Interplay between cartilage and subchondral bone contributing to pathogenesis of osteoarthritis. Int J Mol Sci. 2013;14:19805-19830. [PMID: 24084727 PMCID: PMC3821588 DOI: 10.3390/ijms141019805]

High-frequency near-infrared diode laser irradiation suppresses IL-1β-induced inflammatory cytokine expression and NF-κB signaling pathways in human primary chondrocytes

Osteoarthritis (OA) and rheumatoid arthritis (RA) are common inflammation-associated cartilage degenerative diseases. Recent studies have shown that low-level diode laser treatment can reduce inflammatory cytokine expressions in cartilage. We recently reported that high-frequency low-level diode laser irradiation attenuates matrix metalloproteinases (MMPs) expression in human primary chondrocytes. However, the molecular mechanism underlying the effect of high-frequency low-level diode laser on chondrocytes remains unclear. Therefore, we aimed to elucidate the effect of high-frequency low-level diode laser irradiation on inflammatory cytokine expression in human primary chondrocytes. Normal human articular chondrocytes were treated with recombinant interleukin-1 beta (IL-1β) for 30 min or 24 h and irradiated with a high-frequency NIR diode laser at 8 J/cm². The expression of IL-1β, interleukin-6, and tumor necrosis factor-alpha was assessed using western blot analysis. To evaluate the nuclear factor-kappa B (NF-κB) signaling pathway, the phosphorylation, translocation, and DNA-binding activity of NF-κB were detected using western blot analysis, immunofluorescence analysis, electrophoretic mobility shift assay, and enzyme-linked immunosorbent assay analysis. High-frequency low-level diode laser irradiation decreased inflammatory cytokine expression in IL-1β-treated chondrocytes. Moreover, high-frequency low-level diode laser irradiation decreased the phosphorylation, nuclear translocation, and DNA-binding activity of NF-κB in the IL-1β-treated state. However, irradiation alone did not affect NF-κB activity. Thus, high-frequency low-level diode laser irradiation at 8 J/cm² can reduce inflammatory cytokine expressions in normal human articular chondrocytes through NF-κB regulation. These findings indicate that high-frequency low-level diode laser irradiation may reduce the expression of inflammatory cytokines in OA and RA.

Engineering large, anatomically shaped osteochondral constructs with robust interfacial shear properties

Despite the prevalence of large (>5 cm²) articular cartilage defects involving underlying bone, current tissue-engineered therapies only address small defects. Tissue-engineered, anatomically shaped, native-like implants may address the need for off-the-shelf, tissue-repairing therapies for large cartilage lesions. This study fabricated an osteochondral construct of translationally relevant geometry with robust functional properties. Scaffold-free, self-assembled neocartilage served as the chondral phase, and porous hydroxyapatite served as the osseous phase of the osteochondral constructs. Constructs in the shape and size of an ovine femoral condyle (31 × 14 mm) were assembled at day 4 (early) or day 10 (late) of neocartilage maturation. Early osteochondral assembly increased the interfacial interdigitation depth by 244%, interdigitation frequency by 438%, interfacial shear modulus by 243-fold, and ultimate interfacial shear strength by 4.9-fold, compared to late assembly. Toward the development of a bioprosthesis for the repair of cartilage lesions encompassing up to an entire condylar surface, this study generated a large, anatomically shaped osteochondral construct with robust interfacial mechanical properties and native-like neocartilage interdigitation.

Greater heterogeneity of the bone mineralisation density distribution and low bone matrix mineralisation characterise tibial subchondral bone marrow lesions in knee osteoarthritis patients

Tibial subchondral bone marrow lesions (BMLs) identified by MRI have been recognised as potential disease predictors in knee osteoarthritis (KOA), and may associate with abnormal bone matrix mineralisation and reduced bone quality. However, these tissue-level changes of BMLs have not been extensively investigated. Thus, the aim of this study was to quantify the degree of subchondral bone matrix mineralisation (both plate and trabeculae) in relation to histomorphometric parameters of bone remodelling and osteocyte lacunae (OL) characteristics in the tibial plateau (TP) of KOA patients with and without BMLs (OA-BML and OA No-BML, respectively) in comparison to nonOA cadaveric controls (CTL). Osteochondral (cartilage-bone) tissue was sampled from the BML signal region within the medial compartment for each OA-BML TP, and from a corresponding medial region for OA No-BML and CTL TPs. The tissue samples were embedded in resin, and sections stained with Von-Kossa Haematoxylin and Eosin (H&E) for quantitation of static indices of bone remodelling. Resin blocks were then further polished, and carbon-coated for quantitative backscattered electron imaging (qBEI) to determine the bone mineralisation density distribution (BMDD), as well as OL characteristics. It was found that OA-BML contained higher osteoid volume per tissue volume (OV/TV; %) and per bone volume (OV/BV; %) in both subchondral plate and trabecular bone compared to OA No-BML and CTL. The BMDD of OA-BML in both subchondral plate and trabecular bone was shifted toward a lower degree of mineralisation. Typically, an increase in both the heterogeneity of mineralisation density (Ca Width; wt%Ca) and the percentage of lower calcium (Ca Low; % B.Ar) in trabecular bone with OA-BML versus CTL was observed. Further, unmineralised OL density (#/mm²) in subchondral plate was distinctly higher in OA-BML samples compared to CTL. The KOA patients with and without BMLs had significantly decreased density of mineralised OL (#/mm²) in trabecular bone compared to CTL. Taken together, these findings indicate that tibial BMLs in advanced KOA patients are characterised by significantly hypo-mineralised subchondral bone compared with CTL. These differences associated with evidence of increased bone remodelling in OA-BML, and may influence the mechanical properties of the subchondral bone, with implications for the overlying cartilage.

Transthyretin: From Structural Stability to Osteoarticular and Cardiovascular Diseases

Transthyretin (TTR) is a tetrameric protein transporting hormones in the plasma and brain, which has many other activities that have not been fully acknowledged. TTR is a positive indicator of nutrition status and is negatively correlated with inflammation. TTR is a neuroprotective and oxidative-stress-suppressing factor. The TTR structure is destabilized by mutations, oxidative modifications, aging, proteolysis, and metal cations, including Ca2+. Destabilized TTR molecules form amyloid deposits, resulting in senile and familial amyloidopathies. This review links structural stability of TTR with the environmental factors, particularly oxidative stress and Ca2+, and the processes involved in the pathogenesis of TTR-related diseases. The roles of TTR in biomineralization, calcification, and osteoarticular and cardiovascular diseases are broadly discussed. The association of TTR-related diseases and vascular and ligament tissue calcification with TTR levels and TTR structure is presented. It is indicated that unaggregated TTR and TTR amyloid are bound by vicious cycles, and that TTR may have an as yet undetermined role(s) at the crossroads of calcification, blood coagulation, and immune response.

Sclerostin-Mediated Impaired Osteogenesis by Fibroblast-Like Synoviocytes in the Particle-Induced Osteolysis Model

Engineered biomaterials are envisioned to replace, augment, or interact with living tissues for improving the functional deformities associated with end-stage joint pathologies. Unfortunately, wear debris from implant interfaces is the major factor leading to periprosthetic osteolysis. Fibroblast-like synoviocytes (FLSs) populate the intimal lining of the synovium and are in direct contact with wear debris. This study aimed to elucidate the effect of Ti particles as wear debris on human FLSs and the mechanism by which they might participate in the bone remodeling process during periprosthetic osteolysis. FLSs were isolated from synovial tissue from patients, and the condition medium (CM) was collected after treating FLSs with sterilized Ti particles. The effect of CM was analyzed for the induction of osteoclastogenesis or any effect on osteogenesis and signaling pathways. The results demonstrated that Ti particles could induce activation of the NFκB signaling pathway and induction of COX-2 and inflammatory cytokines in FLSs. The amount of Rankl in the conditioned medium collected from Ti particle–stimulated FLSs (Ti CM) showed the ability to stimulate osteoclast formation. The Ti CM also suppressed the osteogenic initial and terminal differentiation markers for osteoprogenitors, such as alkaline phosphate activity, matrix mineralization, collagen synthesis, and expression levels of Osterix, Runx2, collagen 1α, and bone sialoprotein. Inhibition of the WNT and BMP signaling pathways was observed in osteoprogenitors after the treatment with the Ti CM. In the presence of the Ti CM, exogenous stimulation by WNT and BMP signaling pathways failed to stimulate osteogenic activity in osteoprogenitors. Induced expression of sclerostin (SOST: an antagonist of WNT and BMP signaling) in Ti particle–treated FLSs and secretion of SOST in the Ti CM were detected. Neutralization of SOST in the Ti CM partially restored the suppressed WNT and BMP signaling activity as well as the osteogenic activity in osteoprogenitors. Our results reveal that wear debris–stimulated FLSs might affect bone loss by not only stimulating osteoclastogenesis but also suppressing the bone-forming ability of osteoprogenitors. In the clinical setting, targeting FLSs for the secretion of antagonists like SOST might be a novel therapeutic approach for preventing bone loss during inflammatory osteolysis.

Analysis of spatial osteochondral heterogeneity in advanced knee osteoarthritis exposes influence of joint alignment

Osteoarthritis (OA) is considerably affected by joint alignment. Here, we investigate the patterns of spatial osteochondral heterogeneity in patients with advanced varus knee OA together with clinical data. We report strong correlations of osteochondral parameters within individual topographical patterns, highlighting their fundamental and location-dependent interactions in OA. We further identify site-specific effects of varus malalignment on the lesser loaded compartment and, conversely, an unresponsive overloaded compartment. Last, we trace compensatory mechanisms to the overloaded subarticular spongiosa in patients with additional high body weight. We therefore propose to consider and to determine axial alignment in clinical trials when selecting the location to assess structural changes in OA. Together, these findings broaden the scientific basis of therapeutic load redistribution and weight loss in varus knee OA.

A Novel Method Facilitating the Simple and Low-Cost Preparation of Human Osteochondral Slice Explants for Large-Scale Native Tissue Analysis

For in vitro modeling of human joints, osteochondral explants represent an acceptable compromise between conventional cell culture and animal models. However, the scarcity of native human joint tissue poses a challenge for experiments requiring high numbers of samples and makes the method rather unsuitable for toxicity analyses and dosing studies. To scale their application, we developed a novel method that allows the preparation of up to 100 explant cultures from a single human sample with a simple setup. Explants were cultured for 21 days, stimulated with TNF-α or TGF-β3, and analyzed for cell viability, gene expression and histological changes. Tissue cell viability remained stable at >90% for three weeks. Proteoglycan levels and gene expression of COL2A1, ACAN and COMP were maintained for 14 days before decreasing. TNF-α and TGF-β3 caused dose-dependent changes in cartilage marker gene expression as early as 7 days. Histologically, cultures under TNF-α stimulation showed a 32% reduction in proteoglycans, detachment of collagen fibers and cell swelling after 7 days. In conclusion, thin osteochondral slice cultures behaved analogously to conventional punch explants despite cell stress exerted during fabrication. In pharmacological testing, both the shorter diffusion distance and the lack of need for serum in the culture suggest a positive effect on sensitivity. The ease of fabrication and the scalability of the sample number make this manufacturing method a promising platform for large-scale preclinical testing in joint research.

The evaluation of a multiphasic 3D-bioplotted scaffold seeded with adipose derived stem cells to repair osteochondral defects in a porcine model

There is a need for the development of effective treatments for focal articular cartilage injuries. We previously developed a multiphasic 3D-bioplotted osteochondral scaffold design that can drive site-specific tissue formation when seeded with adipose-derived stem cells (ASC). The objective of this study was to evaluate this scaffold in a large animal model. Osteochondral defects were generated in the trochlear groove of Yucatan minipigs and repaired with scaffolds that either contained or lacked an electrospun tidemark and were either unseeded or seeded with ASC. Implants were monitored via computed tomography (CT) over the course of 4 months of in vivo implantation and compared to both open lesions and autologous explants. ICRS II evaluation indicated that defects with ASC-seeded scaffolds had healing that most closely resembled the aulogous explant. Scaffold-facilitated subchondral bone repair mimicked the structure of native bone tissue, but cartilage matrix staining was not apparent within the scaffold. The open lesions had the highest volumetric infill detected using CT analysis (p < 0.05), but the repair tissue was largely disorganized. The acellular scaffold without a tidemark had significantly more volumetric filling than either the acellular or ASC seeded groups containing a tidemark (p < 0.05), suggesting that the tidemark limited cell infiltration into the cartilage portion of the scaffold. Overall, scaffold groups repaired the defect more successfully than an open lesion but achieved limited repair in the cartilage region. With further optimization, this approach holds potential to treat focal cartilage lesions in a highly personalized manner using a human patient's own ASC cells.

Assessment of the efficacy of intra-articular platelet rich plasma treatment in an ACLT experimental model by dynamic contrast enhancement MRI of knee subchondral bone marrow and MRI T2∗ measurement of articular cartilage

OBJECTIVE

The vascularization of subchondral bone plays a significant role in the progression of knee osteoarthritis (OA). Treatment with platelet-rich plasma (PRP) has positive effects on cartilage lesions. However, PRP's efficacy for subchondral bone marrow lesions and the relationship of these lesions to cartilage are still undiscovered. Therefore, our aims were first to longitudinally investigate the change in subchondral flow by dynamic contrast enhanced MRI and degeneration of cartilage by MRI T2∗ in an anterior cruciate transection rodent (ACLT) model, and second to examine changes in parameters after intra-articular PRP injection.

DESIGN

A 32-week investigation in 18 rats allocated to sham-control, ACLT with normal saline injection (ACLT + NS), and ACLT with PRP injection groups ended with histological evaluation. Another rat was used as a donor of allogenic PRP.

RESULTS

Compared to the sham-control group, the ACLT + NS group had higher subchondral blood volume A (0.051, 95% confidence interval: 0.009, 0.092) and lower venous washout kel (-0.030: -0.055, -0.005) from week 4; lower permeability kep from week 18 (-0.954: -1.339, -0.569); higher cartilage T2∗ values (1.803: 1.504, 2.102) reflecting collagen loss beginning at week 10. For the PRP treatment group, subchondral bone marrow A and cartilage T2∗ decreased from week 10. Histological results confirmed and were correlated with the MRI findings.

CONCLUSION

Subchondral hyper-perfusion plays a vital role in the pathogenesis of OA and was associated with cartilage degeneration. The efficacy of PRP can be observed from reduced perfusion and MRI T2∗ values.

Articular Chondrocyte Phenotype Regulation through the Cytoskeleton and the Signaling Processes That Originate from or Converge on the Cytoskeleton: Towards a Novel Understanding of the Intersection between Actin Dynamics and Chondrogenic Function

Numerous studies have assembled a complex picture, in which extracellular stimuli and intracellular signaling pathways modulate the chondrocyte phenotype. Because many diseases are mechanobiology-related, this review asked to what extent phenotype regulators control chondrocyte function through the cytoskeleton and cytoskeleton-regulating signaling processes. Such information would generate leverage for advanced articular cartilage repair. Serial passaging, pro-inflammatory cytokine signaling (TNF-α, IL-1α, IL-1β, IL-6, and IL-8), growth factors (TGF-α), and osteoarthritis not only induce dedifferentiation but also converge on RhoA/ROCK/Rac1/mDia1/mDia2/Cdc42 to promote actin polymerization/crosslinking for stress fiber (SF) formation. SF formation takes center stage in phenotype control, as both SF formation and SOX9 phosphorylation for COL2 expression are ROCK activity-dependent. Explaining how it is molecularly possible that dedifferentiation induces low COL2 expression but high SF formation, this review theorized that, in chondrocyte SOX9, phosphorylation by ROCK might effectively be sidelined in favor of other SF-promoting ROCK substrates, based on a differential ROCK affinity. In turn, actin depolymerization for redifferentiation would “free-up” ROCK to increase COL2 expression. Moreover, the actin cytoskeleton regulates COL1 expression, modulates COL2/aggrecan fragment generation, and mediates a fibrogenic/catabolic expression profile, highlighting that actin dynamics-regulating processes decisively control the chondrocyte phenotype. This suggests modulating the balance between actin polymerization/depolymerization for therapeutically controlling the chondrocyte phenotype.

The effect and mechanism of QufengZhitong capsule for the treatment of osteoarthritis in a rat model

Objective

The purpose of this study was to evaluate the therapeutic effects and mechanism of Qufeng Zhitong (QFZT)capsule for the treatment of osteoarthritis (OA) in a rat model.

Methods

8-10-week-old male Sprague–Dawley rats were randomly divided into the sham group (vehicle-treated), OA group (vehicle-treated), high-dose, middle-dose, low-dose of QFZT capsule-treated groups. OA was induced by transecting the medial collateral ligament and the medial meniscus in the right limb. The Sprague–Dawley rats were treated daily for 12 weeks with different concentrations of QFZT capsule: low (QFZT-L, 128 ​mg/kg), medium (QFZT-M, 256.5 ​mg/kg), and high (QFZT-H, 513 ​mg/kg) by gavage administration for a period of 4 and 12 weeks respectively. Vehicle-treated rats served as controls and administered 0.5% Carboxymethyl Cellulose Sodium (CMC-Na) by gavage on the same schedule. Weekly measurement of dynamic weight-bearing capacity, grip strength, joint swelling was were performed to monitor the progression of disease for 3 weeks. After euthanasia, the knee joints were articular cartilage changes. Pro-inflammatory gene expression in synovial joints was examined to assess the bone and cartilage changes. Gene expression of pro-inflammatory cytokines in synovial joints was measured to determine the therapeutic effect of QFZT.

Results

2 weeks after the treatment, the grip strength and weight-bearing capacity were significantly increased in the QFZT-M and QFZT-H groups, compared with the OA group. The joint widths were decreased significantly in the QFZT-L and QFZT- H groups, compared with the OA group as well. The mRNA level in the articular cartilage of knee joint of IL-1β in the QFZT-L group and IL-6 in the QFZT-H group was significantly suppressed at week 4, compared with the OA group. The radiology score was significantly decreased in the QFZT-H group compared with the OA group 12 weeks after treatment. Furthermore, the rats on QFZT treatment decreased the progression of OA, which was characterised by decreased cartilage degradation. However, the bone changes were no different in OA group and QFZT groups.

Conclusion

In a rat model of OA, QFZT capsule shows the tendency to reduce the destruction of cartilage, joint swelling and bone erosion which provides new evidence for the therapeutic potential of QFZT capsule in the treatment of OA in clinics.

The translational potential of this article

The QFZT capsule can improve the symptoms of the OA in rodent animal rats by attenuating pain and retarding cartilage damage. This study indicated that the QFZT capsule has the potential clinical application of in OA therapy.

The physiopathology of osteoarthritis: Paleopathological implications of non-articular lesions from a modern surgical sample

OBJECTIVES

This research focused on osteoarthritis (OA) lesions on modern patients to 1) identify consistently observed lesions not included within current paleopathological measures of OA, 2) assess the correspondence of bone and cartilage lesions with clinical OA diagnostic criteria, and 3) discuss the correspondence of bone lesions with sources of pain reported in clinical literature.

MATERIALS

Tibial plateaus from 62 patients undergoing total knee replacement surgery due to OA were examined.

METHODS

Plateaus were scored for several non-standard OA criteria, including non-articular and X-ray visible lesions and pre-maceration cartilage lesions, as well as articular surface criteria standard in paleopathology.

RESULTS

Proliferative bone in the intercondylar region was present in 95 % of specimens, while areas of dense trabecular bone and lytic defects, both on the inferior side of the plateaus, were present in 98 % and 83 %, respectively.

CONCLUSIONS

The inferior lytic defects may be physical evidence of bone marrow lesions (BML), a clinical OA indicator visible via MRI. Previous research has linked BML to pain, inflammation, and ligament pathology. The latter conditions have also been associated with intercondylar enthesophytes and third intercondylar tubercle of Parsons (TITP), both of which were observed in the intercondylar regions.

SIGNIFICANCE

Several non-articular lesions not currently included in paleopathological measures of OA were consistently observed.

SUGGESTIONS FOR FUTURE RESEARCH

A similar analysis of a control sample of non-OA tibial plateaus would better contextualize these results.

LIMITATIONS

The sample's high average age (65.8 years) and severe OA stage may hamper generalizability to archaeological collections.

Bisphosphonates as a treatment modality in osteoarthritis

Osteoarthritis (OA) is affecting large proportions of the population worldwide. So far, no effective disease modifying drug has been developed for this disease, limiting the therapeutic options to pain medications, physiotherapy and ultimately surgical approaches, mainly joint implant surgery. In vitro and animal studies have demonstrated that bisphosphonates have the potential to become effective modalities for the treatment of OA. This group of pharmacological agents modulates crucial aspects of OA pathogenesis (subchondral bone turnover and loss, bone marrow edema formation, cartilage degeneration and synovitis), and have shown clear efficacy in animal models of OA. Human studies have, however, so far been disappointing with only one of six clinical studies showing clear short-term efficacy. Possible reasons for these discrepancies will be discussed.

Identifying the Potential Differentially Expressed miRNAs and mRNAs in Osteonecrosis of the Femoral Head Based on Integrated Analysis

Purpose

Osteonecrosis of the femoral head is a common disease of the hip that leads to severe pain or joint disability. We aimed to identify potential differentially expressed miRNAs and mRNAs in osteonecrosis of the femoral head.

Methods

The data of miRNA and mRNA were firstly downloaded from the database. Secondly, the regulatory network of miRNAs-mRNAs was constructed, followed by function annotation of mRNAs. Thirdly, an in vitro experiment was applied to validate the expression of miRNAs and targeted mRNAs. Finally, GSE123568 dataset was used for electronic validation and diagnostic analysis of targeted mRNAs.

Results

Several regulatory interaction pairs between miRNA and mRNAs were identified, such as hsa-miR-378c-WNT3A/DACT1/CSF1, hsa-let-7a-5p-RCAN2/IL9R, hsa-miR-28-5p-RELA, hsa-miR-3200-5p-RELN, and hsa-miR-532-5p-CLDN18/CLDN10. Interestingly, CLDN10, CLDN18, CSF1, DACT1, IL9R, RCAN2, RELN, and WNT3A had the diagnostic value for osteonecrosis of the femoral head. Wnt signaling pathway (involved WNT3A), chemokine signaling pathway (involved RELA), focal adhesion and ECM-receptor interaction (involved RELN), cell adhesion molecules (CAMs) (involved CLDN18 and CLDN10), cytokine-cytokine receptor interaction, and hematopoietic cell lineage (involved CSF1 and IL9R) were identified.

Conclusion

The identified differentially expressed miRNAs and mRNAs may be involved in the pathology of osteonecrosis of the femoral head.

Intra-Articular Injection of Umbilical Cord Mesenchymal Stem Cells Loaded With Graphene Oxide Granular Lubrication Ameliorates Inflammatory Responses and Osteoporosis of the Subchondral Bone in Rabbits of Modified Papain-Induced Osteoarthritis

AIM

This study is to investigate the effects of umbilical cord mesenchymal stem cells (UCMSCs) loaded with the graphene oxide (GO) granular lubrication on ameliorating inflammatory responses and osteoporosis of the subchondral bone in knee osteoarthritis (KOA) animal models.

METHODS

The KOA animal models were established using modified papain joint injection. 24 male New Zealand rabbits were classified into the blank control group, GO group, UCMSCs group, and GO + UCMSCs group, respectively. The concentration in serum and articular fluid nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), type II collagen (COL-II), and glycosaminoglycan (GAG) was detected using ELISA, followed by the dissection of femoral condyles and staining of HE and Micro-CT for observation via the microscope.

RESULTS

GO granular lubrication and UCMSCs repaired the KOA animal models. NO, IL-6, TNF-α, GAG, and COL-II showed optimal improvement performance in the GO + UCMSCs group, with statistical significance in contrast to the blank group (P <0.01). Whereas, there was a great difference in levels of inflammatory factors in serum and joint fluid. Micro-CT scan results revealed the greatest efficacy of the GO + UCMSCs group in improving joint surface damage and subchondral bone osteoporosis. HE staining pathology for femoral condyles revealed that the cartilage repair effect in GO + UCMSCs, UCMSCs, GO, and blank groups were graded down.

CONCLUSION

UCMSCs loaded with graphene oxide granular lubrication can promote the secretion of chondrocytes, reduce the level of joint inflammation, ameliorate osteoporosis of the subchondral bone, and facilitate cartilage repair.

Varying development of femoral and tibial subchondral bone tissue and their interaction with articular cartilage during progressing osteoarthritis

INTRODUCTION

Differences between tibial and femoral joint surfaces and knee compartments concerning coupled bone and cartilage turnover or bone-cartilage cross talk have not been previously examined, although the mechanical and biological interaction of the mineralized subchondral tissues with articular cartilage is of great importance for advancing osteoarthritis.

MATERIALS AND METHODS

Therefore, with the help of immunohistochemistry and real-time polymerase chain reaction (RT-PCR), human knee joint cartilage tissue was investigated for expression of key molecules of the extracellular matrix and cartilage composition (collagen type I and II, aggrecan) plus proteoglycan content (colorimetric analysis). Furthermore, we correlated the results with 3D microcomputed tomography of the underlying subchondral bone (high-resolution micro-CT system). Measurements were performed in dependence of the anatomical site (femoral vs. tibial, medial and lateral each) to identify regional differences during the osteoarthritic process. From an enduring series of 108 patients undergoing implantation of TKA, 34 osteochondral samples with lesions macroscopically classified as ICRS grade 1b (group A) and 34 samples with ICRS grade 3a/3b lesions (group B) were compared with 21 healthy controls.

RESULTS

Concerning 3D analysis, the medial femoral condyle and tibia showed the most significant increase in bone volume fraction and a decrease in the trabecular number in group B frequently accompanied by subchondral bone resorption pits and enchondral ossification. Under physiological conditions, tibia plateaus show lower bone volume fraction than the corresponding femoral site and this difference enlarges with advancing OA. Partially even contradictory behavior was observed such as trabecular separation at the lateral tibial and medial plateau in osteochondral OA samples of the same patients. Collagen type II expression levels show faster and varying changes than type I during the OA process, leading to a lower positive or negative correlation with bone microstructural analysis, especially on the tibia plateau.

CONCLUSIONS

Structural bone and cartilage parameter changes showed varying developments and correlations among each other in the different compartments of the knee. As a clinical conclusion, therapies to postpone or prevent cartilage degeneration by influencing the loss of mineralized bone could be site dependent.

Irisin inhibits osteocyte apoptosis by activating the Erk signaling pathway in vitro and attenuates ALCT-induced osteoarthritis in mice

Moderate exercise can alleviate symptoms of osteoarthritis (OA) such as pain, stiffness, and joint deformities that are associated with progressive cartilaginous degeneration, osteophyte formation, subchondral bone changes, and synovial inflammation. Irisin is an exercise-related myokine that reportedly plays a crucial role in bone remodeling. However, its role in OA remains unknown. This study aimed to determine whether irisin can attenuate OA progression and the mechanism of its therapeutic effect. Three-month-old male C57BL/6J mice were randomized to groups that underwent sham operation, and anterior cruciate ligament transection (ACLT) intraperitoneally injected with vehicle or irisin in vivo. Apoptosis was induced by stretching murine osteocyte-like MLO-Y4 cells in vitro. Irisin reduced wear, maintained the proportion of hyaline cartilage, a more complete cartilage structure, and lower Osteoarthritis Research Society International (OARSI) scores at 4 weeks after ACLT. Irisin reduced the expression of matrix metalloproteinase (MMP)-13 in cartilage and caspase 3 in the subchondral bone. Irisin exerted rescue effects in microstructural parameters of subchondral trabecular bone including bone volume fraction (BV/TV), trabecular number (Tb.N), connection density (Conn. D), and the structure model index (SMI) compared with ACLT-vehicle group. Bone histomorphometry showed that irisin increased subchondral bone remodeling. The decreasing ratio (%) of the eroded surface (ES/BS) was reversed by irisin in the ACLT+vehicle group. Staining with tartrate-resistant acid phosphatase showed a decreased number of osteoclasts. Irisin significantly increased the proliferation of osteocytes, protected them from apoptosis, and maintained cellular activity by regulating the expression of Bax, Bcl-2, and osteoprotegerin/receptor activator of nuclear factor (NF)-kB-ligand (OPG/Rankl). Irisin activated serine/threonine-selective protein kinases (Erk) and p38 signaling, and its anti-apoptosis function depended on the Erk signaling pathway. Irisin attenuated OA progression by decreasing osteocyte apoptosis and improving the microarchitecture of subchondral bone. Activation of the Erk pathway by irisin plays an important role in reducing osteocyte apoptosis in vitro.

Conventional MRI-based subchondral trabecular biomarkers as predictors of knee osteoarthritis progression: data from the Osteoarthritis Initiative

OBJECTIVES

To evaluate the reliability and validity of measuring subchondral trabecular biomarkers in "conventional" intermediate-weighted (IW) MRI sequences and to assess the predictive value of biomarker changes for predicting near-term symptomatic and structural progressions in knee osteoarthritis (OA).

METHODS

For this study, a framework for measuring trabecular biomarkers in the proximal medial tibia in the "conventional" IW MRI sequence was developed. The reliability of measuring these biomarkers (trabecular thickness [cTbTh], spacing [cTbSp], connectivity density [cConnD], and bone-to-total volume ratio [cBV/TV]) was evaluated in the Bone Ancillary Study (within the Osteoarthritis Initiative [OAI]). The validity of these measurements was assessed by comparing to "apparent" biomarkers (from high-resolution steady-state MRI sequence) and peri-articular bone marrow density (BMD, from dual-energy X-ray absorptiometry). The association of these biomarker changes from baseline to 24 months (using the Reliable Change Index) with knee OA progression was studied in the FNIH OA Biomarkers Consortium (within the OAI). Pain and radiographic progression were evaluated by comparing baseline WOMAC pain score and radiographic joint space width with the 24-to-48-month scores/measurements. Associations between biomarker changes and these outcomes were studied using logistic regression adjusted for the relevant covariates.

RESULTS

With acceptable reliability, the cTbTh and cBV/TV, but not cTbSp or cConnD, were modestly associated with the "apparent" biomarkers and peri-articular BMD (β: 1.10 [95% CI: 0.45-1.75], p value: 0.001 and β: 3.69 [95% CI: 2.56-4.83], p value: < 0.001, respectively). Knees with increased cTbTh had higher (OR: 1.44 [95% CI: 1.03-2.02], p value: 0.035) and knees with decreased cTbTh (OR: 0.69 [95% CI: 0.49-0.95], p value: 0.026) or decreased cBV/TV (OR: 0.67 [95% CI: 0.48-0.93], p value: 0.018) had lower odds of experiencing OA pain progression over the follow-ups.

CONCLUSIONS

Measurement of certain "conventional" MRI-based subchondral trabecular biomarkers has high reliability and modest validity. Though modest, there are significant associations between these biomarker changes and knee OA pain progression up to 48-month follow-up.

KEY POINTS

• Despite the lower spatial resolution than what is required to accurately study the subchondral trabecular microstructures, the "conventional" IW MRI sequences may retain adequate information that allows quantification of trabecular microstructure biomarkers. • Subchondral trabecular biomarkers obtained from "conventional" IW MRI sequences (i.e., cTbTh, cTbSp, and cBV/TV) are reliable and valid measures of trabecular microstructure changes compared to those from "apparent" trabecular biomarkers (from the FISP MRI sequence) and peri-articular BMD (from DXA). • Increased trabecular thickness and bone-to-total ratio (cTbTh and cBV/TV, obtained from "conventional" IW MRI sequences) from baseline to 24-month visits may be associated with higher odds of knee OA pain progression over 48 months of follow-up.

Clinical and Radiographic Outcomes After Fixation of Chondral Fragments of the Knee in 6 Adolescents Using Autologous Bone Pegs

Background:

Little is known regarding the optimal treatment for displaced, purely chondral fragments in the knee.

Purpose:

To report the clinical and radiographic outcomes of chondral fragment fixation in adolescents through use of autologous bone pegs.

Study Design:

Case series; Level of evidence, 4.

Methods:

This retrospective, single-center study evaluated 6 patients (mean age, 12.9 years) who underwent fixation of chondral fragments (no visualized bone attached) using autologous bone pegs (mean postoperative follow-up, 5.2 years; range, 1.4-10.9 years). The causes were trauma (n = 5) and osteochondritis dissecans (n = 1). Lesions were located in the trochlear groove (lateral, n = 3; medial, n = 2) or posterior part of the lateral femoral condyle (n = 1). The mean lesion size was 3.8 cm² (range, 0.8-9.0 cm²). Patients were evaluated via physical examination and magnetic resonance imaging (MRI) using magnetic resonance observation of cartilage repair tissue scores.

Results:

In total, 5 patients successfully returned to sports without restrictions at a mean of 7 months (range, 6-8 months) postoperatively. At the latest follow-up, these 5 patients had full range of motion and no joint effusion. The mean magnetic resonance observation of cartilage repair tissue score was 85 (range, 70-95) at a mean duration of 3 years (range, 1-5 years). One patient experienced failure at 1.3 years postoperatively after a traumatic injury and subsequently underwent removal of the fixed fragment and a drilling procedure.

Conclusion:

In most adolescents, fixation of chondral fragments with no visualized bony portion using autologous bone pegs provided a satisfactory success rate and good healing of cartilage tissue confirmed on MRI scans.

Principal Component Analysis of Simultaneous PET-MRI Reveals Patterns of Bone-Cartilage Interactions in Osteoarthritis

BACKGROUND

Bone-cartilage interactions have been implicated in causing osteoarthritis (OA).

PURPOSE

To use [18 F]-NaF PET-MRI to 1) develop automatic image processing code in MatLab to create a model of bone-cartilage interactions and 2) find associations of bone-cartilage interactions with known manifestations of OA.

STUDY TYPE

Prospective study aimed to evaluate a data analysis method.

POPULATION

Twenty-nine patients with knee pain or joint stiffness.

FIELD STRENGTH/SEQUENCE

3T MRI (GE), 3D CUBE FSE, 3D combined T1 ρ/T2 MAPSS, [18F]-sodium fluoride, SIGNA TOF (OSEM).

ASSESSMENT

Correlation between MRI (cartilage) and PET (bone) quantitative parameters, bone-cartilage interactions model described by modes of variation as derived by principal component analysis (PCA), WORMS scoring on cartilage lesions, bone marrow abnormalities, subchondral cysts.

STATISTICAL TESTS

Linear regression, Pearson correlation.

RESULTS

Mode 1 was a positive predictor of the bone abnormality score (P = 0.0003, P = 0.001, P = 0.0007) and the cartilage lesion score (P = 0.03, P = 0.01, P = 0.02) in the femur, tibia, and patella, respectively. For the cartilage lesion scores, mode 5 was the most important positive predictor in the femur (P = 3.9E-06), and mode 2 were predictors, significant negative predictor in the tibia (P = 0.007). In the patella, mode 1 was a significant positive predictor of the bone abnormality score (P = 0.0007).

DATA CONCLUSION

By successfully building an automatic code to create a bone-cartilage interface, we were able to observe dynamic relationships between biochemical changes in the cartilage accompanied with bone remodeling, extended to the whole knee joint instead of simple colocalized observations, shedding light on the interactions that occur between bone and cartilage in OA. Evidence Level: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;52:1462-1474.

TWIST1-MicroRNA-10a-MAP3K7 Axis Ameliorates Synovitis of Osteoarthritis in Fibroblast-like Synoviocytes

Synovitis refers to the inflammation of the synovial membrane and is commonly detected in patients with osteoarthritis (OA). Recent reports have suggested that microRNAs (miRNAs) could be a promising target for diagnosis and prognosis in OA. This study examines the effect of microRNA-10a (miR-10a) in fibroblast-like synoviocyte (FLS)-mediated synovitis obtained from patients with OA. Expression of miR-10a is negatively associated with the severity of synovitis. miR-10a inhibited proliferation, migration, and secretion of pro-inflammatory cytokines of OA-FLS that were obtained from OA patients in vitro. By using a patient-derived xenograft (PDX) model, miR-10a repressed proliferation of OA-FLSs and production of OA synovium-derived pro-inflammatory cytokines in vivo. Twist Family BHLH Transcription Factor 1 (TWIST1) and mitogen-activated protein kinase kinase kinase 7 (MAP3K7) were identified as an upstream regulator and direct target of miR-10a in OA-FLSs, respectively. Nuclear factor κB (NF-κB) signaling pathway, a downstream pathway of MAP3K7, was also repressed by miR-10a in OA-FLSs. To summarize, the TWIST1-miR-10a-MAP3K7-NF-κB pathway mediates the development of synovitis in OA. miR-10a functions as an anti-inflammatory mediator in OA-FLS.

Molecular Signaling Interactions and Transport at the Osteochondral Interface: A Review

Articular joints are comprised of different tissues, including cartilage and bone, with distinctive structural and mechanical properties. Joint homeostasis depends on mechanical and biological integrity of these components and signaling exchanges between them. Chondrocytes and osteocytes actively sense, integrate, and convert mechanical forces into biochemical signals in cartilage and bone, respectively. The osteochondral interface between the bone and cartilage allows these tissues to communicate with each other and exchange signaling and nutritional molecules, and by that ensure an integrated response to mechanical stimuli. It is currently not well known how molecules are transported between these tissues. Measuring molecular transport in vivo is highly desirable for tracking cartilage degeneration and osteoarthritis progression. Since transport of contrast agents, which are used for joint imaging, also depend on diffusion through the cartilage extracellular matrix, contrast agent enhanced imaging may provide a high resolution, non-invasive method for investigating molecular transport in the osteochondral unit. Only a few techniques have been developed to track molecular transport at the osteochondral interface, and there appear opportunities for development in this field. This review will describe current knowledge of the molecular interactions and transport in the osteochondral interface and discuss the potential of using contrast agents for investigating molecular transport and structural changes of the joint.

Role of the SDF-1/CXCR4 signaling pathway in cartilage and subchondral bone in temporomandibular joint osteoarthritis induced by overloaded functional orthopedics in rats

OBJECTIVES

To (i) use a mandibular advancement appliance in rats to investigate the role of the stromal cell-derived factor/CXC receptor 4 (SDF-1/CXCR4) signaling pathway in temporomandibular joint osteoarthritis (TMJ OA) induced by overloaded functional orthopedics (OFO) and (ii) provide a cellular and molecular basis for efficacious treatment of skeletal class-II malocclusion and avoidance of TMJ OA.

METHOD

Male Sprague-Dawley rats (6 weeks) were divided randomly into control + normal saline (NS), EXP + ADM3100 (SDF-1 antagonist), EXP + NS, and control + ADM3100 groups. Changes in articular cartilage and subchondral bone after TMJ OA in these four groups were observed by hematoxylin and eosin (H&E), immunofluorescence double staining (IDS), Safranin-O staining, immunohistochemical (IHC) staining, real-time polymerase chain reaction, and micro-computed tomography at 2, 4, and 8 weeks.

RESULTS

OFO led to increased expression of SDF-1, CXCR4, and matrix metalloproteinase (MMP) 13 and decreased expression of collagen II. The thickness of the hypertrophic cartilage layer was reduced at 4 weeks in the EXP + NS group, and damage to subchondral bone was observed at 2 weeks. Using ADM3100 to inhibit SDF-1 signaling could attenuate expression of MMP13, cartilage damage, and osteoblast differentiation. IDS showed that the areas of expression of SDF-1 and OSX in subchondral bone overlapped.

CONCLUSIONS

Overloaded functional orthopedics (OFO) induced TMJ OA. The destruction of subchondral bone in TMJ OA caused by OFO occurred before damage to cartilage. SDF-1/CXCR4 may induce the osteogenic differentiation and cause cartilage degradation in TMJ OA caused by OFO.

Osteochondral repair combining therapeutics implant with mesenchymal stem cells spheroids

Functional articular cartilage regeneration remains challenging, and it is essential to restore focal osteochondral defects and prevent secondary osteoarthritis. Combining autologous stem cells with therapeutic medical device, we developed a bi-compartmented implant that could promote both articular cartilage and subchondral bone regeneration. The first compartment based on therapeutic collagen associated with bone morphogenetic protein 2, provides structural support and promotes subchondral bone regeneration. The second compartment contains bone marrow-derived mesenchymal stem cell spheroids to support the regeneration of the articular cartilage. Six-month post-implantation, the regenerated articular cartilage surface was 3 times larger than that of untreated animals, and the regeneration of the osteochondral tissue occurred during the formation of hyaline-like cartilage. Our results demonstrate the positive impact of this combined advanced therapy medicinal product, meeting the needs of promising osteochondral regeneration in critical size articular defects in a large animal model combining not only therapeutic implant but also stem cells.

Geraniol-mediated osteoarthritis improvement by down-regulating PI3K/Akt/NF-κB and MAPK signals: In vivo and in vitro studies

Osteoarthritis (OA) is a degenerative disease that has received increasing attention among the elderly. Its clinical manifestation is primarily long-term joint pain. Evidence for the pharmacological effects of geraniol in various diseases is accumulating. However, whether geraniol has a therapeutic effect against OA remains to be determined. In this study, we discussed the anti-inflammatory effects of geraniol in IL-1β-induced chondrocytes and the anti-cartilage degradation effects in a mouse model of destabilization of the medial meniscus (DMM). In cell experiments, we found that the treatment of geraniol inhibited the expression of IL-1β-induced PGE2, NO, COX-2, iNOS, TNF-α and IL-6 by western blot, qRT-PCR and immunofluorescence staining. Besides, geraniol inhibited the expression of MMP-9 and ADAMTS-5, and reversed the degradation of aggrecan and type II collagen. Mechanistically, we revealed that geraniol suppressed IL-1β-stimulated PI3K/Akt/NF-κB and MAPK activation. Importantly, we have found in animal experiments that oral treatment of geraniol was beneficial in protecting articular cartilage from degradation. Overall, these data indicated that geraniol may have the potential to be developed as an effective treatment for OA.

Exosomes: roles and therapeutic potential in osteoarthritis

Exosomes participate in many physiological and pathological processes by regulating cell-cell communication, which are involved in numerous diseases, including osteoarthritis (OA). Exosomes are detectable in the human articular cavity and were observed to change with OA progression. Several joint cells, including chondrocytes, synovial fibroblasts, osteoblasts, and tenocytes, can produce and secrete exosomes that influence the biological effects of targeted cells. In addition, exosomes from stem cells can protect the OA joint from damage by promoting cartilage repair, inhibiting synovitis, and mediating subchondral bone remodeling. This review summarizes the roles and therapeutic potential of exosomes in OA and discusses the perspectives and challenges related to exosome-based treatment for OA patients in the future.

Effects of umbilical cord mesenchymal stem cells loaded with graphene oxide granular lubrication on cytokine levels in animal models of knee osteoarthritis

BACKGROUND

The aim of this study was to use umbilical cord mesenchymal stem cells (UCMSCs) loaded with graphene oxide (GO) granular lubricant to treat knee osteoarthritis (KOA) animal models and to analyze their effect on cytokine levels in the articular cavity.

METHODS

Twenty-four New Zealand rabbit models of KOA were established by the modified Hulth and cartilage injury method, and they were assigned to the blank group, the GO group, the UCMSC group, and the GO + UCMSC group, each group containing six animal models. The GO and UCMSC groups were treated by a single intra-articular injection. The treatment was started one month after surgical modeling, and the observation period was eight weeks. The expression levels of nitric oxide (NO), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), glycosaminoglycan (GAG), and collagen-II (COL-II) in serum and articular fluid after treatment were compared to analyze the efficacy.

RESULTS

The GO granular lubricant caused no significant improvement in the intra-articular environment of the knee joint, and UCMSCs caused a certain degree of improvement in the inflammatory environment. The improvement results of NO, IL-6, TNF-α, GAG, and COL-II were the best in the GO + UCMSC group, but the improvement results of inflammatory cytokine levels in serum and articular fluid were not consistent, especially the differences in NO, IL-6, and TNF-α were greater.

CONCLUSION

UCMSCs loaded with the GO granular lubricant can reduce the inflammatory level and improve the level of biochemical environment in the articular cavity, and thus promote cartilage repair.

Local Strain Distribution and Increased Intracellular Ca2+ Signaling in Bovine Articular Cartilage Exposed to Compressive Strain

Articular cartilage is exposed to compressive strain of approximately 10% under physiological loads in vivo, and intracellular Ca2+ signaling is one of the earliest responses in chondrocytes under this physical stimulation. However, it remains unknown whether compressive strain itself evokes intracellular Ca2+ signaling in chondrocytes located within each layer (from surface to deep) in an equal manner with physiological levels of strain. The purpose of this study, therefore, was to determine the distribution of local strain and increased intracellular Ca2+ signaling in layer-dependent cell populations in response to 10% compressive strain loading. For this purpose, the time course of strain was measured in each layer to calculate layer-specific deformation properties. In addition, layer-specific changes in chondrocyte intracellular Ca2+ signals were recorded over time using a fluorescent Ca2+ indicator, Fluo-3, to establish ratios of cells with increased Ca2+ signaling at each depth of cartilage under static conditions or exposed to compression. The results showed that the surface layer was compressed with a larger strain compared with other layers. Few cells with Ca2+ signaling were observed under static conditions. Percentages of responsive cells within compressed cartilage were higher than those within cartilage under static conditions. However, increased intracellular Ca2+ signals were observed in a prominent number of chondrocytes within the deep layer, but not the surface layer, of compressed cartilage. Our results suggest that at a physiological compression level, Ca2+ is upregulated, but the stimulation of Ca2+ signaling in articular cartilage is not simply defined by local deformation.

Biological Regeneration of Articular Cartilage in an Early Stage of Compartmentalized Osteoarthritis: 12-Month Results

BACKGROUND

Biological regeneration in an early stage of osteoarthritis (OA) is an important clinical challenge. An early-stage compartmentalized OA model was used to evaluate different biological regeneration techniques.

HYPOTHESIS

Biological regeneration in an early stage of compartmentalized OA is possible.

STUDY DESIGN

Controlled laboratory study.

METHODS

A 7-mm cartilage defect was surgically created in 24 sheep. After 3 months, by which time early OA had set in, the sheep were randomized into 4 different treatment groups and operated for the second time. One group (CONTROL) served as a long-term follow-up group for the further development of OA. The other 3 groups (regeneration groups) each underwent a different regeneration procedure after abrasion of the subchondral bone (defect size: 20 × 10 mm with a depth of 2.5 mm): spongialization alone (SPONGIO), spongialization followed by implantation of an unseeded hyaluronan matrix (MATRIX), or spongialization followed by implantation of a hyaluronan matrix seeded with autologous chondrocytes (MACT). Then, 12 months after the second operative procedure, the animals were euthanized and the defects subjected to macroscopic and histological grading. Historical 4-month data were compared with the 12-month results.

RESULTS

After 12 months of follow-up, advanced cartilage degeneration was observed in the CONTROL group. On the other hand, all regeneration groups improved significantly compared with the 4-month results using the Mankin score. Cartilage quality in the MACT group was significantly better than in the MATRIX group, as determined by the Mankin and the O'Driscoll scores.

CONCLUSION

There are no existing clinical options for preventing early OA from progressing to a severe disease. This study provides important information on how a surgical intervention can forestall the development of OA.

CLINICAL RELEVANCE

OA of the knee is very common. Total joint replacement is not an acceptable option for active patients. Biological regeneration in OA is successful for focal cartilage defects; however, a long-term follow-up for biological regeneration in OA is missing. It is essential to have long-term results for a regenerative procedure involving cartilage, which is a tissue with a very slow turnover.

Differential Expression Patterns of Rspondin Family and Leucine-Rich Repeat-Containing G-Protein Coupled Receptors in Chondrocytes and Osteoblasts

Objective

Rspondins (RSPOs) are regarded as the significant modulators of WNT signaling pathway and they are expressed dynamically during developmental stages. Since in osteoarthritis (OA) both cartilage and subchondral bone suffer damages and WNT signaling pathway has a crucial role in their maintenance, the objective of the study was to analyze expression profile of RSPO family and its receptors [leucine-rich repeat-containing G-protein coupled receptors (LGRs)] in OA tissue samples as well as in differentiating chondrocytes and osteoblasts.

Materials and Methods

In this experimental study, human early and advanced stage of OA tissue samples were analyzed for the morphological changes of articular cartilage by hematoxylin and eosin (H and E) staining, safranin-O staining and lubricin immunostaining. RSPOs and LGRs expression were confirmed by immunohistochemistry. Human primary chondrocytes and human osteoblast cell line, SaOS-2, were cultured in differentiation medium till day 14 and they were analyzed in terms of expression of RSPOs, LGRs and specific marker for chondrogenesis and osteogenesis by western blotting and quantitative reverse transcription polymerase chain reaction (qRT-PCR).

Results

Advanced stage OA tissue samples showed increased expression of RSPO1 and LGR6 in a region close to subchondral bone. While RSPO2 and LGR5 expression were seen overlapping in the deep region of articular cartilage. Differentiating chondrocytes demonstrated elevated expression of RSPO2 and LGR5 from day 7 to day 14, whereas, osteoblasts undergoing differentiation showed enhanced expression of RSPO1 and LGR6 from day 2 to day 14. Under tumor necrosis factor alpha (TNFα) stimulatory conditions, RSPO2 and RSPO1 recovered the suppressed expression of inflammatory, chondrogenic and osteogenic markers, respectively. A recovery in the stability of β-catenin was also noticed in both cases.

Conclusion

Spatial expression of RSPOs during progression of OA might be dynamically controlled by cartilage and subchondral bone. Interplay amid chondrocytes and osteoblasts, via RSPOs, might provide probable mechanisms for treating inflammatory pathogenic conditions like OA.

Relationships between osteoarthritic changes (osteophytes, porosity, eburnation) based on historical skeletal material

Background: Three main diagnostic types of osteoarthritic changes are distinguished in clinical and anthropological literature: osteophytes, porosity, and eburnation. The nature of the relationship between these changes and how lesions progress over time is still unclear.Aim: The aim of the present study is the analysis of the relationships between osteophytes, porosity, and eburnation based on skeletal material.Subjects and methods: The analysis employed the skeletal collection from Cedynia (199 individuals) from tenth to fourteenth-century Poland. Marginal osteophytes (OP), porosity (POR), and eburnation (EB) were examined on a shoulder, elbow, wrist, hip, knee, and ankle.Results: Osteophytes and porosity occurred independently of each other. Combinations of osteophytes and porosity (OP + POR) and osteophytes, porosity, and eburnation (OP + POR + EB) were rarely observed. Combinations of osteophytes and eburnation (OP + EB) or porosity and eburnation (POR + EB) were not found. There was a significant correlation between osteophytes and porosity in the scapula, proximal end of the ulna and proximal end of the femur. Osteophytes and eburnation were correlated at the distal end of the ulna. Porosity and eburnation were correlated at the distal end of the radius and distal end of the ulna. When all joints were considered together, all the types of osteoarthritic changes were correlated. However, the relationship between osteophytes and eburnation and between porosity and eburnation was only slightly significant. Osteophytes preceded porosity, but there were a few cases where more developed porosity accompanied less developed osteophytes.Conclusions: The findings indicate that correlations between osteoarthritic changes are weak, albeit statistically significant and further studies of the relationship between changes are necessary.

Noggin Inhibits IL-1β and BMP-2 Expression, and Attenuates Cartilage Degeneration and Subchondral Bone Destruction in Experimental Osteoarthritis

Osteoarthritis (OA) is a chronic inflammatory and progressive joint disease that results in cartilage degradation and subchondral bone remodeling. The proinflammatory cytokine interleukin 1 beta (IL-1β) is abundantly expressed in OA and plays a crucial role in cartilage remodeling, although its role in the activity of chondrocytes in cartilage and subchondral remodeling remains unclear. In this study, stimulating chondrogenic ATDC5 cells with IL-1β increased the levels of bone morphogenetic protein 2 (BMP-2), promoted articular cartilage degradation, and enhanced structural remodeling. Immunohistochemistry staining and microcomputed tomography imaging of the subchondral trabecular bone region in the experimental OA rat model revealed that the OA disease promotes levels of IL-1β, BMP-2, and matrix metalloproteinase 13 (MMP-13) expression in the articular cartilage and enhances subchondral bone remodeling. The intra-articular injection of Noggin protein (a BMP-2 inhibitor) attenuated subchondral bone remodeling and disease progression in OA rats. We also found that IL-1β increased BMP-2 expression by activating the mitogen-activated protein kinase (MEK), extracellular signal-regulated kinase (ERK), and specificity protein 1 (Sp1) signaling pathways. We conclude that IL-1β promotes BMP-2 expression in chondrocytes via the MEK/ERK/Sp1 signaling pathways. The administration of Noggin protein reduces the expression of IL-1β and BMP-2, which prevents cartilage degeneration and OA development.

The use of large animals to facilitate the process of MSC going from laboratory to patient-'bench to bedside'

Large animal models have been widely used to facilitate the translation of mesenchymal stem cells (MSC) from the laboratory to patient. MSC, with their multi-potent capacity, have been proposed to have therapeutic benefits in a number of pathological conditions. Laboratory studies allow the investigation of cellular and molecular interactions, while small animal models allow initial 'proof of concept' experiments. Large animals (dogs, pigs, sheep, goats and horses) are more similar physiologically and structurally to man. These models have allowed clinically relevant assessments of safety, efficacy and dosing of different MSC sources prior to clinical trials. In this review, we recapitulate the use of large animal models to facilitate the use of MSC to treat myocardial infarction-an example of one large animal model being considered the 'gold standard' for research and osteoarthritis-an example of the complexities of using different large animal models in a multifactorial disease. These examples show how large animals can provide a research platform that can be used to evaluate the value of cell-based therapies and facilitate the process of 'bench to bedside'.

Assessment of Cartilage Growth After Biopsy of Osteochondral Loose Bodies in Adolescent Knees for Use in Autologous Chondrocyte Implantation

BACKGROUND

The goal of this study is to determine whether harvested cartilage from an osteochondral loose body maintains the same viability for implantation as cartilage harvested from the traditional locations within the adolescent knee for autologous chondrocyte implantation (ACI).

METHODS

A retrospective study was performed on all ACI procedures performed from 2014 to 2017 at a single institution. Biopsies were derived from 2 groups: osteochondral loose body verses the intercondylar notch. The viability, yield, identity, potency, and density were obtained from each sample in addition to basic demographics and concomitant injuries. A total of 12 patients with osteochondral loose bodies 14.6 (SD=2.9) and 20 patients 13.6 (SD=3.3) with intercondylar notch biopsies were evaluated for the study.

RESULTS

In the microscopic and histologic comparison, there was no significant difference in viability: 94% in the loose bodies and 93% in the intercondylar notch groups, identity: 7.4 d5L versus 6.3 d5L, or yield. Minimum yield is presented as different units in Carticel (1.2×10 cells/vial) and matrix-induced ACI (>8500 relative fluorescent units) products; however, there was no difference between groups and all samples were above the acceptable limit. Minimum identity value is recorded as d5L> -2.00 and all samples were above this limit. In addition, no sample had signs of contamination or endotoxin in either group.

CONCLUSION

These results demonstrate an alternative method for obtaining cartilage biopsies in ACI procedures that may limit short-term and long-term donor site morbidity.

LEVEL OF EVIDENCE

Level III.

Electrospun Polymers in Cartilage Engineering-State of Play

Articular cartilage defects remain a clinical challenge. Articular cartilage defects progress to osteoarthritis, which negatively (e.g., remarkable pain, decreased mobility, distress) affects millions of people worldwide and is associated with excessive healthcare costs. Surgical procedures and cell-based therapies have failed to deliver a functional therapy. To this end, tissue engineering therapies provide a promise to deliver a functional cartilage substitute. Among the various scaffold fabrication technologies available, electrospinning is continuously gaining pace, as it can produce nano- to micro- fibrous scaffolds that imitate architectural features of native extracellular matrix supramolecular assemblies and can deliver variable cell populations and bioactive molecules. Herein, we comprehensively review advancements and shortfalls of various electrospun scaffolds in cartilage engineering.

Treatment With Platelet Lysate Inhibits Proteases of Synovial Fluid in Equines With Osteoarthritis

Osteoarthritis (OA) is the most prevalent arthropathy in sport horses. The administration of a platelet lysate (PL) is an alternative method for the treatment of musculoskeletal conditions. The mechanisms by which PL exerts its beneficial effects have not been determined, and less is known about its effect on the activity of the proteolytic enzymes of the synovial fluid of equines with OA. In this work, the effect of the administration of PL to horses with OA was analyzed both clinically and molecularly by determining the levels of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), glycosaminoglycans (GAGs), and tissue inhibitor of metalloproteinase 1 (TIMP-1) in synovial fluid. One mL of PL was administered intra-articularly followed by the extraction of synovial fluid on days 0, 10, 30, and 60. Results were evaluated by an analysis of variance for repeated measures. The levels of MMP-9 decreased significantly (P < .05) on day 10 after treatment with PL. A disintegrin and metalloproteinase with thrombospondin motifs 5 decreased significantly on days 10 (P < .05), 30 (P < .05), and 60 (P < .01) after treatment. The levels of synovial TIMP-1 increased significantly on day 30 (P < .001) after treatment. Glycosaminoglycans showed a significant increase on days 10 (P < .05) and 30 (P < .01). A significant decrease was found for MMP-2 on day 10 (P < .01), 30 (P < .01), and 60 (P < .001). In conclusion, the beneficial effects of PL in OA could be attributed to the decreased activity of MMP-2, MMP-9, and ADAMTS-5 and the increased concentration of GAGs and TIMP-1 after the administration of platelet-rich plasma.

Chondroprotective Effect of Cynaroside in IL-1β-Induced Primary Rat Chondrocytes and Organ Explants via NF-κB and MAPK Signaling Inhibition

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. Interleukin-1β is the key player in the pathogenesis of OA, which induces the expression of various catabolic factors that contribute to cartilage degradation. Cynaroside (luteolin-7-O-glucoside or luteoloside) is a flavonoid that has various pharmacological properties, such as antitumor, anti-inflammatory, and antioxidant activities. In this study, we investigated the chondroprotective effects of cynaroside on IL-1β-stimulated chondrocytes and organ explants. The production of nitrite, PGE₂, collagen type II, and aggrecan was measured by a Griess reagent and ELISAs, and the production of ROS was measured by H₂DCF-DA fluorescence. The protein levels of iNOS, Cox-2, MMP-1, MMP-3, MMP-13, ADAMTS-4, MAPKs, and the NF-κB p65 subunit were measured by western blot. Proteoglycan analysis was performed by Alcian Blue staining (in vitro) and Safranin O staining (ex vivo). Cynaroside inhibited IL-1β-induced expression of catabolic factors (nitrite, iNOS, ROS, PGE₂, Cox-2, MMP-1, MMP-3, MMP-13, and ADAMTS-4) and degradation of anabolic factors (collagen type II and aggrecan). Furthermore, cynaroside suppressed IL-1β-induced phosphorylation of MAPKs and translocation of the NF-κB p65 subunit into the nucleus. Collectively, these results suggest that cynaroside may be a potential candidate for the development of new therapeutic drugs for the alleviation of OA progression.

Three dimensional (3D) printed polylactic acid with nano-hydroxyapatite doped with europium(III) ions (nHAp/PLLA@Eu3+) composite for osteochondral defect regeneration and theranostics

In the current research previously developed composites composed from poly (l-lactide) (PLLA) and nano-hydroxyapatite (10 wt% nHAp/PLLA) were functionalized with different concentrations of europium (III) (Eu³⁺). The aim of this study was to determine whether Eu³⁺ ions doped within the 10 wt% nHAp/PLLA scaffolds will improve the bioactivity of composites. Therefore, first set of experiments was designed to evaluate the effect of Eu³⁺ ions on morphology, viability, proliferation and metabolism of progenitor cells isolated from adipose tissue (hASC). Three different concentration were tested i.e. 1 mol%, 3 mol% and 5%mol. We identified the 10 wt% nHAp/PLLA@3 mol% Eu³⁺ scaffolds as the most cytocompatible. Further, we investigated the influence of the composites doped with 3 mol% Eu³⁺ ions on differentiation of hASC toward bone and cartilage forming cells. Our results showed that 10 wt% nHAp/PLLA@3 mol% Eu³⁺ scaffolds promotes osteogenesis and chondrogenesis of hASCs what was associated with improved synthesis and secretion of extracellular matrix proteins specific for bone and articular cartilage tissue. We also proved that obtained biomaterials have bio-imaging function and their integration with bone can be monitored using micro computed tomography (μCT).

Inhibition of cartilage degeneration and subchondral bone deterioration by Spinacia oleracea in human mimic of ACLT-induced osteoarthritis

Osteoarthritic conditions in ACLT model in rats were attenuated by SOE administration.

Osteoarthritis from evolutionary and mechanistic perspectives

Developmental osteogenesis and the pathologies associated with tissues that normally are mineralized are active areas of research. All of the basic cell types of skeletal tissue evolved in early aquatic vertebrates. Their characteristics, transcription factors, and signaling pathways have been conserved, even as they adapted to the challenge imposed by gravity in the transition to terrestrial existence. The response to excess mechanical stress (among other factors) can be expressed in the pathologic phenotype described as osteoarthritis (OA). OA is mediated by epigenetic modification of the same conserved developmental gene networks, rather than by gene mutations or new chemical signaling pathways. Thus, these responses have their evolutionary roots in morphogenesis. Epigenetic channeling and heterochrony, orchestrated primarily by microRNAs, maintain the sequence of these responses, while allowing variation in their timing that depends at least partly on the life history of the individual.

Osteochondral Tissue Chip Derived From iPSCs: Modeling OA Pathologies and Testing Drugs

Osteoarthritis (OA) is a chronic disease mainly characterized by degenerative changes in cartilage, but other joint elements such as bone are also affected. To date, there are no disease-modifying OA drugs (DMOADs), owing in part to a deficiency of current models in simulating OA pathologies and etiologies in humans. In this study, we aimed to develop microphysiological osteochondral (OC) tissue chips derived from human induced pluripotent stem cells (iPSCs) to model the pathologies of OA. We first induced iPSCs into mesenchymal progenitor cells (iMPCs) and optimized the chondro- and osteo-inductive conditions for iMPCs. Then iMPCs were encapsulated into photocrosslinked gelatin scaffolds and cultured within a dual-flow bioreactor, in which the top stream was chondrogenic medium and the bottom stream was osteogenic medium. After 28 days of differentiation, OC tissue chips were successfully generated and phenotypes were confirmed by real time RT-PCR and histology. To create an OA model, interleukin-1β (IL-1β) was used to challenge the cartilage component for 7 days. While under control conditions, the bone tissue promoted chondrogenesis and suppressed chondrocyte terminal differentiation of the overlying chondral tissue. Under conditions modeling OA, the bone tissue accelerated the degradation of chondral tissue which is likely via the production of catabolic and inflammatory cytokines. These findings suggest active functional crosstalk between the bone and cartilage tissue components in the OC tissue chip under both normal and pathologic conditions. Finally, a selective COX-2 inhibitor commonly prescribed drug for OA, Celecoxib, was shown to downregulate the expression of catabolic and proinflammatory cytokines in the OA model, demonstrating the utility of the OC tissue chip model for drug screening. In summary, the iPSC-derived OC tissue chip developed in this study represents a high-throughput platform applicable for modeling OA and for the screening and testing of candidate DMOADs.

Spinacia oleracea Linn Considered as One of the Most Perfect Foods: A Pharmacological and Phytochemical Review

Background: :

Leaves of Spinacia oleracea have been widely used as vegetarian foods. Some studies on the chemical composition of spinach have shown that it contains a high content of micronutrients (vitamins and minerals), and has an important economic value with some agronomic advantages. S. oleracea in traditional medicine is reported to cure more than one health problem.

Objective: :

This review focuses on the ethnopharmacological uses and pharmacological and phytochemical studies of Spinacia oleracea.

Method: :

Information on S. oleracea was obtained via electronic search of scientific databases such as Scopus, PubMed, Google Scholar, Scirus, Science Direct, Scielo, Web of Science, Medline, Springerlink, BioMed Central (BMC), and SciFinder for publications on this plant. In addition, books on medicinal herbs were also consulted.

Results: :

Approximately 100 chemical compounds were isolated and characterized from S. oleracea. The major active components of the plant are flavones, flavanols, methylenedioxyflavonol glucuronides, glucuronides, and carotenoids, which were extensively investigated. This review revealed potential pharmacological properties of these isolated compounds such as anti-obesity, anti-α-amylase, bileacid binding capacity, anti-mutagenic, anti-oxidant, anticancer, anti-inflammatory, cognitive and mood effect, hypoglycemic, and anti-hypertriglyceridemia.

Conclusions::

S. oleracea is an important edible plant also used for ethnomedical therapy of obesity, inflammation of lungs, lumbago, flatulence, and treatment of urinary calculi. Pharmacological and phytochemical studies of this plant including bioactives, which have been adequately studied, support its uses in traditional medicine. Additionally, prospects and future trends of this plant are proposed.

Multi-arm Avidin nano-construct for intra-cartilage delivery of small molecule drugs

Targeted drug delivery to joint tissues like cartilage remains a challenge that has prevented clinical translation of promising osteoarthritis (OA) drugs. Local intra-articular (IA) injections of drugs suffer from rapid clearance from the joint space and slow diffusive transport through the dense, avascular cartilage matrix comprised of negatively charged glycosaminoglycans (GAGs). Here we apply drug carriers that leverage electrostatic interactions with the tissue's high negative fixed charge density (FCD) for delivering small molecule drugs to cartilage cell and matrix sites. We demonstrate that a multi-arm cationic nano-construct of Avidin (mAv) with 28 sites for covalent drug conjugation can rapidly penetrate through the full thickness of cartilage in high concentration and have long intra-cartilage residence time in both healthy and arthritic cartilage via weak-reversible binding with negatively charged aggrecans. mAv's intra-cartilage mean uptake was found to be 112× and 33× the equilibration bath concentration in healthy and arthritic (50% GAG depleted) cartilage, respectively. mAv was conjugated with Dexamethasone (mAv-Dex), a broad-spectrum glucocorticoid, using a combination of hydrolysable ester linkers derived from succinic anhydride (SA), 3,3-dimethylglutaric anhydride (GA) and phthalic anhydride (PA) in 2:1:1 M ratio that enabled 50% drug release within 38.5 h followed by sustained release in therapeutic doses over 2 weeks. A single 10 μM low dose of controlled release mAv-Dex (2:1:1) effectively suppressed IL-1α-induced GAG loss, cell death and inflammatory response significantly better than unmodified Dex over 2 weeks in cartilage explant culture models of OA. With this multi-arm design, <1 μM Avidin was needed - a concentration which has been shown to be safe, preventing further GAG loss and cytotoxicity. A charge-based cartilage homing drug delivery platform like this can elicit disease modifying effects as well as facilitate long-term symptomatic pain and inflammation relief by enhancing tissue specificity and prolonging intra-cartilage residence time of OA drugs. This nano-construct thus has high translational potential for enabling intra-cartilage delivery of a broad array of small molecule OA drugs and their combinations to chondrocytes, enabling OA treatment with a single injection of low drug doses and eliminating toxicity issues associated with multiple high dose injections.

Viewpoint on the role of tissue maintenance in ageing: focus on biomarkers of bone, cartilage, muscle, and brain tissue maintenance

Specific hallmarks are thought to underlie the ageing process and age-related functional decline. In this viewpoint, we put forward the hypothesis that disturbances in the process of tissue maintenance are an important common denominator that may lie in between specific hallmarks of ageing (i.e. damage and responses to damage) and their ultimate (patho)physiological consequences (i.e. functional decline and age-related disease). As a first step towards verifying or falsifying this hypothesis, it will be important to measure biomarkers of tissue maintenance in future studies in different study populations. The main aim of the current paper is to discuss potential biomarkers of tissue maintenance that could be used in such future studies. Among the many tissues that could have been chosen to explore our hypothesis, to keep the paper manageable, we chose to focus on a selected number of tissues, namely bone, cartilage, muscle, and the brain, which are important for mobility and cognition and affected in several common age-related diseases, including osteoporosis, osteoarthritis, sarcopenia, and neurodegenerative diseases. Furthermore, we discuss the advantages and limitations of potential biomarkers for use in (pre)clinical studies. The proposed biomarkers should be validated in future research, for example by measuring these in humans with different rates of ageing.

Secreted Frizzled-related proteins (sFRPs) in osteo-articular diseases: much more than simple antagonists of Wnt signaling?

Osteo-articular diseases are characterized by a dysregulation of joint and/or bone homeostasis. These include diseases affecting the joints originally, such as osteoarthritis and rheumatoid arthritis, or the bone, such as osteoporosis. Inflammation and the involvement of Wingless-related integration site (Wnt) signaling pathways are key pathophysiological features of these diseases resulting in tissue degradation by matrix-degrading enzymes, namely matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases with thrombospondin motifs (ADAMTs), secreted by the joint resident cells and/or by infiltrating immune cells. Activation of Wnt signaling pathways is modulated by different families of proteins, including Dickkopfs and the secreted Frizzled-related proteins (sFRPs). The sFRP family is composed of five secreted glycoproteins in mammals that regulate Wnt signaling in the extracellular compartment. Indeed, sFRPs are able to bind both to the soluble Wnt ligands and to their cell membrane receptors, the Frizzled proteins. Their expression profile is altered in osteo-articular diseases, suggesting that they could account for the abnormal activation of Wnt pathways. In the present article, we review how sFRPs are more than simple antagonists of the Wnt signaling pathways and discuss their pathophysiological relevance in the context of osteo-articular diseases. We detail their Wnt-dependent and their Wnt-independent roles, with a particular emphasis on their ability to modulate the inflammatory response and extracellular matrix (ECM) remodeling. We also discuss their potential therapeutic use with a focus on bone remodeling, osteo-articular cancers, and tissue engineering.

Protective effects of extracorporeal shockwave on rat chondrocytes and temporomandibular joint osteoarthritis; preclinical evaluation with in vivo99mTc-HDP SPECT and ex vivo micro-CT

OBJECTIVE

Extracorporeal shockwave therapy (ESWT) has been shown to have chondroprotective effects on arthritic diseases. We investigated the effects of ESWT on temporomandibular joint osteoarthritis (TMJOA) using rat chondrocytes and TMJOA rat models.

DESIGN

Cell viability and expression of pro-inflammatory cytokines, cartilage degradation, and apoptosis markers were measured in control, monosodium iodoacetate (MIA)-treated and ESWT plus MIA-treated chondrocytes in vitro, and intra-articular MIA injection (TMJOA) and ESWT on TMJOA rats in vivo. In vivo^99mTc-hydroxymethylene diphosphonate (HDP) single-photon emission computerized tomography/computerized tomography (SPECT/CT) and ex-vivo micro-CT and histologic examinations were performed in rat models.

RESULTS

ESWT plus MIA-treated chondrocytes showed increased cell viability significantly (P = 0.007), while decreased genetic expression of pro-inflammatory cytokines [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6); P < 0.001 for each] and cartilage degradation markers [matrix metalloproteinase-3 (MMP3), matrix metalloproteinase-13 (MMP13), and bone morphogenetic protein 7 (BMP7); P < 0.001 for each], and number of apoptotic cells (P < 0.001) compared to MIA-treated chondrocytes. Changes in cytochrome c and cleaved caspase-3 levels relative to procaspase-3 were decreased over MIA-treated chondrocytes. ESWT on TMJOA rat models was associated with a significant decrease in pro-inflammatory and cartilage degradation markers, as demonstrated by real-time PCR and immunohistochemistry stains (P < 0.001 for each). On ^99mTc-HDP SPECT/CT, the ESWT group showed a significantly lower uptake ratio compared to the TMJOA group (P = 0.008). Micro-CT analysis revealed that the ESWT group showed improved structure and bone quality compared to the TMJOA control group.

CONCLUSIONS

ESWT was associated with a protective effect on cartilage and subchondral bone structures of TMJOA by reducing inflammation, cartilage degradation, and chondrocyte apoptosis.

Articular Cartilage Regeneration in Osteoarthritis

There has been considerable advancement over the last few years in the treatment of osteoarthritis, common chronic disease and a major cause of disability in older adults. In this pathology, the entire joint is involved and the regeneration of articular cartilage still remains one of the main challenges, particularly in an actively inflammatory environment. The recent strategies for osteoarthritis treatment are based on the use of different therapeutic solutions such as cell and gene therapies and tissue engineering. In this review, we provide an overview of current regenerative strategies highlighting the pros and cons, challenges and opportunities, and we try to identify areas where future work should be focused in order to advance this field.

Regulatory Effects and Interactions of the Wnt and OPG-RANKL-RANK Signaling at the Bone-Cartilage Interface in Osteoarthritis

Cartilage and the bordering subchondral bone form a functionally active regulatory interface with a prominent role in osteoarthritis pathways. The Wnt and the OPG-RANKL-RANK signaling systems, as key mediators, interact in subchondral bone remodeling. Osteoarthritic osteoblasts polarize into two distinct phenotypes: a low secretory and an activated, pro-inflammatory and anti-resorptive subclass producing high quantities of IL-6, PGE2, and osteoprotegerin, but low levels of RANKL, thus acting as putative effectors of subchondral bone sclerosis. Wnt agonists, Wnt5a, Wisp-1 initiate excessive bone remodeling, while Wnt3a and 5a simultaneously cause loss of proteoglycans and phenotype shift in chondrocytes, with decreased expression of COL2A, aggrecan, and Sox-9. Sclerostin, a Wnt antagonist possesses a protective effect for the cartilage, while DKK-1 inhibits VEGF, suspending neoangiogenesis in the subchondral bone. Experimental conditions mimicking abnormal mechanical load, the pro-inflammatory milieu, but also a decreased OPG/RANKL ratio in the cartilage, trigger chondrocyte apoptosis and loss of the matrix via degradative matrix metalloproteinases, like MMP-13 or MMP-9. Hypoxia, an important cofactor exerts a dual role, promoting matrix synthesis via HIF-1α, a Wnt silencer, but turning on HIF-2α that enhances VEGF and MMP-13, along with aberrant collagen expression and extracellular matrix deterioration in the presence of pro-inflammatory cytokines.

Minimally Invasive Approach for Diagnosing TMJ Osteoarthritis

This study's objectives were to test correlations among groups of biomarkers that are associated with condylar morphology and to apply artificial intelligence to test shape analysis features in a neural network (NN) to stage condylar morphology in temporomandibular joint osteoarthritis (TMJOA). Seventeen TMJOA patients (39.9 ± 11.7 y) experiencing signs and symptoms of the disease for less than 10 y and 17 age- and sex-matched control subjects (39.4 ± 15.2 y) completed a questionnaire, had a temporomandibular joint clinical exam, had blood and saliva samples drawn, and had high-resolution cone beam computed tomography scans taken. Serum and salivary levels of 17 inflammatory biomarkers were quantified using protein microarrays. A NN was trained with 259 other condyles to detect and classify the stage of TMJOA and then compared to repeated clinical experts' classifications. Levels of the salivary biomarkers MMP-3, VE-cadherin, 6Ckine, and PAI-1 were correlated to each other in TMJOA patients and were significantly correlated with condylar morphological variability on the posterior surface of the condyle. In serum, VE-cadherin and VEGF were correlated with one another and with significant morphological variability on the anterior surface of the condyle, while MMP-3 and CXCL16 presented statistically significant associations with variability on the anterior surface, lateral pole, and superior-posterior surface of the condyle. The range of mouth opening variables were the clinical markers with the most significant associations with morphological variability at the medial and lateral condylar poles. The repeated clinician consensus classification had 97.8% agreement on degree of degeneration within 1 group difference. Predictive analytics of the NN's staging of TMJOA compared to the repeated clinicians' consensus revealed 73.5% and 91.2% accuracy. This study demonstrated significant correlations among variations in protein expression levels, clinical symptoms, and condylar surface morphology. The results suggest that 3-dimensional variability in TMJOA condylar morphology can be comprehensively phenotyped by the NN.