Surgically-induced Osteoarthritis Research Articles

Infrared Spectroscopy of Synovial Fluid Shows Accuracy as an Early Biomarker in an Equine Model of Traumatic Osteoarthritis.

Osteoarthritis is a leading cause of lameness and joint disease in horses. A simple, economical, and accurate diagnostic test is required for routine screening for OA. This study aimed to evaluate infrared (IR)-based synovial fluid biomarker profiling to detect early changes associated with a traumatically induced model of equine carpal osteoarthritis (OA). Unilateral carpal OA was induced arthroscopically in 9 of 17 healthy thoroughbred fillies; the remainder served as Sham-operated controls. The median age of both groups was 2 years. Synovial fluid (SF) was obtained before surgical induction of OA (Day 0) and weekly until Day 63. IR absorbance spectra were acquired from dried SF films. Following spectral pre-processing, predictive models using random forests were used to differentiate OA, Sham, and Control samples. The accuracy for distinguishing between OA and any other joint group was 80%. The classification accuracy by sampling day was 87%. For paired classification tasks, the accuracies by joint were 75% for OA vs. OA Control and 70% for OA vs. Sham. The accuracy for separating horses by group (OA vs. Sham) was 68%. In conclusion, SF IR spectroscopy accurately discriminates traumatically induced OA joints from controls.

The recombinant Link module of human TSG-6 suppresses cartilage damage in models of osteoarthritis: A potential disease-modifying OA drug

To investigate the role of endogenous TSG-6 in human osteoarthritis (OA) and assess the disease-modifying potential of a TSG-6-based biological treatment in cell, explant and animal models of OA. Knee articular cartilages from OA patients were analyzed for TSG-6 protein and mRNA expression using immunohistochemistry and RNAscope, respectively. The inhibitory activities of TSG-6 and its isolated Link module (Link_TSG6) on cytokine-induced degradation of OA cartilage explants were compared. Human mesenchymal stem/stromal cell-derived chondrocyte pellet cultures were used to determine the effects of Link_TSG6 and full-length TSG-6 on IL-1α-, IL-1β-, or TNF-stimulated ADAMTS4, ADAMTS5, and MMP13 mRNA expression. Link_TSG6 was administered i.a. to the rat ACLTpMMx model; cartilage damage and tactile allodynia were assessed. TSG-6 is predominantly associated with chondrocytes in regions of cartilage damage where high TSG-6 expression aligns with low MMP13, the major collagenase implicated in OA progression. Link_TSG6 is more potent than full-length TSG-6 at inhibiting cytokine-mediated matrix breakdown in human OA cartilage explants;>50% of donor cartilages, from 59 tested, were responsive to Link_TSG6 treatment. Link_TSG6 also displayed more potent effects in 3D pellet cultures, suppressing ADAMTS4, ADAMTS5, and MMP13 gene expression, which was consistent with reduced aggrecanase and collagenase activities in explant cultures. Link_TSG6 treatment reduced touch-evoked pain behavior and dose-dependently inhibited cartilage damage in a rodent model of surgically-induced OA. Link_TSG6 has enhanced chondroprotective activity compared to the full-length TSG-6 protein and shows potential as a disease modifying OA drug via its inhibition of aggrecanase and collagenase activity.

MiR-26a deficiency is associated with bone loss and reduced muscle strength but does not affect severity of cartilage damage in osteoarthritis

Osteoarthritis (OA) is the most common age-related joint disease. However, the role of many microRNAs (miRNA) in skeletal development and OA pathogenesis has not been sufficiently elucidated using genetically modified mice with gain- and loss-of-function models. We generated Cartilage-specific miR-26a overexpressing (Col2a1-Cre;miR-26a Tgfl/fl: Cart-miR-26a Tg) mice and global miR-26a knockout (miR-26a KO) mice. The purpose of the present study was to determine the role of miR-26a in OA pathogenesis using aging and surgically induced models. Skeletal development of Cart-miR-26a Tg and miR-26a KO mice was grossly normal. Knee joints were evaluated by histological grading systems. In surgically-induced OA and aging models (12 and 18 months of age), Cart-miR-26a Tg mice and miR-26a KO mice exhibited OA-like changes such as proteoglycan loss and cartilage fibrillation with no significant differences in OARSI score (damage of articular cartilage) compared with control mice. However, miR-26a KO mice reduced muscle strength and bone mineral density at 12 months of age. These findings indicated that miR-26a modulates bone loss and muscle strength but has no essential role in aging-related or post-traumatic OA.

Defective chaperone-mediated autophagy is a hallmark of joint disease in patients with knee osteoarthritis

Defects in autophagy contribute to joint aging and Osteoarthritis (OA). Identifying specific autophagy types could be useful for developing novel treatments for OA. An autophagy-related gene array was performed in blood from non-OA and knee OA subjects from the Prospective Cohort of A Coruña (PROCOAC). The differential expression of candidate genes was confirmed in blood and knee cartilage and a regression analysis was performed adjusting for age and BMI. HSP90A, a chaperone mediated autophagy (CMA) marker was validated in human knee joint tissues, as well as, in mice with aging-related and surgically-induced OA. The consequences of HSP90AA1 deficiency were evaluated on OA pathogenesis. Finally, the contribution of CMA to homeostasis was studied by assessing the capacity to restore proteostasis upon ATG5-mediated macroautophagy deficiency and genetic HSP90AA1 overexpression. 16 autophagy-related genes were significantly down-regulated in blood from knee OA subjects. Validation studies showed that HSP90AA1 was down-regulated in blood and human OA cartilage and correlated with risk incidence of OA. Moreover, HSP90A was reduced in human OA joints tissues and with aging and OA in mice. HSP90AA1 knockdown was linked to defective macroautophagy, inflammation, oxidative stress, senescence and apoptosis. However, macroautophagy deficiency increased CMA, highlighting the CMA-macroautophagy crosstalk. Remarkably, CMA activation was sufficient to protect chondrocytes from damage. We show that HSP90A is a key chaperone for chondrocyte homeostasis, while defective CMA contributes to joint damage. We propose that CMA deficiency is a relevant disease mechanism and could represent a therapeutic target for OA.

Brief research report: Effects of Pinch deficiency on cartilage homeostasis in adult mice.

Pinch1 and Pinch2 are LIM domain-containing proteins with crucial functions in mediating focal adhesion formation. Our previous studies have demonstrated that Pinch1/2 expression is essential for cartilage and bone formation during skeletal development in mice. Loss of Pinch expression (Prx1Cre; Pinch1flox/flox; Pinch2-/-) inhibits chondrocyte proliferation and promotes chondrocyte apoptosis, resulting in severe chondrodysplasia and limb shortening. Based on these observations, we wonder if Pinch proteins have a role in adult cartilage and whether Pinch deficiency will compromise cartilage homeostasis and promote osteoarthritis (OA)-related defects in adult mice. To this end, we generated the AggrecanCreERT2; Pinch1flox/flox; Pinch2-/- mice, in which the Pinch1 gene can be inducibly deleted in aggrecan-expressing chondrocytes by tamoxifen and the Pinch2 gene is globally inactivated. Immunofluorescent staining confirmed that the expression of Pinch proteins was significantly decreased in articular cartilage in tamoxifen-treated adult AggrecanCreERT2; Pinch1flox/flox; Pinch2-/- mice. Unexpectedly, our results showed that Pinch loss did not induce marked abnormalities in articular cartilage and other joint tissues in the knee joints of either adult (10-month-old) mice or aged (17-month-old) mice. In a destabilization of the medial meniscus (DMM)-induced OA model, the surgically-induced OA lesions were comparable between Pinch-deficient mice and control mice. Given the fact that Pinch proteins are essential for chondrogenesis and cartilage formation during skeletal development, these findings suggest that Pinch expression is seemingly not indispensable for adult cartilage homeostasis in mice.

MiR-23a/b clusters are not essential for the pathogenesis of osteoarthritis in mouse aging and post-traumatic models.

Osteoarthritis (OA), the most prevalent aging-related joint disease, is characterized by insufficient extracellular matrix synthesis and articular cartilage degradation and is caused by various risk factors including aging and traumatic injury. Most microRNAs (miRNAs) have been associated with pathogenesis of osteoarthritis (OA) using in vitro models. However, the role of many miRNAs in skeletal development and OA pathogenesis is uncharacterized in vivo using genetically modified mice. Here, we focused on miR-23-27-24 clusters. There are two paralogous miR-23-27-24 clusters: miR-23a-27a-24-2 (miR-23a cluster) and miR-23b-27b-24-1 (miR-23b cluster). Each miR-23a/b, miR-24, and miR-27a/b is thought to function coordinately and complementary to each other, and the role of each miR-23a/b, miR-24, and miR-27a/b in OA pathogenesis is still controversial. MiR-23a/b clusters are highly expressed in chondrocytes and the present study examined their role in OA. We analyzed miRNA expression in chondrocytes and investigated cartilage-specific miR-23a/b clusters knockout (Col2a1-Cre; miR-23a/bflox/flox: Cart-miR-23clus KO) mice and global miR-23a/b clusters knockout (CAG-Cre; miR-23a/bflox/flox: Glob-miR-23clus KO) mice. Knees of Cart- and Glob-miR-23a/b clusters KO mice were evaluated by histological grading systems for knee joint tissues using aging model (12 and/or 18 month-old) and surgically-induced OA model. miR-23a/b clusters were among the most highly expressed miRNAs in chondrocytes. Skeletal development of Cart- and Glob-miR-23clus KO mice was grossly normal although Glob-miR-23clus KO had reduced body weight, adipose tissue and bone density. In the aging model and surgically-induced OA model, Cart- and Glob-miR-23clus KO mice exhibited mild OA-like changes such as proteoglycan loss and cartilage fibrillation. However, the histological scores were not significantly different in terms of the severity of OA in Cart- and Glob-miR-23clus KO mice compared with control mice. Together, miR-23a/b clusters, composed of miR-23a/b, miR-24, miR-27a/b do not significantly contribute to OA pathogenesis.

Diosmetin inhibits subchondral bone loss and indirectly protects cartilage in a surgically-induced osteoarthritis mouse model

Osteoarthritis (OA) is a common degenerative disease characterized by articular cartilage destruction, subchondral bone remodeling, ectopic osteophyte formation and synovitis. It is now recognized that the integrity of the underlying subchondral bone is crucial for the maintenance of the overlying articular cartilage. Therapeutic agents that can prevent subchondral bone loss are demonstrate potential in the prevention and treatment of OA. Diosmetin (DIOS; 3′,5,7 -trihydroxy-4′-methoxy flavone), a natural flavonoid, has been shown to exert anti-oxidative, anti-inflammatory, anti-apoptotic and anticancer properties. In this study, we found that diosmetin suppressed the DMM-induced subchondral bone loss and reduced subsequent cartilage degradation in vivo. Cellular-based assays showed that diosmetin inhibited RANKL-induced osteoclast formation and bone resorption,but did not affect IL-1β-induced chondrocyte hypertrophy. Biochemical analyses demonstrated that the anti-osteoclastic effect of diosmetin was at least in part due to the suppression of RANKL-induced activation of the ERK, p38, and JNK MAPK signaling pathways. Collectively, our results show that diosmetin have potential as a therapeutic agent the treatment of abnormal subchondral bone loss and cartilage degradation associated with the onset of OA.

Effect of osteoarthritis on alveolar bone loss in experimental periodontitis in rats.

There is scarce information about the relationship between periodontal disease and osteoarthritis. This study investigated the effect of surgically induced osteoarthritis on alveolar bone loss in experimental periodontitis in rats. 12 rats were divided into test and control groups. On day 1, the animals were anaesthetized, and silk ligatures were ligated around 6 maxillary posterior teeth in each animal from both groups. Surgical induction of osteoarthritis was performed on the left knees in the test group. No knee surgeries were performed in the control group. The ligatures were kept in place for 30 days, at which time the animals were euthanatized, and the maxillae and knee joints were harvested and processed for histological analysis. The alveolar bone loss was assessed using a zoom stereomicroscope. The knee joint histologic sections of the control group showed normal joint features, whereas in the test group there were substantial changes typical of osteoarthritis, including wide joint spaces, prominent monocytic infiltration of the synovium, invasion of periarticular bone, and decreased chondrocyte density. Comparison of the bone height between the groups showed a significantly higher bone loss in the test than in the control group The marginal mean bone height, adjusted for covariates and the intraclass correlation between sites, was 1.19 and 0.78 mm in the test and control groups, respectively (p < .0001). Surgically induced osteoarthritis leads to greater alveolar bone loss in the experimental periodontitis model in rats.

Nuclear receptor subfamily 1 group D member 1 in the pathology of obesity-induced osteoarthritis progression.

Mechanical overload and chemical factors are both related to obesity-induced progression of knee osteoarthritis. The circadian rhythm is related to the development of metabolic syndrome and the progression of osteoarthritis, and the core clock genes nuclear receptor subfamily 1 group D member 1 (NR1D1) and brain and muscle arnt-like protein 1 (BMAL1) are dysregulated in cartilage from patients with osteoarthritis. Here, we focused on NR1D1 and investigated osteoarthritis-related changes and gene expression in a mouse model of diet-induced obesity. A high-fat diet was provided to C57BL6/J mice, and changes in body weight, blood lipids, and gene expression were investigated. Destabilization of the medial meniscus or sham surgery was performed on mice fed a high-fat diet or normal diet, and histological osteoarthritis-related changes and NR1D1 expression were investigated. The effects of the NR1D1 agonist SR9009 were also assessed. Mice fed a high-fat diet developed significant obesity and dyslipidemia. Nr1d1 and Bmal1 gene expression levels decreased in the liver and knee joints. Moreover, increased osteoarthritis progression and decreased NR1D1 protein expression were observed in high-fat diet-fed mice after surgical osteoarthritis induction. SR9009 decreased the progression of obesity, dyslipidemia, and osteoarthritis. Overall, obesity and dyslipidemia induced by the high-fat diet led to osteoarthritis progression and decreased NR1D1 expression. Thus, NR1D1 may play an important role in obesity-induced osteoarthritis.

Exosomes derived from umbilical cord mesenchymal stem cells protect cartilage and regulate the polarization of macrophages in osteoarthritis

BackgroundOsteoarthritis (OA) is one of the most common joint diseases and a major global public health concern. Mesenchymal stem cells (MSCs) have been widely used for the treatment of OA owing to their paracrine secretion of trophic factors, a phenomenon in which exosomes may play a major role. Here, we investigate the potential of exosomes from human umbilical cord-derived MSCs (hUC-MSCs-Exos) in alleviating OA.MethodsThe hUC-MSCs-Exos were harvested from hUC-MSC-conditioned medium using ultracentrifugation. Rats with surgically-induced OA were intra-articularly injected with hUC-MSCs-Exos. The effect of hUC-MSCs-Exos in repairing osteoarticular cartilage was assessed using hematoxylin and eosin (HE) staining, safranin-O and fast green staining and immunohistochemistry. The in vitro experiments were further carried out to verify the therapeutic effect. The effects of hUC-MSCs-Exos on the proliferation and migration of human chondrocytes were evaluated using the cell counting kit-8, EdU-555 cell proliferation kit, and transwell assays. Annexin V-FITC/PI staining were used to evaluate the effect of exosomes on chondrocyte apoptosis. An in vitro model of human articular chondrocytes treated with interleukin 1 beta (IL-1β) was used to evaluate the effects of exosomes, analyses involved using quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence, and western blotting. The role of hUC-MSCs-Exos in macrophage polarization was examined in the monocyte cell line, Tohoku Hospital Pediatrics-1 (THP-1) by qRT-PCR and immunofluorescence.ResultsThe results showed that hUC-MSCs-Exos prevented severe damage to the knee articular cartilage in the rat OA model. We confirmed the high efficacy of hUC-MSCs-Exos in promoting chondrocyte proliferation and migration and inhibiting chondrocyte apoptosis. Additionally, hUC-MSCs-Exos could reverse IL-1β-induced injury of chondrocytes and regulate the polarization of macrophages in vitro.ConclusionsThere is potential for hUC-MSCs-Exos to be used as a treatment strategy for OA.

Comparison of biological characteristics of human adipose- and umbilical cord- derived mesenchymal stem cells and their effects on delaying the progression of osteoarthritis in a rat model

BackgroundThe prevalence of osteoarthritis (OA) is constantly increasing with age. Adipose-derived (AD-) and umbilical cord-derived (UC-) mesenchymal stem cells (MSCs) are attractive alternatives in OA therapy and regenerative medicine. However, whether there are differences in the efficacy of MSCs derived from different tissues in the cartilage regeneration, and the frequency of administration of MSCs needs to be further studied. ExperimentUC-MSCs and AD-MSC were isolated from the umbilical cord and subcutaneous fatty tissue of humans respectively and identified by flow cytometry. In vitro, the proliferation ability and chondrogenic potential of AD-MSCs and UC-MSCs were analyzed. In vivo, forty-three Sprague-Dawley rats were used for the OA model induced by ACLT surgery. OA rats were divided into a sham group, an ACLT model group, and two therapy groups (treated with AD-MSCs or UC-MSCs). Therapy groups were treated using a single or repeated twice injection of AD-MSCs and UC-MSCs at a concentration of 1.0 × 106 cells and were followed up for 12 weeks. Serial sections of knees were examined for histological, immunohistochemical and TUNEL analysis. ResultsWe demonstrated that the proliferation of UC-MSCs was higher than that of AD-MSCs, consistent with the bigger pellets from UC-MSCs in a chondrogenic induction medium. Degeneration of articular cartilage was observed in histological appearance of Safranine O and Toluidine blue staining, and quantitative results of modified Mankin’s Score. Importantly, both AD-MSCs and UC-MSCs transplantation significantly attenuated ACLT surgical-induced OA development. In addition, ACLT-induced reduction in cartilage extracellular matrix synthesis (aggrecan) was significantly suppressed by AD-MSCs or UC-MSCs transplantation. TUNEL assay showed that AD-MSCs and UC-MSCs treatments significantly protected chondrocytes against apoptosis compared with the ACLT group. No significant differences were observed between single injections and repeated twice injections. ConclusionsThe current study suggested that, in vitro, AD-MSCs and UC-MSCs showed a comparable chondrogenic potential, although UC-MSCs displayed a superior proliferation capacity. Furthermore, our results confirmed that the injection of AD-MSCs and UC-MSCs, either single or repeated twice, could significantly inhibit the progression of ACLT-induced osteoarthritis with a similar effect, and MSCs transplantation can decrease the apoptosis of articular chondrocytes caused by ACLT.

Apple polyphenols exhibits chondroprotective changes of synovium and prevents knee osteoarthritis

Apple polyphenols (AP) have strong antioxidant and anti-inflammatory properties. We examined the effects of AP on the progression of osteoarthritis (OA) AP was administered to surgically-induced OA model rats for 4 or 8 weeks. This treatment suppressed inflammation and oxidative stress in the synovium, resulting in a decrease in the OA severity score, and the expression of tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMP)-13 in the synovium. It was suggested that long-term administration of AP may be effective for the treatment of OA. In addition, superoxide dismutase (SOD) activity was enhanced in serum samples by AP. AP or its constituent procyanidin B2 (PC) were added to HIG-82 synoviocytes. The results showed that AP enhanced cell proliferation and hyaluronan production. This indicates that AP may improve synovial conditions in OA and suppress OA progression. These effects may be attributed to the antioxidant and anti-inflammatory properties of AP.

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

BackgroundThis study aims to explore the relationship between surgically-induced ankle instability and posttraumatic osteoarthritis (PTOA) in a mouse model, and to provide reference for clinical practice.ResultsLigamentectomy was performed on 24 eight-week-old male C57BL/6 J mice, which were divided into three groups. Both the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) were severed in the CFL + ATFL group, while only the CFL was removed in the CFL group. The SHAM group was set as the blank control group. A wheel-running device was used to accelerate the development of ankle osteoarthritis (OA). Balance measurement, footprint analysis, and histological analysis were used to assess the degree of ankle instability and OA. According to the balance test results, the CFL + ATFL group demonstrated the highest number of slips and the longest crossing beam time at 8 weeks postoperatively. The results of gait analysis exhibited that the CFL + ATFL group had the most significant asymmetry in stride length, stance length, and foot base width compared to the CFL and SHAM groups. The OARSI score of the CFL + ATFL group (16.7 ± 2.18) was also much higher than those of the CFL group (5.1 ± 0.96) and the SHAM group (1.6 ± 1.14).ConclusionBased on the mouse model, the findings indicate that severe ankle instability has nearly three times the chance to develop into ankle OA compared to moderate ankle instability.

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

BackgroundAnimal models are significant for understanding human osteoarthritis (OA). This study compared the synovial fluid proteomics changes in surgical and chemical induced OA models.MethodsThirty rabbits either had anterior cruciate ligament transection (ACLT) procedure or injected intra-articularly with monosodium iodoacetate (MIA, 8 mg) into the right knee. The joints were anatomically assessed, and the synovial fluid proteins analyzed using two-dimensional polyacrylamide gel electrophoresis (2DGE) and MALDI TOF/TOF mass spectrometry analysis at 4, 8 and 12 weeks. The proteins’ upregulation and downregulation were compared with control healthy knees.ResultsSeven proteins (histidine-rich glycoprotein, beta-actin-like protein 2 isoform X1, retinol-binding protein-4, alpha-1-antiproteinase, gelsolin isoform, serotransferrin, immunoglobulin kappa-b4 chain-C-region) were significantly expressed by the surgical induction. They characterized cellular process (27%), organization of cellular components or biogenesis (27%), localization (27%) and biological regulation (18%), which related to synovitis, increased cellularity, and subsequently cartilage damage. Three proteins (apolipoprotein I-IV precursor, serpin peptidase inhibitor and haptoglobin precursor) were significantly modified by the chemical induction. They characterized stimulus responses (23%), immune responses (15%), biological regulations (15%), metabolism (15%), organization of cellular components or biogenesis (8%), cellular process (8%), biological adhesions (8%) and localization (8%), which related to chondrocytes glycolysis/death, neovascularization, subchondral bone necrosis/collapse and inflammation.ConclusionsThe surgical induced OA model showed a wider range of protein changes, which were most upregulated at week 12. The biological process proteins expressions showed the chemical induced joints had slower OA progression compared to surgical induced joints. The chemical induced OA joints showed early inflammatory changes, which later decreased.

Intra-articular Injection of Kartogenin-Enhanced Bone Marrow–Derived Mesenchymal Stem Cells in the Treatment of Knee Osteoarthritis in a Rat Model

Background: In this study, we investigated the in vitro and in vivo chondrogenic capacity of kartogenin (KGN)–enhanced bone marrow–derived mesenchymal stem cells (BMSCs) for cartilage regeneration. Purpose: To determine (1) whether functionalized nanographene oxide (NGO) can effectively deliver KGN into BMSCs and (2) whether KGN would enhance BMSCs during chondrogenesis in vitro and in vivo in an animal model. Study Design: Controlled laboratory study. Methods: Functionalized NGO with line chain amine-terminated polyethylene glycol (PEG) and branched polyethylenimine (BPEI) were used to synthesize biocompatible NGO-PEG-BPEI (PPG) and for loading hydrophobic KGN molecules noncovalently via π–π stacking and hydrophobic interactions (PPG-KGN). Then, PPG-KGN was used for the intracellular delivery of hydrophobic KGN by simple mixing and co-incubation with BMSCs to acquire KGN-enhanced BMSCs. The chondrogenic efficacy of KGN-enhanced BMSCs was evaluated in vitro. In vivo, osteoarthritis (OA) was induced by anterior cruciate ligament transection in rats. A total of 5 groups were established: normal (OA treated with nothing), phosphate-buffered saline (PBS; intra-articular injection of PBS), PPG-KGN (intra-articular injection of PPG-KGN), BMSCs (intra-articular injection of BMSCs), and BMSCs + PPG-KGN (intra-articular injection of PPG-KGN–preconditioned BMSCs). At 6 and 9 weeks after the surgical induction of OA, the rats received intra-articular injections of PPG-KGN, BMSCs, or KGN-enhanced BMSCs. At 14 weeks after the surgical induction of OA, radiographic and behavioral evaluations as well as histological analysis of the knee joints were performed. Results: The in vitro study showed that PPG could be rapidly uptaken in the first 4 hours after incubation, reaching saturation at 12 hours and accumulating in the lysosome and cytoplasm of BMSCs. Thus, PPG-KGN could enhance the efficiency of the intracellular delivery of KGN, which showed a remarkably high chondrogenic differentiation capacity of BMSCs. When applied to an OA model of cartilage injuries in rats, PPG-KGN–preconditioned BMSCs contributed to protection from joint space narrowing, pathological mineralization, OA development, and OA-induced pain, as well as improved tissue regeneration, as evidenced by radiographic, weightbearing, and histological findings. Conclusion: Our results demonstrate that KGN-enhanced BMSCs showed markedly improved capacities for chondrogenesis and articular cartilage repair. We believe that this work demonstrates that a multifunctional nanoparticle-based drug delivery system could be beneficial for stem cell therapy. Our results present an opportunity to reverse the symptoms and pathophysiology of OA. Clinical Relevance: The intracellular delivery of KGN to produce BMSCs with enhanced chondrogenic potential may offer a new approach for the treatment of OA.

Mitochondrial DNA impact on joint damaged process in a conplastic mouse model after being surgically induced with osteoarthritis

It has been suggested that mitochondrial dysfunction and mtDNA variations may contribute to osteoarthritis (OA) pathogenesis. However, the causative link to support this claim is lacking. Here, we surgically-induced OA in conplastic mice in order to evaluate the functional consequences of mtDNA haplotypes in their joint degeneration. BL/6NZB strain was developed with C57BL/6JOlaHsd nuclear genome and NZB/OlaHsdmtDNA while BL/6C57, which is the original, was developed with C57BL/6JOlaHsd nuclear genome and C57/OlaHsdmtDNA for comparison. The surgical DMM OA model was induced in both strains. Their knees were processed and examined for histopathological changes. Cartilage expression of markers of autophagy, apoptosis, oxidative stress and senescence were also analyzed by immunohistochemistry. The joints of BL/6NZB mice that were operated presented more cellularity together with a reduced OARSI histopathology score, subchondral bone, menisci score and synovitis compared to those of BL/6C57 mice. This was accompanied with higher autophagy and a lower apoptosis in the cartilage of BL/6NZB mice that were operated. Therefore, the study demonstrates the functional impact of non-pathological variants of mtDNA on OA process using a surgically-induced OA model. Conplastic (BL/6NZB ) mice develop less severe OA compared to the BL/6C57original strain. These findings demonstrate that mitochondria and mtDNA are critical targets for potential novel therapeutic approaches to treat osteoarthritis.

Genetic deletion of nuclear protein-1 reduces the severity of cartilage lesions in a mouse model of post-traumatic osteoarthritis

Purpose: We recently found that Nuclear protein 1 (Nupr1), a stress-inducible transcription factor, is highly expressed in aged and osteoarthritic cartilage and in the knee joints of mice fed on high-fat diet. However, the role of Nupr1 in the development of OA is not clear. This study aimed to determine if genetic deletion of Nupr1 reduces the severity of cartilage lesions in surgically-induced osteoarthritis (OA) in mice

Optimization of histologic grading schemes in spontaneous and surgically-induced murine models of osteoarthritis

Purpose: Murine models of osteoarthritis (OA) are commonly used to discover new pathways involved in OA and histologic evaluation is the gold standard for determination of OA severity. The primary objective of this study was to determine the ramifications of applying the Articular Cartilage Structure (ACS) or Osteoarthritis Research Society International (OARSI) grading scheme to either a single mid-coronal section or multiple sections of the stifle (knee joint) in two murine models: young mice with surgically-induced (destabilization of the medial meniscus/DMM) OA and older mice with naturally occurring OA.

Exosomes derived from miR-126-3p-overexpressing synovial fibroblasts suppress chondrocyte inflammation and cartilage degradation in a rat model of osteoarthritis

MicroRNAs (miRNAs) encapsulated within exosomes can serve as essential regulators of intercellular communication and represent promising biomarkers of several aging-associated disorders. However, the relationship between exosomal miRNAs and osteoarthritis (OA)-related chondrocytes and synovial fibroblasts (SFCs) remain to be clarified. Herein, we profiled synovial fluid-derived exosomal miRNAs and explored the effects of exosomal miRNAs derived from SFCs on chondrocyte inflammation, proliferation, and survival, and further assessed their impact on cartilage degeneration in a surgically-induced rat OA model. We identified 19 miRNAs within synovial fluid-derived exosomes that were differentially expressed when comparing OA and control patients. We then employed a microarray-based approach to confirm that exosomal miRNA-126-3p expression was significantly reduced in OA patient-derived synovial fluid exosomes. At a functional level, miRNA-126-3p mimic treatment was sufficient to promote rat chondrocyte migration and proliferation while also suppressing apoptosis and IL-1β, IL-6, and TNF-α expression. SFC-miRNA-126-3p-Exos were able to suppress apoptotic cell death and associated inflammation in chondrocytes. Our in vivo results revealed that rat SFC-derived exosomal miRNA-126-3p was sufficient to suppress the formation of osteophytes, prevent cartilage degeneration, and exert anti-apoptotic and anti-inflammatory effects on articular cartilage. Overall, our findings indicate that SFC exosome‐delivered miRNA-126-3p can constrain chondrocyte inflammation and cartilage degeneration. As such, SFC-miRNA-126-3p-Exos may be of therapeutic value for the treatment of patients suffering from OA.

Interleukin 13 (IL-13)-regulated expression of the chondroprotective metalloproteinase ADAM15 is reduced in aging cartilage

ObjectiveThe adamalysin metalloproteinase 15 (ADAM15) has been shown to protect against development of osteoarthritis in mice. Here, we have investigated factors that control ADAM15 levels in cartilage. DesignSecretomes from wild-type and Adam15−/− chondrocytes were compared by label-free quantitative mass spectrometry. mRNA was isolated from murine knee joints, either with or without surgical induction of osteoarthritis on male C57BL/6 mice, and the expression of Adam15 and other related genes quantified by RT-qPCR. ADAM15 in human normal and osteoarthritic cartilage was investigated similarly and by fluorescent immunohistochemistry. Cultured HTB94 chondrosarcoma cells were treated with various anabolic and catabolic stimuli, and ADAM15 mRNA and protein levels evaluated. ResultsThere were no significant differences in the secretomes of chondrocytes from WT and Adam15−/− cartilage. Expression of ADAM15 was not altered in either human or murine osteoarthritic cartilage relative to disease-free controls. However, expression of ADAM15 was markedly reduced upon aging in both species, to the extent that expression in joints of 18-month-old mice was 45-fold lower than in that 4.5-month-old animals. IL-13 increased expression of ADAM15 in HTB94 ​cells by 2.5-fold, while modulators of senescence and autophagy pathways had no effect. Expression of Il13 in the joint was reduced with aging, suggesting this cytokine may control ADAM15 levels in the joint. ConclusionExpression of the chondroprotective metalloproteinase ADAM15 is reduced in aging human and murine joints, possibly due to a concomitant reduction in IL-13 expression. We thus propose IL-13 as a novel factor contributing to increased osteoarthritis risk upon aging.