Targeting cartilage EGFR pathway for osteoarthritis treatment

Temporal progression of subchondral bone alterations in OA models involving induction of compromised meniscus integrity in mice and rats: A scoping review

OBJECTIVE

To categorize the temporal progression of subchondral bone alterations induced by compromising meniscus integrity in mouse and rat models of knee osteoarthritis (OA).

METHOD

Scoping review of investigations reporting subchondral bone changes with appropriate negative controls in the different mice and rat models of OA induced by compromising meniscus integrity.

RESULTS

The available literature provides appropriate temporal detail on subchondral changes in these models, covering the entire spectrum of OA with an emphasis on early and mid-term time points. Microstructural changes of the subarticular spongiosa are comprehensively described; those of the bone plate are not. In mouse models, global subchondral bone alterations are unidirectional, involving an advancing sclerosis of the trabecular structure over time. In rats, biphasic subchondral bone alterations begin with an osteopenic degeneration and loss of subchondral trabeculae, progressing to a late sclerosis of the entire subchondral bone. Rat models, independently from the applied technique, relatively faithfully mirror the early bone loss detected in larger animals, and the late subchondral bone sclerosis observed in human advanced OA.

CONCLUSION

Mice and rats allow us to study the microstructural consequences of compromising meniscus integrity at high temporal detail. Thickening of the subchondral bone plate, an early loss of thinner subarticular trabecular elements, followed by a subsequent sclerosis of the entire subchondral bone are all important and reliable hallmarks that occur in parallel with the advancing articular cartilage degeneration. Thoughtful decisions on the study design, laterality, selection of controls and volumes of interest are crucial to obtain meaningful data.

Attenuation of osteoarthritis progression via locoregional delivery of Klotho-expressing plasmid DNA and Tanshinon IIA through a stem cell-homing hydrogel

BACKGROUND

Osteoarthritis (OA) is an aging-related degenerative joint disorder marked by joint discomfort and rigidity. Senescent chondrocytes release pro-inflammatory cytokines and extracellular matrix-degrading proteins, creating an inflammatory microenvironment that hinders chondrogenesis and accelerates matrix degradation. Targeting of senescent chondrocytes may be a promising approach for the treatment of OA. Herein, we describe the engineering of an injectable peptide-hydrogel conjugating a stem cell-homing peptide PFSSTKT for carrying plasmid DNA-laden nanoparticles and Tanshinon IIA (pPNP + TIIA@PFS) that was designed to attenuate OA progression by improving the senescent microenvironment and fostering cartilage regeneration.

RESULTS

Specifically, pPNP + TIIA@PFS elevates the concentration of the anti-aging protein Klotho and blocks the transmission of senescence signals to adjacent healthy chondrocytes, significantly mitigating chondrocyte senescence and enhancing cartilage integrity. Additionally, pPNP + TIIA@PFS recruit bone mesenchymal stem cells and directs their subsequent differentiation into chondrocytes, achieving satisfactory chondrogenesis. In surgically induced OA model rats, the application of pPNP + TIIA@PFS results in reduced osteophyte formation and attenuation of articular cartilage degeneration.

CONCLUSIONS

Overall, this study introduces a novel approach for the alleviation of OA progression, offering a foundation for potential clinical translation in OA therapy.

Machine learning-based identification and immune characterization of ferroptosis-related molecular clusters in osteoarthritis and validation

Osteoarthritis (OA), a degenerative joint disease, involves synovial inflammation, subchondral bone erosion, and cartilage degeneration. Ferroptosis, a regulated non-apoptotic programmed cell death, is associated with various diseases. This study investigates ferroptosis-related molecular subtypes in OA to comprehend underlying mechanisms. The Gene Expression Omnibus datasets GSE206848, GSE55457, GSE55235, GSE77298 and GSE82107 were used utilized. Unsupervised clustering identified the ferroptosis-related gene (FRG) subtypes, and their immune characteristics were assessed. FRG signatures were derived using LASSO and SVM-RFE algorithms, forming models to evaluate OA's ferroptosis-related immune features. Three FRG clusters were found to be immunologically heterogeneous, with cluster 1 displaying robust immune response. Models identified nine key signature genes via algorithms, demonstrating strong diagnostic and prognostic performance. Finally, qRT-PCR and Western blot validated these genes, offering consistent results. In addition, some of these genes may have implications as new therapeutic targets and can be used to guide clinical applications.

Harnessing Nanomedicine for Cartilage Repair: Design Considerations and Recent Advances in Biomaterials

Cartilage injuries are escalating worldwide, particularly in aging society. Given its limited self-healing ability, the repair and regeneration of damaged articular cartilage remain formidable challenges. To address this issue, nanomaterials are leveraged to achieve desirable repair outcomes by enhancing mechanical properties, optimizing drug loading and bioavailability, enabling site-specific and targeted delivery, and orchestrating cell activities at the nanoscale. This review presents a comprehensive survey of recent research in nanomedicine for cartilage repair, with a primary focus on biomaterial design considerations and recent advances. The review commences with an introductory overview of the intricate cartilage microenvironment and further delves into key biomaterial design parameters crucial for treating cartilage damage, including microstructure, surface charge, and active targeting. The focal point of this review lies in recent advances in nano drug delivery systems and nanotechnology-enabled 3D matrices for cartilage repair. We discuss the compositions and properties of these nanomaterials and elucidate how these materials impact the regeneration of damaged cartilage. This review underscores the pivotal role of nanotechnology in improving the efficacy of biomaterials utilized for the treatment of cartilage damage.

Collagen type X expression and chondrocyte hypertrophic differentiation during OA and OS development

Chondrocyte hypertrophy and the expression of its specific marker, the collagen type X gene (COL10A1), constitute key terminal differentiation stages during endochondral ossification in long bone development. Mutations in the COL10A1 gene are known to cause schmid type metaphyseal chondrodysplasia (SMCD) and spondyloepiphyseal dyschondrodysplasia (SMD). Moreover, abnormal COL10A1 expression and aberrant chondrocyte hypertrophy are strongly correlated with skeletal diseases, notably osteoarthritis (OA) and osteosarcoma (OS). Throughout the progression of OA, articular chondrocytes undergo substantial changes in gene expression and phenotype, including a transition to a hypertrophic-like state characterized by the expression of collagen type X, matrix metalloproteinase-13, and alkaline phosphatase. This state is similar to the process of endochondral ossification during cartilage development. OS, the most common pediatric bone cancer, exhibits characteristics of abnormal bone formation alongside the presence of tumor tissue containing cartilaginous components. This observation suggests a potential role for chondrogenesis in the development of OS. A deeper understanding of the shifts in collagen X expression and chondrocyte hypertrophy phenotypes in OA or OS may offer novel insights into their pathogenesis, thereby paving the way for potential therapeutic interventions. This review systematically summarizes the findings from multiple OA models (e.g., transgenic, surgically-induced, mechanically-loaded, and chemically-induced OA models), with a particular focus on their chondrogenic and/or hypertrophic phenotypes and possible signaling pathways. The OS phenotypes and pathogenesis in relation to chondrogenesis, collagen X expression, chondrocyte (hypertrophic) differentiation, and their regulatory mechanisms were also discussed. Together, this review provides novel insights into OA and OS therapeutics, possibly by intervening the process of abnormal endochondral-like pathway with altered collagen type X expression.

Composite Hydrogel Containing Collagen-Modified Polylactic Acid-Hydroxylactic Acid Copolymer Microspheres Loaded with Tetramethylpyrazine Promotes Articular Cartilage Repair

Articular cartilage defects pose a significant challenge due to the limited self-healing ability of cartilage. However, traditional techniques face limitations including autologous chondrocyte expansion issues. This study aims to investigate the effects of the polylactic acid-glycolic acid (PLGA) and collagen-surface modified polylactic acid-glycolic acid (CPLGA) microspheres loaded with tetramethylpyrazine (TMP) on two cell types and the regeneration potential of articular cartilage. CPLGA microspheres are prepared by Steglich reaction and characterized. They evaluated the effect of TMP-loaded microspheres on HUVECs (Human Umbilical Vein Endothelial Cells) and examined the compatibility of blank microspheres with BMSCs (Bone marrow mesenchymal stromal cells) and their potential to promote cartilage differentiation. Subcutaneous implant immune tests and cartilage defect treatment are conducted to assess biocompatibility and cartilage repair potential. The results highlight the efficacy of CPLGA microspheres in promoting tissue regeneration, attributed to improved hydrophilicity and collagen-induced mitigation of degradation. Under hypoxic conditions, both CPLGA and PLGA TMP-loaded microspheres exhibit inhibitory effects on HUVEC proliferation, migration, and angiogenesis. Notably, CPLGA microspheres show enhanced compatibility with BMSCs, facilitating chondrogenic differentiation. Moreover, the CPLGA microsphere-composite hydrogel exhibits potential for cartilage repair by modulating angiogenesis and promoting BMSC differentiation.

Current developments and future perspectives of nanotechnology in orthopedic implants: an updated review

Orthopedic implants are the most commonly used fracture fixation devices for facilitating the growth and development of incipient bone and treating bone diseases and defects. However, most orthopedic implants suffer from various drawbacks and complications, including bacterial adhesion, poor cell proliferation, and limited resistance to corrosion. One of the major drawbacks of currently available orthopedic implants is their inadequate osseointegration at the tissue-implant interface. This leads to loosening as a result of immunological rejection, wear debris formation, low mechanical fixation, and implant-related infections. Nanotechnology holds the promise to offer a wide range of innovative technologies for use in translational orthopedic research. Nanomaterials have great potential for use in orthopedic applications due to their exceptional tribological qualities, high resistance to wear and tear, ability to maintain drug release, capacity for osseointegration, and capability to regenerate tissue. Furthermore, nanostructured materials possess the ability to mimic the features and hierarchical structure of native bones. They facilitate cell proliferation, decrease the rate of infection, and prevent biofilm formation, among other diverse functions. The emergence of nanostructured polymers, metals, ceramics, and carbon materials has enabled novel approaches in orthopaedic research. This review provides a concise overview of nanotechnology-based biomaterials utilized in orthopedics, encompassing metallic and nonmetallic nanomaterials. A further overview is provided regarding the biomedical applications of nanotechnology-based biomaterials, including their application in orthopedics for drug delivery systems and bone tissue engineering to facilitate scaffold preparation, surface modification of implantable materials to improve their osteointegration properties, and treatment of musculoskeletal infections. Hence, this review article offers a contemporary overview of the current applications of nanotechnology in orthopedic implants and bone tissue engineering, as well as its prospective future applications.

Modification of Mesenchymal Stem/Stromal Cell-Derived Small Extracellular Vesicles by Calcitonin Gene Related Peptide (CGRP) Antagonist: Potential Implications for Inflammation and Pain Reversal

During the progression of knee osteoarthritis (OA), the synovium and infrapatellar fat pad (IFP) can serve as source for Substance P (SP) and calcitonin gene-related peptide (CGRP), two important pain-transmitting, immune, and inflammation modulating neuropeptides. Our previous studies showed that infrapatellar fat pad-derived mesenchymal stem/stromal cells (MSC) acquire a potent immunomodulatory phenotype and actively degrade Substance P via CD10 both in vitro and in vivo. On this basis, our hypothesis is that CD10-bound IFP-MSC sEVs can be engineered to target CGRP while retaining their anti-inflammatory phenotype. Herein, human IFP-MSC cultures were transduced with an adeno-associated virus (AAV) vector carrying a GFP-labelled gene for a CGRP antagonist peptide (aCGRP). The GFP positive aCGRP IFP-MSC were isolated and their sEVs' miRNA and protein cargos were assessed using multiplex methods. Our results showed that purified aCGRP IFP-MSC cultures yielded sEVs with cargo of 147 distinct MSC-related miRNAs. Reactome analysis of miRNAs detected in these sEVs revealed strong involvement in the regulation of target genes involved in pathways that control pain, inflammation and cartilage homeostasis. Protein array of the sEVs cargo demonstrated high presence of key immunomodulatory and reparative proteins. Stimulated macrophages exposed to aCGRP IFP-MSC sEVs demonstrated a switch towards an alternate M2 status. Also, stimulated cortical neurons exposed to aCGRP IFP-MSC sEVs modulate their molecular pain signaling profile. Collectively, our data suggest that yielded sEVs can putatively target CGRP in vivo, while containing potent anti-inflammatory and analgesic cargo, suggesting the promise for novel sEVs-based therapeutic approaches to diseases such as OA.

HSPB1 as an RNA-binding protein mediates the pathological process of osteoarthritis

Heat-shock protein beta1 (HSPB1) is a member of the small HSP family, downregulated in osteoarthritis (OA) chondrocytes and demonstrated the capacity to serve as an RNA-binding protein (RBP). This work aimed to explore the profile of HSPB1 bound RNA and reveal the potential regulation mechanism of HSPB1 in OA. In this work, we captured an unbiased HSPB1-RNA interaction map in Hela cells using the iRIP-seq. The results demonstrated that HSPB1 interacted with plentiful of mRNAs and genomic location toward the CDS region. Functional enrichment of HSPB1-related peaks showed the involvement in gene expression, translation initiation, cellular protein metabolic process, and nonsense-mediated decay. HOMER software analysis showed that HSPB1 bound peaks were over-represented in GAGGAG sequences. In addition, ABLIRC and CIMS algorithm indicated that HSPB1 bound to AU-rich motifs and the proportion of AU-rich peaks in 3' UTR were slightly higher than that in other regions. Moreover, HSPB1-binding targets analysis revealed several gens were associated with OA including EGFR, PLEC, COL5A1, and ROR2. The association of OA-related mRNAs to HSPB1 was additionally confirmed in OA tissues by the quantitative RIP-PCR experiments. Further experiment demonstrated the downregulation of HSPB1 in OA tissues. In conclusion, our current study confirmed HSPB1 as an RNA-binding protein and revealed its potential function in the pathological process of OA, providing a reliable insight to further investigate the molecular regulation mechanism of HSPB1 in OA.

Nanoparticle-based inhibition of vascular endothelial growth factor receptors alleviates osteoarthritis pain and cartilage damage

Osteoarthritis (OA) is characterized by cartilage damage, inflammation, and pain. Vascular endothelial growth factor receptors (VEGFRs) have been associated with OA severity, suggesting that inhibitors targeting these receptors alleviate pain (via VEGFR1) or cartilage degeneration (via VEGFR2). We have developed a nanoparticle-based formulation of pazopanib (Votrient), an FDA-approved anticancer drug that targets both VEGFR1 and VEGFR2 (Nano-PAZII). We demonstrate that a single intraarticular injection of Nano-PAZII can effectively reduce joint pain for a prolonged time without substantial side effects in two different preclinical OA rodent models involving either surgical (upon partial medial meniscectomy) or nonsurgical induction (with monoiodoacetate). The injection of Nano-PAZII blocks VEGFR1 and relieves OA pain by suppressing sensory neuronal ingrowth into the knee synovium and neuronal plasticity in the dorsal root ganglia and spinal cord. Simultaneously, the inhibition of VEGFR2 reduces cartilage degeneration. These findings provide a mechanism-based disease-modifying drug strategy that addresses both pain symptoms and cartilage loss in OA.

Endogenus chondrocytes immobilized by G-CSF in nanoporous gels enable repair of critical-size osteochondral defects

Injured articular cartilage is a leading cause for osteoarthritis. We recently discovered that endogenous stem/progenitor cells not only reside in the superficial zone of mouse articular cartilage, but also regenerated heterotopic bone and cartilage in vivo. However, whether critical-size osteochondral defects can be repaired by pure induced chemotatic cell homing of these endogenous stem/progenitor cells remains elusive. Here, we first found that cells in the superficial zone of articular cartilage surrounding surgically created 3 × 1 mm defects in explant culture of adult goat and rabbit knee joints migrated into defect-filled fibrin/hylaro1nate gel, and this migration was significantly more robust upon delivery of exogenous granulocyte-colony stimulating factor (G-CSF). Remarkably, G-CSF-recruited chondrogenic progenitor cells (CPCs) showed significantly stronger migration ability than donor-matched chondrocytes and osteoblasts. G-CSF-recruited CPCs robustly differentiated into chondrocytes, modestly into osteoblasts, and barely into adipocytes. In vivo, critical-size osteochondral defects were repaired by G-CSF-recruited endogenous cells postoperatively at 6 and 12 weeks in comparison to poor healing by gel-only group or defect-only group. ICRS and O'Driscoll scores of articular cartilage were significantly higher for both 6- and 12-week G-CSF samples than corresponding gel-only and defect-only groups. Thus, endogenous stem/progenitor cells may be activated by G-CSF, a Food and Drug Administration (FDA)-cleared bone-marrow stimulating factor, to repair osteochondral defects.

Current therapies for osteoarthritis and prospects of CRISPR-based genome, epigenome, and RNA editing in osteoarthritis treatment

Osteoarthritis (OA) is one of the most common degenerative joint diseases worldwide, causing pain, disability, and decreased quality of life. The balance between regeneration and inflammation-induced degradation results in multiple etiologies and complex pathogenesis of OA. Currently, there is a lack of effective therapeutic strategies for OA treatment. With the development of CRISPR-based genome, epigenome, and RNA editing tools, OA treatment has been improved by targeting genetic risk factors, activating chondrogenic elements, and modulating inflammatory regulators. Supported by cell therapy and in vivo delivery vectors, genome, epigenome, and RNA editing tools may provide a promising approach for personalized OA therapy. This review summarizes CRISPR-based genome, epigenome, and RNA editing tools that can be applied to the treatment of OA and provides insights into the development of CRISPR-based therapeutics for OA treatment. Moreover, in-depth evaluations of the efficacy and safety of these tools in human OA treatment are needed.

Network pharmacology prediction and molecular docking-based strategy to explore the potential mechanism of Duhuo-Jisheng pair against osteoarthritis

OBJECTIVE

The Duhuo-Jisheng pair is the ruling herb in Duhuo Jisheng decoction, which is a classic formula first recorded in the preparedness and urgency of the thousand jewels.

METHODS

We obtained the primary constituents of Duhuo-Jisheng and their associated protein targets from the TCMSP database. We constructed a composite target network using Cytoscape 3.9.1. To identify potential targets for the treatment of osteoarthritis (OA), we retrieved disease targets from OMIM and GeneCards databases and compared them with the composite targets. We imported the overlapping targets into the STRING database to construct a protein-protein interaction (PPI) network. We also conducted Gene ontology (GO) and KEGG enrichment analyses on the targets.

RESULTS

The component target network consisted of numerous nodes and edges. Notably, quercetin, ammidin, and β-sitosterol were identified as the compounds with high degrees. The PPI network identified tumour necrosis factor (TNF), TP53, and NOS2 as proteins with high degrees. The results of GO and KEGG analyses revealed that the signalling pathways used by DHQJD to treat OA included the NF-κB, PI3K-AKT, and TNF pathways.

CONCLUSION

Our study provides insights into the effective components and potential molecular mechanisms of Duhuo-Jisheng in treating OA, thus serving as a reference for further basic research in this field.

WGA-M001, a Mixture of Total Extracts of Tagetes erecta and Ocimum basilicum, Synergistically Alleviates Cartilage Destruction by Inhibiting ERK and NF-κB Signaling

Tagetes erecta and Ocimum basilicum are medicinal plants that exhibit anti-inflammatory effects against various diseases. However, their individual and combined effects on osteoarthritis (OA) are unknown. Herein, we aimed to demonstrate the effects of T. erecta, O. basilicum, and their mixture, WGA-M001, on OA pathogenesis. The administration of total extracts of T. erecta and O. basilicum reduced cartilage degradation and inflammation without causing cytotoxicity. Although WGA-M001 contained lower concentrations of the individual extracts, it strongly inhibited the expression of pathogenic factors. In vivo OA studies also supported that WGA-M001 had protective effects against cartilage destruction at lower doses than those of T. erecta and O. basilicum. Moreover, its effects were stronger than those observed using Boswellia and Perna canaliculus. WGA-M001 effectively inhibited the interleukin (IL)-1β-induced nuclear factor kappa-light-chain-enhancer of the activated B cell (NF-κB) pathway and ERK phosphorylation. Furthermore, RNA-sequence analysis also showed that WGA-M001 decreased the expression of genes related to the IL-1β-induced NF-κB and ERK signaling pathways. Therefore, WGA-M001 is more effective than the single total extracts of T. erecta and O. basilicum in attenuating OA progression by regulating ERK and NF-κB signaling. Our results open new possibilities for WGA-M001 as a potential therapeutic agent for OA treatment.

FUNDC1/PFKP-mediated mitophagy induced by KD025 ameliorates cartilage degeneration in osteoarthritis

Osteoarthritis (OA) is the most common joint disease, but no disease-modifying drugs have been approved for OA treatment. Mitophagy participates in mitochondrial homeostasis regulation by selectively clearing dysfunctional mitochondria, which might contribute to cartilage degeneration in OA. Here, we provide evidence of impaired mitophagy in OA chondrocytes, which exacerbates chondrocyte degeneration. Among the several classic mitophagy-regulating pathways and receptors, we found that FUNDC1 plays a key role in preserving chondrocyte homeostasis by inducing mitophagy. FUNDC1 knockdown in vitro and knockout in vivo decreased mitophagy and exacerbated mitochondrial dysfunction, exacerbating chondrocyte degeneration and OA progression. FUNDC1 overexpression via intra-articular injection of adeno-associated virus alleviated cartilage degeneration in OA. Mechanistically, our study demonstrated that PFKP interacts with and dephosphorylates FUNDC1 to induce mitophagy in chondrocytes. Further analysis identified KD025 as a candidate drug for restoring chondrocyte mitophagy by increasing the FUNDC1-PFKP interaction and thus alleviating cartilage degeneration in mice with DMM-induced OA. Our study highlights the role of the FUNDC1-PFKP interaction in chondrocyte homeostasis via mitophagy induction and identifies KD025 as a promising agent for treating OA by increasing chondrocyte mitophagy.

Biomaterial-Based Gene Delivery: Advanced Tools for Enhanced Cartilage Regeneration

Gene therapy has emerged as a promising and innovative approach in cartilage regeneration. Integrating biomaterials into gene therapy offers a unique opportunity to enhance gene delivery efficiency, optimize gene expression dynamics, modulate immune responses, and promote tissue regeneration. Despite the rapid progress in biomaterial-based gene delivery, there remains a deficiency of comprehensive discussions on recent advances and their specific application in cartilage regeneration. Therefore, this review aims to provide a thorough overview of various categories of biomaterials employed in gene delivery, including both viral and non-viral vectors, with discussing their distinct advantages and limitations. Furthermore, the diverse strategies employed in gene therapy are discussed and summarized, such as the utilization of growth factors, anti-inflammatory cytokines, and chondrogenic genes. Additionally, we highlights the significant challenges that hinder biomaterial-based gene delivery in cartilage regeneration, including immune response modulation, gene delivery efficiency, and the sustainability of long-term gene expression. By elucidating the functional properties of biomaterials-based gene therapy and their pivotal roles in cartilage regeneration, this review aims to enhance further advances in the design of sophisticated gene delivery systems for improved cartilage regeneration outcomes.

Tenascin-C-EGFR activation induces functional human satellite cell proliferation and promotes wound-healing of skeletal muscles via oleanic acid

Human satellite cells (HuSCs) have been deemed to be the potential cure to treat muscular atrophy diseases such as Duchenne muscular dystrophy. However, the clinical trials of HuSCs were restricted to the inadequacy of donors because of that freshly isolated HuSCs quickly lost the Pax7 expression and myogenesis capacity in vivo after a few days of culture. Here we found that oleanic acid, a kind of triterpenoid endowed with diverse biological functions with treatment potential, could efficiently promote HuSCs proliferation. The HuSCs cultured in the medium supplement with oleanic acid could maintain a high expression level of Pax7 and retain the ability to differentiate into myotubes as well as facilitate muscle regeneration in injured muscles of recipient mice. We further revealed that Tenascin-C acts as the core mechanism to activate the EGFR signaling pathway followed by HuSCs proliferation. Taken together, our data provide an efficient method to expand functional HuSCs and a novel mechanism that controls HuSCs proliferation, which sheds light on the HuSCs-based therapy to treat muscle diseases.

Cationic mesoporous silica nanoparticles alleviate osteoarthritis by targeting multiple inflammatory mediators

Osteoarthritis (OA) is a common and complex inflammatory disorder that is frequently compounded by cartilage degradation, synovial inflammation, and osteophyte formation. Damaged chondrocytes release multiple danger mediators that exacerbate synovial inflammation and accelerate the progression to OA. Conventional treatments targeting only a single mediator of OA have failed to achieve a strong therapeutic effect. Addressing the crucial role of multiple danger mediators in OA progression, we prepared polyethylenimine (PEI)-functionalized diselenide-bridged mesoporous silica nanoparticles (MSN-PEI) with cell-free DNA (cfDNA)-binding and anti-oxidative properties. In models of surgery-induced and collagenase-induced arthritis, we showed that these cationic nanoparticles attenuated cartilage degradation and provided strong chondroprotection against joint damage. Mechanistically, multiple target blockades alleviated oxidative stress and dampened cfDNA-induced inflammation by suppressing the M1 polarization of macrophages. This study suggests a beneficial direction for targeting multiple danger mediators in the treatment of intractable arthritis.

Identification of anterior cruciate ligament fibroblasts and their contribution to knee osteoarthritis progression using single-cell analyses

The mechanical properties of the anterior cruciate ligament (ACL) in the knee have been highlighted, but its role in the regulation of the joint microenvironment remains unclear, especially in the progression of Knee Osteoarthritis (KOA). Here, single-cell RNA sequencing (scRNA-seq) and single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq) data were integrated to reveal the transcriptional and epigenomic landscape of ACL in normal and OA states. We identified a novel subpopulation of fibroblasts in ACL, which provides new insights into the role of the ACL in knee homeostasis and disease. Degeneration of the ACL during OA mechanically alters the knee joint homeostasis and influences the microenvironment by regulating inflammatory- and osteogenic-related factors, thereby contributing to the progression of KOA. Additionally, the specific mechanism by which these Inflammation-associated Fibroblasts (IAFs) regulate KOA progression was uncovered, providing new foundation for the development of targeted treatments for KOA.

Repurposing EGFR Inhibitors for Oral Cancer Pain and Opioid Tolerance

Oral cancer pain remains a significant public health concern. Despite the development of improved treatments, pain continues to be a debilitating clinical feature of the disease, leading to reduced oral mobility and diminished quality of life. Opioids are the gold standard treatment for moderate-to-severe oral cancer pain; however, chronic opioid administration leads to hyperalgesia, tolerance, and dependence. The aim of this review is to present accumulating evidence that epidermal growth factor receptor (EGFR) signaling, often dysregulated in cancer, is also an emerging signaling pathway critically involved in pain and opioid tolerance. We presented preclinical and clinical data to demonstrate how repurposing EGFR inhibitors typically used for cancer treatment could be an effective pharmacological strategy to treat oral cancer pain and to prevent or delay the development of opioid tolerance. We also propose that EGFR interaction with the µ-opioid receptor and glutamate N-methyl-D-aspartate receptor could be two novel downstream mechanisms contributing to pain and morphine tolerance. Most data presented here support that repurposing EGFR inhibitors as non-opioid analgesics in oral cancer pain is promising and warrants further research.

Molecular Trojan Horses for treating lysosomal storage diseases

Lysosomal storage diseases (LSDs) are caused by monogenic mutations in genes encoding for proteins related to the lysosomal function. Lysosome plays critical roles in molecule degradation and cell signaling through interplay with many other cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes. Even though several strategies (i.e., protein replacement and gene therapy) have been attempted for LSDs with promising results, there are still some challenges when hard-to-treat tissues such as bone (i.e., cartilages, ligaments, meniscus, etc.), the central nervous system (mostly neurons), and the eye (i.e., cornea, retina) are affected. Consistently, searching for novel strategies to reach those tissues remains a priority. Molecular Trojan Horses have been well-recognized as a potential alternative in several pathological scenarios for drug delivery, including LSDs. Even though molecular Trojan Horses refer to genetically engineered proteins to overcome the blood-brain barrier, such strategy can be extended to strategies able to transport and deliver drugs to specific tissues or cells using cell-penetrating peptides, monoclonal antibodies, vesicles, extracellular vesicles, and patient-derived cells. Only some of those platforms have been attempted in LSDs. In this paper, we review the most recent efforts to develop molecular Trojan Horses and discuss how this strategy could be implemented to enhance the current efficacy of strategies such as protein replacement and gene therapy in the context of LSDs.

Single-cell communication patterns and their intracellular information flow in synovial fibroblastic osteoarthritis and rheumatoid arthritis

BACKGROUND

Synovial fibroblasts are critical for maintaining homeostasis in major autoimmune diseases involving joint inflammation, including osteoarthritis and rheumatoid arthritis. However, little is known about the interactions among different cell subtypes and the specific sets of signaling pathways and activities that they trigger.

METHODS

Using social network analysis, pattern recognition, and manifold learning approaches, we identified patterns of single-cell communication in OA (osteoarthritis) and RA (rheumatoid arthritis).

RESULTS

Our results suggest that OA and RA have distinct cellular communication patterns and signaling pathways. The LAMININ (Laminin) and COLLAGEN (Collagen) pathways predominate in osteoarthritis, while the EGF (Epidermal growth factor), NT (Neurotrophin) and CDH5 (Cadherin 5) pathways predominate in rheumatoid arthritis, with a central role for THY1 (Thy-1 cell surface antigen) +CDH11 (Cadherin 11) + cells. The OA opens the PDGF (Platelet-derived growth factors) pathway (driver of bone angiogenesis), the RA opens the EGF pathway (bone formation) and the SEMA3 (Semaphorin 3A) pathway (involved in immune regulation). Interestingly, we found that OA no longer has cell types involved in the MHC complex (Major histocompatibility complex) and their activity, whereas the MHC complex functions primarily in RA in the presentation of inflammatory antigens, and that the complement system in OA has the potential to displace the function of the MHC complex. The specific signaling patterns of THY1+CDH11+ cells and their secreted ligand receptors are more conducive to cell migration and lay the foundation for promoting osteoclastogenesis. This subpopulation may also be involved in the accumulation of lymphocytes, affecting the recruitment of immune cells. Members of the collagen family (COL1A1 (Collagen Type I Alpha 1 Chain), COL6A2 (Collagen Type VI Alpha 2 Chain) and COL6A1 (Collagen Type VI Alpha 1 Chain)) and transforming growth factor (TGFB3) maintain the extracellular matrix in osteoarthritis and mediate cell migration and adhesion in rheumatoid arthritis, including the PTN (Pleiotrophin) / THBS1 (Thrombospondin 1) interaction.

CONCLUSION

Increased understanding of the interaction networks between synovial fibroblast subtypes, particularly the shared and unique cellular communication features between osteoarthritis and rheumatoid arthritis and their hub cells, should help inform the design of therapeutic agents for inflammatory joint disease.

Exploring the translational potential of PLGA nanoparticles for intra-articular rapamycin delivery in osteoarthritis therapy

Osteoarthritis (OA) is a prevalent joint disease that affects all the tissues within the joint and currently lacks disease-modifying treatments in clinical practice. Despite the potential of rapamycin for OA disease alleviation, its clinical application is hindered by the challenge of achieving therapeutic concentrations, which necessitates multiple injections per week. To address this issue, rapamycin was loaded into poly(lactic-co-glycolic acid) nanoparticles (RNPs), which are nontoxic, have a high encapsulation efficiency and exhibit sustained release properties for OA treatment. The RNPs were found to promote chondrogenic differentiation of ATDC5 cells and prevent senescence caused by oxidative stress in primary mouse articular chondrocytes. Moreover, RNPs were capable to alleviate metabolism homeostatic imbalance of primary mouse articular chondrocytes in both monolayer and 3D cultures under inflammatory or oxidative stress. In the mouse destabilization of the medial meniscus (DMM) model, intra-articular injection of RNPs effectively mitigated joint cartilage destruction, osteophyte formation, chondrocytes hypertrophy, synovial inflammation, and pain. Our study demonstrates the feasibility of using RNPs as a potential clinically translational therapy to prevent the progression of post-traumatic OA.

Single-cell RNA sequencing reveals neurovascular-osteochondral network crosstalk during temporomandibular joint osteoarthritis: Pilot study in a human condylar cartilage

Purpose

Temporomandibular joint osteoarthritis (TMJ-OA) is one of the most complex temporomandibular disorders, causing pain and dysfunction. The main pathological feature of TMJ-OA is neurovascular invasion from the subchondral bone to the condylar cartilage. This study aimed to discover the cells and genes that play an important role in the neurovascular-osteochondral network crosstalk in human TMJ-OA.

Materials and methods

Condylar cartilages from patient with TMJ-OA were divided into OA group, and others from patients with benign condylar hyperplasia (CH) were used as control for further single-cell RNA-sequencing (scRNA-seq). Hematoxylin and eosin staining were performed. The cells and genes in the condylar cartilage were identified and analyzed by scRNA-seq.

Results

Histological analysis revealed blood vessel invasion and ossification in the TMJ-OA condylar cartilage. The scRNA-seq identified immune cells, endothelial cells, and chondrocytes in the TMJ-OA condylar cartilage. Macrophages, especially M1-like macrophages, contributed to the inflammation, angiogenesis, and innervation. CD31+ endothelial cells contributed to the bone mineralization. The TMJ-OA cartilage chondrocytes highly expressed genes related to inflammation, angiogenesis, innervation, and ossification. The hub genes contributing to these processes in the TMJ-OA chondrocytes included CTGF, FBN1, FN1, EGFR, and ITGA5.

Conclusion

Our study marks the first time scRNA-seq was used to identify the cells and genes in a human TMJ-OA condylar cartilage, and neurovascular-osteochondral network crosstalk during the human TMJ-OA process was demonstrated. Targeting the crosstalk of these processes may be a potential comprehensive and effective therapeutic strategy for human TMJ-OA.

Effects and action mechanisms of individual cytokines contained in PRP on osteoarthritis

Osteoarthritis (OA) is defined as a degenerative joint disease that can affect all tissues of the joint, including the articular cartilage, subchondral bone, ligaments capsule, and synovial membrane. The conventional nonoperative treatments are ineffective for cartilage repair and induce only symptomatic relief. Platelet-rich plasma (PRP) is a platelet concentrate derived from autologous whole blood with a high concentration of platelets, which can exert anti-inflammatory and regenerative effects by releasing multiple growth factors and cytokines. Recent studies have shown that PRP exhibits clinical benefits in patients with OA. However, high operational and equipment requirements greatly limit the application of PRP to OA treatment. Past studies have indicated that high-concentration PRP growth factors and cytokines may be applied as a commercial replacement for PRP. We reviewed the relevant articles to summarize the feasibility and mechanisms of PRP-based growth factors in OA. The available evidence suggests that transforming growth factor-α and β, platelet-derived growth factors, epidermal growth factor, insulin-like growth factor-1, and connective tissue growth factors might benefit OA, while vascular endothelial growth factor, tumor necrosis factor-α, angiopoietin-1, and stromal cell derived factor-1α might induce negative effects on OA. The effects of fibroblast growth factor, hepatocyte growth factor, platelet factor 4, and keratinocyte growth factor on OA remain uncertain. Thus, it can be concluded that not all cytokines released by PRP are beneficial, although the therapeutic action of PRP has a valuable potential to improve.

Nanotechnology-Boosted Biomaterials for Osteoarthritis Treatment: Current Status and Future Perspectives

Osteoarthritis (OA) is a prevalent global health concern, posing a significant and increasing public health challenge worldwide. Recently, nanotechnology-boosted biomaterials have emerged as a highly promising strategy for OA therapy due to their exceptional physicochemical properties and capacity to regulate pathological processes. However, there is an urgent need for a deeper understanding of the potential therapeutic applications of these biomaterials in the clinical management of diseases, particularly in the treatment of OA. In this comprehensive review, we present an extensive discussion of the current status and future prospects concerning nanotechnology-boosted biomaterials for OA therapy. Initially, we discuss the pathophysiology of OA and the constraints associated with existing treatment modalities. Subsequently, various types of nanomaterials utilized for OA therapy, including nanoparticles, nanofibers, and nanocomposites, are thoroughly discussed and summarized, elucidating their respective advantages and challenges. Furthermore, we analyze recent preclinical and clinical studies that highlight the potential of nanotechnology-boosted biomaterials in OA therapy. Additionally, future research directions in this evolving field are highlighted. By establishing a link between the structural properties of nanotechnology-boosted biomaterials and their therapeutic functions in OA treatment, we aim to foster advances in designing sophisticated nanomaterials for OA, ultimately resulting in improved therapeutic efficacy of OA therapy through translation into clinical setting in the near future.

Identification of EGFR as an essential regulator in chondrocytes ferroptosis of osteoarthritis using bioinformatics, in vivo, and in vitro study

Objective

The mechanisms of chondrocytes ferroptosis in osteoarthritis (OA) have not yet been fully elucidated. This study aimed to identify key ferroptosis related genes (FRGs) involved in chondrocytes ferroptosis.

Methods

LASSO, SVM-RFE, and receiver operating characteristic curve (ROC) were performed to screen key differentially expressed FRGs (DEFRGs). Functional analyses were conducted using GO, and KEGG analyses. Unsupervised clustering analysis was used to identify ferroptosis related patterns. The CeRNA network was constructed to predict the upstream miRNAs and lncRNAs. Finally, we validated the role of EGFR in chondrocytes ferroptosis using in vivo and in vitro experiments.

Results

A total of 42 DEFRGs were identified between OA and normal cartilages. GO and KEGG analyses indicated that these DEFRGs were significantly engaged in ferroptosis related biological processes and pathways, such as cellular response to oxidative stress, positive regulation of programmed cell death, MAPK and PI3K-Akt signaling pathways. Moreover, four key DEFRGs, including ACSF2, AURKA, EGFR, and KLHL24, were considered as potential biomarkers of OA. Moreover, two distinct ferroptosis related patterns were determined, and a total of 882 differentially expressed genes were identified which might participate in extracellular matrix degradation and inflammatory response. In addition, the CeRNA network showed that EGFR could be competitively regulated by 3 lncRNAs and 4 miRNAs. Significantly, the expression of EGFR was downregulated in human OA cartilages, OA mouse model, and erastin induced chondrocytes. EGFR inhibition could induce the occurrence of chondrocytes ferroptosis and ECM degradation which could be reversed by the addition of Ferrostatin-1.

Conclusion

Our study has identified ACSF2, AURKA, EGFR, and KLHL24 as ferroptosis-related biomarkers in OA. Furthermore, we have conducted a preliminary investigation into the role of EGFR in regulating chondrocytes ferroptosis. These findings offer novel insights into the molecular mechanisms underlying OA.

Anabolic phenotype in cartilage-specific mitogen-inducible gene-6 knockout mice is independent of transforming growth factor-α

Background/objective

Osteoarthritis (OA) is a whole joint disorder with no disease modifying treatment currently available. The Epidermal Growth Factor Receptor (EGFR) signaling pathway plays an important role in cartilage/bone development and its ligand transforming growth factor-α (TGFα) is upregulated in OA. In contrast, Mitogen-inducible gene 6 (Mig6) is a negative regulator of EGFR, and cartilage-specific Mig-6 deletion results in anabolic effects on cartilage and formation of chondro-osseus nodules (CON). We aimed to attenuate EGFR signaling by inhibiting TGFα production in cartilage-specific Mig6 deficient mice, to test whether this would prevent the formation of CONs.

Methods

We generated double knockout mice by crossing cartilage-specific Mig-6fl/flCol2a1-Cre+/- and whole-body Tgfa± mice to generate experimental and control wild-type mice. Knee and elbow sections were used to examine articular cartilage thickness, cell density, and osteoclast presence. Additionally, immunohistochemistry was completed to analyze phospho-EGFR and SOX9.

Results

Mig-6 deficient mice display cartilage thickening and CONs at 12 weeks in both the elbow and knee joints, which is independent of TGFα ligand presence. Similarly, articular cartilage cell density is increased in Mig6-cKO/Tgfa-KO and Mig6-cKOmice, but not Tgfa-KO mice, and displays increased SOX9 and phospho-EGFR staining.

Conclusion

The articular cartilage displays increased thickness/cell density and CON formation independent of the presence of TGFα, suggesting the anabolic phenotype in the Mig6-deficient mice is independent of TGFα/EGFR binding. The anabolic phenotype may be due to an alternative EGFR ligand activation, or other non-EGFR specific mechanism. More research is required to elucidate the exact pathway responsible for the anabolic effects.

The identification of distinct protective and susceptibility mechanisms for hip osteoarthritis: findings from a genome-wide association study meta-analysis of minimum joint space width and Mendelian randomisation cluster analyses

BACKGROUND

Hip minimum joint space width (mJSW) provides a proxy for cartilage thickness. This study aimed to conduct a genome-wide association study (GWAS) of mJSW to (i) identify new genetic determinants of mJSW and (ii) identify which mJSW loci convey hip osteoarthritis (HOA) risk and would therefore be of therapeutic interest.

METHODS

GWAS meta-analysis of hip mJSW derived from plain X-rays and DXA was performed, stratified by sex and adjusted for age and ancestry principal components. Mendelian randomisation (MR) and cluster analyses were used to examine causal effect of mJSW on HOA.

FINDINGS

50,745 individuals were included in the meta-analysis. 42 SNPs, which mapped to 39 loci, were identified. Mendelian randomisation (MR) revealed little evidence of a causal effect of mJSW on HOA (ORIVW 0.98 [95% CI 0.82-1.18]). However, MR-Clust analysis suggested the null MR estimates reflected the net effect of two distinct causal mechanisms cancelling each other out, one of which was protective, whereas the other increased HOA susceptibility. For the latter mechanism, all loci were positively associated with height, suggesting mechanisms leading to greater height and mJSW increase the risk of HOA in later life.

INTERPRETATIONS

One group of mJSW loci reduce HOA risk via increased mJSW, suggesting possible utility as targets for chondroprotective therapies. The second group of mJSW loci increased HOA risk, despite increasing mJSW, but were also positively related to height, suggesting they contribute to HOA risk via a growth-related mechanism.

FUNDING

Primarily funded by the Medical Research Council and Wellcome Trust.

Translation of nanotechnology-based implants for orthopedic applications: current barriers and future perspective

The objective of bioimplant engineering is to develop biologically compatible materials for restoring, preserving, or altering damaged tissues and/or organ functions. The variety of substances used for orthopedic implant applications has been substantially influenced by modern material technology. Therefore, nanomaterials can mimic the surface properties of normal tissues, including surface chemistry, topography, energy, and wettability. Moreover, the new characteristics of nanomaterials promote their application in sustaining the progression of many tissues. The current review establishes a basis for nanotechnology-driven biomaterials by demonstrating the fundamental design problems that influence the success or failure of an orthopedic graft, cell adhesion, proliferation, antimicrobial/antibacterial activity, and differentiation. In this context, extensive research has been conducted on the nano-functionalization of biomaterial surfaces to enhance cell adhesion, differentiation, propagation, and implant population with potent antimicrobial activity. The possible nanomaterials applications (in terms of a functional nanocoating or a nanostructured surface) may resolve a variety of issues (such as bacterial adhesion and corrosion) associated with conventional metallic or non-metallic grafts, primarily for optimizing implant procedures. Future developments in orthopedic biomaterials, such as smart biomaterials, porous structures, and 3D implants, show promise for achieving the necessary characteristics and shape of a stimuli-responsive implant. Ultimately, the major barriers to the commercialization of nanotechnology-derived biomaterials are addressed to help overcome the limitations of current orthopedic biomaterials in terms of critical fundamental factors including cost of therapy, quality, pain relief, and implant life. Despite the recent success of nanotechnology, there are significant hurdles that must be overcome before nanomedicine may be applied to orthopedics. The objective of this review was to provide a thorough examination of recent advancements, their commercialization prospects, as well as the challenges and potential perspectives associated with them. This review aims to assist healthcare providers and researchers in extracting relevant data to develop translational research within the field. In addition, it will assist the readers in comprehending the scope and gaps of nanomedicine's applicability in the orthopedics field.

BAG3 regulates bone marrow mesenchymal stem cell proliferation by targeting INTS7

Background

BAG3 is an essential regulator of cell survival and has been investigated in the context of heart disease and cancer. Our previous study used immunoprecipitation-liquid chromatography-tandem mass spectrometry to show that BAG3 might directly interact with INTS7 and regulate bone marrow mesenchymal stem cell (BMMSCs) proliferation. However, whether BAG3 bound INTS7 directly and how it regulated BMMSCs expansion was unclear.

Methods

BAG3 expression was detected by quantitative real-time PCR in BMMSCs after siRNA-mediated BAG3 knockdown. BMMSC proliferation was determined using the CCK-8 and colony formation assays. The transwell migration, flow cytometry and TUNEL assays were performed to measure BMMSC migration, cell cycle and apoptosis, respectively. Moreover, co-immunoprecipitation, protein half-life assay and western blotting analyses were used to determine the regulatory mechanism underlying the BAG3-mediated increase in BMMSC proliferation.

Results

The results showed that knocking down BAG3 in BMMSCs markedly decreased their proliferative activity, colony formation and migratory capacity, and induced cell apoptosis as well as cell cycle arrest. Meanwhile, overexpression of BAG3 had the opposite effect. Bioinformatics and BAG3-INTS7 co-immunoprecipitation analyses revealed that BAG3 directly interacted with INTS7. Moreover, the downregulation of BAG3 inhibited the expression of INTS7 and promoted its ubiquitination. We also observed that BAG3 knockdown increased the levels of reactive oxygen species and the extent of DNA damage in BMMSCs. Notably, the upregulation of INTS7 or the addition of an antioxidant scavenger could rescue the BMMSC phenotype induced by BAG3 downregulation.

Conclusions

BAG3 directly interacts with INTS7 and promotes BMMSC expansion by reducing oxidative stress.

Osteoarthritis related epigenetic variations in miRNA expression and DNA methylation

Osteoarthritis (OA) is chronic arthritis characterized by articular cartilage degradation. However, a comprehensive regulatory network for OA-related microRNAs and DNA methylation modifications has yet to be established. Thus, we aimed to identify epigenetic changes in microRNAs and DNA methylation and establish the regulatory network between miRNAs and DNA methylation. The mRNA, miRNA, and DNA methylation expression profiles of healthy or osteoarthritis articular cartilage samples were downloaded from Gene Expression Omnibus (GEO) database, including GSE169077, GSE175961, and GSE162484. The differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and differentially methylated genes (DMGs) were analyzed by the online tool GEO2R. DAVID and STRING databases were applied for functional enrichment analysis and protein-protein interaction (PPI) network. Potential therapeutic compounds for the treatment of OA were identified by Connectivity map (CMap) analysis. A total of 1424 up-regulated DEGs, 1558 down-regulated DEGs, 5 DEMs with high expression, 6 DEMs with low expression, 1436 hypermethylated genes, and 455 hypomethylated genes were selected. A total of 136 up-regulated and 65 downregulated genes were identified by overlapping DEGs and DEMs predicted target genes which were enriched in apoptosis and circadian rhythm. A total of 39 hypomethylated and 117 hypermethylated genes were obtained by overlapping DEGs and DMGs, which were associated with ECM receptor interactions and cellular metabolic processes, cell connectivity, and transcription. Moreover, The PPI network showed COL5A1, COL6A1, LAMA4, T3GAL6A, and TP53 were the most connective proteins. After overlapping of DEGs, DMGs and DEMs predicted targeted genes, 4 up-regulated genes and 11 down-regulated genes were enriched in the Axon guidance pathway. The top ten genes ranked by PPI network connectivity degree in the up-regulated and downregulated overlapping genes of DEGs and DMGs were further analyzed by the CMap database, and nine chemicals were predicted as potential drugs for the treatment of OA. In conclusion, TP53, COL5A1, COL6A1, LAMA4, and ST3GAL6 may play important roles in OA genesis and development.

Comparison of Kindlin-2 deficiency-stimulated osteoarthritis-like lesions induced by Prg4CreERT2 versus AggrecanCreERT2 transgene in mice

Background

Genetically modified mice are the most useful tools for investigating the gene functions in articular cartilage biology and the pathogenesis of osteoarthritis. The Aggrecan^CreERT2 mice are one of the most reported mouse lines used for this purpose. The Prg4 (proteoglycan 4) gene encodes the lubricin protein and is expressed selectively in chondrocytes located at the superficial layer of the articular cartilage. While the Prg4^GFPCreERT2 knock-in inducible-Cre transgenic mice were generated a while ago, so far, few studies have used this mouse line to perform gene functional studies in cartilage biology.

Methods

We have recently reported that deleting the Fermt2 gene, which encodes the key focal adhesion protein Kindlin-2, in articular chondrocytes by using the Aggrecan^CreERT2 transgenic mice, results in spontaneous osteoarthritis (OA) lesions, which highly mimics the human OA pathologies. In this study, we have compared the Kindlin-2 deficiency-caused OA phenotypes induced by Prg4^GFPCreERT2 with those caused by Aggrecan^CreERT2 using imaging and histological analyses.

Results

We find that Kindlin-2 protein is deleted in about 75% of the superficial articular chondrocytes in the tamoxifen (TAM)-treated Prg4^GFPCreERt2/+; Fermt2^fl/fl mice compared to controls. At 6 months after TAM injections, the OARSI scores of Aggrecan^CreERT2/+; Fermt2^fl/fl and Prg4^GFPCreERt2/+; Fermt2^fl/fl mice were 5 and 3, respectively. The knee joints histological osteophyte and synovitis scores were also significantly decreased in Prg4^GFPCreERT2/+; Fermt2^fl/fl mice compared to those in Aggrecan^CreERT2/+; Fermt2^fl/fl mice. Furthermore, magnitudes of upregulation of the extracellular matrix-degrading enzymes Mmp13 and hypertrophic chondrocyte markers Col10a1 and Runx2 were decreased in Prg4^GFPCreERT2/+; Fermt2^fl/fl versus Aggrecan^CreERT2/+; Fermt2^fl/fl mice. We finally examined the susceptibility of Prg4^GFPCreERT2/+; Fermt2^fl/fl mouse model to surgically induce OA lesions. The pathological features of OA in the TAM-DMM model exhibited significant enhancement in cartilage erosion, proteoglycan loss, osteophyte, and synovitis and an increase in OARSI score in articular cartilage compared with those in corn-oil DMM mice.

Conclusion

Kindlin-2 loss causes milder OA-like lesions in Prg4^{GFPCreERT2/+;}Fermt2^fl/fl than in Aggrecan^CreERT2/+; Fermt2^fl/fl mice. In contrast, Kindlin-2 loss similarly accelerates the destabilization of the medial meniscus-induced OA lesions in both mice.Translational Potential of this Article: Our study demonstrates that Prg4^GFPCreERT2 is a useful tool for gene functional study in OA research. This study provides useful information for investigators to choose appropriate Cre mouse lines for their research in cartilage biology.

MicroRNA-224-5p nanoparticles balance homeostasis via inhibiting cartilage degeneration and synovial inflammation for synergistic alleviation of osteoarthritis

MicroRNAs play a crucial role in regulating cartilage extracellular matrix (ECM) metabolism and are being explored as potential therapeutic targets for osteoarthritis (OA). The present study indicated that microRNA-224-5p (miR-224-5p) could balance the homeostasis of OA via regulating cartilage degradation and synovium inflammatory simultaneously. Multifunctional polyamidoamine dendrimer with amino acids used as efficient vector to deliver miR-224-5p. The vector could condense miR-224-5p into transfected nanoparticles, which showed higher cellular uptake and transfection efficiency compared to lipofectamine 3000, and also protected miR-224-5p from RNase degradation. After treatment with the nanoparticles, the chondrocytes showed an increase in autophagy rate and ECM anabolic components, as evidenced by the upregulation of autophagy-related proteins and OA-related anabolic mediators. This led to a corresponding inhibition of cell apoptosis and ECM catabolic proteases, ultimately resulting in the alleviation of ECM degradation. In addition, miR-224-5p also inhibited human umbilical vein endothelial cells angiogenesis and fibroblast-like synoviocytes inflammatory hyperplasia. Integrating the above synergistic effects of miR-224-5p in regulating homeostasis, intra-articular injection of nanoparticles performed outstanding therapeutic effect by reducing articular space width narrowing, osteophyte formation, subchondral bone sclerosis and inhibiting synovial hypertrophy and proliferation in the established mouse OA model. The present study provides a new therapy target and an efficient intra-articular delivery method for improving OA therapy. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) is the most prevalent joint disease worldwide. Gene therapy, which involves delivering microRNAs, has the potential to treat OA. In this study, we demonstrated that miR-224-5p can simultaneously regulate cartilage degradation and synovium inflammation, thereby restoring homeostasis in OA gene therapy. Moreover, compared to traditional transfection reagents such as lipofectamine 3000, G5-AHP showed better efficacy in both microRNA transfection and protection against degradation due to its specific surface structure. In summary, G5-AHP/miR-224-5p was developed to meet the clinical needs of OA patients and the high requirement of gene transfection efficiency, providing a promising paradigm for the future application and development of gene therapy.

A Gel-Based Proteomic Analysis Reveals Synovial α-Enolase and Fibrinogen β-Chain Dysregulation in Knee Osteoarthritis: A Controlled Trial

BACKGROUND

The identification of synovial fluid (SF) biomarkers that could anticipate the diagnosis of osteoarthritis (OA) is gaining increasing importance in orthopaedic clinical practice. This controlled trial aims to assess the differences between the SF proteome of patients affected by severe OA undergoing Total Knee Replacement (TKR) compared to control subjects (i.e., subjects younger than 35, undergoing knee arthroscopy for acute meniscus injury).

METHODS

The synovial samples were collected from patients with Kellgren Lawrence grade 3 and 4 knee osteoarthritis undergoing THR (study group) and young patients with meniscal tears and no OA signs undergoing arthroscopic surgery (control group). The samples were processed and analyzed following the protocol defined in our previous study. All of the patients underwent clinical evaluation using the International Knee Documentation Committee (IKDC) subjective knee evaluation (main outcome), Knee Society Clinical Rating System (KSS), Knee injury and Osteoarthritis Outcome Score (KOOS), and Visual Analogue Scale (VAS) for pain. The drugs' assumptions and comorbidities were recorded. All patients underwent preoperative serial blood tests, including complete blood count and C-Reactive Protein (CRP).

RESULTS

The synovial samples' analysis showed a significantly different fibrinogen beta chain (FBG) and alpha-enolase 1 (ENO1) concentration in OA compared to the control samples. A significant correlation between clinical scores, FBG, and ENO1 concentration was observed in osteoarthritic patients.

CONCLUSIONS

Synovial fluid FBG and ENO1 concentrations are significantly different in patients affected by knee OA compared with non-OA subjects.

Chondrocyte Thrombomodulin Protects against Osteoarthritis

Osteoarthritis (OA) is a prevalent form of arthritis that affects over 32.5 million adults worldwide, causing significant cartilage damage and disability. Unfortunately, there are currently no effective treatments for OA, highlighting the need for novel therapeutic approaches. Thrombomodulin (TM), a glycoprotein expressed by chondrocytes and other cell types, has an unknown role in OA. Here, we investigated the function of TM in chondrocytes and OA using various methods, including recombinant TM (rTM), transgenic mice lacking the TM lectin-like domain (TM^LeD/LeD), and a microRNA (miRNA) antagomir that increased TM expression. Results showed that chondrocyte-expressed TM and soluble TM [sTM, like recombinant TM domain 1 to 3 (rTMD123)] enhanced cell growth and migration, blocked interleukin-1β (IL-1β)-mediated signaling and protected against knee function and bone integrity loss in an anterior cruciate ligament transection (ACLT)-induced mouse model of OA. Conversely, TM^LeD/LeD mice exhibited accelerated knee function loss, while treatment with rTMD123 protected against cartilage loss even one-week post-surgery. The administration of an miRNA antagomir (miR-up-TM) also increased TM expression and protected against cartilage damage in the OA model. These findings suggested that chondrocyte TM plays a crucial role in counteracting OA, and miR-up-TM may represent a promising therapeutic approach to protect against cartilage-related disorders.

Accelerated aging in articular cartilage by ZMPSTE24 deficiency leads to osteoarthritis with impaired metabolic signaling and epigenetic regulation

Osteoarthritis (OA) is an age-related degenerative disease without disease-modifying therapy. The lack of aging-induced osteoarthritis models makes the discovery of therapeutic drugs more challenging. The deficiency of ZMPSTE24 could induce Hutchinson-Gilford progeria syndrome (HGPS), a genetic disorder of rapid aging. However, the relationship between HGPS and OA remains unclear. Our results found that the expression of Zmpste24 was decreased in the articular cartilage during the aging process. Zmpste24 knockout mice, Prx1-Cre; Zmpste24^fl/fl mice and Col2-CreERT2; Zmpste24^fl/fl mice displayed OA phenotype. Loss of Zmpste24 in articular cartilage could exacerbate the occurrence and development of osteoarthritis. Transcriptome sequencing revealed that deletion of Zmpste24 or accumulation of progerin affects chondrocyte metabolism, inhibits cell proliferation and promotes cell senescence. Using this animal model, we elucidate the upregulation of H3K27me3 during chondrocyte senescence and discover the molecular mechanism by which lamin A mutant stabilizes EZH2 expression. The construction of aging-induced osteoarthritis models and the elucidation of the signaling pathways and molecular mechanisms of articular chondrocyte senescence would benefit the discovery and development of new drugs for OA.

Fracture healing-orthobiologics: from basic science to clinical application

Orthopaedics as a field and a profession is fundamentally concerned with the treatment of musculoskeletal disease, in all of its many forms. Our collective understanding of the cellular mechanisms underlying musculoskeletal pathology resulting from injury continues to evolve, opening novel opportunities to develop orthobiologic treatments to improve care. It is a long path to move from an understanding of cellular pathology to development of successful clinical treatment, and this article proposes to discuss some of the challenges to achieving translational therapies in orthopaedics. The article will focus on challenges that clinicians will likely face in seeking to bring promising treatments forward to clinical practice and strategies for improving success in translational efforts.

Deletion of DYRK1A Accelerates Osteoarthritis Progression Through Suppression of EGFR-ERK Signaling

Dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A) signaling is involved in the dynamic balance of catabolism and anabolism in articular chondrocytes. This study aimed to investigate the roles and mechanism of DYRK1A in the pathogenesis of osteoarthritis (OA). The expressions of DYRK1A and its downstream signal epidermal growth factor receptor (EGFR) were detected in the cartilage of adult wild-type mice with destabilized medial meniscus (DMM) and articular cartilage of patients with OA. We measured the progression of osteoarthritis in chondrocyte-specific knockout DYRK1A(DYRK1A-cKO) mice after DMM surgery. Knee cartilage was histologically scored and assessed the effects of DYRK1A deletion on chondrocyte catabolism and anabolism. The effect of inhibiting EGFR signaling in chondrocytes from DYRK1A-cKO mice was analyzed. Trauma-induced OA mice and OA patients showed downregulation of DYRK1A and EGFR signaling pathways. Conditional DYRK1A deletion aggravates DMM-induced cartilage degeneration, reduces the thickness of the superficial cartilage, and increases the number of hypertrophic chondrocytes. The expression of collagen type II, p-ERK, and aggrecan was also downregulated, and the expression of collagen type X was upregulated in the articular cartilage of these mice. Our findings suggest that DYRK1A delays the progression of knee osteoarthritis in mice, at least in part, by maintaining EGFR-ERK signaling in articular chondrocytes.

MiR-760 targets HBEGF to control cartilage extracellular matrix degradation in osteoarthritis

The present study was developed to explore whether microRNA (miR)-760 targets heparin-binding EGF-like growth factor (HBEGF) to control cartilage extracellular matrix degradation in osteoarthritis. Both miR-760 and HBEGF expression levels were analysed in human degenerative cartilage tissues and in interleukin (IL)-1β/tumour necrosis factor (TNF)-α-treated chondrocytes in vitro. A series of knockdown and overexpression assays were then used to gauge the functional importance of miR-760 and HBEGF in OA, with qPCR and western immunoblotting analyses. Bioinformatics assays were used to identify putative miR-760 target genes, with these predictions then being validated through RNA pulldown and luciferase reporter assays. A murine anterior cruciate ligament transection model of OA was then established to prove the in vivo relevance of these findings. These experiments revealed that human degenerative cartilage tissues exhibited significant increases in miR-760 expression with a concomitant drop in HBEGF levels. IL-1β/TNF-α-treated chondrocytes also exhibited significant increases in miR-760 expression with a concomitant drop in HBEGF expression. When chondrocytes were transfected with either miR-760 inhibitor or HBEGF overexpression constructs, this was sufficient to interfere with degradation of the extracellular matrix (ECM). Moreover, miR-760 was confirmed to control chondrocyte matrix homeostasis by targeting HBEGF, and the overexpression of HBEGF partially reversed the effects of miR-760 mimic treatment on the degradation of the cartilage ECM. When OA model mice were administered an intra-articular knee injection of an adenoviral vector encoding a miR-760 mimic construct, cartilage ECM degradation was aggravated. Conversely, the overexpression of HBEGF in OA model mice partially reversed the effects of miR-760 overexpression, restoring appropriate ECM homeostasis. In summary, these data indicated that the miR-760/HBEGF axis plays a central role in orchestrating the pathogenesis of OA, making it a candidate target for therapeutic efforts in OA.

Intra-articular nanodrug delivery strategies for treating osteoarthritis

Osteoarthritis (OA) is characterized by progressive cartilage degeneration. Pharmaceutical intervention remains a main treatment approach. However, drug delivery via intra-articular administration (IA) can be restricted by rapid clearance, the dense and highly negatively charged extracellular matrix (ECM) of cartilage, and uneven distribution of diseased chondrocytes. Nanodrug delivery systems, such as liposomes, micelles, and nanoparticles (NPs), have shown great potential to prolong intra-articular residence, penetrate the ECM, and achieve diseased chondrocyte-specific delivery. In this review, we discuss the challenges associated with intra-articular drug delivery in OA and the nanodrug delivery strategies developed to overcome these challenges. It is anticipated that these nanodrug delivery strategies will advance IA of drugs into broader applications in OA treatment.

Dynamic chromatin accessibility tuning by the long noncoding RNA ELDR accelerates chondrocyte senescence and osteoarthritis

Epigenetic reprogramming plays a critical role in chondrocyte senescence during osteoarthritis (OA) pathology, but the underlying molecular mechanisms remain to be elucidated. Here, using large-scale individual datasets and genetically engineered (Col2a1-CreER^T2;Eldr^flox/flox and Col2a1-CreER^T2;ROSA26-LSL-Eldr^+/+ knockin) mouse models, we show that a novel transcript of long noncoding RNA ELDR is essential for the development of chondrocyte senescence. ELDR is highly expressed in chondrocytes and cartilage tissues of OA. Mechanistically, exon 4 of ELDR physically mediates a complex consisting of hnRNPL and KAT6A to regulate histone modifications of the promoter region of IHH, thereby activating hedgehog signaling and promoting chondrocyte senescence. Therapeutically, GapmeR-mediated silencing of ELDR in the OA model substantially attenuates chondrocyte senescence and cartilage degradation. Clinically, ELDR knockdown in cartilage explants from OA-affected individuals decreased the expression of senescence markers and catabolic mediators. Taken together, these findings uncover an lncRNA-dependent epigenetic driver in chondrocyte senescence, highlighting that ELDR could be a promising therapeutic avenue for OA.

The degeneration-pain relationship in the temporomandibular joint: Current understandings and rodent models

Temporomandibular disorders (TMD) represent a group of musculoskeletal conditions involving the temporomandibular joints (TMJ), the masticatory muscles and associated structures. Painful TMD are highly prevalent and conditions afflict 4% of US adults annually. TMD include heterogenous musculoskeletal pain conditions, such as myalgia, arthralgia, and myofascial pain. A subpopulations of TMD patients show structural changes in TMJ, including disc displacement or degenerative joint diseases (DJD). DJD is a slowly progressing, degenerative disease of the TMJ characterized by cartilage degradation and subchondral bone remodeling. Patients with DJD often develop pain (TMJ osteoarthritis; TMJ OA), but do not always have pain (TMJ osteoarthrosis). Therefore, pain symptoms are not always associated with altered TMJ structures, which suggests that a causal relationship between TMJ degeneration and pain is unclear. Multiple animal models have been developed for determining altered joint structure and pain phenotypes in response to various TMJ injuries. Rodent models of TMJOA and pain include injections to induce inflammation or cartilage destruction, sustained opening of the oral cavity, surgical resection of the articular disc, transgenic approaches to knockout or overexpress key genes, and an integrative approach with superimposed emotional stress or comorbidities. In rodents, TMJ pain and degeneration occur during partially overlapping time periods in these models, which suggests that common biological factors may mediate TMJ pain and degeneration over different time courses. While substances such as intra-articular pro-inflammatory cytokines commonly cause pain and joint degeneration, it remains unclear whether pain or nociceptive activities are causally associated with structural degeneration of TMJ and whether structural degeneration of TMJ is necessary for producing persistent pain. A thorough understanding of the determining factors of pain-structure relationships of TMJ during the onset, progression, and chronification by adopting novel approaches and models should improve the ability to simultaneously treat TMJ pain and TMJ degeneration.

Osteoarthritis: pathogenic signaling pathways and therapeutic targets

Osteoarthritis (OA) is a chronic degenerative joint disorder that leads to disability and affects more than 500 million population worldwide. OA was believed to be caused by the wearing and tearing of articular cartilage, but it is now more commonly referred to as a chronic whole-joint disorder that is initiated with biochemical and cellular alterations in the synovial joint tissues, which leads to the histological and structural changes of the joint and ends up with the whole tissue dysfunction. Currently, there is no cure for OA, partly due to a lack of comprehensive understanding of the pathological mechanism of the initiation and progression of the disease. Therefore, a better understanding of pathological signaling pathways and key molecules involved in OA pathogenesis is crucial for therapeutic target design and drug development. In this review, we first summarize the epidemiology of OA, including its prevalence, incidence and burdens, and OA risk factors. We then focus on the roles and regulation of the pathological signaling pathways, such as Wnt/β-catenin, NF-κB, focal adhesion, HIFs, TGFβ/ΒΜP and FGF signaling pathways, and key regulators AMPK, mTOR, and RUNX2 in the onset and development of OA. In addition, the roles of factors associated with OA, including MMPs, ADAMTS/ADAMs, and PRG4, are discussed in detail. Finally, we provide updates on the current clinical therapies and clinical trials of biological treatments and drugs for OA. Research advances in basic knowledge of articular cartilage biology and OA pathogenesis will have a significant impact and translational value in developing OA therapeutic strategies.

Advances in nanomaterial-based targeted drug delivery systems

Nanomaterial-based drug delivery systems (NBDDS) are widely used to improve the safety and therapeutic efficacy of encapsulated drugs due to their unique physicochemical and biological properties. By combining therapeutic drugs with nanoparticles using rational targeting pathways, nano-targeted delivery systems were created to overcome the main drawbacks of conventional drug treatment, including insufficient stability and solubility, lack of transmembrane transport, short circulation time, and undesirable toxic effects. Herein, we reviewed the recent developments in different targeting design strategies and therapeutic approaches employing various nanomaterial-based systems. We also discussed the challenges and perspectives of smart systems in precisely targeting different intravascular and extravascular diseases.

Elucidation of the Key Therapeutic Targets and Potential Mechanisms of Marmesine against Knee Osteoarthritis via Network Pharmacological Analysis and Molecular Docking

Background

Marmesine, a major active ingredient isolated from Radix Angelicae biseratae (Duhuo), has been reported to have multiple pharmacological activities. However, its therapeutic effects against knee osteoarthritis (OA) remain poorly investigated. The present study is aimed at uncovering the core targets and signaling pathways of marmesine against osteoarthritis using a combined method of bioinformatics and network pharmacology.

Methods

We utilized SwissTargetPrediction and PharmMapper to collect the potential targets of marmesine. OA-related differentially expressed genes (DEGs) were identified from GSE98918 dataset. Then, the intersection genes between DEGs and candidate genes of marmesine were subjected to protein-protein interaction (PPI) network construction and functional enrichment analysis. The core targets were verified using the molecular docking technology.

Results

A total of 320 marmesine-related genes and 5649 DEGs and 60 ingredient-disease targets between them were identified. The results of functional enrichment analyses revealed that response to oxygen levels, neuroinflammatory response, PI3K-Akt signaling pathway, MAPK signaling pathway, FoxO signaling pathway, and osteoclast differentiation was identified as the potential mechanisms of marmesine against OA. EGFR, CASP3, MMP9, PPARG, and MAPK1 served as hub genes regulated by marmesine in the treatment of OA, and the molecular docking further verified the results.

Conclusion

Marmesine exerts the therapeutic effects against OA through multitarget and multipathways, in which EGFR, CASP3, MMP9, PPARG, and MAPK1 might be hub genes. Our research indicated that the combination of bioinformatics and network pharmacology could serve as an effective approach for investigating the potential mechanisms of natural product.

Sirt6 attenuates chondrocyte senescence and osteoarthritis progression

Sirt6 has been implicated as a key regulator in aging-related diseases, including osteoarthritis. However, its functional role and molecular mechanism in chondrocyte senescence and osteoarthritis pathophysiology remain largely undefined. Here we show that Sirt6 deficiency exaggerates chondrocyte senescence and osteoarthritis progression, whereas intra-articular injection of adenovirus-Sirt6 markedly attenuates surgical destabilization of medial meniscus-induced osteoarthritis. Mechanistically, Sirt6 can directly interact with STAT5 and deacetylate STAT5, thus inhibiting the IL-15/JAK3-induced STAT5 translocation from cytoplasm to nucleus, which inactivates IL-15/JAK3/STAT5 signaling. Mass spectrometry revealed that Sirt6 deacetylated conserved lysine 163 on STAT5. Mutation of lysine 163 to arginine in STAT5 abolished the regulatory effect of Sirt6. In vivo, specific ablation of Sirt6 in chondrocytes exacerbated osteoarthritis. Pharmacological activation of Sirt6 substantially alleviated chondrocyte senescence. Taken together, Sirt6 attenuates chondrocyte senescence by inhibiting IL-15/JAK3/STAT5 signaling. Targeting Sirt6 represents a promising new approach for osteoarthritis.