Increase in degraded collagen type II in synovial fluid early in the rabbit meniscectomy model of osteoarthritis

The Combined Intraosseous Administration of Orthobiologics Outperformed Isolated Intra-articular Injections in Alleviating Pain and Cartilage Degeneration in a Rat Model of MIA-Induced Knee Osteoarthritis

BACKGROUND

Intra-articular (IA) platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) injections have shown efficacy and safety in treating osteoarthritis (OA). However, the effectiveness and mechanisms of combined intraosseous (IO) administration of these orthobiologics have yet to be explored.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate the effect on pain, cartilage, synovium/infrapatellar fat pad (IFP), and subchondral bone in rat knee OA, comparing isolated IA with combined IA and IO (IA+IO) injections of PRP or BMAC. It was hypothesized that combined injections would be superior to sole IA injections.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 48 rats were divided into 6 groups: sham (only joint puncture during OA induction with IA+IO saline injection treatment) and 5 groups with OA induction, control (IA+IO saline injection), PRP (IA PRP+IO saline injection), BMAC IA (IA BMAC+IO saline injection), PRP IA+IO (IA+IO PRP injection), and BMAC IA+IO (IA+IO BMAC injection). OA was induced by IA injection of monosodium iodoacetate (MIA). Rats were administered different orthobiologics according to their grouping 3 weeks after the MIA injection. Pain changes were evaluated using the weightbearing ratio assay at weeks 3, 4, 5, 7, and 9 after OA induction. Rats were euthanized at week 9 for gross, radiological, histological, immunohistochemical, and immunofluorescence assessments of cartilage, synovium, and subchondral bone.

RESULTS

Compared with the control group, all orthobiologics injection groups had reduced joint pain. Compared with IA injection, IA+IO injections provided superior pain relief by suppressing calcitonin gene-related peptide and substance P in both the synovium/IFP and subchondral bone. IA+IO injections slowed the progression of subchondral bone lesions by inhibiting CD31hiEmcnhi vessel formation and excessive osteoclast and osteoblast turnover while preserving subchondral bone microarchitecture, slowing cartilage degeneration. However, IA+IO injections did not outperform isolated IA injections in reducing synovitis and synovium/IFP fibrosis. Compared with PRP, BMAC exhibited superior inhibition of pain-related mediators, but no significant differences were observed in synovitis suppression, infrapatellar fat pad fibrosis, and subchondral bone protection.

CONCLUSION

IA+IO injections of orthobiologics were more effective in relieving pain, slowing cartilage degeneration, and inhibiting abnormal vascularization and remodeling compared with isolated IA injections. BMAC showed superior pain relief in the synovium/IFP and subchondral bone compared with PRP. Further research is needed to optimize PRP and BMAC components for enhanced efficacy in OA management.

CLINICAL RELEVANCE

Our findings contribute to advancing the understanding of pain relief mechanisms and support the endorsement of IO injection of orthobiologics for the treatment of OA and joint pain.

Donor-Matched Peripheral Blood-Derived Mesenchymal Stem Cells Combined With Platelet-Rich Plasma Synergistically Ameliorate Surgery-Induced Osteoarthritis in Rabbits: An In Vitro and In Vivo Study

BACKGROUND

Osteoarthritis (OA) is a common disease that causes joint pain and disability. Stem cell therapy is emerging as a promising treatment for OA.

PURPOSE

To evaluate the ability of peripheral blood-derived mesenchymal stem cells (PBMSCs) combined with donor-matched platelet-rich plasma (PRP) to treat OA in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

PBMSCs and donor-matched PRP were isolated and prepared from the same rabbit. PBMSCs were treated with serum-free medium, fetal bovine serum, and PRP; a series of PBMSC behaviors, including proliferation, migration, and adhesion, were compared among groups. The ability of PBMSCs or PRP alone and PBMSCs+PRP to protect chondrocytes against proinflammatory cytokine (interleukin 1β [IL-1β]) treatment was compared by analyzing reactive oxygen species (ROS)-scavenging ability and apoptosis. Real-time quantitative polymerase chain reaction and immunofluorescence were used to investigate the expression of extracellular matrix (ECM) metabolism genes and proteins, and Western blotting was used to explore the potential mechanism of the corresponding signaling pathway. In vivo, the effect of PBMSCs+PRP on cartilage and inflammation of the synovium was observed in a surgery-induced OA rabbit model via gross observation, histological and immunohistochemical staining, and enzyme-linked immunosorbent assay.

RESULTS

Proliferation, migration, and adhesion ability were enhanced in PBMSCs treated with PRP. Moreover, compared with either PBMSCs or PRP alone, PBMSCs+PRP enhanced ROS-scavenging ability and inhibited apoptosis in IL-1β-treated chondrocytes. PBMSCs+PRP also reversed the IL-1β-induced degradation of collagen type 2 and aggrecan and increased expression of matrix metalloproteinase 13, and this effect was related to increased expression of ECM synthesis and decreased expression of degradation and inflammatory genes and proteins. Mechanistically, PBMSCs+PRP reduced the phosphorylation of inhibitor of nuclear factor-κBα (IκBα), which further inhibited the phosphorylation of downstream nuclear factor-κB (NF-κB) in the NF-κB signaling pathway. In vivo, compared with PBMSCs or PRP alone, intra-articular (IA) injection of PBMSCs+PRP enhanced cartilage regeneration and attenuated synovial inflammation in OA-induced rabbits.

CONCLUSION

These results demonstrate that PRP could enhance biological activities, including viability, migration, and adhesion, in PBMSCs. PBMSCs+PRP could rescue ECM degeneration by inhibiting inflammatory signaling in IL-1β-treated OA chondrocytes. In addition, IA injection of PBMSCs+PRP effectively attenuated OA progression in a surgery-induced OA rabbit model.

CLINICAL RELEVANCE

PBMSCs+PRP may provide a promising treatment for knee OA, and this study can advance the related basic research.

Collagen type II-hyaluronan interactions - the effect of proline hydroxylation: a molecular dynamics study

Hyaluronan-collagen composites have been employed in numerous biomedical applications. Understanding the interactions between hyaluronan and collagen is particularly important in the context of joint cartilage function and the treatment of joint diseases. Many factors affect the affinity of collagen for hyaluronan. One of the important factors is the ratio of 3- or 4-hydroxy proline to proline residues. This article presents the results from molecular dynamics calculations of HA-collagen type II interactions with hyaluronan. The applied protocol employed docking and geometry optimization of complexes built using collagen structures with different numbers of hydroxyl groups attached to proline moieties. It was established that the hydroxyproline/proline ratio affects both structural and energetic features of the collagen-hyaluronan complex. Proline hydroxylation was found to significantly influence the number of all identified types of molecular forces, hydrophobic interactions, water bridges and hydrogen bonds, which can be formed between collagen and hyaluronan. Importantly, an increase in the hydroxyproline/proline ratio in the collagen chain increases the binding affinity for hyaluronan. This is illustrated by the linear correlation between the binding free energy and the hydroxylation degree. A comparison of the results obtained for 3 and 4 hydroxylation of proline indicates that the hydroxyl group attachment position plays a minor role in complex stabilization. However, a slightly stronger affinity was observed for 4 hydroxylation. In order to evaluate the effect of the aqueous environment on the collagen-hyaluronan complex stability, the enthalpic and entropic contributions to the free energy of solvation were analyzed.

Early impairment of cartilage poroelastic properties in an animal model of ACL tear

BACKGROUND

In more than 50% of cases, anterior cruciate ligament (ACL) lesions lead to post-traumatic osteoarthritis. Ligament reconstruction stabilizes the joint, but the tear seems to impair the poroelasticity of the cartilage: synovial membrane fluid inflammation is observed 3 weeks after tearing. There have been some descriptions of visible cartilage changes, but poroelasticity has never been analyzed at this early stage. The present animal study aimed to determine (1) whether cartilage showed early poroelastic deterioration after ACL tear; (2) whether an impairment correlated with macroscopic changes; and (3) whether cartilage poroelasticity deteriorated over time.

HYPOTHESIS

In the days following trauma, cartilage poroelasticity is greatly impaired, without macroscopically visible change.

MATERIAL AND METHODS

ACL tear was surgically induced in 18 New-Zealand rabbits. Cartilage poroelasticity was assessed on indentation-relaxation test in 3 groups: "early", at 2 weeks postoperatively (n=6), "mid-early" at 6 weeks (n=6) and in a non-operated control group ("non-op"). Macroscopic changes were scored in the same groups.

RESULTS

Poroelastic impairment was greatest at the early time-point (2 weeks). Permeability ranged from a mean 0.08±0.05×10^-15 m⁴/Ns (range, 0.028-0.17) in the "non-op" group to 1.03±0.60×10^-15 m⁴/Ns (range, 0.24-2.15) in the "early" group (p=0.007). Shear modulus ranged from 0.53±0.11MPa (range, 0.36-0.66) to 0.23±0.10MPa (range, 0.12-0.43), respectively (p=0.013). Macroscopic deterioration, on the other hand, differed significantly only between the "mid-early" and the "non-op" groups: p=0.011 for cartilage deterioration and p=0.008 for osteophyte formation. At the "mid-early" time point, poroelastic deterioration was less marked, with 0.33±0.33×10^-15 m⁴/Ns permeability (range, 0.06-1.06) and shear modulus 0.30±0.10MPa (range, 0.13-0.41: respectively p=0.039 and p=0.023 compared to the "non-op" group.

DISCUSSION

The severe rapid deterioration in poroelasticity following ACL tear in an animal model, as notably seen in increased permeability, corresponds to changes in cartilage microstructure, with easier outflows of interstitial fluid. This mechanical degradation may underlie onset of microcracks within the cartilage, leading to physiological loading that the cartilage by its nature is unable to repair. Further investigations are needed to correlate these experimental data with clinical findings.

LEVEL OF EVIDENCE

III; comparative study with control group.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

Five differential metabolites in SF were found as potential biomarkers for the early detection of cartilage degeneration in the rabbit ACLT model.

Tibiofemoral articular cartilage composition differs based on serum biochemical profiles following anterior cruciate ligament reconstruction

OBJECTIVE

Biochemical joint changes contribute to posttraumatic osteoarthritis (PTOA) development following anterior cruciate ligament reconstruction (ACLR). The purpose of this longitudinal cohort study was to compare tibiofemoral cartilage composition between ACLR patients with different serum biochemical profiles. We hypothesized that profiles of increased inflammation (monocyte chemoattractant protein-1 [MCP-1]), type-II collagen turnover (type-II collagen breakdown [C2C]:synthesis [CPII]), matrix degradation (matrix metalloproteinase-3 [MMP-3] and cartilage oligomeric matrix protein [COMP]) preoperatively to 6-months post-ACLR would be associated with greater tibiofemoral cartilage T1ρ relaxation times 12-months post-ACLR.

DESIGN

Serum was collected from 24 patients (46% female, 22.1 ± 4.2 years old, 24.0 ± 2.6 kg/m2 body mass index [BMI]) preoperatively (6.4 ± 3.6 days post injury) and 6-months post-ACLR. T1ρ Magnetic Resonance Imaging (MRI) was collected for medial and lateral tibiofemoral articular cartilage at 12-months post-ACLR. A k-means cluster analysis was used to identify profiles based on biomarker changes over time and T1ρ relaxation times were compared between cluster groups controlling for sex, age, BMI, concomitant injury (either meniscal or chondral pathology), and Marx Score.

RESULTS

One cluster exhibited increases in MCP-1 and COMP while the other demonstrated decreases in MCP-1 and COMP preoperatively to 6-months post-ACLR. The cluster group with increases in MCP-1 and COMP demonstrated greater lateral tibial (adjusted mean difference = 3.88, 95% confidence intervals [1.97-5.78]) and femoral (adjusted mean difference = 12.71, 95% confidence intervals [0.41-23.81]) T1ρ relaxation times.

CONCLUSION

Profiles of increased serum levels of inflammation and matrix degradation markers preoperatively to 6-months post-ACLR are associated with MRI changes consistent with lesser lateral tibiofemoral cartilage proteoglycan density 12-months post-ACLR.

Treating Full Depth Cartilage Defects with Intraosseous Infiltration of Plasma Rich in Growth Factors: An Experimental Study in Rabbits

OBJECTIVE

Intraarticular (IA) administration of platelet-rich plasma (PRP) has been proposed as a new strategy to halt osteoarthritis (OA) progression. In patients with severe OA, its potential is limited because it is unable to reach the subchondral bone, so a new strategy is needed, and intraosseous (IO) infiltration has been suggested. The purpose is to assess the impact of IA together with IO infiltration of plasma rich in growth factors (PRGF) in serum hyaluronic acid (HA) and type II collagen cleavage neoepitope (C2C) levels.

DESIGN

A total of 32 rabbits were included in the study and randomly divided into 2 groups: control and treatment. A 4-mm chondral defect was created in the medial femoral condyle and IA followed by IO infiltration were performed. Serum C2C and HA levels were measured using enzyme-linked immunosorbent assay (ELISA) tests before infiltration and 28, 56, and 84 days post-infiltration.

RESULTS

Significant lower C2C serum levels were obtained in treatment group (IA + IO infiltration of PRGF) at 84 days post-infiltration than in control group (IA infiltration of PRGF + IO infiltration of saline solution), while no significant differences between groups were reported at any other study times. Regarding HA, at 56 days post-infiltration, greater significant levels were seen in the treatment group. However, at 84 days post-infiltration, no significant differences were obtained, although lower levels were reported in the treatment group.

CONCLUSIONS

Despite inconclusive, the results suggest that the combination of IA and IO infiltration with PRGF may enhance cartilage and subchondral bone regeneration, but further studies are needed.

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.

Diagnostic value of combined serum marker changes and quantitative MRI evaluation of cartilage volume of tibial plateau in a surgically-induced osteoarthritis dog model

Objective

To evaluate the combined diagnostic value of two serum osteoarthritis (OA) markers and quantitative magnetic resonance imaging (MRI) evaluation of the cartilage volume of the tibial plateau in a canine model of experimental OA.

Methods

A total of 18 male Beagle dogs were used in this longitudinal study. OA was surgically induced via anterior cruciate ligament transection (ACLT) of the right knee in 10 dogs. The remaining eight dogs formed the sham operation control group and underwent the same procedure without ACLT. At various times after surgery, enzyme-linked immunosorbent assay was used to measure serum C-telopeptide of type II collagen (CTX-II) and type X collagen (ColX) levels. Quantitative evaluation of the tibial plateau volume was undertaken using MRI and ImageJ software.

Results

The serum CTX-II levels were significantly higher in the OA group at weeks 8, 12 and 16 after surgery, but not at week 4, compared with the control group. The serum ColX levels in the OA group were significantly higher than in the control group at weeks 8 and 12. The tibial plateau cartilage volumes in the OA group were significantly lower than in the control group at weeks 8 and 16.

Conclusion

Serum CTX-II and ColX levels combined with quantitative MRI evaluation of the tibial plateau cartilage volume in a canine model of OA demonstrated the potential to detect and monitor OA progression.

Review of Soluble Biomarkers of Osteoarthritis: Lessons From Animal Models

Objective Osteoarthritis (OA) is one of the leading causes of disability within the adult population. Currently, its diagnosis is mainly based on clinical examination and standard radiography. To date, there is no way to detect the disease at a molecular level, before the appearance of structural changes and symptoms. So an attractive alternative for monitoring OA is the measurement of biochemical markers in blood, urine, or synovial fluid, which could reflect metabolic changes in joint tissue and therefore disease onset and progression. Animal models are relevant to investigate the early stage of OA and metabolic changes occurring in joint tissues. The goal of this narrative review is to summarize the scientific data available in the literature on soluble biomarkers in animal models of OA. Design A literature search was conducted using the PubMed/Medline and Scopus databases between February 1995 and December 2015. All original articles, systematic and narrative reviews published in French or in English were considered. Results We summarized the data of 69 studies and proposed a classification scheme for OA biomarkers in animal studies, largely inspired by the BIPEDS classification. Conclusions Studies about biomarkers and animal models indicate that some markers could be valuable to monitor OA progression and assess therapeutic response in some animal models.

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

Expressing human SHOX in Shox2SHOX KI/KI mice leads to congenital osteoarthritis‑like disease of the temporomandibular joint in postnatal mice

The temporomandibular joint (TMJ), a unique synovial joint whose development differs from that of other synovial joints, develops from two distinct mesenchymal condensations that grow toward each other and ossify through different mechanisms. The short stature homeobox 2 (Shox2) gene serves an important role in TMJ development and previous studies have demonstrated that Shox2^{SHOX KI}/^KI mice display a TMJ defective phenotype, congenital dysplasia and premature eroding of the articular disc, which is clinically defined as a TMJ disorder. In the present study, Shox2^{SHOX KI}/^KI mouse models were used to investigate the mechanisms of congenital osteoarthritis (OA)-like disease during postnatal TMJ growth. Shox2^{SHOX KI}/^KI mice were observed to develop a severe muscle wasting syndrome from day 7 postnatal. Histological examination indicated that the condyle and glenoid fossa of Shox2^{SHOX KI}/^KI mice was reduced in size in the second week after birth. The condyles of Shox2^{SHOX KI}/^KI mice exhibited reduced expression levels of collagen type II and Indian hedgehog, and increased expression of collagen type I. A marked increase in matrix metalloproteinase 9 (MMP9) and MMP13 in the condyles was also observed. These cellular and molecular defects may contribute to the observed (OA)-like phenotype of Shox2^{SHOX KI}/^KI mouse TMJs.

The biomarkers changes in serum and the correlation with quantitative MRI markers by histopathologic evaluation of the cartilage in surgically-induced osteoarthritis rabbit model

Purpose

To investigate the biomarkers change in serum and the correlation with quantitative MRI markers by histopathologic evaluation of the cartilage in surgically-induced osteoarthritis(OA) rabbit model.

Materials and Methods

Thirty-six mature New Zealand rabbits were used. Eighteen rabbits were divided into six groups randomly and equally and subjected to surgery using the improved Hulth method. The other eighteen rabbits were also allocated into six groups randomly and equally which served as the control. At multiple time points after surgery, the BMP-2, CTX-II and COMP levels in the serum were analyzed by ELISA, and quantitative MRI was performed. Histopathology was examined with HE, and Mankin scores were assessed. The changes in the biochemical biomarkers and imaging markers in the OA groups were compared with those in the control groups using paired-samples T tests. The correlation of quantitative MRI markers with biomarkers and Mankin scores were analyzed. The analysis of Mankin scores was conducted with non-parametric wilcoxon signed rank tests.

Results

The BMP-2 levels were increased at various times after surgery, and significant differences were observed between the OA and control groups(all the P values <0.001). CTX-II levels were significantly elevated at several intervals after surgery, including W2, W8, W12, W16 and W20(P=0.019, 0.004, 0.007, <0.001 and 0.016 respectively), but not at W4(P=0.764). Significant differences in the COMP levels from W2 to W20 were observed between the OA and the control groups(P<0.001, <0.001, <0.001, <0.001,=0.002 and =0.004 respectively). The T2 values increased at W8 post-surgery and were significantly different between the OA and control groups(P=0.001, <0.001, <0.001 and <0.001 respectively). T2* values increased from W2 to W20 and were significantly different between the control and OA groups(P=0.002, =0.001, <0.001, <0.001, =0.001 and <0.001 respectively). T2 values had significant correlation with BMP-2 and CTX-II(P<0.001 and =0.014), except COMP(P=0.305)., while the correlation of T2* values with BMP-2, CTX-II and COMP was significant(P=0.043, 0.005 and 0.025 respectively). In addition, a positive correlation of T2 values and Mankin scores was observed(P<0.001).

Conclusion

With the relevance of the multiple time point analysis of the serum biomarkers and imaging markers compared with histological findings, BMP-2, CTX-II and COMP combined with T2 and T2* can be used to reflect and monitor OA progression potentially.

Evaluation of meniscal mechanics and proteoglycan content in a modified anterior cruciate ligament transection model

Post-traumatic osteoarthritis (PTOA) develops as a result of traumatic loading that causes tears of the soft tissues in the knee. A modified transection model, where the anterior cruciate ligament (ACL) and both menisci were transected, was used on skeletally mature Flemish Giant rabbits. Gross morphological assessments, elastic moduli, and glycosaminoglycan (GAG) coverage of the menisci were determined to quantify the amount of tissue damage 12 weeks post injury. This study is one of the first to monitor meniscal changes after inducing combined meniscal and ACL transections. A decrease in elastic moduli as well as a decrease in GAG coverage was seen.

Effect of age-related cartilage turnover on serum C-telopeptide of collagen type II and osteocalcin levels in growing rabbits with and without surgically induced osteoarthritis

This study aims to determine the effect of age-related cartilage turnover on the serum C-telopeptide of type II collagen (CTX-II) and osteocalcin (OC) levels in growing rabbits with and without surgically induced osteoarthritis. Twenty-four New Zealand male 3-month-old rabbits were randomized into three operated groups (n = 6 per group, with surgically induced osteroarthritis in the right knee; after blood sampling, the knees were harvested following euthanization at 2, 3, and 6 months after surgery) and a control group (n = 6, blood samples were obtained monthly between 3 and 15 months). Histomorphologically, the medial femoral condyles, particularly the central parts, harbored the most severe osteoarthritic changes among the operated rabbits. The serum levels of CTX-II and OC decreased in the controls from 3 to 11 months and then remained stable. No significant differences in the serum CTX-II and OC levels between the osteoarthritic rabbits and controls were observed. The osteoarthritic-to-normal ratios (ONRs, the ratios of serum CTX-II or OC levels in osteoarthritic rabbits to those of the controls at same ages) enabled an overall assessment of osteoarthritis and age-related cartilage turnover. Elevated CTX-II ONRs were observed in rabbits with mild to advanced osteoarthritis. However, the OC ONRs were unhelpful in assessing osteoarthritic growing rabbits.

Changes induced by chronic in vivo load alteration in the tibiofemoral joint of mature rabbits

We investigated the relationship between the magnitude and duration of chronic compressive load alteration and the development and progression of degenerative changes in the rabbit tibiofemoral joint. Varus loading devices were attached to the hind limb of mature NZW rabbits. Altered compressive loads of 0%, 50%, and 80% body weight (BW) were applied to the tibiofemoral joint for 12 h per day for 12 and 24 weeks (n = 4 animals/group). Compartment-specific assessment of the tibial plateau included histological assessments (articular cartilage, calcified cartilage, and subchondral bone thicknesses, degeneration score, and articular cartilage cellularity) and biomechanical measures (aggregate modulus, permeability, Poisson's ratio). Analyses of variance techniques were used to examine the relationship between each outcome measure with load magnitude and duration as independent variables in the model. Degenerative changes developed in the medial compartment with increased magnitude of compressive loading and included fibrillation, increased degeneration score, and reduced cellularity of the articular cartilage. Increased calcified cartilage thickness was observed in both the medial and lateral compartments following exposure to altered loading of 80% BW for 24 weeks. This work demonstrates that in vivo chronic compressive load alteration to the tibiofemoral joint can initiate progressive macroscopic and histological-based degenerative changes analogous to the early changes occurring in OA.

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 dog

The dog is a common model for study of osteoarthritis (OA). Subjective histologic scoring systems have often served as the reference standard for presence and severity of OA. However, these scoring systems have perceived shortcomings. The system developed for this report attempts to address these shortcomings by providing a standardized methodology for global assessment of the joint, versatility and the potential for relative weighting of pathology, allowing for comparison among time points, studies, and centers, and critical analysis of the system's reliability. The proposed system for assessment of canine tissues appears to provide an effective method for global assessment of articular pathology in OA. The system is versatile, comprehensive, and reliable and appears to have advantages over conventional scoring systems.

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.

The effects of early or late treatment of osteochondral defects on joint homoeostasis: an experimental study in rabbits

A 3.5 x 4 mm tubular osteochondral defect was created on the right medial femoral condyles of 51 adult rabbits. In the control group (CG), defects were left untreated. In the early-(ETG) and late-(LTG) treatment groups, defects were treated by an osteoperiosteal graft 1 and 12 weeks, respectively, after the index procedure. Synovial fluid (SF) samples were collected regularly and proteoglycan fragments (PF), total collagen (TC) and collagenase (MMP-1) levels were measured. Rabbits were killed at 4 (early period), 12 (intermediate period), or 24 (late period) weeks postoperatively. Histological examination indicated a more successful healing in both grafting groups than in the CG, but without any difference at any time period between the grafting groups. In the CG, PF, and TC levels in SF increased continuously until the late period, indicating an ongoing degenerative activity in the joints. In contrast, SF marker levels in both grafting groups indicated that normalization in joint metabolism could be achieved-at least partially-after treatment. However, PF levels in the SF showed that the treatment of defects in earlier stages might result in better outcomes since the negative effects were more prominent in chronic stages, presumably due to the more prolonged period of disturbed homeostasis. Thus, histological values and SF marker levels indicated that treatment of osteochondral defects at any time of the disease had a positive effect on healing when compared to no treatment. Early treatment might better assist the recovery of joint homeostasis than late treatment.

Raman spectroscopy of synovial fluid as a tool for diagnosing osteoarthritis

For many years, viscosity has been the primary method used by researchers in rheumatology to assess the physiochemical properties of synovial fluid in both normal and osteoarthritic patients. However, progress has been limited by the lack of methods that provide multiple layers of information, use small sample volumes, and are rapid. Raman spectroscopy was used to assess the biochemical composition of synovial fluid collected from 40 patients with clinical evidence of knee osteoarthritis (OA) at the time of elective surgical treatment. Severity of knee osteoarthritis was assessed by a radiologist using Kellgren/Lawrence (K/L) scores from knee joint x rays, while light microscopy and Raman spectroscopy were used to examine synovial fluid (SF) aspirates (2 to 10 microL), deposited on fused silica slides. We show that Raman bands used to describe protein secondary structure and content can be used to detect changes in synovial fluid from osteoarthritic patients. Several Raman band intensity ratios increased significantly in spectra collected from synovial fluid in patients with radiological evidence of moderate-to-severe osteoarthritis damage. These ratios can be used to provide a "yes/no" damage assessment. These studies provide evidence that Raman spectroscopy would be a suitable candidate in the evaluation of joint damage in knee osteoarthritis patients.

Novel synovial fluid recovery method allows for quantification of a marker of arthritis in mice

OBJECTIVE

We evaluated three methodologies--a calcium sodium alginate compound (CSAC), polyacrylate beads (PABs), and Whatman paper recovery (WPR)--for the ability to recover synovial fluid (SF) from mouse knees in a manner that facilitated biochemical marker analysis.

METHODS

Pilot testing of each of these recovery vehicles was conducted using small volumes of waste human SF. CSAC emerged as the method of choice, and was used to recover and quantify SF from the knees of C57BL/6 mice (n=12), six of which were given left knee articular fractures. SF concentrations of cartilage oligomeric matrix protein (COMP) were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean concentration ratio [(COMP(left knee))/(COMP(right knee))] was higher in the mice subjected to articular fracture when compared to the non-fracture mice (P=0.026). The mean total COMP ratio (taking into account the quantitative recovery of SF) best discriminated between fracture and non-fracture knees (P=0.004).

CONCLUSIONS

Our results provide the first direct evidence of accelerated joint tissue turnover in a mouse model responding to acute joint injury. These data strongly suggest that mouse SF recovery is feasible and that biomarker analysis of collected SF samples can augment traditional histological analyses in mouse models of arthritis.

Type II collagen markers in osteoarthritis: what do they indicate?

PURPOSE OF REVIEW

We provide a critical review of recent in-vitro, animal and human clinical studies on type II collagen biomarkers. In describing the human studies, we have applied the BIPED (burden of disease, investigative, prognostic, efficacy of intervention, and diagnostic) classification scheme recently proposed by the Osteoarthritis Biomarkers Network (a consortium of five US National Institutes of Health designated sites). Based on this analysis, we propose an update to the classification of the type II collagen biomarkers.

RECENT FINDINGS

Various type II collagen epitopes have been described as potential biomarkers for osteoarthritis. Some have demonstrated ability in the following areas: classification of individuals as either diseased or nondiseased; assessment of severity or extent of osteoarthritis; prediction of future onset of osteoarthritis among those without osteoarthritis at baseline or the progression of osteoarthritis among those with existing disease; and monitoring treatment efficacy.

SUMMARY

Type II collagen biomarkers provide useful information for clinical and research applications. Furthermore, they are promising tools for the monitoring the influence of drug treatment on cartilage metabolism in joint diseases such as osteoarthritis.

Animal models of osteoarthritis: lessons learned while seeking the "Holy Grail"

PURPOSE OF REVIEW

Difficulties in studying osteoarthritis in humans that stem from both the low sensitivity of diagnostic tools and the low availability of diseased tissues explain why research on animal models remains highly dynamic. This review will summarize the recent advances in this field.

RECENT FINDINGS

With regard to the etiology of osteoarthritis, synovial macrophages mediate osteophyte formation, whereas increased ligament laxity could be responsible for spontaneous osteoarthritis in guinea pigs. The concomitant changes in subchondral bone and cartilage reported in several models, and the structure-modifying effects of some bone inhibitors have confirmed the importance of bone in osteoarthritis. With regard to cartilage pathobiology, ADAMTS-5 is the major aggrecanase responsible for cartilage destruction, whereas inadequate control of oxidative stress and decreased expression of transforming growth factor-beta receptors could predispose to osteoarthritis. New models include a postmenopausal rat model, the groove model and a joint-specific bone morphogenetic receptor-deficient mouse. The iodoacetate model was also validated as the first pain model of osteoarthritis.

SUMMARY

In view of the multiple animal models available, there is a need to reach a consensus on one or several gold standard animal model(s). New studies indicate that important differences in therapeutic response exist between young and old animals, and between spontaneous and surgical models, suggesting that not all models are adequate models of osteoarthritis.

Urinary levels of type II collagen C-telopeptide crosslink are unrelated to joint space narrowing in patients with knee osteoarthritis

OBJECTIVE

To determine whether urinary concentrations of the cross linked C-telopeptide of type II collagen (CTx-II) distinguish subjects with progressive radiographic or symptomatic knee osteoarthritis from those with stable disease.

METHODS

SUBJECTS

were 120 obese women with unilateral knee osteoarthritis who participated in a 30 month, randomised, placebo controlled trial of structure modification by doxycycline, in which a standardised semiflexed anteroposterior view of the knee was obtained at baseline and 30 months. Subjects were selected from a larger sample to permit comparisons of urinary CTx-II levels between 60 progressors and 60 non-progressors with respect to medial joint space narrowing. Each group contained 30 subjects who, across five semi-annual assessments, reported on at least two occasions an increase of > or =20% in 50 ft walk pain (minimum = 1 cm on a 10 cm visual analogue scale), relative to the previous visit. The remainder reported no increases in knee pain. Urine samples were obtained semi-annually for determination of the CTx-II and creatinine concentrations.

RESULTS

In an analysis of the placebo group only, the frequency of radiographic progressors in the upper and middle tertiles (48% and 60%, respectively) of the baseline CTx-II distribution was not significantly different than that in the lower tertile (64%). These results were unchanged after inclusion of data from subjects in the doxycycline group. Furthermore, serial CTx-II levels did not distinguish subjects with progressive radiographic or symptomatic knee osteoarthritis from those with stable disease.

CONCLUSIONS

In this pilot study, urinary CTx-II concentration was not a useful biomarker of osteoarthritis progression.

The utility of measuring C-terminal telopeptides of collagen type II (CTX-II) in serum and synovial fluid samples for estimation of articular cartilage status in experimental models of destructive joint diseases

OBJECTIVE

To characterize and validate a novel, enzyme-linked immunoassay for measuring cross-linked dimer forms of C-terminal telopeptides of type II collagen (CTX-II) in serum and synovial fluid of rodents, and investigate whether CTX-II measurements can reflect joint status in two established animal models of destructive joint diseases.

METHODS

Firstly, the specificity, in vivo validity, antigen recovery, and reproducibility of the assay were investigated. Secondly, we induced arthritis in rats using either bovine collagen type II or mono-iodoacetate. CTX-II levels were measured in the serum and synovial fluid of the affected femoro-tibial joint and correlated with microscopic severity of joint lesions as determined by validated scoring systems.

RESULTS

The F4601 monoclonal antibody (mAb) is highly specific for the EKGPDP sequence at the CTX-II. Strong CTX-II signals were detected during enzymatic degradation of articular cartilage explants by matrix metalloproteinase (MMP)-9 or MMP-13. The assay presented a good degree of precision and reproducibility (inter- and intra-assay CVs< 8.0%). In the collagen-induced arthritis (CIA) model, the assay indicated markedly increased levels of CTX-II in both the synovial fluid and the serum. Furthermore, CTX-II levels in both the synovial fluid (r = 0.76; P < 0.0001) and the serum (r = 0.85; P < 0.0001) showed strong correlations with the microscopic severity scores of joint lesions at Day 22. In the mono-iodoacetate-induced arthritis (MIA) model, CTX-II concentration in the synovial fluid (r = 0.53; P < 0.0001), but not in the serum, correlated with the microscopic severity score.

CONCLUSIONS

The Preclinical CTX-II assay could provide a useful supplement to currently available methods for the non-invasive assessment of cartilage status. The utility of serum CTX-II to reflect joint status appeared to be limited to systemic forms of destructive joint diseases.

Review: Collagen markers in early arthritic diseases

In arthritic diseases e.g. osteoarthritis (OA) and rheumatoid arthritis (RA), the stability of the collagen type II (CII) fibers, a major component of articular cartilage, is compromised with extensive proteolytic breakdown leading to cartilage erosion and joint deterioration. A clinical need for molecular markers that give instantaneous measure of rate of joint deterioration has developed, as other measurements e.g. arthroscopy, and joint space narrowing are insensitive to small changes in disease status over short periods of time. Owing to its exclusive presence in cartilaginous tissues, markers of CII synthesis and degradation have been extensively studied. Assays that measure these markers in biological fluids e.g. synovial fluid (SF), serum, and urine have been developed and applied to detect early disease onset, monitor disease progression, and response to anti-arthritic drugs. CII synthesis markers include the procollagen type II C-propeptide (PIICP) and the procollagen type IIA N-propeptide (PIIANP). CII degradation markers include CII C-telopeptide (CII-X), CII neoepitope (TIINE), helix II, C2C, CNBr 9.7, Coll 2-1, and Coll 2-1 NO(2). Most of these markers differentiate between early stages of OA, RA and reference controls. The best correlations with structural changes occur when measurements are made in SF while serum measurement frequently did not correlate with structural changes. Although the selection of an optimal marker or a set of markers is still problematic, few markers are of considerable utility in early detection and monitoring of arthritic diseases. The current challenge is to improve the discriminatory power of these markers so they can be used to guide therapeutic decisions.

Sport-related differences in biomarkers of bone resorption and cartilage degradation in endurance athletes

OBJECTIVE

By measuring urinary cross-linked N-telopeptide (NTx) as a bone resorption marker and urinary C-telopeptide of type II collagen (CTx-II) as a cartilage degradation marker, we asked whether differences in skeletal stresses in college athletes undergoing high-intensity training for diverse types of aerobic sports affect their skeletal metabolism and, if so, differentially or in unison.

METHODS

The study was cross-sectional at a Division 1 college campus with 60 student athletes representing crew, cross-country running and swimming. Controls were 16 non-athlete undergraduates. Urine samples were collected for NTx and CTx-II analysis by enzyme-linked immunosorbent assay, normalizing results to creatinine. Two-way analysis of variance models and pair-wise comparisons were used to test whether biomarker levels differed by sport and the significance when adjusted for body mass index (BMI).

RESULTS

NTx and CTx-II showed significant differences between groups before and after adjusting for BMI. NTx was highest in the rowers, and higher in rowers and runners than in swimmers or controls. CTx-II was significantly higher in runners than in crew, swimmers or controls, when unadjusted for BMI. After adjusting for BMI, these group differences remained significant except for runners over crew.

CONCLUSION

Athletes in-training in the three sports show significant differences in these markers of bone resorption and cartilage collagen degradation. The results suggest that crew undergo the highest bone remodeling and runners the highest cartilage degradation. The results also show how these markers can vary physiologically between individuals, at extremes of skeletal exercise.

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.