Recent progress on the role of miR-140 in cartilage matrix remodelling and its implications for osteoarthritis treatment

Control and interplay of scaffold-biomolecule interactions applied to cartilage tissue engineering

Cartilage tissue engineering based on the combination of biomaterials, adult or stem cells and bioactive factors is a challenging approach for regenerative medicine with the aim of achieving the formation of a functional neotissue stable in the long term. Various 3D scaffolds have been developed to mimic the extracellular matrix environment and promote cartilage repair. In addition, bioactive factors have been extensively employed to induce and maintain the cartilage phenotype. However, the spatiotemporal control of bioactive factor release remains critical for maximizing the regenerative potential of multipotent cells, such as mesenchymal stromal cells (MSCs), and achieving efficient chondrogenesis and sustained tissue homeostasis, which are essential for the repair of hyaline cartilage. Despite advances, the effective delivery of bioactive factors is limited by challenges such as insufficient retention at the site of injury and the loss of therapeutic efficacy due to uncontrolled drug release. These limitations have prompted research on biomolecule-scaffold interactions to develop advanced delivery systems that provide sustained release and controlled bioavailability of biological factors, thereby improving therapeutic outcomes. This review focuses specifically on biomaterials (natural, hybrid and synthetic) and biomolecules (molecules, proteins, nucleic acids) of interest for cartilage engineering. Herein, we review in detail the approaches developed to maintain the biomolecules in scaffolds and control their release, based on their chemical nature and structure, through steric, non-covalent and/or covalent interactions, with a view to their application in cartilage repair.

Potential and challenges of utilizing exosomes in osteoarthritis therapy (Review)

Exosomes are integral to the pathophysiology of osteoarthritis (OA) due to their roles in mediating intercellular communication and regulating inflammatory processes. Exosomes are integral to the transport of bioactive molecules, such as proteins, lipids and nucleic acids, which can influence chondrocyte behavior and joint homeostasis. Given their properties of regeneration and ability to target damaged tissues, exosomes represent a promising therapeutic avenue for OA treatment. Exosomes have potential in promoting cartilage repair, reducing inflammation and improving overall joint function. However, several challenges remain, including the need for standardized isolation and characterization methods, variability in exosomal content, and regulatory hurdles. The present review aims to provide a comprehensive overview of the current understanding of exosome mechanisms in OA and their therapeutic potential, while also addressing the ongoing challenges faced in translating these findings into clinical practice. By consolidating existing research, the present review aims to pave the way for future studies aimed at optimizing exosome‑based therapies for effective OA management.

Deciphering the role of Wnt/β-catenin and miR-214 in knee osteoarthritis: molecular and clinical insights

Introduction

Understanding the molecular mechanism underlying the pathogenesis of knee osteoarthritis (KOA) may be beneficial in fetching new therapeutics. Our study aims to investigate the implication of Wnt/ β-catenin pathway in development of KOA by detection of the downstream target genes and their crosstalk with miR-214 in patients with KOA and to correlate that with the clinical findings.

Methods

Sixty participants were involved in the study. The levels of miR-214, β-catenin, Wnt4, matrix metalloproteinase 3 (MMP3), Bax, caspase 3, and phosphorylated glycogen synthase kinase-3 beta (pGSK3β) were determined. All participants were assessed clinically and radiologically regarding knee joint pain, stiffness, range of motion, and knee medial cartilage thickness. Besides, a correlation between Western Ontario and McMaster Universities (WOMAC) score, clinical, and radiological data, and the measured parameters was conducted.

Results and discussion

Patients with KOA showed downregulated miR-214 with upregulated β-catenin, Wnt4, MMP3, Bax, caspase 3, and pGSK3β compared to healthy individuals. Statistically significant positive correlation between WOMAC score, knee joint pain regarding Visual Analogue Scale (VAS) with β-catenin, pGSK3β, Wnt4, MMP3, Bax, and caspase 3, and significant negative relationship between them and knee joint medial cartilage thickness; while there was a statistically significant negative correlation between WOMAC, and clinical findings of osteoarthritis and miR-214 and significant positive relationship between it and knee joint medial cartilage thickness. This study provides valuable insights into involvement of the Wnt/β-catenin and miR-214 in KOA pathogenesis. By targeting these molecular components, future therapeutics may modulate their activity and mitigate chondrocyte apoptosis and matrix degradation, potentially halting KOA progression.

Microfluidic Synthesis of miR-200c-3p Lipid Nanoparticles: Targeting ZEB2 to Alleviate Chondrocyte Damage in Osteoarthritis

Introduction

Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degeneration. Chondrocyte inflammation, apoptosis, and extracellular matrix degradation accelerated OA progression. MicroRNA (miRNA) has the potential to be a therapeutic method for osteoarthritis. However, it is difficult to penetrate the cell to exercise its biological function, and its extracellular effect is unclear.

Methods

lipo-AgPEI-miR-200c-3p was created by combining miR-200c-3p with silver nitrate polyvinylimine nanoparticles on a microfluidic device. The drug release curve, stability, temperature sensitivity, cytotoxicity, and the impact of lipo-AgPEI-miR-200c-3p on the expression of proteins linked to matrix disintegration, apoptosis, and inflammatory factors were all detected.

Results

Results showed that the particle size of Lipo-AgPEI-miR-200c-3p was about 130 nm, the Zeta potential was lowered to 1.08±0.12 mV. Lipo-AgPEI-miR-200c-3p could increase cell viability, prevent cell apoptosis, and decrease the expression levels of TNF-α, IL-6, IL-1β, and MCP-1 in ADTC5 cells following LPS stimulation. MMP3, MMP13, and ADAMTS-4 expression was downregulated whereas collagen II expression was upregulated. The ZEB2 expression was greatly elevated following LPS stimulation and dramatically decreased following transfection of miR-200c-3p. Collagen II expression rose following transfection of si-ZEB2, whereas the expression levels of inflammatory factors, apoptosis-related proteins, MMP3, MMP13, and ADAMTS-4 decreased. The dual luciferase experiment demonstrated that ZEB2 was the target gene of miR-200c-3p.

Conclusion

The synergistic effect of AgPEI and miR-200c-3p can inhibit the inflammatory response, apoptosis, and matrix degradation of chondrocytes. Lipo-AgPEI-miR-200c-3p can also improve transfection efficiency and obtain good physicochemical properties of drugs. miR-200c-3p may be crucial in the development of OA and can influence the target gene ZEB2, control the inflammatory response, apoptosis, and chondrocyte matrix breakdown.

Light-regulated microRNAs shape dynamic gene expression in the zebrafish circadian clock

A key property of the circadian clock is that it is reset by light to remain synchronized with the day-night cycle. An attractive model to explore light input to the circadian clock in vertebrates is the zebrafish. Circadian clocks in zebrafish peripheral tissues and even zebrafish-derived cell lines are entrainable by direct light exposure thus providing unique insight into the function and evolution of light regulatory pathways. Our previous work has revealed that light-induced gene transcription is a key step in the entrainment of the circadian clock as well as enabling the more general adaptation of zebrafish cells to sunlight exposure. However, considerable evidence points to post-transcriptional regulatory mechanisms, notably microRNAs (miRNAs), playing an essential role in shaping dynamic changes in mRNA levels. Therefore, does light directly impact the function of miRNAs? Are there light-regulated miRNAs and if so, which classes of mRNA do they target? To address these questions, we performed a complete sequencing analysis of light-induced changes in the zebrafish transcriptome, encompassing small non-coding RNAs as well as mRNAs. Importantly, we identified sets of light-regulated miRNAs, with many regulatory targets representing light-inducible mRNAs including circadian clock genes and genes involved in redox homeostasis. We subsequently focused on the light-responsive miR-204-3-3p and miR-430a-3p which are predicted to regulate the expression of cryptochrome genes (cry1a and cry1b). Luciferase reporter assays validated the target binding of miR-204-3-3p and miR-430a-3p to the 3'UTRs of cry1a and cry1b, respectively. Furthermore, treatment with mimics and inhibitors of these two miRNAs significantly affected the dynamic expression of their target genes but also other core clock components (clock1a, bmal1b, per1b, per2, per3), as well as the rhythmic locomotor activity of zebrafish larvae. Thus, our identification of light-responsive miRNAs reveals new intricacy in the multi-level regulation of the circadian clockwork by light.

Mapping the knowledge landscape: A bibliometric analysis of exosome research in osteoarthritis (2004-2023)

Exosomes have emerged as a crucial focus in advancing the diagnosis and treatment of osteoarthritis (OA). However, there are limited bibliometric studies on this topic. This study aimed to delineate the literature landscape on exosomes in OA, identifying global research trends and key areas. We utilised the Web of Science Core Collection to retrieve articles published from 2004 to 2023. Our analysis included 456 publications across 671 institutions from 40 countries/regions. Publication volume, citations, and emerging research foci and trends were examined. Our results reveal a consistently increased interest in exosomes related to OA over the past two decades. Prominent institutions contributing to this research include Shanghai Jiao Tong University and Shenzhen University. The leading journal for these publications is the International Journal of Molecular Sciences, with Stem Cell Research & Therapy being the most frequently co-cited journal. Notable scholars in this field are Li Duan, Yujie Liang, Xiao Xu, and Wei Seong Toh, with Shipin Zhang emerging as the most co-cited author. The principal research themes were elucidating how exosomes contribute to OA pathology and developing novel therapeutic approaches. Research hotspots and new trends are linked to terms such as "cartilage," "mesenchymal stem cell," "miRNA," "treatment," and "biomarkers." This comprehensive analysis offers valuable insights into the prevailing scientific discourse, pivotal topics, and potential future directions. It could serve as a foundational reference for researchers exploring exosomes and their utility in OA diagnostics and therapeutics.

Cartilage-targeted drug nanocarriers for osteoarthritis therapy

Osteoarthritis (OA) is a joint disease common worldwide. Currently, no disease-modifying osteoarthritis drugs (DMOADs) have successfully passed clinical trials, often due to a lack of cartilage penetration. Thus, targeting the extracellular matrix (ECM) is a major priority. The design of cartilage-targeting drug delivery systems (DDSs) for intra-articular administration requires consideration of the physicochemical properties of articular cartilage, such as its porosity and negative fixed charge. Various positively charged biomaterials such as polyaminoacids, proteins, polymers, and lipids can be used as DDSs to enhance cartilage penetration. Cationic nanocarriers interact electrostatically with anionic glycosaminoglycans of the ECM, ensuring passive cartilage-targeting penetration and prolonged retention. Active targeting strategies involve DDSs surface decoration using antibodies or peptides with a strong affinity for collagen II and chondrocytes in the cartilage. This review presents all the relevant bio-physicochemical properties of healthy and OA cartilages, as well as state-of-the-art intra-articular cartilage-targeted DDSs, intending to better understand the recent advances in the application of cartilage-targeting delivery systems for OA therapy.

Cellular crosstalk in the bone marrow niche

The bone marrow niche is a special microenvironment that comprises elements, including hematopoietic stem cells, osteoblasts, and endothelial cells, and helps maintain their characteristic functions. Here, we elaborate on the crosstalk between various cellular components, hematopoietic stem cells, and other cells in the bone marrow niche. We further explain the mechanism of preserving equilibrium in the bone marrow niche, which is crucial for the directional regulation of bone reconstruction and repair. Additionally, we elucidate the intercommunication among osteocytes, the regulation of osteoblast maturation and activation by lymphocytes, the deficiency of megakaryocytes that can markedly impair osteoblast formation, and the mechanism of interaction between macrophages and mesenchymal stem cells in the bone marrow niche. Finally, we discussed the new immunotherapies for bone tumors in the BM niche. In this review, we aimed to provide a candid overview of the crosstalk among bone marrow niche cells and to highlight new concepts underlying the unknown mechanisms of hematopoiesis and bone reconstruction. Thus, this review may provide a more comprehensive understanding of the role of these niche cells in improving hematopoietic function and help identify their therapeutic potential for different diseases in the future.

Genetics of osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis with well recognized multifactorial nature. While several environmental factors such as older age, obesity and previous joint injury are strongly associated with its development, a genetic influence on OA has been recognized for over 80 years. Identification of genes associated with OA has received considerable attention over the last two decades, aided by the rapidly evolving genotyping and sequencing technologies. More than 300 genomic loci have been identified to be associated with OA at different joints. These findings are likely to help our better understanding of the pathogenesis of OA and lead to important therapeutic and diagnostic advances in this most common disabling rheumatic disorder. This article will review the data that support the role of genetic factors in common idiopathic OA.

Exosomes derived from bone marrow mesenchymal stem cell preconditioned by low-intensity pulsed ultrasound stimulation promote bone-tendon interface fibrocartilage regeneration and ameliorate rotator cuff fatty infiltration

Background

Fibrovascular scar healing of bone-tendon interface (BTI) instead of functional fibrocartilage regeneration is the main concern associated with unsatisfactory prognosis in rotator cuff repair. Mesenchymal stem cells (MSCs) exosomes have been reported to be a new promising cell-free approach for rotator cuff healing. Whereas, controversies abound in whether exosomes of native MSCs alone can effectively induce chondrogenesis.

Purpose

To explore the effect of exosomes derived from low-intensity pulsed ultrasound stimulation (LIPUS)-preconditioned bone marrow mesenchymal stem cells (LIPUS-BMSC-Exos) or un-preconditioned BMSCs (BMSC-Exos) on rotator cuff healing and the underlying mechanism.

Methods

C57BL/6 mice underwent unilateral supraspinatus tendon detachment and repair were randomly assigned to saline, BMSCs-Exos or LIPUS-BMSC-Exos injection therapy. Histological, immunofluorescent and biomechanical tests were detected to investigate the effect of exosomes injection on BTI healing and muscle fatty infiltration of the repaired rotator cuff. In vitro, native BMSCs were incubated with BMSC-Exos or LIPUS-BMSC-Exos and then chondrogenic/adipogenic differentiation were observed. Further, quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the chondrogenesis/adipogenesis-related miRNA profiles of LIPUS-BMSC-Exos and BMSC-Exos. The chondrogenic/adipogenic potential of the key miRNA was verified through function recover test with its mimic and inhibitor.

Results

The results indicated that the biomechanical properties of the supraspinatus tendon-humeral junction were significantly improved in the LIPUS-BMSC-Exos group than that of the BMSCs-Exos group. The LIPUS-BMSC-Exos group also exhibited a higher histological score and more newly regenerated fibrocartilage at the repair site at postoperative 2 and 4 weeks and less fatty infiltration at 4 weeks than the BMSCs-Exos group. In vitro, co-culture of BMSCs with LIPUS-BMSC-Exos could significantly promote BMSCs chondrogenic differentiation and inhibit adipogenic differentiation. Subsequently, qRT-PCR revealed significantly higher enrichment of chondrogenic miRNAs and less enrichment of adipogenic miRNAs in LIPUS-BMSC-Exos compared with BMSC-Exos. Moreover, we demonstrated that this chondrogenesis-inducing potential was primarily attributed to miR-140, one of the most abundant miRNAs in LIPUS-BMSC-Exos.

Conclusion

LIPUS-preconditioned BMSC-Exos can effectively promote BTI fibrocartilage regeneration and ameliorate supraspinatus fatty infiltration by positive regulation of pro-chondrogenesis and anti-adipogenesis, which was primarily through delivering miR-140.

The translational potential of this article

These findings propose an innovative "LIPUS combined Exosomes strategy" for rotator cuff healing which combines both physiotherapeutic and biotherapeutic advantages. This strategy possesses a good translational potential as a local injection of LIPUS preconditioned BMSC-derived Exos during operation can be not only efficient for promoting fibrocartilage regeneration and ameliorating rotator cuff fatty infiltration, but also time-saving, simple and convenient for patients.

Characterization of the Secretome from Spheroids of Adipose-Derived Stem Cells (SASCs) and Its Potential for Tissue Regeneration

INTRODUCTION

Spheroids are spherical aggregates of cells that mimic the three-dimensional (3D) architecture of tissues more closely than traditional two dimensional (2D) cultures. Spheroids of adipose stem cells (SASCs) show special features such as high multilineage differentiation potential and immunomodulatory activity. These properties have been attributed to their secreted factors, such as cytokines and growth factors. Moreover, a key role is played by the extracellular vesicles (EVs), which lead a heterogeneous cargo of proteins, mRNAs, and small RNAs that interfere with the pathways of the recipient cells.

PURPOSE

The aim of this work was to characterize the composition of the secretome and exosome from SASCs and evaluate their regenerative potential.

MATERIALS AND METHODS

SASCs were extracted from adipose samples of healthy individuals after signing informed consent. The exosomes were isolated and characterized by Dinamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Western blotting analyses. The expression of mRNAs and miRNAs were evaluated through real-time PCR. Lastly, a wound-healing assay was performed to investigate their regenerative potential on different cell cultures.

RESULTS

The SASCs' exosomes showed an up-regulation of NANOG and SOX2 mRNAs, typical of stemness maintenance, as well as miR126 and miR146a, related to angiogenic and osteogenic processes. Moreover, the exosomes showed a regenerative effect.

CONCLUSIONS

The SASCs' secretome carried paracrine signals involved in stemness maintenance, pro-angiogenic and pro-osteogenic differentiation, immune system regulation, and regeneration.

Influence of inflammation on the expression of microRNA-140 in extracellular vesicles from 2D and 3D culture models of synovial-membrane-derived stem cells

Background

In osteoarthritis (OA), articular homeostasis is regulated by microRNA-140 that inhibits ADAMTS-5, an enzyme that cleaves aggrecan and stimulates the synthesis of other inflammatory mediators. This study aims to evaluate the expression of microRNA-140 in extracellular vesicles (EVs) derived from equine synovial-membrane-derived mesenchymal stem cells (eqSMMSCs) cultured in monolayer (2D) and three-dimensional (3D) culture models under an in vitro inflammatory environment.

Methods

Four experimental groups of eqSMMSC cultures were defined for isolation of the EVs. The 2D and 3D control groups were cultured in a conventional cell culture medium, while the 2D-OA and 3D-OA treatment groups were exposed to an OA-like medium containing IL-1β and TNFα. The culture media samples were collected at 24 h, 72 h, and 120 h time points for EV isolation and characterization using nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). Reverse transcription quantitative polymerase chain reaction was employed to assess the expressions of microRNA-140 in both the cells and EVs. All statistical analyses were conducted at the 5% significance level.

Results

Encapsulation of the eqSMMSCs protected the cells from the inflammatory media compared to the monolayer cultures. EVs were found in higher concentrations in the 3D-OA cultures. Additionally, higher expressions of microRNA-140 were observed in the cells of the 3D-OA group at 24 and 72 h, whereas microRNA-140 expressions in the EVs were higher in the 3D group at 72 h and in the 2D-OA group at 120 h (p < 0.001). However, the 3D-OA culture showed higher expression of the mRNA Adamts5 in the EVs at 120 h.

Conclusion

The responses of the eqSMMSCs to inflammatory stimuli involve intracellular expression of microRNA-140 and its subsequent transportation via the EVs, with quicker responses observed in the 3D than 2D cultures. This study sheds light on the behaviors of stem cells in restoring homeostasis in osteoarthritic joints.

Unraveling the molecular landscape of osteoarthritis: A comprehensive review focused on the role of non-coding RNAs

Osteoarthritis (OA) poses a significant global health challenge, with its prevalence anticipated to increase in the coming years. This review delves into the emerging molecular biomarkers in OA pathology, focusing on the roles of various molecules such as metabolites, noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Advances in omics technologies have transformed biomarker identification, enabling comprehensive analyses of the complex pathways involved in OA pathogenesis. Notably, ncRNAs, especially miRNAs and lncRNAs, exhibit dysregulated expression patterns in OA, presenting promising opportunities for diagnosis and therapy. Additionally, the intricate interplay between epigenetic modifications and OA progression highlights the regulatory role of epigenetics in gene expression dynamics. Genome-wide association studies have pinpointed key genes undergoing epigenetic changes, providing insights into the inflammatory processes and chondrocyte hypertrophy typical of OA. Understanding the molecular landscape of OA, including biomarkers and epigenetic mechanisms, holds significant potential for developing innovative diagnostic tools and therapeutic strategies for OA management.

Evolution and advancements in genomics and epigenomics in OA research: How far we have come

OBJECTIVE

Osteoarthritis (OA) is the most prevalent musculoskeletal disease affecting articulating joint tissues, resulting in local and systemic changes that contribute to increased pain and reduced function. Diverse technological advancements have culminated in the advent of high throughput "omic" technologies, enabling identification of comprehensive changes in molecular mediators associated with the disease. Amongst these technologies, genomics and epigenomics - including methylomics and miRNomics, have emerged as important tools to aid our biological understanding of disease.

DESIGN

In this narrative review, we selected articles discussing advancements and applications of these technologies to OA biology and pathology. We discuss how genomics, deoxyribonucleic acid (DNA) methylomics, and miRNomics have uncovered disease-related molecular markers in the local and systemic tissues or fluids of OA patients.

RESULTS

Genomics investigations into the genetic links of OA, including using genome-wide association studies, have evolved to identify 100+ genetic susceptibility markers of OA. Epigenomic investigations of gene methylation status have identified the importance of methylation to OA-related catabolic gene expression. Furthermore, miRNomic studies have identified key microRNA signatures in various tissues and fluids related to OA disease.

CONCLUSIONS

Sharing of standardized, well-annotated omic datasets in curated repositories will be key to enhancing statistical power to detect smaller and targetable changes in the biological signatures underlying OA pathogenesis. Additionally, continued technological developments and analysis methods, including using computational molecular and regulatory networks, are likely to facilitate improved detection of disease-relevant targets, in-turn, supporting precision medicine approaches and new treatment strategies for OA.

ROS-induced imbalance of the miR-34a-5p/SIRT1/p53 axis triggers chronic chondrocyte injury and inflammation

Osteoarthritis is a chronic degenerative disease based on the degeneration and loss of articular cartilage. Inflammation and aging play an important role in the destruction of the extracellular matrix, in which microRNA (miRNA) is a key point, such as miRNA-34a-5p. Upregulation of miRNA-34a-5p was previously reported in a rat OA model, and its inhibition significantly suppressed interleukin (IL)-1β-induced apoptosis in rat chondrocytes. However, Oxidative stress caused by reactive oxygen species (ROS) can exacerbate the progression of miRNA regulated OA by mediating inflammatory processes. Thus, oxidative stress effects induced via tert-butyl hydroperoxide (tBHP) in human chondrocytes were assessed in the current research by evaluating mitochondrial ROS production, mitochondrial cyclooxygenase (COX) activity, and cell apoptosis. We also analyzed the activities of antioxidant enzymes including glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD). Additionally, inflammatory factors, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, and IL-24, which contribute to OA development, were detected by enzyme-linked immunosorbent assay (ELISA). The results of this study indicated that miR-34a-5p/silent information regulator 1 (SIRT1)/p53 axis was involved in the ROS-induced injury of human chondrocytes. Moreover, dual-luciferase assay revealed that SIRT1 expression was directly regulated by miR-34a-5p, indicating the presence of a positive feedback loop in the miR-34a-5p/SIRT1/p53 axis that plays an important role in cell survival. However, ROS disrupted the miR-34a-5p/SIRT1/p53 axis, leading to the development of OA, and articular injection of SIRT1 agonist, SRT1720, in a rat model of OA effectively ameliorated OA progression in a dose-dependent manner. Our study confirms that miRNA-34a-5p could participate in oxidative stress responses caused by ROS and further regulate the inflammatory process via the SIRT1/p53 signaling axis, ultimately affecting the onset of OA, thus providing a new treatment strategy for clinical treatment of OA.

Therapeutic potential of mesenchymal stem cell-derived exosomes in skeletal diseases

Skeletal diseases impose a considerable burden on society. The clinical and tissue-engineering therapies applied to alleviate such diseases frequently result in complications and are inadequately effective. Research has shifted from conventional therapies based on mesenchymal stem cells (MSCs) to exosomes derived from MSCs. Exosomes are natural nanocarriers of endogenous DNA, RNA, proteins, and lipids and have a low immune clearance rate and good barrier penetration and allow targeted delivery of therapeutics. MSC-derived exosomes (MSC-exosomes) have the characteristics of both MSCs and exosomes, and so they can have both immunosuppressive and tissue-regenerative effects. Despite advances in our knowledge of MSC-exosomes, their regulatory mechanisms and functionalities are unclear. Here we review the therapeutic potential of MSC-exosomes for skeletal diseases.

Role of crosstalk between synovial cells and chondrocytes in osteoarthritis (Review)

Osteoarthritis (OA) is a low-grade, nonspecific inflammatory disease that affects the entire joint. This condition is characterized by synovitis, cartilage erosion, subchondral bone defects, and subpatellar fat pad damage. There is mounting evidence demonstrating the significance of crosstalk between synovitis and cartilage destruction in the development of OA. To comprehensively explore the phenotypic alterations of synovitis and cartilage destruction, it is important to elucidate the crosstalk mechanisms between chondrocytes and synovial cells. Furthermore, the updated iteration of single-cell sequencing technology reveals the interaction between chondrocyte and synovial cells. In the present review, the histological and pathological alterations between cartilage and synovium during OA progression are described, and the mode of interaction and molecular mechanisms between synovial cells and chondrocytes in OA, both of which affect the OA process mainly by altering the inflammatory environment and cellular state, are elucidated. Finally, the current OA therapeutic approaches are summarized and emerging therapeutic targets are reviewed in an attempt to provide potential insights into OA treatment.

WITHDRAWN: The dysregulated autophagy in osteoarthritis: Revisiting molecular profile

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Synovia tissue-specific exosomes participate in the dual variation of the osteoarthritis microenvironment via miR-182

Osteoarthritis (OA) is the most common type of joint disease and the leading cause of chronic disability among older adults. As an important component of the joint, synovium influences the inflammatory and degenerative process of OA. This study found that miRNA 182 (miR-182) in synovium-specific exosomes can modulate inflammation and apoptotic signaling. It also regulated different biological functions to promote the progression of OA. Experiments based on rat OA model and synovium samples from OA patients, we found that synovium-derived miR-182 regulates inflammatory response in the early stage of OA by regulating the expression level of forkhead box O-3 (FOXO3). However, the expression of miR-182 was significantly increased in synovial tissue of advanced OA, which was involved in the apoptotic signal of severe OA. These findings suggest that miR-182 may directly regulate OA progression by modulating FOXO3 production inflammation, and apoptosis.

Bioinformatics and Integrative Experimental Method to Identifying and Validating Co-Expressed Ferroptosis-Related Genes in OA Articular Cartilage and Synovium

Purpose

Osteoarthritis (OA) is the most common joint disease worldwide and is the primary cause of disability and chronic pain in older adults.Ferroptosis is a type of programmed cell death characterized by aberrant iron metabolism and reactive oxygen species accumulation; however, its role in OA is not known.

Methods

To identify ferroptosis markers co-expressed in articular cartilage and synovium samples from patients with OA, in silico analysis was performed.Signature genes were analyzed and the results were evaluated using a ROC curve prediction model.The biological function, correlation between Signature genes, immune cell infiltration, and ceRNA network analyses were performed. Signature genes and ferroptosis phenotypes were verified through in vivo animal experiments and clinical samples. The expression levels of non-coding RNAs in samples from patients with OA were determined using qRT-PCR. ceRNA network analysis results were confirmed using dual-luciferase assays.

Results

JUN, ATF3, and CDKN1A were identified as OA- and ferroptosis-associated signature genes. GSEA analysis demonstrated an enrichment of these genes in immune and inflammatory responses, and amino acid metabolism. The CIBERSORT algorithm showed a negative correlation between T cells and these signature genes in the cartilage, and a positive correlation in the synovium. Moreover, RP5-894D12.5 and FAM95B1 regulated the expression of JUN, ATF3, and CDKN1A by competitively binding to miR-1972, miR-665, and miR-181a-2-3p. In vivo, GPX4 was downregulated in both OA cartilage and synovium; however, GPX4 and GSH were downregulated, while ferrous ions were upregulated in patient OA cartilage and synovium samples, indicating that ferroptosis was involved in the pathogenesis of OA. Furthermore, JUN, ATF3, and CDKN1A expression was downregulated in both mouse and human OA synovial and cartilage tissues. qRT-PCR demonstrated that miR-1972, RP5-894D12.5, and FAM95B1 were differentially expressed in OA tissues. Targeted interactions between miR-1972 and JUN, and a ceRNA regulatory mechanism between RP5-894D12.5, miR-1972, and JUN were confirmed by dual-luciferase assays.

Conclusion

This study identified JUN, ATF3, and CDKN1A as possible diagnostic biomarkers and therapeutic targets for joint synovitis and OA. Furthermore, our finding indicated that RP5-894D12.5/miR-1972/JUN was a potential ceRNA regulatory axis in OA, providing an insight into the connection between ferroptosis and OA.

Single‑cell sequencing, genetics, and epigenetics reveal mesenchymal stem cell senescence in osteoarthritis (Review)

Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage degeneration, secondary bone hyperplasia, inadequate extracellular matrix synthesis and degeneration of articular cartilage. Mesenchymal stem cells (MSCs) can self‑renew and undergo multidirectional differentiation; they can differentiate into chondrocytes. Aging MSCs have a weakened ability to differentiate, and release various pro‑inflammatory cytokines, which may contribute to OA progression; the other mechanism contributing to OA is epigenetic regulation (for instance, DNA methylation, histone modification and regulation of non‑coding RNA). Owing to the self‑renewal and differentiation ability of MSCs, various MSC‑based exogenous cell therapies have been developed to treat OA. The efficacy of MSC‑based therapy is mainly attributed to cytokines, growth factors and the paracrine effect of exosomes. Recently, extensive studies have been conducted on MSC‑derived exosomes. Exosomes from MSCs can deliver a variety of DNA, RNA, proteins and lipids, thereby facilitating MSC migration and cartilage repair. Therefore, MSC‑derived exosomes are considered a promising therapy for OA. The present review summarized the association between MSC aging and OA in terms of genetics and epigenetics, and characteristics of MSC‑derived exosomes, and the mechanism to alleviate OA cartilage damage.

MicroRNA expression in osteoarthritis: a meta-analysis

Osteoarthritis (OA) is one of the most prevalent musculoskeletal diseases globally, leading to chronic disability and poor prognosis. One of the approaches for optimizing OA treatment is to find early effective diagnostic biomarkers. The contribution of microRNAs (miRNAs) in OA progression is now being increasingly recognized. This review provides a comprehensive summary on studies reporting the expression profiling of miRNAs in OA and associated signaling pathways. We performed a systematic search of the Embase, Web of Science, PubMed, and Cochrane library databases. This systematic review is reported according to the PRISMA checklist. Studies which identified miRNAs with aberrant expression compared to controls during OA progression were included, and a meta-analysis was performed. Results from the random effects model were provided as log10 odds ratios (logORs) and 95% confidence intervals. Sensitivity analysis was conducted to confirm the accuracy of the results. Subgroup analysis was conducted based on tissue source. The target genes of miRNAs identified in this study were extracted from the MiRWalk database, and these target genes were enriched in Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. A total of 191 studies reporting 162 miRNAs were included in our meta-analysis. Among them, 36 miRNAs distributed across 96 studies were expressed in the same direction in at least two studies (13 up-regulated and 23 down-regulated). Subgroup analysis of tissue source revealed that the highest number of studies was conducted using articular cartilage, where the most up-regulated miRNAs were miR-146a-5p (logOR 7.355; P < 0.001) and miR-34a-5p (logOR 6.955; P < 0.001), and the most down-regulated miRNAs were miR-127-5p (logOR 6.586; P < 0.001) and miR-140-5p (logOR 6.373; P < 0.001). Enrichment analysis of 752 downstream target genes of all identified miRNAs was performed, and the regulatory relationships among them were displayed. Mesenchymal stem cells and transforming growth factor-β were found to be the most important downstream effectors regulated by miRNA in OA. This study highlighted the importance of miRNA signaling in OA progression and identified a number of prominent miRNAs including miR-146a-5p, miR-34a-5p, miR-127-5p, and miR-140-5p which might be considered as potential biomarkers for OA.

Electroacupuncture stimulating Neixiyan (EX-LE5) and Dubi (ST35) alleviates osteoarthritis in rats induced by anterior cruciate ligament transaction affecting DNA methylation regulated transcription of miR-146a and miR-140-5p

OBJECTIVE

To explore whether electroacupuncture (EA) could alleviate osteoarthritis (OA) through affecting the DNA methylation regulated transcription of miR-146a and miR-140-5p.

METHODS

Sixty male eight-week-old Sprague-Dawley rats were divided into three groups: normal group (normal healthy rats; no treatment), model group (OA rats; no treatment) and EA group (OA rats treated with EA). Safranin O staining and modified Mankin's score were performed to evaluate the histopathological alterations and degeneration of cartilage 8 weeks after 8 consecutive weeks of treatment. Quantitative real time polymerase chain reaction (qRT-PCR) assay was employed to evaluate the expression of miR-146a in the cartilage tissue and miR-140-5p in the synovium tissue, respectively. The bisulfite sequencing analysis and quantitative methylation specific PCR (qMSP) were used to analyze the status of methylation in the regulatory regions of miR-146a and miR-140-5p. Chromatin immunoprecipitation (ChIP) assay were performed to assess the binding of nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (SMAD-3) in the regulatory regions of miR-146a and miR-140-5p. Western blot analysis was performed to detect the expressions of DNA Methyltransferase 1 (DMNT1), DNA Methyltransferase 3A (DMNT3A), and DNA Methyltransferase 3A (DMNT3b), NF-κB, SMAD3 levels.

RESULTS

Our results showed that EA treatment significantly upregulated miR-146a and miR-140-5p expressions. qMSP analysis showed that EA significantly decreased methylation levels of miR-140-5p regulated region and miR-146a promoter in OA cartilage and synovium. Bisulfite DNA sequencing (BDS) and ChIP analysis showed that EA significantly increased binding affinity of SMAD3 and NF-kB on the hypermethylated miR-140 regulatory region and miR-146a promoter, respectively. Western Blot analysis demonstrated that EA also significantly decreased expressions of methylation related proteins- DMNT1, DMNT3a, and DMNT3b as well as NF-κB and SMAD3.

CONCLUSIONS

Electroacupuncture stimulating Neixiyan (EX-LE5) and Dubi (ST35) may alleviate OA affecting the DNA methylation regulated transcription of miR-146a and miR-140-5p.

Enhancement of the therapeutic efficacy of mesenchymal stem cell-derived exosomes in osteoarthritis

Osteoarthritis (OA), a common joint disorder with articular cartilage degradation as the main pathological change, is the major source of pain and disability worldwide. Despite current treatments, the overall treatment outcome is unsatisfactory. Thus, patients with severe OA often require joint replacement surgery. In recent years, mesenchymal stem cells (MSCs) have emerged as a promising therapeutic option for preclinical and clinical palliation of OA. MSC-derived exosomes (MSC-Exos) carrying bioactive molecules of the parental cells, including non-coding RNAs (ncRNAs) and proteins, have demonstrated a significant impact on the modulation of various physiological behaviors of cells in the joint cavity, making them promising candidates for cell-free therapy for OA. This review provides a comprehensive overview of the biosynthesis and composition of MSC-Exos and their mechanisms of action in OA. We also discussed the potential of MSC-Exos as a therapeutic tool for modulating intercellular communication in OA. Additionally, we explored bioengineering approaches to enhance MSC-Exos' therapeutic potential, which may help to overcome challenges and achieve clinically meaningful OA therapies.

Exploring the Feasibility of Circulating miRNAs as Diagnostic and Prognostic Biomarkers in Osteoarthritis: Challenges and Opportunities

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by progressive cartilage degradation and joint inflammation. As the most common aging-related joint disease, OA is marked by inadequate extracellular matrix synthesis and the breakdown of articular cartilage. However, traditional diagnostic methods for OA, relying on clinical assessments and radiographic imaging, often need to catch up in detecting early-stage disease or i accurately predicting its progression. Consequently, there is a growing interest in identifying reliable biomarkers that can facilitate early diagnosis and prognosis of OA. MicroRNAs (miRNAs) have emerged as potential candidates due to their involvement in various cellular processes, including cartilage homeostasis and inflammation. This review explores the feasibility of circulating miRNAs as diagnostic and prognostic biomarkers in OA, focusing on knee OA while shedding light on the challenges and opportunities associated with their implementation in clinical practice.

YY1/miR-140-5p/Jagged1/Notch axis mediates cartilage progenitor/stem cells fate reprogramming in knee osteoarthritis

Osteoarthritis is a multifactorial disease characterized by cartilage degeneration, while cartilage progenitor/stem cells (CPCs) are responsible for endogenous cartilage repair. However, the relevant regulatory mechanisms of CPCs fate reprogramming in OA are rarely reported. Recently, we observed fate disorders in OA CPCs and found that microRNA-140-5p (miR-140-5p) protects CPCs from fate changes in OA. This study further mechanistically investigated the upstream regulator and downstream effectors of miR-140-5p in OA CPCs fate reprogramming. As a result, luciferase reporter assay and validation assays revealed that miR-140-5p targets Jagged1 and inhibits Notch signaling in human CPCs, and the loss-/gain-of-function experiments and rescue assays discovered that miR-140-5p improves OA CPCs fate, but this effect can be counteracted by Jagged1. Moreover, increased transcription factor Ying Yang 1 (YY1) was associated with OA progression, and YY1 could disturb CPCs fate via transcriptionally repressing miR-140-5p and enhancing the Jagged1/Notch signaling. Finally, the relevant changes and mechanisms of YY1, miR-140-5p, and Jagged1/Notch signaling in OA CPCs fate reprogramming were validated in rats. Conclusively, this study identified a novel YY1/miR-140-5p/Jagged1/Notch signaling axis that mediates OA CPCs fate reprogramming, wherein YY1 and Jagged1/Notch signaling exhibits an OA-stimulative role, and miR-140-5p plays an OA-protective effect, providing attractive targets for OA therapeutics.

Comparing Effectiveness of Hyaluronic Acid-Chitosan Nanoparticles Encapsulation Versus Hyaluronic Acid Monotherapy in Osteoarthritis Rat Model: Microarray Screening for miR-140

Osteoarthritis is a debilitating, progressive joint disease linked to lower quality of life and higher health care costs. This study compared hyaluronic acid-chitosan nanoparticle encapsulation to hyaluronic-acid monotherapy in a rat model of knee osteoarthritis. Four groups of 40 adult male albino rats were designed. Group (Gp) I: control; Gp II (osteoarthritis model): intra-articular injection of monoiodoacetate; Gp III (hyaluronic acid-treated): intra-articular injections of hyaluronic-acid on days 14 and 21 after monoiodoacetate injection; and Gp IV (hyaluronic acid-chitosan nanoparticle-treated): intra-articular injections of hyaluronic acid-chitosan nanoparticle on days 14 and 21 after monoiodoacetate injection. After 28 days, knee joints were examined using H&E, Safranin O, and immunohistochemistry for nuclear factor kappa beta (NF-κB), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase (MMP)-13. Quantification for gene expression of collagen-II, aggrecan, and micro-RNA-140; ELISA for interleukin (IL)-1β and IL-8; and western blotting for IKBα and NF-κB was estimated. Osteoarthritis-knee joints showed a severe cartilage damage and synovial inflammation with increased NF-κB, iNOS, and MMP-13 immunostaining, decreased miR-140, collagen II, and aggrecan levels, and increased inflammatory markers' gene expressions. The hyaluronic acid-chitosan nanoparticle significantly improved knee joint structure and reduced inflammatory cytokines compared to hyaluronic acid monotherapy. Intra-articular injection of hyaluronic acid-chitosan nanoparticle encapsulation revealed a significant improvement in the knee joint structure compared to hyaluronic-acid in a rat model of osteoarthritis.

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

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

Monocyte subpopulations display disease-specific miRNA signatures depending on the subform of Spondyloarthropathy

Spondyloarthropathies (SpA) are a family of rheumatic disorders that could be divided into axial (axSpA) and peripheral (perSpA) sub-forms depending on the disease clinical presentation. The chronic inflammation is believed to be driven by innate immune cells such as monocytes, rather than self-reactive cells of adaptive immune system. The aim of the study was to investigate the micro-RNA (miRNA) profiles in monocyte subpopulations (classical, intermediate and non-classical subpopulations) acquired from SpA patients or healthy individuals in search for prospective disease specific and/or disease subtype differentiating miRNA markers. Several SpA-specific and axSpA/perSpA differentiating miRNAs have been identified that appear to be characteristic for specific monocyte subpopulation. For classical monocytes, upregulation of miR-567 and miR-943 was found to be SpA-specific, whereas downregulation of miR-1262 could serve as axSpA-differentiating, and the expression pattern of miR-23a, miR-34c, mi-591 and miR-630 as perSpA-differentiating markers. For intermediate monocytes, expression levels of miR-103, miR-125b, miR-140, miR-374, miR-376c and miR-1249 could be used to distinguish SpA patients from healthy donors, whereas the expression pattern of miR-155 was identified as characteristic for perSpA. For non-classical monocytes, differential expression of miR-195 was recognized as general SpA indicator, while upregulation of miR-454 and miR-487b could serve as axSpA-differentiating, and miR-1291 as perSpA-differentiating markers. Our data indicate for the first time that in different SpA subtypes, monocyte subpopulations bear disease-specific miRNA signatures that could be relevant for SpA diagnosis/differentiation process and may help to understand SpA etiopathology in the context of already known functions of monocyte subpopulations.

miR-140-5p protects cartilage progenitor/stem cells from fate changes in knee osteoarthritis

Cartilage progenitor/stem cells (CPCs) are promising seed cells for cartilage regeneration, but their fate changes and regulatory mechanisms in osteoarthritis (OA) pathogenesis remain unclear. This study aimed to investigate the role and potential mechanism of the microRNA-140-5p (miR-140-5p), whose protective role in knee OA has been confirmed by our previous studies, in OA CPCs fate reprogramming. Firstly, the normal and OA CPCs were isolated, and the fate indicators, miR-140-5p, Jagged1, and Notch signals were detected and analyzed. Then, the effect of miR-140-5p and the Notch pathway on CPCs fate reprogramming and miR-140-5p on Jagged1/Notch signaling was investigated in IL-1β-induced chondrocytes in vitro. Finally, the effect of miR-140-5p on OA CPCs fate reprogramming and the potential mechanisms were validated in OA rats. As a result, CPCs percentage was increased in the mild OA cartilage-derived total chondrocytes while decreased in the advanced OA group. Significant fate changes (including reduced cell viability, migration, chondrogenesis, and increased apoptosis), increased Jagged1 and Notch signals, and reduced miR-140-5p were observed in OA CPCs and associated with OA progression. IL-1β induced OA-like changes in CPCs fate, which could be exacerbated by miR-140-5p inhibitor while alleviated by DAPT (a specific Notch inhibitor) and miR-140-5p mimic. Finally, the in vitro phenomenal and mechanistic findings were validated in OA rats. Overall, miR-140-5p protects CPCs from fate changes via inhibiting Jagged1/Notch signaling in knee OA, providing attractive targets for OA therapeutics.

Combinatorial Effect of Mesenchymal Stem Cells and Extracellular Vesicles in a Hydrogel on Cartilage Regeneration

BACKGROUND

Mesenchymal stem cells (MSCs) are used for tissue regeneration due to their wide differentiation capacity and anti-inflammatory effects. Extracellular vesicles (EVs) derived from MSCs are also known for their regenerative effects as they contain nucleic acids, proteins, lipids, and cytokines similar to those of parental cells. There are several studies on the use of MSCs or EVs for tissue regeneration. However, the combinatorial effect of human MSCs (hMSCs) and EVs is not clear. In this study, we investigated the combinatorial effect of hMSCs and EVs on cartilage regeneration via co-encapsulation in a hyaluronic-acid (HA)-based hydrogel.

METHODS

A methacrylic-acid-based HA hydrogel was prepared to encapsulate hMSCs and EVs in hydrogels. Through in vitro and in vivo analyses, we investigated the chondrogenic potential of the HA hydrogel-encapsulated with hMSCs and EVs.

RESULTS

Co-encapsulation of hMSCs with EVs in the HA hydrogel increased the chondrogenic differentiation of hMSCs and regeneration of damaged cartilage tissue compared with that of the HA hydrogel loaded with hMSCs only.

CONCLUSION

Co-encapsulation of hMSCs and EVs in the HA hydrogel effectively enhances cartilage tissue regeneration due to the combinatorial therapeutic effect of hMSCs and EVs. Thus, in addition to cartilage tissue regeneration for the treatment of osteoarthritis, this approach would be a useful strategy to improve other types of tissue regeneration.

Osteoarthritis and microRNAs: Do They Provide Novel Insights into the Pathophysiology of This Degenerative Disorder?

Osteoarthritis (OA) is one of the most prevalent degenerative joint diseases in older adults and a leading cause of disability. Recent research studies have evidenced the importance of mi-croRNAs (miRs) in the pathogenesis of OA. In the present review, we focused on current literature findings on dysregulated miRs involved in the pathophysiology of OA. From the 35 case-control studies including OA patients compared to healthy controls, a total of 54 human miRs were identified to be dysregulated in OA. In total, 41 miRs were involved in the pathophysiological processes of OA, including apoptosis, inflammation, and proliferation, having either a protective or a progressive role in OA. The discovery of altered miR levels in OA patients compared to healthy controls determines a better understanding of the molecular mechanisms involved in the pathophysiology of OA and could open novel horizons in the field of orthopedics.

miR-140-5p and miR-140-3p: Key Actors in Aging-Related Diseases?

microRNAs (miRNAs) are small single strand non-coding RNAs and powerful gene expression regulators. They mainly bind to the 3′UTR sequence of targeted mRNA, leading to their degradation or translation inhibition. miR-140 gene encodes the pre-miR-140 that generates the two mature miRNAs miR-140-5p and miR-140-3p. miR-140-5p/-3p have been associated with the development and progression of cancers, but also non-neoplastic diseases. In aging-related diseases, miR-140-5p and miR-140-3p expressions are modulated. The seric levels of these two miRNAs are used as circulating biomarkers and may represent predictive tools. They are also considered key actors in the pathophysiology of aging-related diseases. miR-140-5p/-3p repress targets regulating cell proliferation, apoptosis, senescence, and inflammation. This work focuses on the roles of miR-140-3p and miR-140-5p in aging-related diseases, details their regulation (i.e., by long non-coding RNA), and reviews the molecular targets of theses miRNAs involved in aging pathophysiology.

Epigenetic Regulation in Knee Osteoarthritis

Osteoarthritis (OA) is a complicated disease with both hereditary and environmental causes. Despite an increase in reports of possible OA risk loci, it has become clear that genetics is not the sole cause of osteoarthritis. Epigenetics, which can be triggered by environmental influences and result in transcriptional alterations, may have a role in OA pathogenesis. The majority of recent research on the epigenetics of OA has been focused on DNA methylation, histone modification, and non-coding RNAs. However, this study will explore epigenetic regulation in OA at the present stage. How genetics, environmental variables, and epigenetics interact will be researched, shedding light for future studies. Their possible interaction and control processes open up new avenues for the development of innovative osteoarthritis treatment and diagnostic techniques.

miRNA Expression Profile of Magnetic Field Combined with Nano-Scaffolds Enhance Chondrogenesis

The differentiation of mesenchymal stem cells (MSC) into cartilage is a critical step in the cartilage damage repair. Pulsed electromagnetic fields may provide a solution to promote the differentiation and proliferation of MSC, with a promisingly strong synergistic effect apparent when MSC subjected to magnetic nanoparticles and pulsed electromagnetic fields simultaneously. Previously, we developed a magnetic nanoparticles hydrogel (MagGel) that, when combined with magnetic fields, substantially enhanced cartilage tissue repair; however, we still know little about the mechanisms underlying its effectiveness. Here, we examined the role of magnetic fields and nano-scaffolds in promoting differentiation of MSCs into chondrocytes. Our results suggest that the mechanism causing MSC differentiation under these conditions resulted from the activation of multiple miRNAs and signaling pathways. These results can be built upon by future molecular studies to identify which miRNAs are involved in to chondrogenesis. By identifying these miRNAs and their targeted pathways, we can better manipulate the expression of the specific miRNAs that promote MSC differentiation and cartilage repair. Our study provides a starting point for the study of magnetic field-induced differentiation of the magnetic nanoparticles within stem cells.

MicroRNA-378 contributes to osteoarthritis by regulating chondrocyte autophagy and bone marrow mesenchymal stem cell chondrogenesis

Osteoarthritis (OA) is the most common joint disease; thus, understanding the pathological mechanisms of OA initiation and progression is critical for OA treatment. MicroRNAs (miRNAs) have been shown to be involved in the progression of osteoarthritis, one candidate is microRNA-378 (miR-378), which is highly expressed in the synovium of OA patients during late-stage disease, but its function and the underlying mechanisms of how it contributes to disease progression remain poorly understood. In this study, miR-378 transgenic (TG) mice were used to study the role of miR-378 in OA development. miR-378 TG mice developed spontaneous OA and also exaggerated surgery-induced disease progression. Upon in vitro OA induction, miR-378 expression was upregulated and correlated with elevated inflammation and chondrocyte hypertrophy. Chondrocytes isolated from articular cartilage from miR-378 TG mice showed impaired chondrogenic differentiation. The bone marrow mesenchymal stem cells (BMSCs) collected from miR-378 TG mice also showed repressed chondrogenesis compared with the control group. The autophagy-related protein Atg2a, as well as chondrogenesis regulator Sox6, were identified as downstream targets of miR-378. Ectopic expression of Atg2a and Sox6 rescued miR-378-repressed chondrocyte autophagy and BMSC chondrogenesis, respectively. Anti-miR-378 lentivirus intra-articular injection in an established OA mouse model was shown to ameliorate OA progression, promote articular regeneration, and repress hypertrophy. Atg2a and Sox6 were again confirmed to be the target of miR-378 in vivo. In conclusion, miR-378 amplified OA development via repressing chondrocyte autophagy and by inhibiting BMSCs chondrogenesis, thus indicating miR-378 may be a potential therapeutic target for OA treatments.

Material-Assisted Strategies for Osteochondral Defect Repair

The osteochondral (OC) unit plays a pivotal role in joint lubrication and in the transmission of constraints to bones during movement. The OC unit does not spontaneously heal; therefore, OC defects are considered to be one of the major risk factors for developing long-term degenerative joint diseases such as osteoarthritis. Yet, there is currently no curative treatment for OC defects, and OC regeneration remains an unmet medical challenge. In this context, a plethora of tissue engineering strategies have been envisioned over the last two decades, such as combining cells, biological molecules, and/or biomaterials, yet with little evidence of successful clinical transfer to date. This striking observation must be put into perspective with the difficulty in comparing studies to identify overall key elements for success. This systematic review aims to provide a deeper insight into the field of material-assisted strategies for OC regeneration, with particular considerations for the therapeutic potential of the different approaches (with or without cells or biological molecules), and current OC regeneration evaluation methods. After a brief description of the biological complexity of the OC unit, the recent literature is thoroughly analyzed, and the major pitfalls, emerging key elements, and new paths to success are identified and discussed.

Integrated regulation of chondrogenic differentiation in mesenchymal stem cells and differentiation of cancer cells

Chondrogenesis is the formation of chondrocytes and cartilage tissues and starts with mesenchymal stem cell (MSC) recruitment and migration, condensation of progenitors, chondrocyte differentiation, and maturation. The chondrogenic differentiation of MSCs depends on co-regulation of many exogenous and endogenous factors including specific microenvironmental signals, non-coding RNAs, physical factors existed in culture condition, etc. Cancer stem cells (CSCs) exhibit self-renewal capacity, pluripotency and cellular plasticity, which have the potential to differentiate into post-mitotic and benign cells. Accumulating evidence has shown that CSCs can be induced to differentiate into various benign cells including adipocytes, fibrocytes, osteoblast, and so on. Retinoic acid has been widely used in the treatment of acute promyelocytic leukemia. Previous study confirmed that polyploid giant cancer cells, a type of cancer stem-like cells, could differentiate into adipocytes, osteocytes, and chondrocytes. In this review, we will summarize signaling pathways and cytokines in chondrogenic differentiation of MSCs. Understanding the molecular mechanism of chondrogenic differentiation of CSCs and cancer cells may provide new strategies for cancer treatment.

Engineering Closed-Loop, Autoregulatory Gene Circuits for Osteoarthritis Cell-Based Therapies

PURPOSE OF REVIEW

Genetic engineering offers the possibility to simultaneously target multiple cellular pathways in the joints affected by osteoarthritis (OA). The purpose of this review is to summarize the ongoing efforts to develop disease-modifying osteoarthritis drugs (DMOADs) using genetic engineering, including targeting approaches, genome editing techniques, and delivery methods.

RECENT FINDINGS

Several gene circuits have been developed that reprogram cells to autonomously target inflammation, and their efficacy has been demonstrated in chondrocytes and stem cells. Gene circuits developed for metabolic disorders, such as those targeting insulin resistance and obesity, also have the potential to mitigate the impact of these conditions on OA onset and/or progression. Despite the strides made in characterizing the inflammatory environment of the OA joint, our incomplete understanding of how the multiple regulators interact to control signal transduction, gene transcription, and translation to protein limits the development of targeted disease-modifying therapeutics. Continuous advances in targeted genome editing, combined with online toolkits that simplify the design and production of gene circuits, have the potential to accelerate the discovery and clinical application of multi-target gene circuits with disease-modifying properties for the treatment of OA.

Exosomes Derived From Human Urine-Derived Stem Cells Overexpressing miR-140-5p Alleviate Knee Osteoarthritis Through Downregulation of VEGFA in a Rat Model

BACKGROUND

Knee osteoarthritis (KOA) is one of the most common chronic musculoskeletal disorders worldwide, for which exosomes derived from stem cells may provide an effective treatment.

PURPOSE

To assess the effect of exosomes derived from human urine-derived stem cells (hUSCs) overexpressing miR-140-5p (miR means microRNA) on KOA in an in vitro interleukin 1β (IL-1β)-induced osteoarthritis (OA) model and an in vivo rat KOA model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Exosomes derived from hUSCs (hUSC-Exos) were isolated and validated. The hUSCs were transfected with miR-140s using lentivirus, and exosomes secreted from such cells (hUSC-140-Exos) were collected. The roles of hUSC-Exos and hUSC-140-Exos in protecting chondrocytes against IL-1β treatment were compared by analyzing the proliferation, migration, apoptosis, and secretion of extracellular matrix (ECM) in chondrocytes. After vascular endothelial growth factor A (VEGFA) was identified as a target of miR-140, the mechanism by which VEGFA can mediate the beneficial effect of miR-140 on OA was investigated using small interfering RNA transfection or chemical drugs. The expression of VEGFA in cartilage and synovial fluid from patients with KOA was measured and compared with that of healthy controls. Surgery for anterior cruciate ligament transection and destabilization of the medial meniscus were performed on the knee joints of Sprague-Dawley rats to establish an animal model of OA, and intra-articular (IA) injection of hUSC-Exos or hUSC-140-Exos was conducted at 4 to 8 weeks after the surgery. Cartilage regeneration and subchondral bone remodeling were evaluated through histological staining and micro-computed tomography analysis.

RESULTS

Proliferation and migration ability were enhanced and apoptosis was inhibited in chondrocytes treated with IL-1β via hUSC-Exos, with the side effect of decreased ECM secretion. hUSC-140-Exos not only retained the advantages of hUSC-Exos but also increased the secretion of ECM by targeting VEGFA, including collagen II and aggrecan. Increased expression of VEGFA during the progression of KOA was also confirmed in cartilage and synovial fluid samples obtained from patients with OA. In the rat OA model, IA injection of hUSC-140-Exos enhanced cartilage regeneration and subchondral bone remodeling.

CONCLUSION

Our results demonstrated the superiority of hUSC-Exos overexpressing miR-140-5p for treating OA compared with the hUSC-Exos. The effect of hUSC-140-Exos for suppressing the progression of KOA is in part mediated by VEGFA.

CLINICAL RELEVANCE

Exosomes derived from stem cells may provide a promising treatment for KOA, and our study can advance the related basic research.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: Immunomodulatory Effects and Potential Applications in Intervertebral Disc Degeneration

Intervertebral disc (IVD) degenerative disease is a common health problem worldwide. Administration of mesenchymal stem cells (MSCs) in intervertebral disc degeneration (IVDD) has been widely explored in recent years. However, transplantation of MSCs is restricted by several factors. Currently, paracrine signaling is one of the main mechanisms by which MSCs play a therapeutic role in disc regeneration. Extracellular vehicles (EVs) are the main paracrine products of MSCs. They show great potential as an effective alternative to MSCs and play immunomodulation roles such as anti-inflammatory effects, antioxidative stress, antiapoptosis, and antiextracellular matrix (ECM) degradation during treatment of IVDD. This review focuses on the immunomodulatory effect of MSC EVs and their potential applications.

Upregulation of miR-140-5p uncouples mitochondria by targeting Bcl-xL in vascular smooth muscle cells in angiotensin II-induced hypertension

Angiotensin II-induced vascular smooth muscle cell (VSMC) remodeling and dysfunction is a major contributor to the development of hypertension. In spite of the low content of mitochondria and their low contribution to bioenergetics in VSMCs, recent studies have suggested that mitochondria play an important role in the regulation of VSMC function. However, the role of mitochondria in angiotensin II-induced VSMC dysfunction remains unknown. Here, we found that angiotensin II decreased the expression of Bcl-2-like protein 1 (Bcl-xL), a newly identified protein in inhibition of uncoupled proton flux in mitochondria through interaction with the β-subunit of ATP synthase, and uncoupled mitochondria in VSMCs both in vivo and in vitro. Overexpression of Bcl-xL restored the mitochondrial and VSMC function in response to angiotensin II treatment in vitro, suggesting that angiotensin II uncouples mitochondria through downregulation of Bcl-xL. Mechanistically, angiotensin II increased the expression of miR-140-5p, which targeted and downregulated Bcl-xL in VSMCs. Inhibition of miR-140-5p using antagomir-140-5p in vivo attenuated mitochondrial uncoupling and hypertension in angiotensin II-treated mice. These results suggested that upregulation of miR-140-5p uncouples mitochondria by targeting Bcl-xL in VSMCs in angiotensin II-induced hypertension, and miR-140-5p and Bcl-xL are potential targets for treatment of vascular dysfunction.

Long non-coding RNA OIP5-AS1 (Cyrano): A context-specific regulator of normal and disease processes

Long non-coding (lnc) RNAs have been implicated in a plethora of normal biological functions, and have also emerged as key molecules in various disease processes. OIP5-AS1, also commonly known by the alias Cyrano, is a lncRNA that displays broad expression across multiple tissues, with significant enrichment in particular contexts including within the nervous system and skeletal muscle. Thus far, this multifaceted lncRNA has been found to have regulatory functions in normal cellular processes including cell proliferation and survival, as well as in the development and progression of a myriad disease states. These widespread effects on normal and disease states have been found to be mediated through context-specific intermolecular interactions with dozens of miRNAs and proteins identified to date. This review explores recent studies to highlight OIP5-AS1's contextual yet pleiotropic roles in normal homeostatic functions as well as disease oetiology and progression, which may influence its utility in the generation of future theranostics.

Mouse microRNA signatures in joint ageing and post-traumatic osteoarthritis

OBJECTIVE

This study investigated mice serum and joint microRNA expression profiles in ageing and osteoarthritis to elucidate the role of microRNAs in the development and progression of disease, and provide biomarkers for ageing and osteoarthritis.

DESIGN

Whole joints and serum samples were collected from C57BL6/J male mice and subjected to small RNA sequencing. Groups used included; surgically-induced post-traumatic osteoarthritis, (DMM; 24 months-old); sham surgery (24 months-old); old mice (18 months-old); and young mice (8 months-old). Differentially expressed microRNAs between the four groups were identified and validated using real-time quantitative PCR. MicroRNA differential expression data was used for target prediction and pathway analysis.

RESULTS

In joint tissues, miR-140-5p, miR-205-5p, miR-682, miR-208b-3p, miR-499-5p, miR-455-3p and miR-6238 were differentially expressed between young and old groups; miR-146a-5p, miR-3474, miR-615-3p and miR-151-5p were differentially expressed between DMM and Sham groups; and miR-652-3p, miR-23b-3p, miR-708-5p, miR-5099, miR-23a-3p, miR-214-3p, miR-6238 and miR-148-3p between the old and DMM groups. The number of differentially expressed microRNAs in serum was higher, some in common with joint tissues including miR-140-5p and miR-455-3p between young and old groups; and miR-23b-3p, miR-5099 and miR-6238 between old and DMM groups.We confirmed miR-140-5p, miR-499-5p and miR-455-3p expression to be decreased in old mouse joints compared to young, suggesting their potential use as biomarkers of joint ageing in mice.

CONCLUSIONS

MiR-140-5p, miR-499-5p and miR-455-3p could be used as joint ageing biomarkers in mice. Further research into these specific molecules in human tissues is now warranted to check their potential suitability as human biomarkers of ageing.

Controlled Differentiation of Mesenchymal Stem Cells into Hyaline Cartilage in miR-140-Activated Collagen Hydrogel

OBJECTIVE

Hypertrophic cartilage formation is a major setback in mesenchymal stem cells (MSCs)-mediated cartilage repair, and overcoming it requires optimization of differentiation. Here, we tested the miR-140 activated collagen hydrogel for the chondrogenic differentiation of MSCs and to produce hyaline cartilage.

METHODS

Bone marrow MSCs isolated from 3 patients were pretreated with miR-140 and then chondrogenic differentiated. The 3-dimensional (3D) transfection potential of 5 different transfection reagents (Polyethylenimine, Lipofectamine, TransIT-X2, Amide:Cholesterol-based liposomes [AmC] and AmC pegylated with Tocofersolan [AmCTOC]) was compared and the reagent that showed higher green fluorescent protein (GFP) expression was selected. Finally, the collagen hydrogel was activated using miR-140-transfection complex and sustained delivered to MSCs during chondrogenic differentiation. After differentiation, the outcome was assessed by reverse transcription-polymerase chain reaction (RT-PCR), histology, immunohistochemistry, and compared with scrambled miRNA treated control.

RESULTS

Pretreatment of MSCs with miR-140 significantly increased the expression of cartilage-specific genes (COL2A1, SOX9, and ACAN) with reduced hypertrophic chondrocyte (COL10A1) marker expression and better safranin-O staining than the control. The AmCTOC liposome showed a significant increase in 3D transfection of GFP expressing plasmid than the others. Furthermore, the knockdown of GAPDH using siRNA in HEK cells and expression of GFP mRNA in human bone marrow MSCs confirmed the 3D-transfection efficiency of AmCTOC. The sustained delivery of miR-140 using activated matrix formed a hyaline cartilage-like tissue with minimal COL10A1 expression in RT-PCR and immunohistochemistry.

CONCLUSION

Our results demonstrated the therapeutic potential of miR-140-activated hydrogel for MSCs-based cartilage tissue engineering, which could also be used for endogenous stem cells-mediated cartilage repair.

Osteogenic and Chondrogenic Potential of Periosteum-Derived Mesenchymal Stromal Cells: Do They Hold the Key to the Future?

The periosteum, with its outer fibrous and inner cambium layer, lies in a dynamic environment with a niche of pluripotent stem cells for their reparative needs. The inner cambium layer is rich in mesenchymal progenitors, osteogenic progenitors, osteoblasts, and fibroblasts in a scant collagen matrix environment. Their role in union and remodeling of fracture is well known. However, the periosteum as a source of mesenchymal stem cells has not been explored in detail. Moreover, with the continuous expansion of techniques, newer insights have been acquired into the roles and regulation of these periosteal cells. From a therapeutic standpoint, the periosteum as a source of tissue engineering has gained much attraction. Apart from its role in bone repair, analysis of the bone-forming potential of periosteum-derived stem cells is lacking. Hence, this article elucidates the role of the periosteum as a potential source of mesenchymal stem cells along with their capacity for osteogenic and chondrogenic differentiation for therapeutic application in the future.

The non-coding RNA interactome in joint health and disease

Non-coding RNAs have distinct regulatory roles in the pathogenesis of joint diseases including osteoarthritis (OA) and rheumatoid arthritis (RA). As the amount of high-throughput profiling studies and mechanistic investigations of microRNAs, long non-coding RNAs and circular RNAs in joint tissues and biofluids has increased, data have emerged that suggest complex interactions among non-coding RNAs that are often overlooked as critical regulators of gene expression. Identifying these non-coding RNAs and their interactions is useful for understanding both joint health and disease. Non-coding RNAs regulate signalling pathways and biological processes that are important for normal joint development but, when dysregulated, can contribute to disease. The specific expression profiles of non-coding RNAs in various disease states support their roles as promising candidate biomarkers, mediators of pathogenic mechanisms and potential therapeutic targets. This Review synthesizes literature published in the past 2 years on the role of non-coding RNAs in OA and RA with a focus on inflammation, cell death, cell proliferation and extracellular matrix dysregulation. Research to date makes it apparent that 'non-coding' does not mean 'non-essential' and that non-coding RNAs are important parts of a complex interactome that underlies OA and RA.

Mesenchymal Stem Cell-Derived Exosomes and MicroRNAs in Cartilage Regeneration: Biogenesis, Efficacy, miRNA Enrichment and Delivery

Exosomes are the small extracellular vesicles secreted by cells for intercellular communication. Exosomes are rich in therapeutic cargos such as microRNA (miRNA), long non-coding RNA (lncRNA), small interfering RNA (siRNA), DNA, protein, and lipids. Recently, many studies have focused on miRNAs as a promising therapeutic factor to support cartilage regeneration. Exosomes are known to contain a substantial amount of a variety of miRNAs. miRNAs regulate the post-transcriptional gene expression by base-pairing with the target messenger RNA (mRNA), leading to gene silencing. Several exosomal miRNAs have been found to play a role in cartilage regeneration by promoting chondrocyte proliferation and matrix secretion, reducing scar tissue formation, and subsiding inflammation. The exosomal miRNA cargo can be modulated using techniques such as cell transfection and priming as well as post-secretion modifications to upregulate specific miRNAs to enhance the therapeutic effect. Exosomes are delivered to the joints through direct injection or via encapsulation within a scaffold for sustained release. To date, exosome therapy for cartilage injuries has yet to be optimized as the ideal cell source for exosomes, and the dose and method of delivery have yet to be identified. More importantly, a deeper understanding of the role of exosomal miRNAs in cartilage repair is paramount for the development of more effective exosome therapy.