroscopic and microscopic data of this study indicate the injectable HA-DOX hydrogels presented as a long-lasting pharmacotherapeutic agent to apply for OA therapy.

Effect of combined traumatic impact and radial transection of medial meniscus on knee articular cartilage in a rabbit in vivo model

PURPOSE

The purpose of this study was to test the hypothesis that combined meniscectomy and traumatic impact accelerate early degeneration of articular cartilage in the knee versus meniscectomy alone.

METHODS

A previously published in vivo rabbit cartilage impact model was used combined with radial transection of the medial meniscus posterior horn versus meniscal transection alone. Rabbits were killed 3 months after surgery. Quantitative histologic analysis of the articular cartilage proteoglycan depth and glycosaminoglycan (GAG) fraction was performed at the site of impact on the posterior femoral condyle (PFC) and at the distal femoral condyle (DFC) overlying the meniscectomy in the surgical knee and the contralateral control knee.

RESULTS

The articular cartilage in the knees that underwent isolated meniscectomy did not differ significantly from the contralateral control knees for any measured value. The knees with a combined insult had a lower GAG fraction (P = .03) at the PFC and a greater depth of proteoglycan loss at both the PFC (P = .02) and the DFC (P = .04) versus contralateral controls. Compared with meniscectomy alone, the combined-insult knees had a greater depth of proteoglycan loss at the DFC (P = .005).

CONCLUSIONS

On the basis of early results using GAG fraction and proteoglycan depth, combined traumatic impact and meniscectomy are more damaging to articular cartilage than meniscectomy alone.

CLINICAL RELEVANCE

A knee with a combination of meniscal injury and articular cartilage impact may be at particularly high risk for early joint degeneration.

Effect of low-intensity pulsed ultrasound on MMP-13 and MAPKs signaling pathway in rabbit knee osteoarthritis

We evaluated the effect of low-intensity pulsed ultrasound (LIPUS) on MMP-13 and MAPKs expression in rabbit knee osteoarthritis (OA). For this purpose, 18 New Zealand white rabbits were randomly and equally divided into O + L, O - L, and SO groups. In O + L group, animals underwent right back leg ACLT operation and LIPUS radiation. In O - L group, animals underwent ACLT but no LIPUS treatment. In SO (control) group, animals underwent sham operation without LIPUS. After 6 weeks, we assessed the pathologic changes in the articular surface of femoral condyle and compared using Mankin scores. Also, expression of type-II collagen, MMP-13, ERK1/2, p38, and JNK was measured by Western blot. Compared with controls, Mankin scores were higher in O + L (P < 0.05)/O - L (P < 0.01) groups. Compared with O + L group, score was higher in O - L group (P < 0.05). Compared with controls, type-II collagen expression was less in O + L/O - L groups, with more significant decrease in O - L group (P < 0.05). Contrarily, expression of MMP-13, p-ERK1/2, and p-p38 was enhanced in O + L/O - L groups as compared with controls, with more significant increase in O - L group (P < 0.01). Compared with O + L group, expression was higher in O - L group (P < 0.05). We, therefore, concluded that LIPUS application promoted cartilage repair in OA through the downregulation of MMP-13, ERK1/2, and p38.

Significance of the serum CTX-II level in an osteoarthritis animal model: a 5-month longitudinal study

OBJECTIVE

The aim of this study was to investigate the clinical value of serum measurement of C-telopeptide of type II collagen (CTX-II). In correlation with late stages of osteoarthritis (OA) evaluated with histological assessment, the evolution of serum CTX-II concentration was followed during a 20-week longitudinal study in rabbit anterior cruciate ligament transection (ACLT) OA model in adult and growing animals.

METHODS

OA was induced in five adult and nine growing rabbits. Four adult and four young rabbits were unoperated. Serum sampling was made at week 0, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16 and 20 after the surgery in all rabbits. Animals were euthanized 20 weeks after the surgery. Serum CTX-II levels were analyzed with a recently available enzyme-linked immunosorbent assay (ELISA) kit, the protocol of which has been modified to increase the sensitivity of the test.

RESULTS

Significant differences for the CTX-II levels at W3, W6, W8, W10, W12, W14, W16 and W20 were observed between the adult ACLT and the control groups. A negative correlation between CTX-II levels and cartilage thickness of the medial compartment of the knee at W8, W10, W12 and a positive correlation between the CTX-II levels and the histomorphological score of the medial compartment of the knee at W3, W6, W8, W10, W12 were noted in adult animals. In young animals, operated or not, we observed high CTX-II levels at the beginning of the study, which decreased until the end.

CONCLUSION

Our results suggest the interest of the serum CTX-II monitoring for the OA progression and the relevance of the multiple time point analysis of this biomarker. Moreover, they address the question of the importance of correctly choosing the age of the animals used in the pre-clinical studies of OA.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the guinea pig

OBJECTIVE

This review focuses on the criteria for assessing osteoarthritis (OA) in the guinea pig at the macroscopic and microscopic levels, and recommends particular assessment criteria to assist standardization in the conduct and reporting of preclinical trails in guinea pig models of OA.

METHODS

A review was conducted of all OA studies from 1958 until the present that utilized the guinea pig. The PubMed database was originally searched August 1, 2006 using the following search terms: guinea pig and OA. We continued to check the database periodically throughout the process of preparing this chapter and the final search was conducted January 7, 2009. Additional studies were found in a review of abstracts from the OsteoArthritis Research Society International (OARSI) conferences, Orthopaedic Research Society (ORS) conferences, and literature related to histology in other preclinical models of OA reviewed for relevant references. Studies that described or used systems for guinea pig joint scoring on a macroscopic, microscopic, or ultrastructural basis were included in the final comprehensive summary and review. General recommendations regarding methods of OA assessment in the guinea pig were derived on the basis of a comparison across studies and an inter-rater reliability assessment of the recommended scoring system.

RESULTS

A histochemical-histological scoring system (based on one first introduced by H. Mankin) is recommended for semi-quantitative histological assessment of OA in the guinea pig, due to its already widespread adoption, ease of use, similarity to scoring systems used for OA in humans, its achievable high inter-rater reliability, and its demonstrated correlation with synovial fluid biomarker concentrations. Specific recommendations are also provided for histological scoring of synovitis and scoring of macroscopic lesions of OA.

CONCLUSIONS

As summarized herein, a wealth of tools exist to aid both in the semi-quantitative and quantitative assessment of OA in the guinea pig and provide a means of comprehensively characterizing the whole joint organ. In an ongoing effort at standardization, we recommend specific criteria for assessing the guinea pig model of OA as part of an OARSI initiative, termed herein the OARSI-HISTOgp recommendations.

Evaluation of histological scoring systems for tissue-engineered, repaired and osteoarthritic cartilage

OBJECTIVE

Regeneration of hyaline cartilage has been the focus of an increasing number of research groups around the world. One of the most important outcome measures in evaluation of its success is the histological quality of cartilaginous tissue. Currently, a variety of histological scoring systems is used to describe the quality of osteoarthritic, in vivo repaired or in vitro engineered tissue. This review aims to provide an overview of past and currently used histological scoring systems, in an effort to aid cartilage researchers in choosing adequate and validated cartilage histological scoring systems.

METHODS

Histological scoring systems for analysis of osteoarthritic, tissue engineered and in vivo repaired cartilage were reviewed. The chronological development as well as the validity and practical applicability of the scoring systems is evaluated.

RESULTS

The Histological-Histochemical Grading System (HHGS) or a HHGS-related score is most often used for evaluation of osteoarthritic cartilage, however the Osteoarthritis Research Society International (OARSI) Osteoarthritis Cartilage Histopathology Assessment System seems a valid alternative. The O'Driscoll score and the International Cartilage Repair Society (ICRS) II score may be used for in vivo repaired cartilage. The 'Bern score' seems most adequate for evaluation of in vitro engineered cartilage.

CONCLUSION

A great variety of histological scoring systems exists for analysis of osteoarthritic or normal, in vivo repaired or tissue-engineered cartilage, but only few have been validated. Use of these validated scores may considerably improve exchange of information necessary for advances in the field of cartilage regeneration.

Preventing blood-induced joint damage with the use of intra-articular iron chelators: an experimental study in rabbits

INTRODUCTION

This animal model was designed to evaluate the effect of intra-articular iron-chelator treatment in the prevention of blood-induced joint disease.

METHOD

Thirty domestic male rabbits were divided into three equal groups. One milliliter of homologous blood was injected into the left knee of each rabbit in groups 1 and 2. In the second group, 0.1 ml desferroxamine mesilate (DM) was also injected to the blood. In group 3, the animals received injections of 0.1 DM which was mixed with equal amounts of sterile saline solution. The joints were injected three times each week for 12 weeks. At the end of 12 weeks, the knee joints of each rabbit were examined.

RESULTS

The synovium in group 1 was found statistically significantly thicker than in group 2. Obvious erosion and ulceration of the cartilage were seen in all joints in group 1 and absent in group 2. Iron-chelator treatment reduced the formation of blood-induced joint damage in rabbit knees by inhibiting the iron-catalyzed formation of destructive oxygen metabolites that has an effect on joint cartilage and synovium.

Therapeutic effect of Aralia cordata extracts on cartilage protection in collagenase-induced inflammatory arthritis rabbit model

AIM OF THIS STUDY

Aralia cordata has been used to alleviate symptoms of osteoarthritis (OA) in traditional medicine. However, there is no in vivo study related with the therapeutic effects and mechanisms of Aralia cordata. On the basis of this background, our study was designed to examine the cartilage protective and proliferative effects of Aralia cordata by using a collagenase-induced osteoarthritis (CIA) rabbit model.

MATERIALS AND METHODS

The right knees of rabbits were injected intra-articularly with collagenase, and rabbits were orally administered with distilled water (vehicle), Aralia cordata (200mg/kg) and celecoxib (100mg/kg) once a day for 28 days after the initiation of the CIA.

RESULTS

In histopathologic studying by using H&E and Safranin O staining, Aralia cordata showed a cartilage protective effect in CIA rabbit femoral condyle. However, celecoxib had no effect on cartilage protection in CIA. The inflammatory mediators involved in cartilage destruction, such as COX-2 and PGE(2), were inhibited in the Aralia cordata-treated group. Aralia cordata also showed an anti-apoptotic effect through suppression of caspase-3 activity and chondrocyte proliferation induction in both in vivo and in vitro.

CONCLUSION

These results indicate that Aralia cordata showed cartilage protective effects through the down-regulations of COX-2 expression, PGE(2) production, caspase-3 activity, and chondrocyte proliferation in the CIA rabbit model.

Protective effects of butanol fraction from Betula platyphyla var. japonica on cartilage alterations in a rabbit collagenase-induced osteoarthritis

AIM OF THIS STUDY

Many cartilage protective agents have been developed from natural products, and they have resulted in the development of treatments for osteoarthritis. In this study, we determined the osteoarthritic efficacy and mechanism of butanol fraction from the bark of Betula platyphylla var. japonica (BFBP) in collagenase-induced rabbit model of osteoarthritis (CIA).

MATERIALS AND METHODS

The right knees of rabbits were injected intra-articularly with collagenase, and rabbits were orally administrated with distilled water (vehicle), BFBP (50, 100 and 200 mg/kg) or celecoxib (100 mg/kg) once a day for 28 days after the initiation of the CIA.

RESULTS

Oral administration of BFBP dose-dependently suppressed the stiffness and global histologic score. Proteoglycan intensity was considerably increased in a dose-dependent manner. As well, the mRNA expression of MMP-1, and MMP-3 was decreased. On the contrary, the level of TIMP-1 in the synovial fluids was significantly increased in the BFBP treated group. The pathologic inflammatory molecules such as PGE2 and COX-2 were inhibited by BFBP, but COX-1 expression not affected.

CONCLUSION

We suggest that BFBP has shown the protective effect on cartilage alternations through balance of MMPs/TIMP-1 and regulates inflammatory-related molecules in vivo model of osteoarthritis, and great candidate for development of osteoarthritis treatment.

Cyclodextrin polysulphate protects articular cartilage in experimental lapine knee osteoarthritis

OBJECTIVE

To evaluate the in vivo chondroprotective effect of cyclodextrin polysulphate (CDPS) in a rabbit model of experimental osteoarthritis (OA).

DESIGN

Experimental OA was induced in rabbits by anterior cruciate ligament transection (ACLT). Forty-eight hours post-surgery, the rabbits were randomised into three treatment groups (n=15 in each group) and a sham-operated control group. The rabbits were either injected subcutaneously with saline, 0.25 mg/kg CDPS or 1 mg/kg CDPS once a week for a period of 12 weeks, and their weight was monitored as a parameter for their general status. The animals were then sacrificed for macroscopic and histological assessment of the knee joints.

RESULTS

At the lowest dose, CDPS treatment was unable to induce a significant improvement of cartilage degradation vs the saline control in the experimentally induced knee OA. However, subcutaneous injections of 1 mg/kg CDPS induced a marked inhibition (P<0.05) of osteophyte formation. Additionally, a significant reduction of cartilage degradation revealed an overall chondroprotective effect of CDPS at a concentration of 1 mg/kg. No significant effects on weight gain were noted.

CONCLUSIONS

Systemic administration of CDPS is able to protect cartilage in vivo and can therefore be considered as a chondroprotective agent with structure modifying capacities.

Role of fibroblast growth factor 8 (FGF8) in animal models of osteoarthritis

INTRODUCTION

Fibroblast growth factor 8 (FGF8) is isolated as an androgen-induced growth factor, and has recently been shown to contribute to limb morphogenesis. The aim of the present study was to clarify the role of FGF8 in animal models of osteoarthritis (OA).

METHODS

The expression of FGF8 in the partial meniscectomy model of OA in the rabbit knee was examined by immunohistochemistry. The effect of intraperitoneal administration of anti-FGF8 antibody was tested in a model of OA that employed injection of monoiodoacetic acid or FGF8 into the knee joint of rats. The effect of FGF8 was also tested using cultured chondrocytes. Rabbit articular chondrocytes were treated with FGF8 for 48 hours, and the production of matrix metalloproteinase and the degradation of sulfated glycosaminoglycan in the extracellular matrix (ECM) were measured.

RESULTS

The expression of FGF8 in hyperplastic synovial cells and fibroblasts was induced in the meniscectomized OA model, whereas little or no expression was detected in normal synovium. Injection of FGF8 into rat knee joints induced the degradation of the ECM, which was suppressed by anti-FGF8 antibody. In the monoiodoacetic acid-induced arthritis model, anti-FGF8 antibody reduced ECM release into the synovial cavity. In cultured chondrocytes, FGF8 induced the release of matrix metalloproteinase 3 and prostaglandin E2, and caused degradation of the ECM. The combination of FGF8 and IL-1alpha accelerated the degradation of the ECM. Anti-FGF8 antibody suppressed the effects of FGF8 on the cells.

CONCLUSION

FGF8 is produced by injured synovium and enhances the production of protease and prostaglandin E2 from inflamed synoviocytes. Degradation of the ECM is enhanced by FGF8. FGF8 may therefore participate in the degradation of cartilage and exacerbation of osteoarthritis.

Equine osteoarthritis: a brief review of the disease and its causes

Degenerative joint diseases, such as osteoarthritis, adversely impact the health of the equine athlete as well as the economics of the equine industry. Our understanding of the aetiology of osteoarthritis, although not nearly exhaustive, has increased substantially in recent years. Molecules, including cytokines, inflammatory mediators, and metalloproteinases, have been identified and associated with the progression of joint disease. Several factors, including trauma to the joint, immobilization, conformation, shoeing, and ageing, have been linked with osteoarthritis. Our continued efforts into elucidating critical biological mediators and risk factors, coupled with better chondroprotective therapies and diagnostic tools, should facilitate our ability to maintain the skeletal health of the equine athlete

Effect of oral diacerein (DAR) in an experimental hip chondrolysis model

We aimed to reproduce the articular cartilage structural changes in a joint exposed to a metallic implant as in the adolescent pinned hip with persistent joint penetration and secondly, to test the effect of an interleukin inhibitor, diacerein (DAR) in the ensuing articular cartilage lesion. Twenty immature beagles were submitted to a surgical K-wire implantation in the hip with the material left in the joint space for 6 months. Twelve animals were sacrificed for histological and biochemical tests. Eight animals were sacrificed at 10 months (half of them treated with DAR) and analyzed by scanning electron microscopy (SEM) and biochemistry of the articular cartilage. Preoperative and monthly C3 and C4 complement and immunoglobulins serum levels were determined. The histological and the electrophoretic profile changes were significative at 6 months. At 10 months the migration profile (CaCl2) recovered to normal levels in the operated hip and the SEM scores for the acetabulum were similar to the non operated control hip after treatment. The serum level of IgA was elevated at the 4th and 6th month postoperatively. The persistence of a metallic implant resulted in degenerative changes parallel to that described for hip chondrolysis as a complication of in-situ pinning; and the cartilage lesion improved with DAR treatment.

Inflammatory degeneration of joint tissue in adjuvant arthritis after intraarticular treatment with the mixture of silver drug and nicotinic acid

Combination intraarticular administration of Poviargol (0.5 mg/kg) and nicotinic acid (1.0 mg/kg) reduced symptoms of local and general inflammation in rats with adjuvant arthritis. We revealed a decrease in morphological signs of inflammatory degeneration of joint tissue and reduction of metabolic disorders.

Type II collagen synthesis in the articular cartilage of a rabbit model of osteoarthritis: expression of type II collagen C-propeptide and mRNA especially during early-stage osteoarthritis

BACKGROUND

The aim of this study was to observe time course changes in type II collagen synthesis in various regions of articular cartilage affected with osteoarthritis (OA) by examining the expression of type II collagen C-propeptide (pCOL II-C) and mRNA in a rabbit OA model.

METHODS

Osteoarthritis was experimentally induced by partial lateral meniscectomy in the knees of Japanese white rabbits. The cartilage of the animals was then examined histologically over time. The degenerative area of articular cartilage was divided into three areas, according to the degree of degeneration. The ability to synthesize type II collagen was estimated by the immunohistological staining of pCOL II-C and the in situ hybridization of mRNA in type II collagen.

RESULTS

The positive rate of pCOL II-C immunostaining in chondrocytes was highest in the central-degenerative region 1 week after surgery, and the highest rate in the para-degenerative region was observed 2 and 4 weeks after surgery. The percentage of pCOL II-C positive cells increased as the histological degeneration score increased to moderate degeneration and then decreased with further progression of the severity of cartilage degeneration. Examination by in situ hybridization revealed that the regions marked by strong pCOL II-C mRNA expression were similar to those indicated by the immunohistology results.

CONCLUSIONS

These results suggest that the type II collagen-synthesizing potential of chondrocytes is highest in moderately degenerated areas of OA articular cartilage. Cartilage repair continues to be seen even as OA advances, although the reaction varies depending on the stage of OA.

In Vitro, Ex Vivo, andIn VivoMethodological Approaches for Studying Therapeutic Targets of Osteoporosis and Degenerative Joint Diseases: How Biomarkers Can Assist?

Although our approach to the clinical management of osteoporosis (OP) and degenerative joint diseases (DJD)-major causes of disability and morbidity in the elderly-has greatly advanced in the past decades, curative treatments that could bring ultimate solutions have yet to be found or developed. Effective and timely development of candidate drugs is a critical function of the availability of sensitive and accurate methodological arsenal enabling the recognition and quantification of pharmacodynamic effects. The established concept that both OP and DJD arise from an imbalance in processes of tissue formation and degradation draws attention to need of establishing in vitro, ex vivo, and in vivo experimental settings, which allow obtaining insights into the mechanisms driving increased bone and cartilage degradation at cellular, organ, and organism levels. When addressing changes in bone or cartilage turnover at the organ or organism level, monitoring tools adequately reflecting the outcome of tissue homeostasis become particularly critical. In this context, bioassays targeting the quantification of various degradation and formation products of bone and cartilage matrix elements represent a useful approach. In this review, a comprehensive overview of widely used and recently established in vitro, ex vivo, and in vivo set-ups is provided, which in many cases effectively take advantage of the potentials of biomarkers. In addition to describing and discussing the advantages and limitations of each assay and their methods of evaluation, we added experimental and clinical data illustrating the utility of biomarkers for these methodological approaches.

Rabbit knee joint biomechanics: motion analysis and modeling of forces during hopping

Although the rabbit hindlimb has been commonly used as an experimental animal model for studies of osteoarthritis, bone growth and fracture healing, the in vivo biomechanics of the rabbit knee joint have not been quantified. The purpose of this study was to investigate the kinematic and kinetic patterns during hopping of the adult rabbit, and to develop a model to estimate the joint contact force distribution between the tibial plateaus. Force platform data and three-dimensional motion analysis using infrared markers mounted on intracortical bone pins were combined to calculate the knee and ankle joint intersegmental forces and moments. A statically determinate model was developed to predict muscle, ligament and tibiofemoral joint contact forces during the stance phase of hopping. Variations in hindlimb kinematics permitted the identification of two landing patterns, that could be distinguished by variations in the magnitude of the external knee abduction moment. During hopping, the prevalence of an external abduction moment led to the prediction of higher joint contact forces passing through the lateral compartment as compared to the medial compartment of the knee joint. These results represent critical data on the in vivo biomechanics of the rabbit knee joint, which allow for comparisons to both other experimental animal models and the human knee, and may provide further insight into the relationships between mechanical loading, osteoarthritis, bone growth, and fracture healing.

Enforced exercise after blunt trauma significantly affects biomechanical and histological changes in rabbit retro-patellar cartilage

Our laboratory has developed an animal model to study factors leading to chronic disease in a blunt impacted joint. Studies to date indicate post trauma softening of the impacted joint cartilage, but a limited degree of histological degradation in the tissue. The model utilizes treadmill exercise of the animal post trauma. The hypothesis of the current study was that post trauma exercise helps limit histological and mechanical degradation of the impacted retro-patellar cartilage. The study involved a group of animals with enforced exercise on a treadmill and another group with cage-activity post trauma. The animals were sacrificed after 24 months. Mechanical and histological analyses were performed on the retro-patellar cartilage from each group. The impacted versus contra-lateral, non-impacted retro-patellar cartilage was mechanically softened in the exercise group, but not in the cage-activity group. Histological analyses of the tissue from the cage-activity group indicated that this cartilage had less surface integrity, more ossification/calcification, and more erosion than that in the impacted tissue from the exercise group. These tissue changes may lead to an apparent stiffening effect in the impacted cartilage from the cage-activity group at 24 months post-trauma. Potential relationships between the intensity and frequency of post trauma exercise and the mechanical character and histological degradation of the impacted cartilage need additional study. The study indicates that post-trauma exercise can significantly alter the outcome of a blunt knee joint trauma in this experimental animal model.

Effect of inhibition of matrix metalloproteinases on cartilage loss in vitro and in a guinea pig model of osteoarthritis

OBJECTIVE

To study the effects of a matrix metalloproteinase (MMP) inhibitor (S-34219) on osteoarthritis (OA) cartilage cultures and in the meniscectomized guinea pig model of OA.

METHODS

The inhibitory activity of S-34219 on MMPs and aggrecanase was studied by fluorimetry and immunoassay, respectively. The effects of S-34219 on proteoglycan and collagen degradation were studied in cultures of rabbit and human cartilage. Medial meniscectomy was performed on 29 Hartley male guinea pigs, and these animals were randomly allocated to 1 of 3 groups: a control meniscectomized group (MNXc) receiving the vehicle, or a meniscectomized group receiving either 10 mg/kg or 20 mg/kg S-34219, administered twice per day by oral gavage for 12 weeks from day 1 after surgery. An additional group comprised sham-operated animals. Tibial cartilage from the operated left knee was processed for histologic assessment of OA lesions.

RESULTS

The 50% inhibitory concentration (IC(50)) of S-34219 on MMPs 1, 2, 3, 8, 9, and 13 was 55, 0.1, 0.5, 0.1, 0.03, and 0.2 nM, respectively; the IC(50) on aggrecanase 1 was 190 nM. In cultured rabbit cartilage, 100 nM S-34219 strongly inhibited MMP-dependent degradation of collagen and proteoglycans. A concentration 100 times higher was needed to inhibit aggrecanase-dependent degradation. In cultures of human OA cartilage, 100 nM S-34219 inhibited spontaneous type II collagen degradation by 66% and proteoglycan degradation by only 22%. For in vivo studies, treated groups were compared with the MNXc group and the results, expressed as the percentage variation versus MNXc, were as follows: in the 10 and 20 mg/kg groups, a significant decrease (P < 0.05) in global histologic score (-12% and -14%, respectively) was observed, and this was associated with a significant increase (P < 0.05) in cartilage thickness (+19% and +18%, respectively). Neither dose level changed the proteoglycan content.

CONCLUSION

In both treated animal groups, S-34219 significantly prevented the loss of cartilage thickness, probably by inhibiting collagen breakdown that normally leads to the erosion of fibrillated superficial areas. The absence of a protective effect on glycosaminoglycan loss, both in vitro and in vivo, suggests that aggrecanases may have an important role in cartilage loss. This study reinforces the relevance of these models for testing chondroprotective drugs, and the potential role of dual inhibitors of collagenase and aggrecanase as disease-modifying drugs in the management of OA.

Intra-articular hyaluronate in experimental rabbit osteoarthritis can prevent changes in cartilage proteoglycan content

OBJECTIVE

The purpose of this study was to determine the effects of intra-articular injections of high molecular weight (2000 kDa) sodium hyaluronate (HA) on the progression of articular cartilage degeneration in a rabbit partial medial meniscectomy model of osteoarthritis.

DESIGN

Six experimental groups included normal, sham operated, and operated and injected animals, the latter injected once-weekly (for two weeks or twelve weeks, beginning four weeks after surgery) with either 1% (w/v) HA or phosphate buffered saline (PBS). Following assessment of gross morphology, serial adjacent blocks of full-depth articular cartilage were prepared from the tibial condyle for analysis of total water, hydroxyproline, DNA and proteoglycan (uronic acid) content, as well as the ratio of galactosamine to glucosamine. Samples were sub-divided into inner (medial) and outer (lateral) regions.

RESULTS

No morphological differences were recognized between joints injected with PBS and those receiving HA. When analysed biochemically, there were no significant differences in hydration, hydroxyproline or DNA content between the experimental groups. In contrast, HA injection did affect changes in proteoglycan content. Expressed per tissue dry weight, uronic acid content in the operated group injected with PBS for two weeks was lower than normal (P<0.02), a result not seen in the corresponding HA injected group. After 12 weeks of PBS injections, uronic acid content (per dry weight) was higher than normal (P<0.01), an effect again not observed in the corresponding HA injected group. Results for the galactosamine: glucosamine ratio showed a reduction after 12 weeks of injections, but no differences between PBS and HA injected groups.

CONCLUSIONS

Once-weekly, intra-articular injection of high molecular weight HA can prevent changes in proteoglycan content in tibial condylar articular cartilage, compared to PBS injected controls, in the rabbit partial meniscectomy model of osteoarthritis.

Sodium iodoacetate-induced experimental osteoarthritis and associated pain model in rats

Degenerative lesions were induced in the knee joint of Wistar rats by intraarticular injection of chondrocyte metabolism inhibitor mono-iodoacetate (MIA) at doses of 0, 0.3 or 3 mg/joint. Histopathological examination and the measurement of hind paw weight ratio as an index of joint pain by incapacitance tester were performed. Histological findings that are similar to those observed in human osteoarthritis (OA), such as disorganization of chondrocytes, erosion and fibrillation of cartilage surface, and subchondral bone exposure etc., were observed in a MIA-dose-dependent manner. Saflanin-O fast green staining revealed that marked diffuse reduction of proteoglycan in cartilage tissue of rats treated with MIA. The clinical scores of the joint pain were closely correlated to the grade of histological findings. We conclude that the present experimental model in combination with a novel dual channel weight averager would be very useful for the study of human OA, and could be applied for estimation of therapeutic effect of new anti-OA drugs.

Fluorescent microsphere method is suitable for chronic bone blood flow measurement: a long-term study after meniscectomy in rabbits

The fluorescent microsphere (FM) method is considered a reliable technique to determine regional bone blood flow (RBBF) in acute experiments. In this study, we verified the accuracy and validity of this technique for measurement of RBBF in a long-term experiment and examined RBBF after meniscectomy. Twenty-four anesthetized female New Zealand white rabbits (3 groups, each n = 8) received consecutive left ventricular injections of FM in defined time intervals after meniscectomy: group 1 from preoperation to 3 wk postoperation; group 2 from 3 to 7 wk postoperation; and group 3 from 7 to 11 wk postoperation. To test the precision of the FM method, two FM species were injected simultaneously at the first and last measurement. After the experiment, humeri, femora, tibiae, and reference organs (kidney, lung, brain) were removed and dissected according to standardized protocols. Fluorescence was determined in each reference blood and tissue sample, and blood flow values were calculated. Blood flow in kidney, lung, and brain revealed no significant difference between right and left side and remained unchanged during the observation period, thus excluding errors due to shunting and dislodging of spheres in our experiments. Comparison of relative bone blood flow values obtained by simultaneously injected FM showed an excellent correlation at the first and last injection, indicating valid RBBF measurements in long-term experiments. We found a significant increase in RBBF 3 wk after meniscectomy in the right tibial condyles compared with the nonoperated left side. Similar changes were found in the femoral condyles. RBBF in other regions of tibia, femur, and humerus revealed no significant differences between right- and left-sided bone samples of the same region. Our results demonstrate that the FM method is valid for measuring RBBF in long-term experiments. In addition, we were able to demonstrate that meniscectomy leads to an increase in RBBF in the tibial condyles at a very early stage. This increase might be caused by stress-induced alterations of the subchondral bone.

In vivo contrast-enhanced micro MR-imaging of experimental osteoarthritis in the rabbit knee joint at 7.1T1

OBJECTIVE

In this longitudinal MR study the early stages of joint pathology in two surgically-induced rabbit models of osteoarthritis (OA) were monitored by in vivo contrast-enhanced MRI at 7.1T. Qualitative and quantitative MR data were compared with macroscopic and microscopic findings.

METHOD

Scanning of mature, male New Zealand White rabbits (N=12) was performed before surgery, and at 2, 4, and 8 weeks after unilateral transection of the anterior cruciate ligament (ACLT), medial meniscectomy (ME), or sham operation. MR-images were simultaneously obtained of both knee joints after intravenous injection of Magnevist. We implemented a 2D T1-weighted (T1w) coronal, fat-saturated gradientecho protocol (68 x 138 microm2, slice thickness 1 mm). Additionally, consecutive 3D gradientecho images were obtained from two sham-operated and two rabbits of the ME group (234 x 273 x 234 microm(3)). ACLT animals were sacrificed at 2 weeks (N=1), and 8 weeks (N=3), ME animals were sacrificed at 4 weeks (N=2), and 8 weeks (N=4), and sham-operated animals were sacrificed at 2 weeks (N=1) and 8 weeks (N=1), respectively.

RESULTS

Both OA models reflected important characteristics of the clinical picture of OA. With MR we were able to monitor time dependently the decline of synovial effusion and the formation of osteophytes. Morphologic MR examination showed a moderate to high accuracy for detecting synovial effusion (75%), meniscus (86%) and cruciate ligament (91%) lesions, and osteophytes (88%) as assessed by macroscopic examination. False-negative MR findings for gross macroscopic changes were due to the relative high slice thickness in 2D scans and the fact that the slices only covered the main weightbearing area of the femorotibial joint. Contour abnormalities of articular cartilage were not reliably detected. Quantitative analysis revealed a statistically significant increase of cartilage signal intensity in medial tibial cartilage (48+/-9% ACLT, and 29+/-9% ME in 2D datasets) as compared to contralateral control knees in two-week scans. Signal enhancement persisted or increased at later dates.

CONCLUSION

With high-resolution contrast-enhanced MRI at 7.1T the time course of gross pathologic changes in rabbit knees with surgically induced OA can be monitored. Still insufficient spatial resolution and image contrast of the applied 2D protocols limit the sensitivity and prohibit detection of articular cartilage contour abnormalities. However, signal alterations in the cartilage layer indicate alterations of tissue composition at a very early stage of OA development. When used with 3D protocols, contrast-enhanced MRI offers a promising tool for qualitative and quantitative in vivo monitoring of OA in rabbit models.

Distribution of chondroitin 4-sulfate epitopes (2/B/6) in various zones and compartments of articular cartilage in guinea pig osteoarthrosis

We studied changes in the morphology of tibial articular cartilage in early guinea pig osteoarthrosis (OA) at 6 and 12 months of age with quantitative light microscopy, and the distribution of chondroitin-4-sulfate with quantitative ultrastructural immunolabeling, using the 2/B/6 epitope. Labeling was correlated to previous chromatography findings concerning proteoglycan (PG) concentration in animals of the same age. The cell volume fraction had decreased at 12 months in the superficial zone of cartilage with OA (medial condyle) as well as in cartilage without OA (lateral condyle), being lower medially than laterally. The PG concentration differed between the zones and matrix compartments. Medially, a reduction in PG concentration occurred between 6 and 12 months in the interterritorial compartment of the two uppermost zones. Laterally, the concentrations increased. In general, the pericellular PG concentration was higher than the interterritorial in the two uppermost zones. The striking variation in structural and labeling responses in the various zones and compartments indicate a heterogeneous tissue response in guinea pig OA that will probably affect sampling in biochemical analyses of cartilage homogenates and synovial fluid.

Effect of load on articular cartilage matrix and the development of guinea-pig osteoarthritis

OBJECTIVE

To study the biochemical changes in the early development of primary guinea-pig knee osteoarthritis (OA) and its dependence on load.

METHODS

Load distribution was modified with below-knee amputation or femur valgus osteotomy in 9-month-old guinea-pigs. Soft tissue sham operated animals served as controls. The composition of uncalcified and calcified articular cartilage at the medial and lateral tibial condyle was studied by analysing small and large proteoglycans (PG) by gel electrophoresis and sulfation pattern with high-performance liquid chromatography. Collagen concentration was also determined.

RESULTS

The articular surfaces with a presumed higher load after surgery had a slight, but consistent, higher water content. Decreased load-on the ipsilateral medial condyle after femur osteotomy, and on the ipsilateral medial and lateral condyles following tibia amputation-was associated with an increased concentration of PGs, while this concentration decreased in condyles with increased load. Collagen concentration followed a similar pattern in the osteotomy group. In the amputated animals collagen concentration went down in all condyles, regardless of change of load. The aggregability and proportion of large and small PGs, the concentration of hyaluronan and the sulfation pattern of chondroitin sulfate was not affected by load. No consistent changes in PG, collagen or HA concentration, HA aggregability or sulfation pattern were seen in the calcified cartilage.

CONCLUSIONS

Primary guinea-pig knee OA is a reproducible model similar to human OA. It develops slowly and biochemical changes seem to appear before the morphological lesions become evident. The biochemical events are affected by load redistribution and correlate closely to morphological changes. These changes eventually result in a cartilage devoid in aggrecan, as also has been demonstrated in advanced human OA. All of this makes primary guinea-pig OA a suitable model for studying early OA changes.