Engineering exosomes derived from TNF-α preconditioned IPFP-MSCs enhance both yield and therapeutic efficacy for osteoarthritis.

BACKGROUND: The pathogenesis of osteoarthritis (OA) involves the progressive degradation of articular cartilage. Exosomes derived from mesenchymal stem cells (MSC-EXOs) have been shown to mitigate joint pathological injury by attenuating cartilage destruction. Optimization the yield and therapeutic efficacy of exosomes derived from MSCs is crucial for promoting their clinical translation. The preconditioning of MSCs enhances the therapeutic potential of engineered exosomes, offering promising prospects for application by enabling controlled and quantifiable external stimulation. This study aims to address these issues by employing pro-inflammatory preconditioning of MSCs to enhance exosome production and augment their therapeutic efficacy for OA. METHODS: The exosomes were isolated from the supernatant of infrapatellar fat pad (IPFP)-MSCs preconditioned with a pro-inflammatory factor, TNF-α, and their production was subsequently quantified. The exosome secretion-related pathways in IPFP-MSCs were evaluated through high-throughput transcriptome sequencing analysis, q-PCR and western blot analysis before and after TNF-α preconditioning. Furthermore, exosomes derived from TNF-α preconditioned IPFP-MSCs (IPFP-MSC-EXOsTNF-α) were administered intra-articularly in an OA mouse model, and subsequent evaluations were conducted to assess joint pathology and gait alterations. The expression of proteins involved in the maintenance of cartilage homeostasis within the exosomes was determined through proteomic analysis. RESULTS: The preconditioning with TNF-α significantly enhanced the exosome secretion of IPFP-MSCs compared to unpreconditioned MSCs. The potential mechanism involved the activation of the PI3K/AKT signaling pathway in IPFP-MSCs by TNF-α precondition, leading to an up-regulation of autophagy-related protein 16 like 1(ATG16L1) levels, which subsequently facilitated exosome secretion. The intra-articular administration of IPFP-MSC-EXOsTNF-α demonstrated superior efficacy in ameliorating pathological changes in the joints of OA mice. The preconditioning of TNF-α enhanced the up-regulation of low-density lipoprotein receptor-related protein 1 (LRP1) levels in IPFP-MSC-EXOsTNF-α, thereby exerting chondroprotective effects. CONCLUSION: TNF-α preconditioning constitutes an effective and promising method for optimizing the therapeutic effects of IPFP-MSCs derived exosomes in the treatment of OA.

Mesenchymal stem cell-derived extracellular vesicles in joint diseases: Therapeutic effects and underlying mechanisms.

Joint diseases greatly impact the daily lives and occupational functioning of patients globally. However, conventional treatments for joint diseases have several limitations, such as unsatisfatory efficacy and side effects, necessitating the exploration of more efficacious therapeutic strategies. Mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) have demonstrated high therapeutic efficacyin tissue repair and regeneration, with low immunogenicity and tumorigenicity. Recent studies have reported that EVs-based therapy has considerable therapeutic effects against joint diseases, including osteoarthritis, tendon and ligament injuries, femoral head osteonecrosis, and rheumatoid arthritis. Herein, we review the therapeutic potential of various types of MSC-EVs in the aforementioned joint diseases, summarise the mechanisms underlying specific biological effects of MSC-EVs, and discuss future prospects for basic research on MSC-EV-based therapeutic modalities and their clinical translation. In general, this review provides an in-depth understanding of the therapeutic effects of MSC-EVs in joint diseases, as well as the underlying mechanisms, which may be beneficial to the clinical translation of MSC-EV-based treatment. The translational potential of this article: MSC-EV-based cell-free therapy can effectively promote regeneration and tissue repair. When used to treat joint diseases, MSC-EVs have demonstrated desirable therapeutic effects in preclinical research. This review may supplement further research on MSC-EV-based treatment of joint diseases and its clinical translation.

Natural products in osteoarthritis treatment: bridging basic research to clinical applications.

Osteoarthritis (OA) is the most prevalent degenerative musculoskeletal disease, severely impacting the function of patients and potentially leading to disability, especially among the elderly population. Natural products (NPs), obtained from components or metabolites of plants, animals, microorganisms etc., have gained significant attention as important conservative treatments for various diseases. Recently, NPs have been well studied in preclinical and clinical researches, showing promising potential in the treatment of OA. In this review, we summed up the main signaling pathways affected by NPs in OA treatment, including NF-κB, MAPKs, PI3K/AKT, SIRT1, and other pathways, which are related to inflammation, anabolism and catabolism, and cell death. In addition, we described the therapeutic effects of NPs in different OA animal models and the current clinical studies in OA patients. At last, we discussed the potential research directions including in-depth analysis of the mechanisms and new application strategies of NPs for the OA treatment, so as to promote the basic research and clinical transformation in the future. We hope that this review may allow us to get a better understanding about the potential bioeffects and mechanisms of NPs in OA therapy, and ultimately improve the effectiveness of NPs-based clinical conservative treatment for OA patients.

Cir-DNA Sequencing Revealed the Landscape of Extrachromosomal Circular DNA in Articular Cartilage and the Potential Roles in Osteoarthritis.

OBJECTIVE: Extrachromosomal circular DNA (eccDNA) has been shown to be involved in several physiological and pathological processes including immunity, inflammation, aging, and tumor. However, the expression of eccDNA in cartilage has not been reported until now. In this study, we aimed to investigate the landscape of eccDNA in articular cartilage and analyze the potential roles in osteoarthritis (OA). METHODS: The samples of articular cartilage were obtained from total knee arthroplasty (TKA) donors with OA. The mitochondrial DNA (mtDNAs) and the linear DNAs from chondrocytes of articular cartilage were removed. Then the eccDNAs were enriched for cir-DNA sequencing. After quality control evaluation, we systematically revealed the identified eccDNA data including size distribution, the size range, and sequence pattern. Moreover, we explored and discussed the potential roles of eccDNA in OA via motif analysis and Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. RESULTS: The chondrocytes from OA cartilage contained an abundance of eccDNAs, which was termed as OC-eccDNAs (OA cartilage-derived eccDNA). The characteristics of OC-eccDNAs were tissue-specific, including the distribution, the size range, and sequence pattern. Moreover, the functional analysis indicated that eccDNA may be involved in the homeostasis maintenance of chondrocytes and participated in the process of OA. CONCLUSIONS: Our data first showed the landscape of eccDNA in articular cartilage and preliminarily indicated the potential roles of eccDNA in OA.

Autophagy in the pathogenesis and therapeutic potential of post-traumatic osteoarthritis.

Autophagy, as a fundamental mechanism for cellular homeostasis, is generally involved in the occurrence and progression of various diseases. Osteoarthritis (OA) is the most common musculoskeletal disease that often leads to pain, disability and economic loss in patients. Post-traumatic OA (PTOA) is a subtype of OA, accounting for >12% of the overall burden of OA. PTOA is often caused by joint injuries including anterior cruciate ligament rupture, meniscus tear and intra-articular fracture. Although a variety of methods have been developed to treat acute joint injury, the current measures have limited success in effectively reducing the incidence and delaying the progression of PTOA. Therefore, the pathogenesis and intervention strategy of PTOA need further study. In the past decade, the roles and mechanisms of autophagy in PTOA have aroused great interest in the field. It was revealed that autophagy could maintain the homeostasis of chondrocytes, reduce joint inflammatory level, prevent chondrocyte death and matrix degradation, which accordingly improved joint symptoms and delayed the progression of PTOA. Moreover, many strategies that target PTOA have been revealed to promote autophagy. In this review,  we summarize the roles and mechanisms of autophagy in PTOA and the current strategies for PTOA treatment that depend on autophagy regulation, which may be beneficial for PTOA patients in the future.