MSC-EVs alleviate osteoarthritis by regulating microenvironmental cells in the articular cavity and maintaining cartilage matrix homeostasis

Unveiling the potential of MSC extracellular vesicles: MiR-122-5p enhancing chondrocyte regeneration in osteoarthritis via autophagy mechanism

Background

Osteoarthritis (OA) is one of the most prevalent degenerative joint diseases, while the mechanism by which extracellular vesicles (EVs) promote chondrocyte regeneration remains unclear. The study assessed the effect of hypoxic mesenchymal stem cells (MSCs)-derived EVs on cartilage repair in a rat OA model.

Methods

The effects of EVs on chondrocyte regeneration and autophagy were evaluated in vitro. The influence of specific micro RNA (miRNA) and downstream target genes was examined following EV miRNA sequencing and multiple intersecting database analysis.

Results

We found EVs derived from hypoxia preconditioned human MSCs to promote cartilage repair in rat OA and enhance the proliferation and migration of chondrocytes in vitro, mediated via chondrocyte autophagy. MiRNA sequencing revealed a significant enrichment of miRNA122-5p in hypoxic MSCs EV, which through regulation of the target gene, DUSP2 , mediated autophagy and participated in chondrocyte regeneration. DUSP2 regulation of chondrocyte autophagy could act via the phosphorylation of ERK1/2 and P38.

Conclusions

This study demonstrates that EVs released by MSCs under hypoxic conditions have a beneficial effect on chondrocyte regeneration. A novel mechanism for chondrocyte autophagy is mediated by miR122-5P and DUSP2 target molecules, providing new insights into OA treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-025-04412-4.

From Mechanism to Therapy: The Role of MSC-EVs in Alleviating Radiation-Induced Injuries

Radiation injury is a severe issue in both nuclear accidents and cancer radiotherapy. Ionizing radiation impairs the regenerative and repair capabilities of tissues and organs, resulting in a scarcity of effective therapeutic approaches to prevent or mitigate such injuries. Mesenchymal stem cells (MSCs) possess favorable biological characteristics and have emerged as ideal candidates for the treatment of radiation injury. However, the use of MSCs as therapeutic agents is associated with uncertainties in therapeutic efficacy, transient effects, and the risk of immune rejection. Recent advances in research have revealed that extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC-EVs) exhibit similar beneficial properties to MSCs and represent a promising cell-free therapy for mitigating radiation injuries. MSC-EVs are enriched with microRNAs (miRNAs), proteins, and lipids, which can modulate immune responses, inflammatory reactions, cell survival, and proliferation in irradiated tissues. This review synthesizes recent studies on the application of MSC-EVs in radiation injury, focusing on the therapeutic effects and mechanisms of MSC-EVs derived from various sources in radiation-induced diseases of different organs. The therapeutic potential of MSC-EVs for radiation injury provides valuable insights for addressing ionizing radiation-induced injuries and offers a reference for future clinical applications.

Heat Shock Strengthens the Protective Potential of MSCs in Liver Injury by Promoting EV Release Through Upregulated Autophagosome Formation

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) show powerful potential in the treatment of multiple diseases. However, the low yield of MSC-EVs severely restricts their clinical application. Here, heat shock (HS), a moderate external stimulus, can enhance EVs release of MSCs by upregulating autophagosome formation. Mechanistically, HS elevates TRPV2 expression to induce Ca2+ influx and then promotes the activity of two succinylases, SUCLG2 and OXCT1, followed by increasing the succinylation of YWHAZ (a 14-3-3 protein) at lysine 11 (K11). Acting as an adaptor protein, YWHAZ's succinylation at K11 inhibits its degradation, reinforcing YWHAZ-ULK1 binding, which upregulates ULK1 S555 phosphorylation to promote autophagosome formation and enhance EV release of MSCs. Additionally, the improved therapeutic efficacy of HS-treated MSCs via EV release has been shown in two liver injury models-hepatic ischemia/reperfusion injury (HIRI) and acetaminophen-induced liver injury. These findings proved that HS, an easily implementable and cost-effective method, can be used to elevate MSC-EV yield in mass production.

Development of a dual-responsive injectable GelMA/F127DA hydrogel for enhanced cartilage regeneration in osteoarthritis: Harnessing MMP-triggered and mechanical stress-induced release of therapeutic agents

Osteoarthritis (OA) presents a significant challenge in clinical settings due to the limited self-renewal capability of cartilage tissue. To address this, engineered biomaterials employing biomimetic strategies have been developed to modulate and enhance cell-microenvironment interactions, facilitating cartilage regeneration. Nonetheless, excessive mechanical stress on joint structures can induce inflammatory responses, thereby impeding the process of cartilage repair. In this study, we focus on the OA microenvironment, characterized by the overexpression of matrix metalloproteinases (MMPs), and the mechanical stimuli due to joint movement. We engineered a dual-responsive injectable hydrogel: a blend of MMP-responsive, thermo-sensitive GelMA and mechanically robust, reverse thermo-sensitive F127DA. This hydrogel was designed to deliver TGF-β and KGN in a controlled manner via simple temperature modulation. The hydrophilic properties of GelMA and the hydrophobic nature of F127DA allow for efficient intra-articular delivery of diverse drug types, optimizing their therapeutic effects. Photocrosslinking the hydrogel in situ effectively seals cartilage defects and prevents further degradation. The overexpressed MMP in the OA environment triggers the release of TGF-β, recruiting bone marrow-derived stem cells (BMSCs), while mechanical pressure from joint movements releases KGN, promoting chondrogenic differentiation and mitigating inflammation. In summary, our injectable hydrogel, responsive to both the OA microenvironment and mechanical stress, shows promise in enhancing cartilage regeneration in OA. This approach holds significant potential for advancing the field of OA cartilage tissue engineering.

Therapeutic role of hucMSC-sEV-enriched miR-13896 in cisplatin-induced acute kidney injury through M2 macrophage polarization

Human umbilical cord mesenchymal stem cell-derived small extracellular vesicles (hucMSC-sEV) have recently garnered attention as a potential therapeutic approach for kidney diseases with anti-inflammatory effects. Infiltrated macrophages play an important role in facilitating tissue regeneration. However, the intricate regulatory effects of hucMSC-sEV on macrophages during cisplatin-induced acute kidney injury (AKI) remain unknown. In this study, we uncovered that hucMSC-sEV exhibited potent anti-inflammation and effectively inhibited the polarization of M1 phenotype macrophages. Mechanically, miRNA sequencing analysis and qRT-PCR indicated that a novel miRNA, named miR-13896, was enriched in hucMSC-sEV. When transfected with miR-13896 mimic, macrophages displayed M2 phenotype with elevated levels of Arg1 and IL-10, while miR-13896 inhibitor promoted M1 phenotype. Furthermore, we firstly established that miR-13896 repressed Tradd expression by targeting its 3' untranslated region and subsequently inhibited NF-κB signaling pathway in macrophages. Additionally, to improve therapeutic effects, hucMSC-sEV were engineered with elevated levels of miR-13896 through electroporation, which resulted in promoting M2 phenotype macrophages, inhibiting inflammatory factors, and enhancing kidney repair. Conclusively, our findings provide novel insights into the mechanisms underlying the effects of hucMSC-sEV on macrophages and AKI, while also highlighting electroporation as a promising strategy for treating cisplatin-induced AKI.

Three-dimensional cell culture-derived extracellular vesicles loaded alginate/hyaluronic acid composite scaffold as an optimal therapy for cartilage defect regeneration

Osteoarthritis (OA) is a chronic musculoskeletal disease characterized by joint inflammation and progressive degeneration of articular cartilage. Currently a definitive cure for OA remains to be a challenge due to the very low self-repair capacity of cartilage, thus development of more effective therapies is needed for cartilage repair. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have shown great potential as therapeutic agents for stimulating regeneration of articular cartilage. However, a standardized protocol is still lacking for manufacturing of highly active EVs for clinical applications. This study aimed to investigate the efficient production of highly active EVs by 3-dimensional (3D) MSC culture, verify the reparative efficacy of EVs on cartilage defect and elucidate the repair mechanisms. Umbilical cord MSCs were embedded in alginate to form MSC spheroids for 3D culture in human platelet lysate (hPL)-containing medium, which produced 3D culture-derived EVs (3D-EVs) with a significantly improved yield. The 3D-EVs expressed higher level of VEGF, and appeared superior to two-dimensional (2D) monolayer MSC culture-derived EVs (2D-EVs) to improve migration and proliferation in MSCs and inflammatory chondrocytes, and to suppress expression of cartilage-degrading factors. Importantly, the 3D-EVs and sodium alginate (SA)-hyaluronic acid (HA) composite hydrogel (3D-EVs/SA-HA) demonstrated significantly improved therapeutic efficacy than 2D-EVs/SA-HA hydrogel for repair of cartilage defectin vivo. The underlying mechanisms are associated with the concomitant upregulation of type II collagen and cartilage synthesis and downregulation of MMP13 in cartilage tissues. Collectively, these data showed that highly active MSC EVs could be efficiently manufactured by 3D cell culture with hPL-containing medium, and these EVs were superior to 2D-EVs for the repair of articular cartilage defect.

Efficacy and safety of mesenchymal stromal cell transplantation in the treatment of autoimmune and rheumatic immune diseases: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study aims to assess the effectiveness and safety of mesenchymal stem cell (MSC) transplantation in the treatment of autoimmune and rheumatic immune diseases through randomized controlled trials (RCTs).

METHODS

Two researchers conducted a comprehensive search of Chinese and English databases from their inception until Dec. 2023. The literature screening and data extraction were then performed. Statistical analysis was carried out using RevMan 5.4 software.

RESULTS

A total of 42 relevant RCTs, involving 2,183 participants, were ultimately included in this study. These RCTs encompassed four types of rheumatic immune and bone diseases, namely rheumatoid arthritis (RA), osteoarthritis (OA), spondyloarthritis, systemic sclerosis arthritis, systemic lupus erythematosus (SLE), inflammatory bowel disease, multiple sclerosis, primary Sjögren's syndrome (PSS). The systematic review indicates that MSC transplantation may improve spondyloarthritis, RA, PSS. The meta-analysis reveals that MSC transplantation significantly improved symptoms in patients with OA [VAS (visual analogue scale): bone marrow: SMD = - 0.95, 95% CI - 1.55 to - 0.36, P = 0.002; umbilical cord: SMD = - 1.25, 95% CI - 2.04 to - 0.46, P = 0.002; adipose tissue: SMD = -1.26, 95% CI -1.99 to - 0.52, P = 0.0009)], SLE [Systemic lupus erythematosus disease activity index (SLEDAI): SMD = - 2.32, 95% CI - 3.59 to - 1.06, P = 0.0003], inflammatory bowel disease [clinical efficacy: RR = 2.02, 95% CI 1.53 to 2.67, P < 0.00001]. However, MSC transplantation may not improve the symptoms of multiple sclerosis and systemic sclerosis (Ssc). Importantly, MSC transplantation did not increase the incidence of adverse events (OA: RR = 1.23, 95% CI 0.93 to 1.65, P = 0.15; SLE: RR = 0.83, 95% CI 0.28 to 2.51, P = 0.76; Inflammatory bowel disease: RR = 0.99, 95% CI 0.81 to 1.22, P = 0.96; Multiple sclerosis: RR = 1.12, 95% CI 0.81 to 1.53, P = 0.50), supporting its safety profile across the included studies. These findings suggest that MSC transplantation holds promise for several rheumatic and autoimmune diseases while highlighting areas where further research is warranted.

CONCLUSION

MSC transplantation may have the potential to treat autoimmune and rheumatic immune diseases. Moreover. MSC transplantation appears to be relatively safe and could be considered as a viable alternative treatment option for autoimmune and rheumatic immune diseases.

Disease-Associated Signatures Persist in Extracellular Vesicles from Reprogrammed Cells of Osteoarthritis Patients

Osteoarthritis (OA) is a prevalent joint disorder that lacks effective therapies to halt cartilage degeneration. Mesenchymal stromal cell (MSC)-derived small extracellular vesicles (sEVs) are being investigated as promising chondroprotective agents. Compared to primary MSCs, induced pluripotent stem cell (iPSC)-derived MSCs (MLCs) offer superior scalability and enhanced paracrine activity. The aim of this study was to explore the feasibility of using autologous MLC-derived sEVs as a potential therapeutic strategy for OA through the analysis of their protein cargo. iPSCs from an OA patient and a healthy donor were differentiated into MLCs. sEVs were isolated from these MLCs and characterized, with a particular focus on their protein cargo. Both iPSC lines were successfully differentiated into MLCs, which secreted sEVs with comparable size distributions and yields. The analysis of differentially expressed proteins revealed a high abundance of proteins associated with OA pathology and cartilage degradation in sEVs from OA MLCs compared to those from healthy MLCs. The persistence of OA-associated protein signatures in autologous MLC-derived sEVs may limit their therapeutic efficacy. These findings underscore the importance of carefully evaluating disease-specific protein profiles in sEVs for regenerative applications.

Cell-free osteoarthritis treatment with dual-engineered chondrocyte-targeted extracellular vesicles derived from mechanical loading primed mesenchymal stem cells

Osteoarthritis (OA) is an age-related chronic inflammatory disease, predominantly characterized by chondrocyte senescence and extracellular matrix (ECM) degradation. Although mesenchymal stem cells (MSCs) derived extracellular vesicles (EVs) are promising for promoting cartilage regeneration, their clinical application is limited by inconsistent therapeutic effects and insufficient targeting capabilities. Mechanical loading shows potential to optimize MSC-EVs for OA treatment, while the underlying mechanism is not clear. In this study, EVs derived from mechanical loading-primed MSCs (ML-EVs) demonstrate prominent efficacy in maintaining ECM homeostasis and relieving chondrocyte senescence, thereby mitigating OA. Subsequent miRNA sequencing reveals that ML-EVs exert their effects by delivering miR-27b-3p, which targets ROR1 mRNA in chondrocytes and suppresses downstream NF-κB pathways. By modulating the ROR1/NF-κB axis, miR-27b-3p effectively restrains ECM degradation and chondrocyte senescence. To optimize therapeutic efficacy of EVs, miR-27b-3p is overexpressed within EVs (miROE-EVs), and a chondrocyte-targeted peptide (CTP) is conjugated to their surface, thereby constructing dual-engineered chondrocyte-targeted EVs (CTP/miROE-EVs). CTP/miROE-EVs exhibit excellent ability to specifically target cartilage and ameliorate OA pathology. In conclusion, this study underscores the critical role of mechanical loading in augmenting effectiveness of EVs in mitigating OA and introduces dual-engineered EVs that specifically target chondrocytes, providing a promising therapeutic strategy for OA.

Bone aging and extracellular vesicles

Bone aging, a major global health concern, is the natural decline in bone mass and strength. Concurrently, extracellular vesicles (EVs), tiny membrane-bound particles produced by cells, have gained recognition for their roles in various physiological processes and age-related diseases. The interaction between EVs and bone aging is of growing interest, particularly their effects on bone metabolism, which become increasingly critical with advancing age. In this review, we explored the biology, types, and functions of EVs and emphasized their regulatory roles in bone aging. We examined the effects of EVs on bone metabolism and highlighted their potential as biomarkers for monitoring bone aging progression. Furthermore, we discussed the therapeutic applications of EVs, including targeted drug delivery and bone regeneration, and addressed the challenges associated with EV-based therapies, including the technical complexities and regulatory issues. We summarized the current research and clinical trials investigating the role of EVs in bone aging and suggested future research directions. These include the potential for personalized medicine using EVs and the integration of EV research with advanced technologies to enhance the management of age-related bone health. This analysis emphasized the transformative potential of EVs in understanding and managing bone aging, thereby marking a significant advancement in skeletal health research.

Extracellular Vesicles: Advanced Tools for Disease Diagnosis, Monitoring, and Therapies

Extracellular vesicles (EVs) are a heterogeneous group of membrane-encapsulated vesicles released by cells into the extracellular space. They play a crucial role in intercellular communication by transporting bioactive molecules such as proteins, lipids, and nucleic acids. EVs can be detected in body fluids, including blood plasma, urine, saliva, amniotic fluid, breast milk, and pleural ascites. The complexity and diversity of EVs require a robust and standardized approach. By adhering to standardized protocols and guidelines, researchers can ensure the consistency, purity, and reproducibility of isolated EVs, facilitating their use in diagnostics, therapies, and research. Exosomes and microvesicles represent an exciting frontier in modern medicine, with significant potential to transform the diagnosis and treatment of various diseases with an important role in personalized medicine and precision therapy. The primary objective of this review is to provide an updated analysis of the significance of EVs by highlighting their mechanisms of action and exploring their applications in the diagnosis and treatment of various diseases. Additionally, the review addresses the existing limitations and future potential of EVs, offering practical recommendations to resolve current challenges and enhance their viability for clinical use. This comprehensive approach aims to bridge the gap between EV research and its practical application in healthcare.

Mesenchymal stem cell-derived extracellular vesicles: A promising therapeutic strategy in diabetic osteoporosis

Diabetic osteoporosis (DOP) is a serious complication of diabetes mellitus. It is urgent to explore efficient clinical treatment strategies for DOP. It has been found that mesenchymal stem cell-derived extracellular vesicles (MSC-EVs), as an emerging cell-free therapy, show great potential in DOP treatment. MSC-EVs can effectively promote bone formation, inhibit bone resorption, and modulate the inflammatory microenvironment by delivering cargoes of microRNAs, long non-coding RNAs, and proteins to target cells, thereby ameliorating bone loss in DOP. However, there are limited reports on the treatment of DOP with MSC-EVs. To evoke more attention to this potential strategy, this article summarised the extant literature on MSC-EVs for DOP to provide new directions for further research and to promote the application of MSC-EVs in the clinical management of DOP.

Effects of Growth Hormone on Osteoarthritis Development

Osteoarthritis (OA), a chronic joint disease characterized by primary or secondary degeneration of articular cartilage and bone dysplasia, is associated with various risk factors and is the leading cause of musculoskeletal pain and disability, severely impacting the quality of life. Growth hormone (GH), secreted by the anterior pituitary gland, is essential in mediating the growth and development of bone and cartilage. Reportedly, osteoarthritis increases, and the growth hormone decreases with age. A negative correlation between GH and OA suggests that GH may be related to the occurrence and development of OA. Considering that abnormal growth hormone levels can lead to many diseases related to bone growth, we focus on the relationship between GH and OA. In this review, we will explain the effects of GH on the growth and deficiency of bone and cartilage based on the local pathological changes of osteoarthritis. In addition, the potential feasibility of treating OA with GH will be further explored and summarized.

Roles of Microenvironment on Mesenchymal Stem Cells Therapy for Osteoarthritis

Osteoarthritis (OA) induced microenvironmental alterations are a common and unavoidable phenomenon that greatly exacerbate the pathologic process of OA. Imbalances in the synthesis and degradation of cartilage extracellular matrix (ECM) have been reported to be associated with an adverse microenvironment. Stem cell therapy is a promising treatment for OA, and mesenchymal stem cells (MSCs) are the main cell sources for this therapy. With multispectral differentiation and immunomodulation, MSCs can effectively regulate the microenvironment of articular cartilage, ameliorate inflammation, promote regeneration of damaged cartilage, and ultimately alleviate OA symptoms. However, the efficacy of MSCs in the treatment of OA is greatly influenced by articular cavity microenvironments. This article reviews the five microenvironments of OA articular cavity, including inflammatory microenvironment, senescence microenvironment, hypoxic microenvironment, high glucose microenvironment and high lipid environment, focus on the positive and negative effects of OA microenvironments on the fate of MSCs. In this regard, we emphasize the mechanisms of the current use of MSCs in OA treatment, as well as its limitations and challenges.

A novel mesenchymal stem cell-targeting dual-miRNA delivery system based on aptamer-functionalized tetrahedral framework nucleic acids: Application to endogenous regeneration of articular cartilage

Articular cartilage injury (ACI) remains one of the key challenges in regenerative medicine, as current treatment strategies do not result in ideal regeneration of hyaline-like cartilage. Enhancing endogenous repair via microRNAs (miRNAs) shows promise as a regenerative therapy. miRNA-140 and miRNA-455 are two key and promising candidates for regulating the chondrogenic differentiation of mesenchymal stem cells (MSCs). In this study, we innovatively synthesized a multifunctional tetrahedral framework in which a nucleic acid (tFNA)-based targeting miRNA codelivery system, named A-T-M, was used. With tFNAs as vehicles, miR-140 and miR-455 were connected to and modified on tFNAs, while Apt19S (a DNA aptamer targeting MSCs) was directly integrated into the nanocomplex. The relevant results showed that A-T-M efficiently delivered miR-140 and miR-455 into MSCs and subsequently regulated MSC chondrogenic differentiation through corresponding mechanisms. Interestingly, a synergistic effect between miR-140 and miR-455 was revealed. Furthermore, A-T-M successfully enhanced the endogenous repair capacity of articular cartilage in vivo and effectively inhibited hypertrophic chondrocyte formation. A-T-M provides a new perspective and strategy for the regeneration of articular cartilage, showing strong clinical application value in the future treatment of ACI.

METTL3 regulates cartilage development and homeostasis by affecting Lats1 mRNA stability in an m6A-YTHDF2-dependent manner

Cartilage maintains the structure and function of joints, with disturbances leading to potential osteoarthritis. N6-methyladenosine (m6A), the most widespread post-transcriptional modification in eukaryotes, plays a crucial role in regulating biological processes. While current research has indicated that m6A affects the progression of osteoarthritis, its function in the development and homeostasis of articular cartilage remains unclear. Here we report that Mettl3 deficiency in chondrocytes leads to mandibular condylar cartilage morphological alterations, early temporomandibular joint osteoarthritis, and diminished adaptive response to abnormal mechanical stimuli. Mechanistically, METTL3 modulates Lats1 mRNA methylation and facilitates its degradation in an m6A-YTHDF2-dependent manner, which subsequently influences the degradation and nuclear translocation of YAP1. Intervention with the Hippo pathway inhibitor XMU-MP-1 alleviates condylar abnormality caused by Mettl3 knockout. Our findings demonstrate the role of METTL3 in cartilage development and homeostasis, offering insights into potential treatment strategies for osteoarthritis.

Pharmacotherapy for osteoarthritis-related pain: current and emerging therapies

INTRODUCTION

Osteoarthritis (OA) related pain has affected millions of people worldwide. However, the current pharmacological options for managing OA-related pain have not achieved a satisfactory effect.

AREAS COVERED

This narrative review provides an overview of the current and emerging drugs for OA-related pain. It covers the drugs' mechanism of action, safety, efficacy, and limitations. The National Library of Medicine (PubMed) database was primarily searched from 2000 to 2024.

EXPERT OPINION

Current treatment options are limited and suboptimal for OA pain management. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are the recognized and first-line treatment in the management of OA-related pain, and other drugs are inconsistent recommendations by guidelines. Emerging treatment options are promising for OA-related pain, including nerve growth factor (NGF) inhibitors, ion channel inhibitors, and calcitonin gene-related peptide (CGRP) antagonists. Besides, drugs repurposing from antidepressants and antiepileptic analgesics are shedding light on the management of OA-related pain. The management of OA-related pain is challenging as pain is heterogeneous and subjective. A more comprehensive strategy combined with non-pharmacological therapy needs to be considered, and tailored management options to individualized patients.

M2 Macrophage-Derived Extracellular Vesicles Encapsulated in Hyaluronic Acid Alleviate Osteoarthritis by Modulating Macrophage Polarization

An imbalance between M1 and M2 macrophage polarization is critical in osteoarthritis (OA) development. We investigated the effect of M2 macrophage-derived extracellular vesicles (M2-EVs) to reprogramme macrophages from the M1 to M2 phenotype for OA treatment. M1 macrophages and mouse OA models were treated with M2-EVs. Proteomic analysis was performed to evaluate macrophage polarization in vitro. The OA models were as follows: destabilization of the medial meniscus (DMM) surgery-induced OA and collagenase-induced OA (CIOA). Hyaluronic acid (HA) was used to deliver M2-EVs. M2-EVs decreased macrophage accumulation, repolarized macrophages from the M1 to M2 phenotype, mitigated synovitis, reduced cartilage degradation, alleviated subchondral bone damage, and improved gait abnormalities in the CIOA and DMM models. Moreover, HA increased the retention time of M2-EVs and enhanced the efficiency of M2-EVs in OA treatment. Furthermore, proteomic analysis demonstrated that M2-EVs exhibited a macrophage reprogramming ability similar to IL-4, and the pathways might be the NOD-like receptor (NLR), TNF, NF-κB, and Toll-like receptor (TLR) signaling pathways. M2-EVs reprogrammed macrophages from the M1 to M2 phenotype, which resulted in beneficial effects on cartilage and attenuation of OA severity. In summary, our study indicated that M2-EV-guided reprogramming of macrophages is a promising treatment strategy for OA.

The evolving landscape of gene therapy strategies for the treatment of osteoarthritis

OBJECTIVES

Significant advances have been made in our understanding of osteoarthritis (OA) pathogenesis; however, no disease-modifying therapies have been identified. This review will summarize the gene therapy landscape, its initial successes for OA, and possible challenges using recent studies and examples of gene therapies in clinical trials.

DESIGN

This narrative review has three major sections: 1) vector systems for OA gene therapy, 2) current and emerging targets for OA gene therapy, and 3) considerations and future directions.

RESULTS

Gene therapy is the strategy by which nucleic acids are delivered to treat and reverse disease progression. Specificity and prolonged expression of these nucleic acids are achieved by manipulating promoters, genes, and vector systems. Certain vector systems also allow for the development of combinatorial nucleic acid strategies that can be delivered in a single intraarticular injection - an approach likely required to treat the complexity of OA pathogenesis. Several viral and non-viral vector-based gene therapies are in clinical trials for OA, and many more are being evaluated in the preclinical arena.

CONCLUSIONS

In a post-coronavirus disease 2019 (COVID-19) era, the future of gene therapy for OA is certainly promising; however, the majority of preclinical validation continues to focus heavily on post-traumatic models and changes in only cartilage and subchondral bone. To ensure successful translation, new candidates in the preclinical arena should be examined against all joint tissues as well as pain using diverse models of injury-, obesity-, and age-induced disease. Lastly, consideration must be given to strategies for repeat administration and the cost of treatment owing to the chronic nature of OA.

Lysosomal destabilization: A missing link between pathological calcification and osteoarthritis

Calcification of cartilage by hydroxyapatite is a hallmark of osteoarthritis and its deposition strongly correlates with the severity of osteoarthritis. However, no effective strategies are available to date on the prevention of hydroxyapatite deposition within the osteoarthritic cartilage and its role in the pathogenesis of this degenerative condition is still controversial. Therefore, the present work aims at uncovering the pathogenic mechanism of intra-cartilaginous hydroxyapatite in osteoarthritis and developing feasible strategies to counter its detrimental effects. With the use of in vitro and in vivo models of osteoarthritis, hydroxyapatite crystallites deposited in the cartilage are found to be phagocytized by resident chondrocytes and processed by the lysosomes of those cells. This results in lysosomal membrane permeabilization (LMP) and release of cathepsin B (CTSB) into the cytosol. The cytosolic CTSB, in turn, activates NOD-like receptor protein-3 (NLRP3) inflammasomes and subsequently instigates chondrocyte pyroptosis. Inhibition of LMP and CTSB in vivo are effective in managing the progression of osteoarthritis. The present work provides a conceptual therapeutic solution for the prevention of osteoarthritis via alleviation of lysosomal destabilization.

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.

Enhanced Surface Immunomodification of Engineered Hydrogel Materials through Chondrocyte Modulation for the Treatment of Osteoarthritis

Osteoarthritis (OA) is characterized by cartilage degeneration and synovial inflammation, with chondrocytes playing a pivotal role in this disease. However, inflammatory mediators, mechanical stress, and oxidative stress can compromise functionality. The occurrence and progression of OA are intrinsically linked to the immune response. Current research on the treatment of OA mainly concentrates on the synergistic application of drugs and tissue engineering. The surface of engineered hydrogel materials can be immunomodified to affect the function of chondrocytes in drug therapy, gene therapy, and cell therapy. Prior studies have concentrated on the drug-loading function of hydrogels but overlooked the immunomodulatory role of chondrocytes. These modifications can inhibit the proliferation and differentiation of chondrocytes, reduce the inflammatory response, and promote cartilage regeneration. The surface immunomodification of engineered hydrogel materials can significantly enhance their efficacy in the treatment of OA. Thus, immunomodulatory tissue engineering has significant potential for treating osteoarthritis.

Can extracellular vesicles be considered as a potential frontier in the treatment of intervertebral disc disease?

As a global public health problem, low back pain (LBP) caused by intervertebral disc degeneration (IDD) seriously affects patients' quality of life. In addition, the prevalence of IDD tends to be younger, which brings a huge burden to individuals and society economically. Current treatments do not delay or reverse the progression of IDD. The emergence of biologic therapies has brought new hope for the treatment of IDD. Among them, extracellular vesicles (EVs), as nanoscale bioactive substances that mediate cellular communication, have now produced many surprising results in the research of the treatment of IDD. This article reviews the mechanisms and roles of EVs in delaying IDD and describes the prospects and challenges of EVs.