IL-1beta and BMPs--interactive players of cartilage matrix degradation and regeneration

Advanced application of carbohydrate-based micro/nanoparticles for rheumatoid arthritis

Rheumatoid arthritis (RA) is a kind of synovitis and progressive joint destruction disease. Dysregulated immune cell activation, inflammatory cytokine overproduction, and subsequent reactive oxidative species (ROS) production contribute to the RA process. Carbohydrates, including cellulose, chitosan, alginate and dextran, are among the most abundant and important biomolecules in nature and are widely used in biomedicine. Carbohydrate-based micro/nanoparticles(M/NPs) as functional excipients have the ability to improve the bioavailability, solubility and stability of numerous drugs used in RA therapy. For on-demand therapy, smart reactive M/NPs have been developed to respond to a variety of chemical and physical stimuli, including light, temperature, enzymes, pH and ROS, alternating their physical and macroscopic properties, resulting in innovative new drug delivery systems. In particular, advanced products with targeted dextran or hyaluronic acid are exploiting multiple beneficial properties at the same time. In addition to those that respond, there are promising new derivatives in development with microenvironment and chronotherapy effects. In this review, we provide an overview of these recent developments and an outlook on how this class of agents will further shape the landscape of drug delivery for RA treatment.

Genomic Determinants of Knee Joint Biomechanics: An Exploration into the Molecular Basis of Locomotor Function, a Narrative Review

In recent years, the nexus between genetics and biomechanics has garnered significant attention, elucidating the role of genomic determinants in shaping the biomechanical attributes of human joints, specifically the knee. This review seeks to provide a comprehensive exploration of the molecular basis underlying knee joint locomotor function. Leveraging advancements in genomic sequencing, we identified specific genetic markers and polymorphisms tied to key biomechanical features of the knee, such as ligament elasticity, meniscal resilience, and cartilage health. Particular attention was devoted to collagen genes like COL1A1 and COL5A1 and their influence on ligamentous strength and injury susceptibility. We further investigated the genetic underpinnings of knee osteoarthritis onset and progression, as well as the potential for personalized rehabilitation strategies tailored to an individual's genetic profile. We reviewed the impact of genetic factors on knee biomechanics and highlighted the importance of personalized orthopedic interventions. The results hold significant implications for injury prevention, treatment optimization, and the future of regenerative medicine, targeting not only knee joint health but joint health in general.

Moderate evidence exists for four microRNAs as potential biomarkers for tendinopathies and degenerative tendon ruptures at the upper extremity in elderly patients: conclusion of a systematic review with best-evidence synthesis

PURPOSE

The aim of this systematic review was to investigate tendon-specific microRNAs (miRNAs) as biomarkers for the detection of tendinopathies or degenerative tendon ruptures. Also, their regulatory mechanisms within the tendon pathophysiology were summarized.

METHODS

A systematic literature research was performed using the PRISMA guidelines. The search was conducted in the Pubmed database. The SIGN checklist was used to assess the study quality of the included original studies. To determine the evidence and direction of the miRNA expression rates, a best-evidence synthesis was carried out, whereby only studies with at least a borderline methodological quality were considered for validity purposes.

RESULTS

Three thousand three hundred seventy studies were reviewed from which 22 fulfilled the inclusion criteria. Moderate evidence was found for miR-140-3p and miR-425-5p as potential biomarkers for tendinopathies as well as for miR-25-3p, miR-29a-3p, miR-140-3p, and miR-425-5p for the detection of degenerative tendon ruptures. This evidence applies to tendons at the upper extremity in elderly patients. All miRNAs were associated with inflammatory cytokines as interleukin-6 or interleukin-1ß and tumor necrosis factor alpha.

CONCLUSIONS

Moderate evidence exists for four miRNAs as potential biomarkers for tendinopathies and degenerative tendon ruptures at the upper extremity in elderly patients. The identified miRNAs are associated with inflammatory processes.

Toward defining the role of the synovium in mitigating normal articular cartilage wear and tear

Cartilage repair has been studied extensively in the context of injury and disease, but the joint's management of regular sub-injurious damage to cartilage, or 'wear and tear,' which occurs due to normal activity, is poorly understood. We hypothesize that this cartilage maintenance is mediated in part by cells derived from the synovium that migrate to the worn articular surface. Here, we demonstrate in vitro that the early steps required for such a process can occur. First, we show that under physiologic mechanical loads, chondrocyte death occurs in the cartilage superficial zone along with changes to the cartilage surface topography. Second, we show that synoviocytes are released from the synovial lining under physiologic loads and attach to worn cartilage. Third, we show that synoviocytes parachuted onto a simulated or native cartilage surface will modify their behavior. Specifically, we show that synoviocyte interactions with chondrocytes lead to changes in synoviocyte mechanosensitivity, and we demonstrate that cartilage-attached synoviocytes can express COL2A1, a hallmark of the chondrogenic phenotype. Our findings suggest that synoviocyte-mediated repair of cartilage 'wear and tear' as a component of joint homeostasis is feasible and is deserving of future study.

Effect of Different Collagen on Anterior Cruciate Ligament Transection and Medial Meniscectomy-Induced Osteoarthritis Male Rats

Osteoarthritis (OA) is a common type of arthritis characterized by degeneration of the articular cartilage and joint dysfunction. Various pharmacological and non-pharmacological techniques have been used to manage these diseases. Due to the diverse therapeutic properties of marine collagen, it has received considerable attention in its pharmacological application. Thus, the purpose of this study was to compare the efficacy of jellyfish collagen, collagen peptide, other sources of marine collagen, and glycine in treating OA. In the OA rat model, an anterior cruciate ligament transection combined with medial meniscectomy surgery (ACLT + MMx) was used to induce osteoarthritis in rats. Two weeks before surgery, male Sprague-Dawley rats were fed a chow-fat diet. After 6 weeks of treatment with collagen, collagen peptide, and glycine, the results show that they could inhibit the production of proinflammatory cytokines and their derivatives, such as COX-2, MMP-13, and CTX-II levels; therefore, it can attenuate cartilage degradation. Moreover, collagen peptides can promote the synthesis of collagen type II in cartilage. These results demonstrate that collagen and glycine have been shown to have protective properties against OA cartilage degradation. In contrast, collagen peptides have been shown to show cartilage regeneration but less protective properties. Jellyfish collagen peptide at a dose of 5 mg/kg b. w. has the most significant potential for treating OA because it protects and regenerates cartilage in the knee.

Pain in Hemophilia: Unexplored Role of Oxidative Stress

Hemophilia is the most common X-linked bleeding diathesis caused by the genetic deficiency of coagulation factors VIII or IX. Despite treatment advances and improvements in clinical management to prevent bleeding, management of acute and chronic pain remains to be established. Repeated bleeding of the joints leads to arthropathy, causing pain in hemophilia. However, mechanisms underlying the pathogenesis of pain in hemophilia remain underexamined. Herein, we describe the novel perspectives on the role for oxidative stress in the periphery and the central nervous system that may contribute to pain in hemophilia. Specifically, we cross examine preclinical and clinical studies that address the contribution of oxidative stress in hemophilia and related diseases that affect synovial tissue to induce acute and potentially chronic pain. This understanding would help provide potential treatable targets using antioxidants to ameliorate pain in hemophilia.

Silencing of circ_0000205 mitigates interleukin-1β-induced apoptosis and extracellular matrix degradation in chondrocytes via targeting miR-766-3p/ADAMTS5 axis

The aim of this study was to explore the role of hsa_circRNA_0000205 (circ_0000205) in chondrocyte injury in osteoarthritis (OA) and the underlying mechanism. Expression of circ_0000205, microRNA (miR)-766-3p and a disintegrin and metalloproteinase with thrombospondin motif (ADAMTS)-5 was detected by quantitative real time (qRT)-polymerase chain reaction (PCR) and Western blot assays. Cell proliferation, apoptosis, and extracellular matrix (ECM) synthesis were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and 5-ethynyl-2-deoxyuridine assays, flow cytometry, and qRT-PCR and Western blot assays. The target relationship between miR-766-3p and circ_0000205 or ADAMTS5 was confirmed by luciferase reporter assay and RNA immunoprecipitation. IL-1β treatment could attenuate cell viability of primary chondrocytes and proliferating cell nuclear antigen (PCNA) and collagen II type alpha-1 (COL2A1) levels, and elevate apoptosis rate and cleaved caspase-3, ADAMTS5 and matrix metalloproteinase-13 (MMP13) levels, suggesting that IL-1β induced chondrocyte apoptosis and ECM degradation. Expression of circ_0000205 was up-regulated in OA tissues and IL-1β-induced primary chondrocytes, accompanied with miR-766-3p down-regulation and ADAMTS5 up-regulation. Knockdown of circ_0000205 could mitigate IL-1β-induced above effects and improve cell proliferation. Moreover, both depleting miR-766-3p and promoting ADAMTS5 could partially counteract circ_0000205 knockdown roles in IL-1β-cultured primary chondrocytes. Notably, circ_0000205 was verified as a sponge for miR-766-3p via targeting, and ADAMTS5 was a direct target for miR-766-3p. Silencing circ_0000205 could protect chondrocytes from IL-1β-induced proliferation reduction, apoptosis, and ECM degradation by targeting miR-766-3p/ADAMTS5 axis.

A novel prostaglandin E receptor 4 (EP4) small molecule antagonist induces articular cartilage regeneration

Articular cartilage repair and regeneration is an unmet clinical need because of the poor self-regeneration capacity of the tissue. In this study, we found that the expression of prostaglandin E receptor 4 (PTGER4 or EP4) was largely increased in the injured articular cartilage in both humans and mice. In microfracture (MF) surgery-induced cartilage defect (CD) and destabilization of the medial meniscus (DMM) surgery-induced CD mouse models, cartilage-specific deletion of EP4 remarkably promoted tissue regeneration by enhancing chondrogenesis and cartilage anabolism, and suppressing cartilage catabolism and hypertrophy. Importantly, knocking out EP4 in cartilage enhanced stable mature articular cartilage formation instead of fibrocartilage, and reduced joint pain. In addition, we identified a novel selective EP4 antagonist HL-43 for promoting chondrocyte differentiation and anabolism with low toxicity and desirable bioavailability. HL-43 enhanced cartilage anabolism, suppressed catabolism, prevented fibrocartilage formation, and reduced joint pain in multiple pre-clinical animal models including the MF surgery-induced CD rat model, the DMM surgery-induced CD mouse model, and an aging-induced CD mouse model. Furthermore, HL-43 promoted chondrocyte differentiation and extracellular matrix (ECM) generation, and inhibited matrix degradation in human articular cartilage explants. At the molecular level, we found that HL-43/EP4 regulated cartilage anabolism through the cAMP/PKA/CREB/Sox9 signaling. Together, our findings demonstrate that EP4 can act as a promising therapeutic target for cartilage regeneration and the novel EP4 antagonist HL-43 has the clinical potential to be used for cartilage repair and regeneration.

Sulforaphane-loaded hyaluronic acid-poloxamer hybrid hydrogel enhances cartilage protection in osteoarthritis models

Sulforaphane (SFN) is an isothiocyanate with anti-arthritic and immuno-regulatory activities, supported by the downregulation of NF-κB pathway, reduction on metalloproteinases expression and prevention of cytokine-induced cartilage degeneration implicated in OA progression. SFN promising pharmacological effects associated to its possible use, by intra-articular route and directly in contact to the site of action, highlight SFN as promising candidate for the development of drug-delivery systems. The association of poloxamers (PL) and hyaluronic acid (HA) supports the development of osteotrophic and chondroprotective pharmaceutical formulations. This study aims to develop PL-HA hybrid hydrogels as delivery systems for SFN intra-articular release and evaluate their biocompatibility and efficacy for osteoarthritis treatment. All formulations showed viscoelastic behavior and cubic phase organization. SFN incorporation and drug loading showed a concentration-dependent behavior following HA addition. Drug release profiles were influenced by both diffusion and relaxation of polymeric chains mechanisms. The PL407-PL338-HA-SFN hydrogel did not evoke pronounced cytotoxic effects on either osteoblast or chondrosarcoma cell lines. In vitro/ex vivo pharmacological evaluation interfered with an elevated activation of NF-κB and COX-2, increased the type II collagen expression, and inhibited proteoglycan depletion. These results highlight the biocompatibility and the pharmacological efficacy of PL-HA hybrid hydrogels as delivery systems for SFN intra-articular release for OA treatment.

Chondroprotective and antiarthritic effects of galangin in osteoarthritis: An in vitro and in vivo study

Osteoarthritis (OA) is a common degenerative joint disease blamed for pain and disability in the elderly. Galangin (GAL) is a natural flavonoid that exhibits anti-inflammatory properties in various inflammation diseases. However, the role of GAL in OA remains unclear. In this study, we investigate the role of GAL in the progress and development of OA in vitro and vivo. The results showed that IL-1β exposure resulted in increased expression of iNOS, COX-2, MMP1, MMP3, MMP13 and ADAMTS5 in rat chondrocytes. However, co-treatment with GAL significantly decreased theses inflammatory cytokines and catabolic factors expression. In addition, GAL reduced IL-1β-induced degradation of collagen II and aggrecan in chondrocytes. Furthermore, GAL significantly suppressed IL-1β-induced Akt phosphorylation and NF-κB activation in rat chondrocytes. In vivo, intra-articular injection of GAL could also reduce the cartilage degradation in the ACLT rat model. This study reveals galangin may act as a promising novel agent in the treatment of OA.

A Roadmap of In Vitro Models in Osteoarthritis: A Focus on Their Biological Relevance in Regenerative Medicine

Osteoarthritis (OA) is a multifaceted musculoskeletal disorder, with a high prevalence worldwide. Articular cartilage and synovial membrane are among the main biological targets in the OA microenvironment. Gaining more knowledge on the accuracy of preclinical in vitro OA models could open innovative avenues in regenerative medicine to bridge major gaps, especially in translation from animals to humans. Our methodological approach entailed searches on Scopus, the Web of Science Core Collection, and EMBASE databases to select the most relevant preclinical in vitro models for studying OA. Predicting the biological response of regenerative strategies requires developing relevant preclinical models able to mimic the OA milieu influencing tissue responses and organ complexity. In this light, standard 2D culture models lack critical properties beyond cell biology, while animal models suffer from several limitations due to species differences. In the literature, most of the in vitro models only recapitulate a tissue compartment, by providing fragmented results. Biotechnological advances may enable scientists to generate new in vitro models that combine easy manipulation and organ complexity. Here, we review the state-of-the-art of preclinical in vitro models in OA and outline how the different preclinical systems (inflammatory/biomechanical/microfluidic models) may be valid tools in regenerative medicine, describing their pros and cons. We then discuss the prospects of specific and combinatorial models to predict biological responses following regenerative approaches focusing on mesenchymal stromal cells (MSCs)-based therapies to reduce animal testing.

Characteristics of MSCs in Synovial Fluid and Mode of Action of Intra-Articular Injections of Synovial MSCs in Knee Osteoarthritis

We have been studying mesenchymal stem cells (MSCs) in synovial fluid and the intra-articular injection of synovial MSCs in osteoarthritis (OA) knees. Here, mainly based on our own findings, we overview the characteristics of endogenous MSCs in the synovial fluid of OA knees and their mode of action when injected exogenously into OA knees. Many MSCs similar to synovial MSCs were detected in the synovial fluid of human OA knees, and their number correlated with the radiological OA grade. Our suspended synovium culture model demonstrated the release of MSCs from the synovium through a medium into a non-contacting culture dish. In OA knees, endogenous MSCs possibly mobilize in a similar manner from the synovium through the synovial fluid and act protectively. However, the number of mobilized MSCs is limited; therefore, OA progresses in its natural course. Synovial MSC injections inhibited the progression of cartilage degeneration in a rat OA model. Injected synovial MSCs migrated into the synovium, maintained their MSC properties, and increased the gene expressions of TSG-6, PRG-4, and BMP-2. Exogenous synovial MSCs can promote anti-inflammation, lubrication, and cartilage matrix synthesis in OA knees. Based on our findings, we have initiated a human clinical study of synovial MSC injections in OA knees.

Effects of Intra-Articular Resveratrol Injections on Cartilage Destruction and Synovial Inflammation in Experimental Temporomandibular Joint Osteoarthritis

PURPOSE

The aim of this study was to investigate the effects of intra-articular resveratrol injections on cartilage destruction and synovial inflammation in an experimental temporomandibular joint osteoarthritis (TMJ-OA) model.

MATERIALS AND METHODS

Freund's complete adjuvant injection method was used to construct the TMJ-OA model. Twenty-eight male Wistar rats were randomly placed into 4 groups: control (n = 4), TMJ arthritis (n = 8), low-dose intra-articular resveratrol (RES[L]; n = 8), and high-dose intra-articular resveratrol (RES[H]; n = 8). Intra-articular injections of resveratrol were performed 3 times at 1-week intervals, 1 week after the administration of a single dose of Freund's complete adjuvant to the TMJ. The effects of resveratrol on cartilage destruction and synovial inflammation were examined histopathologically. The histomorphometric examination revealed condylar cartilage and articular disc thickness. An apoptotic chondrocyte count was performed with terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and matrix metalloproteinase 13 expression was evaluated through an immunohistochemical examination.

RESULTS

The thickness of the condylar cartilage in the RES(L) and RES(H) groups was statistically significantly greater than that in the control and TMJ arthritis groups (P < .05). The inflammation-induced articular disc thickening was significantly lower in the RES(L) and RES(H) groups (P < .05). The chondrocyte apoptosis in the RES(L) and RES(H) groups was significantly lower than that in the TMJ arthritis group (P < .05). The matrix metalloproteinase 13 expression in the RES(L) and RES(H) groups was obviously less than that in the TMJ arthritis group (P < .05).

CONCLUSIONS

The intra-articular resveratrol treatment exerted a curative effect by preventing the inflammation and cartilage destruction associated with TMJ-OA.

Circular RNA-CDR1as acts as the sponge of microRNA-641 to promote osteoarthritis progression

Background

The antisense cerebellar degenerative-related protein-1 (CDR1as) has been identified as a sponge for several microRNAs. MiR-641 has been shown to be downregulated in osteoarthritic human chondrocytes, but its regulation and function in osteoarthritis (OA) has not been reported.

Methods

OA cartilage samples were obtained from the knee joints of 12 patients (8 males and 4 females at age of 57–73 years old) who underwent total knee arthroplasty. Normal articular cartilage samples were obtained from the knee joints of 10 trauma patients at age of 29–65 years old (6 males and 4 females). The levels of circRNA-CDR1as mRNA and miR-641 were examined by qRT-PCR and the contents of type II collagen (Col II), IL-6, MMP13 and GAPDH in chondrocytes were examined by Western blot.

Results

In this study, we found that circRNA-CDR1as level was significantly upregulated in OA chondrocytes, and negatively related with that of miR-641. RNA pull down assay confirmed that circRNA-CDR1as directly targets to miR-641. Furthermore, downregulation of circRNA-CDR1as increased type II collagen level but reduced MMP13 and IL-6 contents, while these effects were partly reversed by down-regulation of miR-641.

Conclusion

Overall, our results indicate that circRNA-CDR1as plays a crucial role in regulating OA progression via modulating extracellular matrix metabolism and inflammation via sponging miR-641 and provide a novel regulatory role of circRNA-CDR1as in OA.

miR‑146a‑5p expression is upregulated by the CXCR4 antagonist TN14003 and attenuates SDF‑1‑induced cartilage degradation

Osteoarthritis (OA) is an aseptic inflammatory disease which is associated with the stromal cell-derived factor 1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis. Accumulating studies have identified numbers of microRNAs (miRNAs) that serve important roles in the pathogenesis of OA. However, whether and how the inhibition of the SDF-1/CXCR4 axis induces alterations in miRNA expression remains largely unclear. miRNA profiling was performed in OA chondrocytes stimulated with SDF-1 alone, or SDF-1 with the CXCR4 antagonist TN14003 by miRNA microarray. Candidate miRNAs were verified by reverse transcription quantitative polymerase chain reaction. Bioinformatic analyses including target prediction, gene ontology (GO) and pathway analysis were performed to explore the potential functions of candidate miRNAs. Notably, 7 miRNAs (miR-146a-5p, miR-221-3p, miR-126-3p, miR-185-5p, miR-155-5p, miR-124-3p and miR-130a-3p) were significantly differentially expressed. GO analysis indicated that miR-146a-5p and its associated genes were enriched in receptor regulatory activity, nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB)-inducing kinase activity, cellular response to interleukin-1, cytokine-cytokine receptor interaction, NF-κB signaling pathway and osteoclast differentiation pathways. CXCR4 was predicted to be a target of miR-146a-5p with high importance. The mRNA and protein levels of key factors involved in cartilage degeneration were measured following manipulation of the expression levels of miR-146a-5p in OA chondrocytes. CXCR4 and MMP-3 levels were negatively associated with miR-146a-5p expression, while the levels of type II collagen and aggrecan were positively associated. These data reveal that TN14003 upregulates miR-146a-5p expression, and also pinpoints a novel role of miR-146a-5p in inhibiting cartilage degeneration by directly targeting the SDF-1/CXCR4 axis.

Interleukin-1β signaling in osteoarthritis - chondrocytes in focus

Osteoarthritis (OA) can be regarded as a chronic, painful and degenerative disease that affects all tissues of a joint and one of the major endpoints being loss of articular cartilage. In most cases, OA is associated with a variable degree of synovial inflammation. A variety of different cell types including chondrocytes, synovial fibroblasts, adipocytes, osteoblasts and osteoclasts as well as stem and immune cells are involved in catabolic and inflammatory processes but also in attempts to counteract the cartilage loss. At the molecular level, these changes are regulated by a complex network of proteolytic enzymes, chemokines and cytokines (for review: [1]). Here, interleukin-1 signaling (IL-1) plays a central role and its effects on the different cell types involved in OA are discussed in this review with a special focus on the chondrocyte.

Cartilage Metabolism is Modulated by Synovial Fluid Through Metalloproteinase Activity

Synovial fluid (SF) contains various cytokines that regulate chondrocyte metabolism and is dynamically associated with joint disease. The objective of this study was to investigate the effects of diluted normal SF on catabolic metabolism of articular cartilage under inflammatory conditions. For this purpose, SF was isolated from healthy bovine joints, diluted, and added to cartilage explant cultures stimulated with interleukin-1 (IL-1) for 12 days. The kinetic release of sulfated glycosaminoglycan (sGAG) and collagen, as well as nitric oxide and gelatinase matrix metalloproteinases were analyzed in the supernatant. Chondrocyte survival and matrix integrity in the explants were evaluated with Live/Dead and histological staining. Diluted synovial fluid treatment suppressed sGAG and collagen release, downregulated the production of nitric oxide and matrix metalloproteinases, reduced IL-1-induced chondrocyte death, and rescued matrix depletion. Our results demonstrate that normal SF can counteract inflammation-driven cartilage catabolism. This study reports on the protective function of healthy SF and the therapeutic potential of recapitulation of SF for cartilage repair.

CTHRC1 mediates IL‑1β‑induced apoptosis in chondrocytes via JNK1/2 signaling

Osteoarthritis (OA), also known as degenerative joint disease or degenerative arthritis, is characterized by chondrocyte apoptosis. The aim of the present study was to investigate the effects of collagen triple helix repeat containing 1 (CTHRC1) and the c‑Jun N‑terminal kinase (JNK) 1/2 inhibitor SP600125 on rat chondrocytes cultured in vitro with interleukin (IL)‑1β. Chondrocytes were treated with different doses of IL‑1β and cell viability and CTHRC1 expression were assessed using Cell Counting Kit‑8 and western blot assays, respectively. In separate experiments, chondrocytes were treated with CTHRC1‑expressing constructs (pLVX‑Puro‑CTHRC1) and/or SP600125, or IL‑1β with either CTHRC1 short hairpin (sh)RNA constructs (shNRA‑CTHRC1) or SP600125. The expression of CTHRC1, B‑cell lymphoma (Bcl)‑2, Bcl‑2‑associated X protein (Bax), cleaved caspase‑3, poly ADP ribose polymerase (PARP)‑1 and matrix metalloproteinase (MMP)‑13 was measured using reverse transcription‑quantitative polymerase chain reaction and western blotting assays. A Cell Counting Kit‑8 assay was performed to examine cell viability. Annexin V/propidium iodide staining and flow cytometry assays were used to detect chondrocyte apoptosis. The expression of JNK1/2 and phosphorylated JNK1/2 was measured using western blotting. CTHRC1 was highly expressed in patients with OA compared with normal controls. IL‑1β treatment (5, 10 and 20 ng/ml) increased the protein expression of CTHRC1 in a dose‑dependent manner and decreased the viability of chondrocytes in a time‑dependent manner. pLVX‑Puro‑CTHRC1 mimics the effect of IL‑1β on chondrocyte apoptosis and JNK1/2 activity, and this is reversed by SP600125 treatment. However, transfection with shRNA‑CTHRC1 or treatment with SP600125 inhibited IL‑1β‑induced cell apoptosis and JNK1/2 activation. These results indicate that CTHRC1 downregulation may protect chondrocytes from IL‑1β‑induced apoptosis by inactivating the JNK1/2 pathway.

Bone morphogenetic protein-2 and -7 mediate the anabolic function of nucleus pulposus cells with discrete mechanisms

Bone morphogenetic proteins (BMPs) play roles in promoting cell anabolism, especially in extracellular matrix production. The difference between BMP members in their capacity to modulate intervertebral disc cell activity is yet to be defined. BMP-7/OP-1 has been shown to retard disc degeneration. We compared the activity of BMP-7 with that of BMP-2 on nucleus pulposus (NP) cell phenotype and function, and investigated how they differentially affect the gene expression profiles of signaling cascade components in human NP cells under degenerative states. We found that while both BMP-2 and BMP-7 enhanced matrix production of bovine NP cells, BMP-7 is more potent than BMP-2 at various dosages (50-800 ng/ml). BMP-7 exerted a relatively stronger stimulation on sulfated glycosaminoglycan production and proliferation in human NP cells. Degenerated NP cells showed an overall weaker response to the BMPs than non-degenerated cells, and were more sensitive to BMP-7 than BMP-2 stimulation. Compared to BMP-2, BMP-7 not only induced the gene expression of canonical BMP components, but also evoked changes in MAPKs as well as CREB1 and EP300 gene expression in degenerated NP cells, suggesting potential activation of the cAMP dependent protein kinase related pathways. In contrast to BMP-2, BMP-7 concomitantly inhibited the expression of profibrotic genes. We propose that BMP-2 and BMP-7, and likely other BMPs, may operate multifaceted but discrete molecular machineries that give rise to their different capacity in regulating NP cell phenotype. Further investigations into such differential capacity may possibly derive alternative cues important for IVD repair or engineering.

Celastrol attenuates pain and cartilage damage via SDF-1/CXCR4 signalling pathway in osteoarthritis rats

OBJECTIVES

Celastrol has attracted wide interests for its anticancer and anti-inflammation properties, and studies have demonstrated that celastrol negatively modulates the stromal cell-derived factor-1 (SDF-1) and receptor C-X-C chemokine receptor type 4 (CXCR4) signalling. We aim in this study to investigate the effects of celastrol in osteoarthritis (OA) in vivo and explored the underlying molecular mechanisms.

METHODS

We established a monoiodoacetate (MIA)-induced rat OA model and evaluated the joint pain and cartilage damage with or without celastrol treatments. We further assessed the alterations of the SDF-1/CXCR4 pathway and cartilage-specific genes, at both mRNA and protein levels.

KEY FINDINGS

Celastrol significantly attenuated the joint pain and cartilage damage induced by MIA in OA rats and suppressed the upregulation of SDF-1/CXCR4 and associated genes caused by MIA injections. Furthermore, MIA induced a decrease in cartilage-specific genes which was also prevented by celastrol treatments.

CONCLUSIONS

Celastrol ameliorate OA in vivo as evidenced by the attenuated joint pain and less cartilage damage in OA rats given celastrol treatments, an effect mediated via suppression of the SDF-1/CXCR4 pathway.

Association of ADAM 12 polymorphisms with the risk of knee osteoarthritis: meta-analysis of 5048 cases and 6848 controls

Several studies have suggested the association between ADAM 12 polymorphisms and the risk of osteoarthritis (OA), but the results remained controversial. Therefore, we designed a meta-analysis to systematically evaluate the association on this issue. A literature search for eligible studies was conducted in PubMed, Web of Science and Google Scholar databases. The association between ADAM 12 polymorphisms and knee OA risk was calculated by odds ratios (ORs) and 95% confidence intervals (CIs). Study heterogeneity, sensitivity and publication bias analyses were also conducted. Ten articles covering 5048 cases and 6848 controls met our criteria for the final analysis. We found that the rs1871054 was significantly associated with the risk of knee OA (allele model OR 1.72, 95% CI 1.43-2.07, P < 0.001; additive model: OR 2.06, 95% CI 1.19-3.56, P = 0.010; dominant model: OR 2.45, 95% CI 1.85-3.25, P < 0.001; recessive model: OR 1.54, 95% CI 1.13-2.10, P = 0.007). rs1044122 was significantly associated with knee OA susceptibility in recessive model (OR 1.45, 95% CI 1.03-2.04, P = 0.031). For rs3740199 and rs1278279, no significant associations with knee OA were found. In the stratified analysis by gender, significant association was identified with the risk of knee OA for rs3740199 in men in allele model (OR 2.41, 95% CI 1.51-3.84, P < 0.001), dominant model (OR 2.68, 95% CI 1.17-6.14, P = 0.02) and recessive model (OR 3.51, 95% CI 1.68-7.36, P = 0.001), but not for additive model (OR 1.30, 95% CI 0.81-2.08, P = 0.28). This meta-analysis suggests that the ADAM 12 genetic polymorphisms rs1871054 and rs1044122 might be associated with risk of knee OA; rs3740199 might be associated with risk of knee OA in men. Further well-designed and large scale studies are warranted to validate these associations.

Fibrous Synovium Releases Higher Numbers of Mesenchymal Stem Cells Than Adipose Synovium in a Suspended Synovium Culture Model

PURPOSE

To develop an in vitro model, the "suspended synovium culture model," to demonstrate the mobilization of mesenchymal stem cells (MSCs) from the synovium into a noncontacted culture dish through culture medium. In addition, to examine which synovium, fibrous synovium or adipose synovium, released more MSCs in the knee with osteoarthritis.

METHODS

Human synovial tissue was harvested during total knee arthroplasty from knee joints of 34 patients with osteoarthritis (28 patients: only fibrous synovium, 6 patients: fibrous and adipose synovium). One gram of synovium was suspended with a thread in a bottle containing 40 mL of culture medium and a 3.5-cm-diameter culture dish at the bottom. After 7 days, the culture dish in the bottle was examined. For the cells harvested, multipotentiality and surface epitopes were analyzed. The numbers of colonies derived from fibrous synovium and adipose synovium were also compared.

RESULTS

Colonies of spindle-shaped cells were observed in the culture dish in all 28 donors. Colonies numbered 26 on average, and the cells derived from colony-forming cells had multipotentiality for chondrogenesis, adipogenesis, calcification, and surface epitopes similar to MSCs. The number was colonies was significantly higher in fibrous synovium than in adipose synovium (P < .05, n = 6).

CONCLUSIONS

We developed a suspended synovium culture model. Suspended synovium was able to release MSCs into a noncontacted culture dish through medium in a bottle. Fibrous synovium was found to release greater numbers of MSCs than adipose synovium in our culture model. CLINICAL RELEVANCE: This model could be a valuable tool to screen drugs capable of releasing MSCs from the synovium into synovial fluid.

The Expression of Osteopontin and Wnt5a in Articular Cartilage of Patients with Knee Osteoarthritis and Its Correlation with Disease Severity

Objectives. This study is undertaken to investigate the relation between osteopontin (OPN) and Wnt5a expression in the progression and pathogenesis of osteoarthritis (OA). Methods. 50 cartilage tissues from knee OA patients and normal controls were divided into four groups of severe, moderate, minor, and normal lesions based on the modified grading system of Mankin. Immunohistochemistry and real-time PCR were utilized to analyze the OPN and Wnt5a expression in articular cartilage. Besides, the relations between OPN and Wnt5a expression and the severity of OA were explored. Results. OPN and Wnt5a could be identified in four groups' tissues. Amongst the groups, the intercomparisons of OPN expression levels showed statistical differences (P < 0.01). Besides, the intercomparisons of Wnt5a expression degrees showed statistical differences (P < 0.05), except that between the minor and normal groups (P > 0.05). The scores of Mankin were demonstrated to relate to OPN expression (r = -0.847, P < 0.01) and Wnt5a expression in every group (r = -0.843, P < 0.01). Also, a positive correlation can be observed between the OPN and Wnt5a expression (r = 0.769, P < 0.01). Conclusion. In articular cartilage, the expressions of OPN and Wnt5a are positively related to progressive damage of knee OA joint. The correlation between Wnt5a and OPN might be important to the progression and pathogenesis of knee OA.

A Porcine Animal Model for Early Meniscal Degeneration - Analysis of Histology, Gene Expression and Magnetic Resonance Imaging Six Months after Resection of the Anterior Cruciate Ligament

BACKGROUND/OBJECTIVE

The menisci of the mammalian knee joint balance the incongruence between femoral condyle and tibial plateau and thus menisci absorb and distribute high loads. Degeneration processes of the menisci lead to pain syndromes in the knee joint. The origin of such degenerative processes on meniscal tissue is rarely understood and may be described best as an imbalance of anabolic and catabolic metabolism. A standardized animal model of meniscal degeneration is needed for further studies. The aim of the current study was to develop a porcine animal model with early meniscal degeneration.

MATERIAL AND METHODS

Resection of the anterior cruciate ligament (ACLR) was performed on the left knee joints of eight Göttingen minipigs. A sham operation was carried out on the right knee joint. The grade of degeneration was determined 26 weeks after the operation using histology and magnetic resonance imaging (MRI). Furthermore, the expression of 14 genes which code for extracellular matrix proteins, catabolic matrix metalloproteinases and inflammation mediators were analyzed.

RESULTS

Degenerative changes were detected by a histological analysis of the medial meniscus after ACLR. These changes were not detected by MRI. In terms of their gene expression profile, these degenerated medial menisci showed a significantly increased expression of COL1A1.

CONCLUSION

This paper describes a new animal model for early secondary meniscal degeneration in the Göttingen minipig. Histopathological evidence of the degenerative changes could be described. This early degenerative changes could not be seen by NMR imaging.

Osteoarthritis in morbidly obese children and adolescents, an age-matched controlled study

PURPOSE

Main objective of this study was to investigate the association of pain and early cartilage lesions in morbidly obese children and adolescents.

METHODS

A total of 57 subjects were included in the study. Morbidly obese patients (n = 39) were subdivided into two groups: Group A: (11 males and 9 females, 14.2 ± 2.7 years) with permanent knee pain; and Group B: (10 males and 9 females, 14.4 ± 2.2 years) without permanent or without any knee pain. Group C (8 males and 10 females, 15.0 ± 2.9 years) included age-matched children and adolescents of normal weight. MRI examinations were performed in all subjects, and an extensive analysis of the images was conducted according to the condition of the cartilage surface and the meniscus. Patients' subjective health was assessed by means of four well-known knee scores (IKDC, KOOS, Tegner/Lysholm, and VAS). Nonparametric Jonckheere-Terpstra test was used to test the trend of the natural order between the three groups.

RESULTS

In 38 of 39 morbidly obese children and adolescents, in at least one region of the knee, a marked cartilage lesion could be shown by MRI. Group A showed significantly (p < 0.001) more cartilage lesions (mean 3.7) compared to Group B (mean 2.8) and Group C (mean 0.8). IKDC, and all the KOOS subunits, showed significantly (p < 0.001, p Bonferroni < 0.001) increasing scores from Group A to B to C, in addition to KOOS symptoms.

CONCLUSIONS

Morbid obesity causes early lesions of the knee cartilage, even in young patients. Significantly, more patients with reported pain show more severe damages.

Danshen prevents articular cartilage degeneration via antioxidation in rabbits with osteoarthritis

OBJECTIVE

To evaluate the efficacy of Danshen on histological parameters and antioxidative activity in the articular cartilage of rabbits with osteoarthritis (OA).

DESIGN

Twenty-four rabbits were randomly divided into three groups (control, OA, and Danshen OA; eight rabbits per group). Anterior cruciate ligament transection (ACLT) of the left hind knees was performed in all rabbits in the OA and Danshen OA group for induction of OA. The rabbits in the control group underwent a sham operation. After surgery, 3 g/kg body weight of Danshen granules dissolved in 5 mL distilled water was administered by gastric intubation once per day and over a 6-week period to the Danshen OA group. The same volume of distilled water was administered to the OA and control groups. After 6 weeks, the medial femoral condyles and synoviums of the left hind knees in all three groups were harvested and used for histological and biochemical analyses.

RESULTS

Severe articular cartilage degeneration as well as lower proteoglycan (PG) content were noted in the OA group compared to the Danshen OA group (P < 0.05). The glutathione (GSH) levels in the synovium and articular cartilage of the rabbits in the Danshen OA group were significantly higher compared to the OA group (P < 0.001). The malondialdehyde (MDA) levels of the synovium and articular cartilage in the Danshen OA group was markedly depleted compared to the OA group (P < 0.001).

CONCLUSION

Danshen can prevent articular cartilage degeneration in OA through the defense against oxidative stress.

Ultra-structural changes and expression of chondrogenic and hypertrophic genes during chondrogenic differentiation of mesenchymal stromal cells in alginate beads

Chondrogenic differentiation of mesenchymal stromal cells (MSCs) in the form of pellet culture and encapsulation in alginate beads has been widely used as conventional model for in vitro chondrogenesis. However, comparative characterization between differentiation, hypertrophic markers, cell adhesion molecule and ultrastructural changes during alginate and pellet culture has not been described. Hence, the present study was conducted comparing MSCs cultured in pellet and alginate beads with monolayer culture. qPCR was performed to assess the expression of chondrogenic, hypertrophic, and cell adhesion molecule genes, whereas transmission electron microscopy (TEM) was used to assess the ultrastructural changes. In addition, immunocytochemistry for Collagen type II and aggrecan and glycosaminoglycan (GAG) analysis were performed. Our results indicate that pellet and alginate bead cultures were necessary for chondrogenic differentiation of MSC. It also indicates that cultures using alginate bead demonstrated significantly higher (p < 0.05) chondrogenic but lower hypertrophic (p < 0.05) gene expressions as compared with pellet cultures. N-cadherin and N-CAM1 expression were up-regulated in second and third weeks of culture and were comparable between the alginate bead and pellet culture groups, respectively. TEM images demonstrated ultrastructural changes resembling cell death in pellet cultures. Our results indicate that using alginate beads, MSCs express higher chondrogenic but lower hypertrophic gene expression. Enhanced production of extracellular matrix and cell adhesion molecules was also observed in this group. These findings suggest that alginate bead culture may serve as a superior chondrogenic model, whereas pellet culture is more appropriate as a hypertrophic model of chondrogenesis.

Chitosan-Coated Collagen Membranes Promote Chondrocyte Adhesion, Growth, and Interleukin-6 Secretion

Designing scaffolds made from natural polymers may be highly attractive for tissue engineering strategies. We sought to produce and characterize chitosan-coated collagen membranes and to assess their efficacy in promoting chondrocyte adhesion, growth, and cytokine secretion. Porous collagen membranes were placed in chitosan solutions then crosslinked with glutaraldehyde vapor. Fourier transform infrared (FTIR) analyses showed elevated absorption at 1655 cm-1 of the carbon-nitrogen (N=C) bonds formed by the reaction between the (NH₂) of the chitosan and the (C=O) of the glutaraldehyde. A significant peak in the amide II region revealed a significant deacetylation of the chitosan. Scanning electron microscopy (SEM) images of the chitosan-coated membranes exhibited surface variations, with pore size ranging from 20 to 50 µm. X-ray photoelectron spectroscopy (XPS) revealed a decreased C-C groups and an increased C-N/C-O groups due to the reaction between the carbon from the collagen and the NH2 from the chitosan. Increased rigidity of these membranes was also observed when comparing the chitosan-coated and uncoated membranes at dried conditions. However, under wet conditions, the chitosan coated collagen membranes showed lower rigidity as compared to dried conditions. Of great interest, the glutaraldehyde-crosslinked chitosan-coated collagen membranes promoted chondrocyte adhesion, growth, and interleukin (IL)-6 secretion. Overall results confirm the feasibility of using designed chitosan-coated collagen membranes in future applications, such as cartilage repair.

Intra-articular resveratrol injection prevents osteoarthritis progression in a mouse model by activating SIRT1 and thereby silencing HIF-2α

We investigated the feasibility of the intra-articular injection of resveratrol for preventing the progression of existing cartilage degeneration in a mouse model of osteoarthritis (OA). The effects of resveratrol on the expression of silent information regulator 2 type 1 (SIRT1), hypoxia-inducible factor-2α (HIF-2α) and catabolic factors in OA cartilage was explored. OA was induced in the mouse knee via destabilization of the medial meniscus (DMM). Resveratrol was injected weekly into the operated knee beginning 4 weeks after surgery. The OA phenotype was evaluated via histological and immunohistochemical analyses at 8 weeks after DMM. Western blot analysis was performed to identify whether resveratrol modulated the interleukin (IL)-1β-induced expression of HIF-2α in human chondrocytes. Histologically, resveratrol treatment preserved the structural homeostasis of the articular cartilage and the subchondral bone. Following resveratrol injection, the expression of collagen type II was retained, but the expression of inducible nitric oxide synthase and matrix metalloproteinase-13 was reduced in OA cartilage. Moreover, the administration of resveratrol significantly induced the activation of SIRT1 and the inhibition of HIF-2α expression in mouse OA cartilage and in IL-1β-treated human chondrocytes. These findings indicate that the intra-articular injection of resveratrol significantly prevents the destruction of OA cartilage by activating SIRT1 and thereby suppressing the expression of HIF-2α and catabolic factors.

Correlation between osteopontin and caveolin-1 in the pathogenesis and progression of osteoarthritis

Previous studies have produced contradictory results with regard to the role of osteopontin (OPN) and caveolin-1 in the pathology of osteoarthritis (OA). Thus, the aim of the present study was to investigate the correlation between OPN and caveolin-1 in the pathogenesis and progression of OA. Cartilage tissue samples were obtained from 50 individuals, of which 40 had been diagnosed with OA and 10 were normal healthy individuals. The samples were ascribed to four groups, namely the normal, minor, moderate and severe groups, on the basis of the improved Mankin grading system. Immunohistochemistry was applied to analyse the expression of OPN and caveolin-1. OPN and caveolin-1 were detected in the tissues of all four groups. The mutual comparisons of OPN expression levels among the groups revealed statistically significant differences (P<0.05). In addition, the mutual comparisons of caveolin-1 expression levels among the four groups demonstrated statistically significant differences (P<0.05), with the exception of that between the moderate and severe groups (P>0.05). Improved Mankin grading system scores were shown to correlate with the average grey level of OPN expression in each group (r=-0.824, P<0.01) and the average grey level of caveolin-1 expression (r=0.725, P<0.01). Furthermore, a statistically significant negative correlation was observed between the average grey levels of OPN and caveolin-1 expression (r=-0.676, P﹤0.05). Therefore, the results of the present study indicated that the correlation between OPN and caveolin-1 may play a significant role in the pathogenesis and progression of OA.

Effects of cyclic tensile strain on chondrocyte metabolism: a systematic review

Chondrocytes reorganize the extracellular matrix of articular cartilage in response to externally applied loads. Thereby, different loading characteristics lead to different biological responses. Despite of active research in this area, it is still unclear which parts of the extracellular matrix adapt in what ways, and how specific loading characteristics affect matrix changes. This review focuses on the influence of cyclic tensile strain on chondrocyte metabolism in vitro. It also aimed to identify anabolic or catabolic chondrocyte responses to different loading protocols. The key findings show that loading cells up to 3% strain, 0.17 Hz, and 2 h, resulted in weak or no biological responses. Loading between 3–10% strain, 0.17–0.5 Hz, and 2–12 h led to anabolic responses; and above 10% strain, 0.5 Hz, and 12 h catabolic events predominated. However, this review also discusses that various other factors are involved in the remodeling of the extracellular matrix in response to loading, and that parameters like an inflammatory environment might influence the biological response.

Analysis of single nucleotide polymorphisms within ADAM12 and risk of knee osteoarthritis in a Chinese Han population

Objective. Osteoarthritis (OA) is a complex arthritic condition in which the genetic factor plays a major role. One of the candidate genes of is the ADAM12 gene, but no consistency has been reached till now. This study aims to investigate the potential role of four single nucleotide polymorphisms (SNPs) of the ADAM12 gene in susceptibility to knee OA and its progression in Chinese Han population. Methods. The rs1278279, rs3740199, rs1044122, and rs1871054 polymorphisms were genotyped and compared in a population based cohort consisting of 164 OA subjects and 200 age- and gender-matched controls. Results. The SNP rs1871054 was found with increased risk of OA susceptibility in comparing the genotype frequencies between the case and control groups no matter for which model of comparison (allele level, dominant model, recessive model, and extreme genotype model). Additionally, the SNP rs1871054 was found associated with increased OA severity according to the K/L grade. Conclusion. In summary, we have identified that the rs1871054 variant within the ADAM12 gene is a risk factor for increased osteoarthritis susceptibility and severity.

Posttraumatic knee osteoarthritis following anterior cruciate ligament injury: Potential biochemical mediators of degenerative alteration and specific biochemical markers

As a common injury, anterior cruciate ligament (ACL) injury is unable to heal itself naturally, which possibly increases knee instability, accelerates the risk of joint degeneration and leads to knee osteoarthritis (OA) in the ACL-injured knee. Thus, ACL reconstruction using an autograft or allograft tendon is proposed to maintain the biomechanical stability of the knee joint. However, previous studies demonstrate that surgical management of ACL reconstruction failed to abrogate the development of OA completely, indicating that biochemical disturbance is responsible for the osteoarthritic changes observed following ACL injury. Inflammatory mediators are elevated subsequent to ACL injury or rupture, inducing matrix metalloproteinase production, proteoglycan degradation, collagen destruction, chondrocyte necrosis and lubricin loss. These potential biochemical mediators may aid in the development of effective biological management to reduce the onset of future posttraumatic OA. Furthermore, during the degenerative process of cartilage, there are a number of cartilage-specific biomarkers, which play a critical step in the loss of structural and functional integrity of cartilage. The present review illustrates several specific biomarkers in the ACL-injured knee joint, which may provide effective diagnostic and prognostic tools for investigating cartilage degenerative progression and future posttraumatic OA of ACL-injured patients.

Diverse expression of selected cytokines and proteinases in synovial fluid obtained from osteoarthritic and healthy human knee joints

Background

Osteoarthritis (OA) is defined by signs and symptoms of inflammation within the affected joint. The aim of this study is to determine the mRNA expression levels of selected cytokines and matrix-metalloproteinases of cells found in synovial fluid (SF) obtained from osteoarthritic knee joints compared to healthy controls.

Methods

SF was obtained from 40 patients undergoing total knee arthroplasty due to evident OA and from 10 healthy controls. Expression of TNF-α, IL-1β, MMP-1 and MMP-3 was assayed among both groups by performing qPCR. Patients were configured concerning age, gender and BMI.

Results

IL-1β, MMP-1 and MMP-3 showed significantly higher expression among the OA group compared to control (P < 0.001). Strong correlation appeared between expression of MMP-1 and MMP-3 among OA patients (r = 0.856); no correlation was found between age, gender or BMI and cytokine/proteinase expression. Expression of IL-1β, MMP-1 and MMP-3 within SF was elevated in OA-patients.

Conclusion

Consequently, cells within SF expressing cytokines and proteinases may play a relevant role in the progression of joint destruction. Considering the fact that SF in an OA joint comprises abnormal amounts of detrimental bioactive proteins, temporary clearance, dilution or suppression/modulation by means of lavage or disease-modifying medication may be promising to constitute interim relief or even postpone disease progression due to decreased inflammatory and/or degrading activity within the articular environment.

Andrographolide Exerts Chondroprotective Activity in Equine Cartilage Explant and Suppresses Interleukin-1 β -Induced MMP-2 Expression in Equine Chondrocyte Culture

Cartilage erosion in degenerative joint diseases leads to lameness in affected horses. It has been reported that andrographolide from Andrographis paniculata inhibited cartilage matrix-degrading enzymes. This study aimed to explore whether this compound protects equine cartilage degradation in the explant culture model and to determine its effect on matrix metalloproteinase-2 (MMP-2) expression, a matrix-degrading enzyme, in equine chondrocyte culture. Equine articular cartilage explant culture was induced by 25 ng/mL interleukin-1β, a key inducer of cartilage degeneration, in cultures with or without andrographolide ranging from 10 to 50 μM. After 3–21 days, they were analyzed for the markers of cartilage degradation. It was found that interleukin-1β increased the release of sulfated glycosaminoglycans and hyaluronan from the explants into the culture media consistently with the decrease in uronic acid and collagen content in the cartilage explants. These catabolic effects were inhibited when cotreated with interleukin-1β and andrographolide. In primary equine chondrocytes, andrographolide suppressed interleukin-1β-induced MMP-2 mRNA expression and MMP-2 activity in the culture medium. These results confirmed the in vitro potent chondroprotective activities of this compound which were performed in cartilage explants and on a cellular level. These may indicate the application of andrographolide for therapeutic use in equine degenerative joint diseases.

Sanmiao formula inhibits chondrocyte apoptosis and cartilage matrix degradation in a rat model of osteoarthritis

Sanmiao formula (SM) is a basic prescription for the treatment of gouty and rheumatoid arthritis that has been used in China over a long period of history. However, there is no evidence associating SM with the treatment of osteoarthritis (OA). In this study, a characterization of the anti-OA effect of SM was conducted using an in vivo rat model induced by anterior cruciate ligament transection and medial meniscus resection (ACLT plus MMx), together with in vitro studies using chondrocytes for further molecular characterization. Rats subjected to ACLT plus MMx were treated with SM at doses of 0.63, 1.25 and 2.5 g/kg per day for three or six weeks. SM treatment significantly inhibited the histopathological changes of articular cartilage damage and synovial inflammation in the rats following ACLT plus MMx. SM (2.5 g/kg) clearly inhibited chondrocyte apoptosis and prevented cartilage matrix degradation, which was indicated by the increased proteoglycan and collagen content, particularly with regard to type II collagen expression in articular cartilage. Furthermore, SM (2.5 g/kg) markedly inhibited the release of interleukin (IL)-1β, tumor necrosis factor-α and nitric oxide in serum, while simultaneously increasing the levels of bone morphogenetic protein-2 and transforming growth factor-β in the circulation. Notably, SM (2.5 g/kg) clearly attenuated the OA-augmented expression of matrix metalloproteinase (MMP)-13 and augmented the OA-reduced expression of tissue inhibitor of metalloproteinase (TIMP)-1 in the knee joints. In addition, SM significantly reduced the proportion of early and late apoptotic and sub-G₁ phase cells, and clearly decreased the expression of MMP-13 and increased that of TIMP-1 at the mRNA and protein levels in IL-1β-induced chondrocytes. These findings provide the first evidence that SM effectively treats OA by inhibiting chondrocyte apoptosis, cartilage matrix degradation and the inflammatory response.

Scaffold structure and fabrication method affect proinflammatory milieu in three-dimensional-cultured chondrocytes

Cartilage tissue engineering has emerged as an attractive therapeutic option for repairing damaged cartilage tissue in the arthritic joint. High levels of proinflammatory cytokines present at arthritic joints can cause cartilage destruction and instability of the engineered cartilage tissue, and thus it is critical to engineer strong and stable cartilage that is resistant to the inflammatory environment. In this study, we demonstrate that scaffolding materials with different pore sizes and fabrication methods influence the microenvironment of chondrocytes and the response of these cells to proinflammatory cytokines, interleukin-1beta, and tumor necrosis factor alpha. Silk scaffolds prepared using the organic solvent hexafluoroisopropanol as compared to an aqueous-based method, as well as those with larger pore sizes, supported the deposition of higher cartilage matrix levels and lower expression of cartilage matrix degradation-related genes, as well as lower expression of endogenous proinflammatory cytokines IL-1β in articular chondrocytes. These biochemical properties could be related to the physical properties of the scaffolds such as the water uptake and the tendency to leach or adsorb proinflammatory cytokines. Thus, scaffold structure may influence the behavior of chondrocytes by influencing the microenvironment under inflammatory conditions, and should be considered as an important component for bioengineering stable cartilage tissues.

The morphology and functions of articular chondrocytes on a honeycomb-patterned surface

The present study investigated the potential of a novel micropatterned substrate for neocartilage formation. Articular chondrocytes were cultured on poly(ɛ-caprolactone) materials whose surfaces were either flat or honeycomb-patterned. The latter was prepared using a novel self-organization technique, while the former, was prepared by spin-coating. The chondrocytes attached and proliferated on both surfaces. On the honeycomb films, chondrocytes were found at the top surface and encased within the 10 μm pores. Meanwhile, chondrocytes on the spin-coated surface flattened out. Accumulation of DNA and keratin sulphate was comparatively higher on the honeycomb films within the first 7 days. At their respective peaks, DNA concentration increased on the honeycomb and flat surfaces by approximately 210% and 400% of their day 1 values, respectively. However, cultures on the flat surface took longer to peak. Extracellular Matrix (ECM) concentrations peaked at 900% and 320% increases for the honeycomb and flat cultures. Type II collagen was upregulated on the honeycomb and flat surfaces by as much as 28% and 25% of their day 1 values, while aggrecan was downregulated with time, by 3.4% and 7.4%. These initial results demonstrate the potential usefulness of honeycomb-based scaffolds during early cultures neocartilage and soft tissue engineering.

Molecular mechanisms of the cartilage-specific microRNA-140 in osteoarthritis

Osteoarthritis (OA) is the most widespread chronic degenerative joint disorder, characterized by progressive destruction of articular cartilage, subchondral bone alterations, formation of osteophytes and synovitis. MicroRNAs (miRNAs) are a class of endogenous and non-coding single-strand RNAs with a length of about 22 nucleotides, and many of them are evolutionarily conserved. miRNAs have been implicated in the process of development and pathogenesis of diseases, and tissue-specific miRNA functional studies in mice have revealed both pathogenic and protective functions. miRNA-140 (miR-140) was shown to be specifically expressed in cartilage tissues in developing zebrafish and mouse embryos during the development of both long and flat bones. Recently, miR-140 has been reported in many studies to play significant roles in OA pathogenesis. Although the previous results were not always consistent, the molecular mechanisms of the regulation and dual function of miR-140 in cartilage homeostasis and development have been established in previous studies. Further elucidation of the molecular basis of miR-140 will uncover synergistic inhibitory effects of miR-140 and other factors on OA pathogenesis, and provide a novel means of treating OA disease.

Serum cartilage oligomeric matrix protein (COMP) in knee osteoarthritis: a novel diagnostic and prognostic biomarker

A case-control study was conducted to estimate the association of cartilage oligomeric matrix protein (COMP) with knee osteoarthritis (OA) and to examine the potential utility of COMP as a diagnostic and prognostic biomarker in early knee OA. The COMP levels were estimated in the blood sera of 150 subjects belonging to study group (n = 100) and control one (n = 50). Patients with confirmed clinical isolated knee OA diagnosed through American College of Rheumatology criteria were included and were without any other cause of knee pain. ELISA was used to determine the levels of COMP, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The median (range) serum COMP levels were observed to be 1117.21 ng/ml (125.03-4209.75 ng/ml) in OA patients and 338.62 ng/ml (118-589 ng/ml) in control subjects with p < 0.001. The COMP levels of study group were negatively correlated (correlation factor -0.88) with disease duration and positively correlated with age, BMI, pain score and IL-1β with correlation factors 0.86, 0.63, 0.76, and 0.79, respectively with p < 0.001. Gender differentiation was found in study group with 52% higher COMP level in males as compared to that of females. There was no significant correlation of COMP levels with radiological grading, erythrocyte sedimentation rate (ESR), hemoglobin (Hb), and TNF-α. The serum COMP levels may be used as a diagnostic OA marker along with prognostic value in determining the patients at risk of rapidly progressing this debilitating joint disease. The serum COMP level remains significantly high in first 3 years of disease duration.

β-Defensin-4 (HBD-4) is expressed in chondrocytes derived from normal and osteoarthritic cartilage encapsulated in PEGDA scaffold

Defensins are antibiotic peptides involved in host defense mechanisms, wound healing and tissue repair. Furthermore, they seem to play an important role in protection mechanisms in articular joints. The aim of this study was to investigate β-defensin-4 expression in chondrocytes taken from articular cartilage of knees of patients with osteoarthritis (OA) compared to normal cartilage, in vivo in explanted tissue, and in vitro in chondrocytes encapsulated in construct PEGDA hydrogels. The present investigation was conducted to try and elucidate the possible use of β-defensin-4 as a relevant marker for the eventual use of successive scaffold allografts, and to provide new insights for hydrogel PEGDA scaffold efficacy in re-differentiation or repair of OA chondrocytes in vitro. Articular cartilage specimens from OA cartilage and normal cartilage were assessed by histology, histochemistry, immunohistochemistry and Western blot analysis. The results showed strong β-defensin-4 immunoexpression in explanted tissue from OA cartilage and weak β-defensin-4 expression in control cartilage. The chondrocytes from OA cartilage after 4 weeks of culture in PEGDA hydrogels showed the formation of new hyaline cartilage and a decreased expression of β-defensin-4 immunostaining comparable to that of control cartilage. Our results suggest the possibility of applying autologous cell transplantation in conjunction with scaffold materials for repair of cartilage lesions in patients with OA using β-defensin-4 as a relevant marker.

Arthroscopic cartilage regeneration facilitating procedure for osteoarthritic knee

BACKGROUND

The effectiveness of arthroscopic treatment for osteoarthritic knee is a controversy. This study presents the technique of a novel concept of arthroscopic procedure and investigates its clinical outcome.

METHOD

An arthroscopic procedure targeted on elimination of focal abrasion phenomenon and regaining soft tissue balance around patello-femoral joint was applied to treat osteoarthritis knees. Five hundred and seventy-one knees of 367 patients with osteoarthritis received this procedure. There were 70 (19%) male and 297 (81%) female and the mean age was 60 years (SD 10). The Knee Society score (KSS) and the knee injury and osteoarthritis outcome score (KOOS) were used for subjective outcome study. The roentgenographic changes of femoral-tibial angle and joint space width were evaluated for objective outcomes. The mean follow-up period was 38 months (SD 3).

RESULTS

There were 505 knees in 326 patients available with more than 3 years follow-up and the mean follow-up period was 38 months (SD 3). The subjective satisfactory rate for the whole series was 85.5%. For 134 knees with comprehensive follow-up evaluation, the KSS and all subscales of the KOOS improved statistically. The femoral-tibial angle improved from 1.57 degrees (SD 3.92) to 1.93 degrees (SD 4.12) (mean difference: 0.35, SD 0.17). The joint space width increased from 2.02 millimeters (SD 1.24) to 2.17 millimeters (SD 1.17) (mean difference: 0.13, SD 0.05). The degeneration process of the medial compartment was found being reversed in 82.1% of these knees by radiographic evaluation.

CONCLUSIONS

Based on these observations arthroscopic cartilage regeneration facilitating procedure is an effective treatment for osteoarthritis of the knee joint and can be expected to satisfy the majority of patients and reverse the degenerative process of their knees.

DNA damage, discoordinated gene expression and cellular senescence in osteoarthritic chondrocytes

OBJECTIVE

The initiation/progression factors of osteoarthritic (OA) cartilage degeneration and the involved biological mechanisms remain rather enigmatic. One core reason for this might be a cellular senescence-like phenotype of OA chondrocytes, which might show a fundamentally different behavior pattern unexpected from the biological mechanism established in young cells.

DESIGN

This study was designed to investigate one core property of senescent cells, the heterogeneity of gene expression, in OA chondrocytes by double-labeling immunolocalization using two genes (vimentin, S-100 protein) as surrogates, which are constitutively expressed by (normal) chondrocytes. The level of genomic DNA damage in OA chondrocytes was compared to normal chondrocytes and in vitro experiments designed to demonstrate that stochastic genomic DNA damage is able to induce heterogeneity of gene expression in chondrocytes.

RESULTS

We show a significantly increased heterogeneity of gene expression for vimentin and S-100 protein as well as a significantly increased genomic DNA damage in the OA compared to normal chondrocytes, whereas no evidence of critical telomere shortening was found. In vitro experiments demonstrated that stochastic genomic DNA damage induced by increased oxidative or genotoxic stress is able to induce the heterogeneity in gene expression found in the OA cells in situ.

CONCLUSIONS

Our results suggest that OA chondrocytes show a special form of age-related cell degeneration, "progressive/stress-induced senescence", progressing over time due to accumulated DNA damage and subsequent chaotic gene activation pattern. This promotes increased malfunctioning of the cells and finally the loss of their capacity to keep up cell and tissue homeostasis, i.e., prevent OA.