The therapeutic effect of bone marrow-derived mesenchymal stem cells on osteoarthritis is improved by the activation of the KDM6A/SOX9 signaling pathway caused by exposure to hypoxia

Mesenchymal Stem Cell-Derived Exosomes as a Treatment Option for Osteoarthritis

Osteoarthritis (OA) is a leading cause of pain and disability worldwide in elderly people. There is a critical need to develop novel therapeutic strategies that can effectively manage pain and disability to improve the quality of life for older people. Mesenchymal stem cells (MSCs) have emerged as a promising cell-based therapy for age-related disorders due to their multilineage differentiation and strong paracrine effects. Notably, MSC-derived exosomes (MSC-Exos) have gained significant attention because they can recapitulate MSCs into therapeutic benefits without causing any associated risks compared with direct cell transplantation. These exosomes help in the transport of bioactive molecules such as proteins, lipids, and nucleic acids, which can influence various cellular processes related to tissue repair, regeneration, and immune regulation. In this review, we have provided an overview of MSC-Exos as a considerable treatment option for osteoarthritis. This review will go over the underlying mechanisms by which MSC-Exos may alleviate the pathological hallmarks of OA, such as cartilage degradation, synovial inflammation, and subchondral bone changes. Furthermore, we have summarized the current preclinical evidence and highlighted promising results from in vitro and in vivo studies, as well as progress in clinical trials using MSC-Exos to treat OA.

The Role of Circular RNA Variants Generated from the NFIX Gene in Different Diseases

Circular RNAs (circRNAs) have been identified as important regulators in different developmental processes and disease pathogenesis. The loop structure of circRNAs makes them very stable in different conditions and microenvironments. circRNAs can affect microRNA (miRNA) and RNA binding protein (RBP) activity, encode functional proteins and regulate gene transcription. Recently, two circNFIX variants derived from the same gene, the Nuclear Factor I X (NFIX) gene, were determined as participants in the pathological processes of various diseases such as heart diseases and cancers. Both circNFIX variants are exonic circular RNAs and mainly function by sponging miRNAs. In this review, we summarize the current knowledge on circRNAs, elucidate the origins and properties of two circNFIX variants, explore the roles of two circNFIX variants in different diseases, and present clinical perspectives.

Protecting the regenerative environment: selecting the optimal delivery vehicle for cartilage repair-a narrative review

Focal cartilage defects are common in youth and older adults, cause significant morbidity and constitute a major risk factor for developing osteoarthritis (OA). OA is the most common musculoskeletal (MSK) disease worldwide, resulting in pain, stiffness, loss of function, and is currently irreversible. Research into the optimal regenerative approach and methods in the setting of either focal cartilage defects and/or OA holds to the ideal of resolving both diseases. The two fundamentals required for cartilage regenerative treatment are 1) the biological element contributing to the regeneration (e.g., direct application of stem cells, or of an exogenous secretome), and 2) the vehicle by which the biological element is suspended and delivered. The vehicle provides support to the regenerative process by providing a protective environment, a structure that allows cell adherence and migration, and a source of growth and regenerative factors that can activate and sustain regeneration. Models of cartilage diseases include osteochondral defect (OCD) (which usually involve one focal lesion), or OA (which involves a more diffuse articular cartilage loss). Given the differing nature of these models, the optimal regenerative strategy to treat different cartilage diseases may not be universal. This could potentially impact the translatability of a successful approach in one condition to that of the other. An analogy would be the repair of a pothole (OCD) versus repaving the entire road (OA). In this narrative review, we explore the existing literature evaluating cartilage regeneration approaches for OCD and OA in animal then in human studies and the vehicles used for each of these two conditions. We then highlight strengths and challenges faced by the different approaches presented and discuss what might constitute the optimal cartilage regenerative delivery vehicle for clinical cartilage regeneration.

Advanced Therapeutic Medicinal Products in Bone and Cartilage Defects

The number of patients with functional loss of bone and cartilage tissue has shown an increasing trend. Insufficient or inappropriate conventional treatments applied for trauma, orthopedic diseases, or other bone and cartilage-related disorders can lead to bone and cartilage damage. This represents a worldwide public health issue and a significant economic burden. Advanced therapeutic medicinal products (ATMPs) proposed promising alternative therapeutic modalities by application of cell-based and tissue engineering approaches. Recently, several ATMPs have been developed to promote bone and cartilage tissue regeneration. Fifteen ATMPs, two related to bone and 13 related to cartilage, have received regulatory approval and marketing authorization. However, four ATMPs were withdrawn from the market for various reasons. However, ATMPs that are still on the market have demonstrated positive results, their broad application faced limitations. The development and standardization of methodologies will be a major challenge in the coming decades. Currently, the number of ATMPs in clinical trials using mesenchymal stromal cells or chondrocytes indicates a growing recognition that current ATMPs can be improved. Research on bone and cartilage tissue regeneration continues to expand. Cell-based therapies are likely to be clinically supported by the new ATMPs, innovative fabrication processes, and enhanced surgical approaches. In this study, we highlighted the available ATMPs that have been used in bone and cartilage defects and discussed their advantages and disadvantages in clinical applications.

Advances in Stem Cell-Based Therapies in the Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic, degenerative joint disease presenting a significant global health threat. While current therapeutic approaches primarily target symptom relief, their efficacy in repairing joint damage remains limited. Recent research has highlighted mesenchymal stem cells (MSCs) as potential contributors to cartilage repair, anti-inflammatory modulation, and immune regulation in OA patients. Notably, MSCs from different sources and their derivatives exhibit variations in their effectiveness in treating OA. Moreover, pretreatment and gene editing techniques of MSCs can enhance their therapeutic outcomes in OA. Additionally, the combination of novel biomaterials with MSCs has shown promise in facilitating the repair of damaged cartilage. This review summarizes recent studies on the role of MSCs in the treatment of OA, delving into their advantages and exploring potential directions for development, with the aim of providing fresh insights for future research in this critical field.

The role of lysine-specific demethylase 6A (KDM6A) in tumorigenesis and its therapeutic potentials in cancer therapy

Histone demethylation is a key post-translational modification of chromatin, and its dysregulation affects a wide array of nuclear activities including the maintenance of genome integrity, transcriptional regulation, and epigenetic inheritance. Lysine specific demethylase 6A (KDM6A, also known as UTX) is an Fe²⁺- and α-ketoglutarate- dependent oxidase which belongs to KDM6 Jumonji histone demethylase subfamily, and it can remove mono-, di- and tri-methyl groups from methylated lysine 27 of histone H3 (H3K27me1/2/3). Mounting studies indicate that KDM6A is responsible for driving multiple human diseases, particularly cancers and pharmacological inhibition of KDM6A is an effective strategy to treat varieties of KDM6A-amplified cancers in cellulo and in vivo. Although there are several reviews on the roles of KDM6 subfamily in cancer development and therapy, all of them only simply introduce the roles of KDM6A in cancer without systematically summarizing the specific mechanisms of KDM6A in tumorigenesis, which greatly limits the advances on the understanding of roles KDM6A in varieties of cancers, discovering targeting selective KDM6A inhibitors, and exploring the adaptive profiles of KDM6A antagonists. Herein, we present the structure and functions of KDM6A, simply outline the functions of KDM6A in homeostasis and non-cancer diseases, summarize the role of KDM6A and its distinct target genes/ligand proteins in development of varieties of cancers, systematically classify KDM6A inhibitors, sum up the difficulties encountered in the research of KDM6A and the discovery of related drugs, and provide the corresponding solutions, which will contribute to understanding the roles of KDM6A in carcinogenesis and advancing the progression of KDM6A as a drug target in cancer therapy.

Mesenchymal stem cells in osteoarthritis: The need for translation into clinical therapy

Widely used for cell-based therapy in various medical fields, mesenchymal stem cells (MSCs) show capacity for anti-inflammatory effects, anti-apoptotic activity, immunomodulation, and tissue repair and regeneration. As such, they can potentially be used to treat osteoarthritis (OA). However, MSCs from different sources have distinct advantages and disadvantages, and various animal models and clinical trials using different sources of MSCs are being conducted in OA regenerative medicine. It is now widely believed that the primary tissue regeneration impact of MSCs is via paracrine effects, rather than direct differentiation and replacement. Cytokines and molecules produced by MSCs, including extracellular vesicles with mRNAs, microRNAs, and bioactive substances, play a significant role in OA repair. This chapter outlines the properties of MSCs and recent animal models and clinical trials involving MSCs-based OA therapy, as well as how the paracrine effect of MSCs acts in OA cartilage repair. Additionally, it discusses challenges and controversies in MSCs-based OA therapy. Despite its limits and unanticipated hazards, MSCs have the potential to be translated into therapeutic therapy for future OA treatment.

Inhibition of KDM7A/B histone demethylases restores H3K79 methylation and protects against osteoarthritis

OBJECTIVES

In osteoarthritis, methylation of lysine 79 on histone H3 (H3K79me), a protective epigenetic mechanism, is reduced. Histone methylation levels are dynamically regulated by histone methyltransferases and demethylases. Here, we aimed to identify which histone demethylases regulate H3K79me in cartilage and investigate whether their targeting protects against osteoarthritis.

METHODS

We determined histone demethylase expression in human non-osteoarthritis and osteoarthritis cartilage using qPCR. The role of histone demethylase families and subfamilies on H3K79me was interrogated by treatment of human C28/I2 chondrocytes with pharmacological inhibitors, followed by western blot and immunofluorescence. We performed C28/I2 micromasses to evaluate effects on glycosaminoglycans by Alcian blue staining. Changes in H3K79me after destabilisation of the medial meniscus (DMM) in mice were determined by immunohistochemistry. Daminozide, a KDM2/7 subfamily inhibitor, was intra-articularly injected in mice upon DMM. Histone demethylases targeted by daminozide were individually silenced in chondrocytes to dissect their role on H3K79me and osteoarthritis.

RESULTS

We documented the expression signature of histone demethylases in human non-osteoarthritis and osteoarthritis articular cartilage. Inhibition of Jumonji-C demethylase family increased H3K79me in human chondrocytes. Blockade of KDM2/7 histone demethylases with daminozide increased H3K79me and glycosaminoglycans. In mouse articular cartilage, H3K79me decayed rapidly upon induction of joint injury. Early and sustained intra-articular treatment with daminozide enhanced H3K79me and exerted protective effects in mice upon DMM. Individual silencing of KDM7A/B demethylases in human chondrocytes demonstrated that KDM7A/B mediate protective effects of daminozide on H3K79me and osteoarthritis.

CONCLUSION

Targeting KDM7A/B histone demethylases could be an attractive strategy to protect joints against osteoarthritis.

Inhibition of histone lysine demethylase 6A promotes chondrocytic activity and attenuates osteoarthritis development through repressing H3K27me3 enhancement of Wnt10a

Histone hypermethylation represses gene transcription, which affects cartilage homeostasis or joint remodeling. Trimethylation of lysine 27 of histone 3 (H3K27me3) changes epigenome signatures, regulating tissue metabolism. This study aimed to investigate whether loss of H3K27me3 demethylase Kdm6a function affected osteoarthritis development. We revealed that chondrocyte-specific Kdm6a knockout mice developed relatively long femurs and tibiae as compared to wild-type mice. Kdm6a deletion mitigated osteoarthritis symptoms, including articular cartilage loss, osteophyte formation, subchondral trabecular bone loss, and irregular walking patterns of destabilized medial meniscus-injured knees. In vitro, loss of Kdm6a function compromised the loss in expression of key chondrocyte markers Sox9, collagen II, and aggrecan and improved glycosaminoglycan production in inflamed chondrocytes. RNA sequencing showed that Kdm6a loss changed transcriptomic profiles, which contributed to histone signaling, NADPH oxidase, Wnt signaling, extracellular matrix, and cartilage development in articular cartilage. Chromatin immunoprecipitation sequencing uncovered that Kdm6a knockout affected H3K27me3 binding epigenome, repressing Wnt10a and Fzd10 transcription. Wnt10a was, among others, functional molecules regulated by Kdm6a. Forced Wnt10a expression attenuated Kdm6a deletion-induced glycosaminoglycan overproduction. Intra-articular administration with Kdm6a inhibitor GSK-J4 attenuated articular cartilage erosion, synovitis, and osteophyte formation, improving gait profiles of injured joints. In conclusion, Kdm6a loss promoted transcriptomic landscapes contributing to extracellular matrix synthesis and compromised epigenetic H3K27me3-mediated promotion of Wnt10a signaling, preserving chondrocytic activity to attenuate osteoarthritic degeneration. We highlighted the chondroprotective effects of Kdm6a inhibitor for mitigating the development of osteoarthritic disorders.

Mesenchymal Stem Cells and Their Exocytotic Vesicles

Mesenchymal stem cells (MSCs), as a kind of pluripotent stem cells, have attracted much attention in orthopedic diseases, geriatric diseases, metabolic diseases, and sports functions due to their osteogenic potential, chondrogenic differentiation ability, and adipocyte differentiation. Anti-inflammation, anti-fibrosis, angiogenesis promotion, neurogenesis, immune regulation, and secreted growth factors, proteases, hormones, cytokines, and chemokines of MSCs have been widely studied in liver and kidney diseases, cardiovascular and cerebrovascular diseases. In recent years, many studies have shown that the extracellular vesicles of MSCs have similar functions to MSCs transplantation in all the above aspects. Here we review the research progress of MSCs and their exocrine vesicles in recent years.

CircNFIX regulates chondrogenesis and cartilage homeostasis by targeting the miR758 ‐3p/ KDM6A axis

Objectives

Osteoarthritis (OA) is a degenerative disease causing the progressive destruction of articular cartilage; however, the aetiology has not yet been elucidated. Circular RNAs (circRNAs) are reportedly involved in cartilage degeneration and OA development. In the present study, we identified that circNFIX regulates chondrogenesis and cartilage homeostasis.

Materials and Methods

Microarray analysis was performed to explore circRNA expression during the chondrogenic differentiation of human adipose‐drived stem cells (hADSCs). CircNFIX expression was determined using quantitative reverse transcription‐polymerase chain reaction and in situ hybridization. Gain‐ and loss‐of‐function assays were performed to validate the role of circNFIX in cartilage homeostasis. RNA pull‐down, Argonaute2‐RNA immunoprecipitation and luciferase reporter assays were performed to evaluate the interactions among circNFIX, miR758‐3p and KDM6A.

Results

CircNFIX expression was upregulated in the early and middle stages, whereas downregulated in the late stage of hADSC chondrogenesis. CircNFIX inhibition attenuated hADSC chondrogenesis. CircNFIX was remarkably downregulated in OA samples, circNFIX overexpression protected against chondrocyte degradation and alleviated OA progression in the destabilization of the medial meniscus OA model. Mechanistically, circNFIX acted as a sponge of miR758‐3p and played a role in the chondrogenesis and chondrocyte degeneration by targeting the miR‐758‐3p/KDM6A axis.

Conclusions

Our results revealed a key role of circNFIX in chondrogenesis and cartilage homeostasis, which may provide a potential therapeutic strategy for OA treatment.

MiR-20a-5p facilitates cartilage repair in osteoarthritis via suppressing mitogen-activated protein kinase kinase kinase 2

Bone marrow mesenchymal stem cell (BMSC) chondrogenic differentiation contributes to the treatment of osteoarthritis (OA). Numerous studies have indicated that microRNAs (miRNAs) regulate the pathogenesis and development of multiple disorders, including OA. Nevertheless, the role of miR-20a-5p in OA remains obscure. Forty male C57BL/6 mice were divided into four groups and were surgically induced OA or underwent sham surgery in the presence or absence of miR-20a-5p. Flow cytometry was implemented to detect surface markers of BMSCs. Reverse transcription quantitative polymerase chain reaction revealed the upregulation of miR-20a-5p during BMSC chondrogenic differentiation. Western blotting displayed that miR-20a-5p inhibition decreased protein levels of cartilage matrix markers but enhanced those of catabolic and hypertrophic chondrocyte markers in BMSCs. Alcian blue staining, hematoxylin‑eosin staining and micro-CT revealed that miR-20a-5p inhibition restrained chondrogenic differentiation and miR-20a-5p overexpression promoted the repair of damaged cartilage and subchondral bone, respectively. Luciferase reporter assay identified that mitogen activated protein kinase kinase kinase 2 (Map3k2) was a target of miR-20a-5p in BMSCs. Moreover, the expression of miR-20a-5p and Map3k2 was negatively correlated in murine cartilage tissues. Knocking down Map3k2 could rescue the suppressive influence of miR-20a-5p inhibition on chondrogenic differentiation of BMSCs. In conclusion, miR-20a-5p facilitates BMSC chondrogenic differentiation and contributes to cartilage repair in OA by suppressing Map3k2.

The role of Trithorax family regulating osteogenic and Chondrogenic differentiation in mesenchymal stem cells

Mesenchymal stem/stromal cells (MSCs) hold great promise and clinical efficacy in bone/cartilage regeneration. With a deeper understanding of stem cell biology over the past decade, epigenetics stands out as one of the most promising ways to control MSCs differentiation. Trithorax group (TrxG) proteins, including the COMPASS family, ASH1L, CBP/p300 as histone modifying factors, and the SWI/SNF complexes as chromatin remodelers, play an important role in gene expression regulation during the process of stem cell differentiation. This review summarises the components and functions of TrxG complexes. We provide an overview of the regulation mechanisms of TrxG in MSCs osteogenic and chondrogenic differentiation, and discuss the prospects of epigenetic regulation mediated by TrxG in bone and cartilage regeneration.

Preclinical studies and clinical trials on mesenchymal stem cell therapy for knee osteoarthritis: A systematic review on models and cell doses

AIM

To provide a systematic analysis of the study design in knee osteoarthritis (OA) preclinical studies, focusing on the characteristics of animal models and cell doses, and to compare these to the characteristics of clinical trials using mesenchymal stem cells (MSCs) for the treatment of knee OA.

METHOD

A systematic and comprehensive search was conducted using the PubMed, Web of Science, Ovid, and Embase electronic databases for research papers published in 2009-2020 on testing MSC treatment in OA animal models. The PubMed database and ClinicalTrials.gov website were used to search for published studies reporting clinical trials of MSC therapy for knee OA.

RESULTS

In total, 9234 articles and two additional records were retrieved, of which 120 studies comprising preclinical and clinical studies were included for analysis. Among the preclinical studies, rats were the most commonly used species for modeling knee OA, and anterior cruciate ligament transection was the most commonly used method for inducing OA. There was a correlation between the cell dose and body weight of the animal. In clinical trials, there was large variation in the dose of MSCs used to treat knee OA, ranging from 1 × 10⁶ to 200 × 10⁶ cells with an average of 37.91 × 10⁶ cells.

CONCLUSION

Mesenchymal stem cells have shown great potential in improving pain relief and tissue protection in both preclinical and clinical studies of knee OA. Further high-quality preclinical and clinical studies are needed to explore the dose effectiveness relationship of MSC therapy and to translate the findings from preclinical studies to humans.

Paeonol inhibits inflammatory response and protects chondrocytes by upregulating sirtuin 1

Paeonol is the bioactive component in Paeonia lactiflora Pall., Cynanchum paniculatum and Paeonia × suffruticosa Andr. Paeonol has been previously demonstrated to inhibit the release of tumor necrosis factor α (TNF-α) and interluekin 6 (IL-6) in chondrocytes. Sirtuin 1 (SIRT1) is downregulated in degraded cartilage and paeonol could induce nuclear accumulation of SIRT1. Therefore, the present study aims to investigate the possible role of paeonol in chondrocyte inflammation and cartilage protection in osteoarthritis (OA) as well as its regulation of SIRT1. Primary chondrocytes from rat knee joints were transfected with short hairpin (sh) - SIRT1 and (or) paeonol prior to IL-1β exposure, and then inflammatory response, apoptosis, and extracellular matrix (ECM) degradation in the cells were evaluated concurrent with the activation of the nuclear factor κβ (NF-κβ) signaling pathway. Increased levels of TNF-α, IL-17, IL-6, matrix metalloproteinase 1 (MMP-1), MMP-3, and MMP-13 along with decreased tissue inhibitor of metalloproteinases 1 and type II collagen levels were found in IL-1β-stimulated chondrocytes. Chondrocyte apoptosis was elevated and the NF-κβ signaling pathway was activated in response to IL-1β treatment. Paeonol enhanced SIRT1 expression to inactivate the NF-κβ signaling pathway, thereby ameliorating inflammatory cytokine secretion, ECM degradation, and chondrocyte apoptosis. In conclusion, the results of the present study confirm the potential of paeonol as a candidate OA drug.

Attenuation of osteoarthritis progression through intra-articular injection of a combination of synovial membrane-derived MSCs (SMMSCs), platelet-rich plasma (PRP) and conditioned medium (secretome)

PURPOSE

Osteoarthritis (OA) as a progressive destructive disease of articular cartilage is the most common joint disease characterized by reduction of joint cartilage thickness, demolition of cartilage surface and new bone formation. To overcome these problems, the purpose of the current research was to evaluate and compare the in vivo effects of synovial membrane-derived mesenchymal stem cell (SMMSCs), platelet-rich plasma (PRP) and conditioned medium (secretome) on collagenase II-induced rat knee osteoarthritis (KOA) remedy.

METHODS

For the first step, SMMSCs were isolated and characterized. Also, secretome was collected from SMMSCs culture. Furthermore, PRP was collect from the rat heart venous blood. Second, two injection of collagenase II with an interval of 3 days was performed in the knee intra-articular space to induce osteoarthritis. Two weeks later, animals were randomly divided into 6 groups. Control group without treatment, positive group: taken an intra-articular sodium hyaluronate injection (0.1 ml), treatment groups taken an intra-articular injection of; treatment 1: SMMSCs (5 × 10⁶), treatment 2: SMMSCs (5 × 10⁶)/secretome (50 µl), treatment 3: SMMSCs (5 × 10⁶)/PRP (50 µl), and treatment 4: SMMSCs (5 × 10⁶)/ secretome (50 µl)/ PRP (50 µl). Three months later, rats were killed and the following assessments were executed: radiography, histopathology, and immunohistochemistry.

RESULTS

Our findings represented that a combination of the SMMSCs/secretome/PRP had a considerable effect on glycosaminoglycans (GAGs) and collagen II contents, articular cartilage preservation, compared with other groups. In addition, combination of the SMMSCs with PRP and secretome showed the lowest expression of mmp3, while SOX9 had the highest expression in comparison with other groups. Also, SMMSCs-injected groups demonstrated better results compared with positive and control groups.

CONCLUSIONS

Injecting a combination of the SMMSCs/secretome/PRP resulted in better efficacy in terms of joint space width, articular cartilage surface continuity and integrity, sub-chondral bone and ECM constituents such as collagen II. Indeed, transplantation of this combination could be considered as a preliminary therapy for clinical trial study in the future.

Mesenchymal stromal cell-based therapy for cartilage regeneration in knee osteoarthritis

Osteoarthritis, as a degenerative disease, is a common problem and results in high socioeconomic costs and rates of disability. The most commonly affected joint is the knee and characterized by progressive destruction of articular cartilage, loss of extracellular matrix, and progressive inflammation. Mesenchymal stromal cell (MSC)-based therapy has been explored as a new regenerative treatment for knee osteoarthritis in recent years. However, the detailed functions of MSC-based therapy and related mechanism, especially of cartilage regeneration, have not been explained. Hence, this review summarized how to choose, authenticate, and culture different origins of MSCs and derived exosomes. Moreover, clinical application and the latest mechanistical findings of MSC-based therapy in cartilage regeneration were also demonstrated.

Cell and Cell Free Therapies in Osteoarthritis

Osteoarthritis (OA) is the most common articular disease in adults and has a current prevalence of 12% in the population over 65 years old. This chronic disease causes damage to articular cartilage and synovial joints, causing pain and leading to a negative impact on patients' function, decreasing quality of life. There are many limitations regarding OA conventional therapies-pharmacological therapy can cause gastrointestinal, renal, and cardiac adverse effects, and some of them could even be a threat to life. On the other hand, surgical options, such as microfracture, have been used for the last 20 years, but hyaline cartilage has a limited regeneration capacity. In recent years, the interest in new therapies, such as cell-based and cell-free therapies, has been considerably increasing. The purpose of this review is to describe and compare bioregenerative therapies' efficacy for OA, with particular emphasis on the use of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP). In OA, these therapies might be an alternative and less invasive treatment than surgery, and a more effective option than conventional therapies.

Extracellular vesicles from mesenchymal stromal cells: Therapeutic perspectives for targeting senescence in osteoarthritis

Osteoarthritis (OA) is a common age-related disease that correlates with a high number of senescent cells in joint tissues. Senescence has been reported to be one of the main drivers of OA pathogenesis, in particular via the release of senescence-associated secretory phenotype (SASP) factors. SASP factors are secreted as single molecules and/or packaged within extracellular vesicles (EVs), thereby contributing to senescent phenotype dissemination. Targeting senescent cells using senolytics or senomorphics has therefore been tested and improvement of OA-associated features has been reported in murine models. Mesenchymal stromal cells (MSCs) and their derived EVs (MSC-EVs) are promising treatments for OA, exerting pleiotropic functions by producing a variety of factors. However, functions of MSCs and MSC-EVs are affected by aging. In this review, we discuss on the impact of the senescent environment on functions of aged MSC-EVs and on the anti-aging properties of MSC-EVs in the context of OA.

MicroRNA-3100 from Bone Marrow Mesenchymal Stem Cells (BMSCs) Exosomes Alleviates Autoimmune Arthritis in Mice via Regulating Forkhead Box P3 Acetylase

To study the effect and mechanism of microRNA-3100 from exosome of BMSCs on autoimmune arthritis in mice. CIA mice model was established and treated with BMSCs exosomes or DMSO. The expression of Foxp3 was detected by PCR and Western blot. The Treg/Th17 population of T cells and the expression of related inflammatory factors were analyzed by flow cytometry. BMSCs trans-fected with MicroRNA-3100 inhibitor or MicroRNA-3100 was used to treat CIA mice through intravenous injection. The levels of Foxp3 and its acetylation, Treg/Th17 differentiation and inflammatory factors were detected, and the synovial tissues of mice were collected for analysis of its inflammatory infiltration. RA rats exhibited down-regulated Treg population and increased Th17 population in PBMC and SF, accompanied by reduced Foxp3 and acetylated Foxp3 expression, suppressed Tip60 expression in SF, in relative to normal control. However, exosomes of BMSCs administration recovered the changes. Further result showed that exosomes from BMSCs was enriched for miR-3100. miR-3100 inhibitor exposed CD4+ T cell exhibited reduced Tip60 and acetylated-Foxp3 expression, decreased Tregs population and increased Th17 cell population, vice versa as the miR-3100 mimics does. In addition, Tip60 inhibitors NU905 exerted the same effect as miR-3100 inhibitor transfection dose. Finally, miR-3100 overexpression could significantly reduce inflammation and immune cell infiltration, correct the dysfunction between Th17 and Tregs, recovered Tip60 and acetylation Foxp3 expression. MiRNA-3100 is enriched in exosomes of BMSCs, and can up-regulatethe expression of Foxp3, acetylated Foxp3 and Tip60 level, improving the imbalance of Treg/Th17 ratio, and improve autoimmune arthritis in mice.

d-Mannose suppresses osteoarthritis development in vivo and delays IL-1β-induced degeneration in vitro by enhancing autophagy activated via the AMPK pathway

Osteoarthritis (OA) is a heterogeneous disease that is consistently difficult to treat due to the complexity of the regulatory network involved in OA pathogenesis, especially in terms of cartilage degeneration. As a C-2 epimer of glucose, d-mannose can alleviate bone loss and repress immunopathology by upregulating regulatory T cells; however, the role of d-mannose in OA-related cartilage degeneration remains unknown. In this study, we investigated the chondroprotective effect of d-mannose in vitro and in vivo on OA. We found that incubating interleukin (IL)-1β-treated rat chondrocytes with d-mannose restrained OA degeneration by elevating cell proliferation, strongly activating autophagy, reducing apoptosis, and downregulating catabolism. Additionally, oral gavage administration of d-mannose to monosodium iodoacetate (MIA)-treated rats revealed that a median (1.25 g/kg/day) rather than high or low dose of d-mannose suppressed OA progression and attenuated OA development based on lower macroscopic scores for cartilage, decreased histological scores for cartilage and synovium, strongly activated autophagy, and downregulated catabolism. In terms of a downstream mechanism, we showed that d-mannose might attenuate OA degeneration by activating autophagy in IL-1β-treated rat chondrocytes by promoting the phosphorylation of 5' AMP-activated protein kinase (AMPK). Our in vitro findings revealed that d-mannose delayed IL-1β-induced OA degeneration in rat chondrocytes by enhancing autophagy activation through the AMPK pathway. Furthermore, the in vivo results indicated that a median dose of d-mannose suppressed MIA-induced OA development. These results suggested that d-mannose exhibits chondroprotective effects and represents a potential disease-modifying drug and novel therapeutic agent for OA.