Exosomes derived from microRNA-21 overexpressed adipose tissue-derived mesenchymal stem cells alleviate spine osteoporosis in ankylosing spondylitis mice

Adipose exosomal noncoding RNAs: Roles and mechanisms in metabolic diseases

Exosomes are extracellular vesicles, measuring 40-160 nm in diameter, that are released by many cell types and tissues, including adipose tissue. Exosomes are critical mediators of intercellular communication and their contents are complex and diverse. In recent years, accumulating evidence has proved that multiple adipose tissue-derived exosomal noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), play pivotal roles in the pathogenesis of diverse metabolic diseases, such as obesity. In this narrative review, we focus on the adipose tissue-derived exosomal ncRNAs, especially exosomal miRNAs, and their dysregulation in multiple types of metabolic diseases. A deeper understanding of the role of adipose tissue-derived exosomal ncRNAs may help provide new diagnostic and treatment methods for metabolic diseases.

miR-21-5p-loaded bone mesenchymal stem cell-derived exosomes repair ovarian function in autoimmune premature ovarian insufficiency by targeting MSX1

RESEARCH QUESTION

What is the effect of micro-RNA (miR)-21-5p-loaded bone marrow mesenchymal stem cell-derived exosomes (miR-21-Exo) on autoimmune premature ovarian insufficiency (POI)?

DESIGN

The Cell Counting Kit 8 (CCK8) assay, fluorescence-activated cell sorting, western blotting, quantitative reverse transcriptase (qRT)-PCR and enzyme-linked immunosorbent assay (ELISA) verified the effect of miR-21-Exo on interferon-γ (IFN-γ)-induced KGN cells. qRT-PCR, western blotting and dual-luciferase reporter gene assays verified that miR-21-Exo mediated Msh homeobox 1 (MSX1) regulation of the Notch signalling pathway and that miR-21 interacted directly with MSX1. The effects of miR-21-Exo on the ovaries were verified by monitoring of the oestrous cycle, haematoxylin and eosin staining, follicle counts, ELISA, immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL), western blotting and qRT-PCR.

RESULTS

The results showed that miR-21-Exo promoted IFN-γ-induced KGN cell proliferation and hormone synthesis, and inhibited apoptosis. Using dual-luciferase reporter gene assays, miR-21 and MSX1 were shown to have direct interactions. Moreover, the findings elucidated that miR-21-Exo inhibited cell apoptosis and promoted hormone synthesis by mediating MSX1 to regulate the Notch signalling pathway. miR-21-Exo restored the ovarian structure in a mouse model of autoimmune POI, promoted endocrine function and proliferation, and inhibited apoptosis and inflammation in vivo.

CONCLUSIONS

This study demonstrates that miR-21-Exo regulates the MSX1-mediated Notch signalling pathway to inhibit granulosa cell apoptosis and improve hormone synthesis function, providing insight into a potential mechanism of molecular therapy for the treatment of autoimmune POI.

The Mechanism of "Treating Different Diseases with the Same Treatment" by Qiangji Jianpi Decoction in Ankylosing Spondylitis Combined with Inflammatory Bowel Disease: A Comprehensive Analysis of Multiple Methods

Background

Ankylosing spondylitis (AS) and inflammatory bowel disease (IBD) are prevalent autoimmune disorders that often co-occur, posing significant treatment challenges. This investigation adopts a multidisciplinary strategy, integrating bioinformatics, network pharmacology, molecular docking, and Mendelian randomization, to elucidate the relationship between AS and IBD and to investigate the potential mechanisms of traditional Chinese medicine formulations, represented by Qiangji Jianpi (QJJP) decoction, in treating these comorbid conditions.

Methods

We utilized databases to pinpoint common targets among AS, IBD, and QJJP decoction's active compounds through intersection analysis. Through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, we mapped a network in Cytoscape, isolating critical targets. Molecular docking with AutoDock validated the affinity between targets and compounds. ROC analysis and dataset validation assessed diagnostic performance, while Gene Set Enrichment Analysis (GSEA) offered pathway insights. Mendelian randomization explored the AS-IBD causal relationship.

Results

Screening identified 105 targets for QJJP decoction, 414 for AS, and 2420 for IBD, with 85 overlapping. These targets predominantly participate in organismal responses and DNA transcription factor binding, with a significant cellular presence in the endoplasmic reticulum and vesicle lumen. Molecular docking, facilitated by Cytoscape, confirmed IL1A, IFNG, TGFB1, and EDN1 as critical targets, with IFNG demonstrating diagnostic potential through GEO dataset validation. The integration of GSEA with network pharmacology highlighted the therapeutic significance of the relaxin, osteoclast differentiation, HIF-1, and AGE-RAGE signaling pathways in QJJP decoction's action. Mendelian randomization analysis indicated a positive causal relationship between IBD and AS, pinpointing rs2193041 as a key SNP influencing IFNG.

Conclusion

Based on the principle of "treating different diseases with the same method" in traditional Chinese medicine theory, we explored the intricate mechanisms through which QJJP decoction addresses AS and IBD comorbidity. Our research spotlighted the pivotal role of the IFNG gene. IFNG emerges not only as a key therapeutic target but also assumes significance as a potential diagnostic biomarker through its genetic underpinnings. This investigation establishes a solid base for subsequent experimental inquiries. Our findings introduce novel approaches for incorporating traditional Chinese medicine into the treatment of AS-IBD comorbidity, setting the stage for groundbreaking research directions.

The Potential of Exosomes for Osteoporosis Treatment: A Review

As a continuous process comprising bone resorption and formation, bone remodeling, plays an essential role in maintaining the balance of bone metabolism. One type of metabolic osteopathy is osteoporosis, which is defined by low bone mass and deteriorating bone microstructure. Osteoporosis patients are more likely to experience frequent osteoporotic fractures, which makes osteoporosis prevention and treatment crucial. A growing body of research has revealed that exosomes, which are homogenous vesicles released by most cell types, play a major role in mediating a number of pathophysiological processes, including osteoporosis. Exosomes may act as a mediator in cell-to-cell communication and offer a fresh perspective on information sharing. This review discusses the characteristics of exosomes and outlines the exosomes' underlying mechanism that contributes to the onset of osteoporosis. Recent years have seen a rise in interest in the role of exosomes in osteoporosis, which has given rise to innovative therapeutic approaches for the disease prevention and management.

The role and applications of extracellular vesicles in osteoporosis

Osteoporosis is a widely observed condition characterized by the systemic deterioration of bone mass and microarchitecture, which increases patient susceptibility to fragile fractures. The intricate mechanisms governing bone homeostasis are substantially impacted by extracellular vesicles (EVs), which play crucial roles in both pathological and physiological contexts. EVs derived from various sources exert distinct effects on osteoporosis. Specifically, EVs released by osteoblasts, endothelial cells, myocytes, and mesenchymal stem cells contribute to bone formation due to their unique cargo of proteins, miRNAs, and cytokines. Conversely, EVs secreted by osteoclasts and immune cells promote bone resorption and inhibit bone formation. Furthermore, the use of EVs as therapeutic modalities or biomaterials for diagnosing and managing osteoporosis is promising. Here, we review the current understanding of the impact of EVs on bone homeostasis, including the classification and biogenesis of EVs and the intricate regulatory mechanisms of EVs in osteoporosis. Furthermore, we present an overview of the latest research progress on diagnosing and treating osteoporosis by using EVs. Finally, we discuss the challenges and prospects of translational research on the use of EVs in osteoporosis.

Proteomic and genomic profiling of plasma exosomes from patients with ankylosing spondylitis

INTRODUCTION

Recent advances in understanding the biology of ankylosing spondylitis (AS) using innovative genomic and proteomic approaches offer the opportunity to address current challenges in AS diagnosis and management. Altered expression of genes, microRNAs (miRNAs) or proteins may contribute to immune dysregulation and may play a significant role in the onset and persistence of inflammation in AS. The ability of exosomes to transport miRNAs across cells and alter the phenotype of recipient cells has implicated exosomes in perpetuating inflammation in AS. This study reports the first proteomic and miRNA profiling of plasma-derived exosomes in AS using comprehensive computational biology analysis.

METHODS

Plasma samples from patients with AS and healthy controls (HC) were isolated via ultracentrifugation and subjected to extracellular vesicle flow cytometry analysis to characterise exosome surface markers by a multiplex immunocapture assay. Cytokine profiling of plasma-derived exosomes and cell culture supernatants was performed. Next-generation sequencing was used to identify miRNA populations in exosomes enriched from plasma fractions. CD4+ T cells were sorted, and the frequency and proliferation of CD4+ T-cell subsets were analysed after treatment with AS-exosomes using flow cytometry.

RESULTS

The expression of exosome marker proteins CD63 and CD81 was elevated in the patients with AS compared with HC (q<0.05). Cytokine profiling in plasma-derived AS-exosomes demonstrated downregulation of interleukin (IL)-8 and IL-10 (q<0.05). AS-exosomes cocultured with HC CD4+ T cells induced significant upregulation of IFNα2 and IL-33 (q<0.05). Exosomes from patients with AS inhibited the proliferation of regulatory T cells (Treg), suggesting a mechanism for chronically activated T cells in this disease. Culture of CD4+ T cells from healthy individuals in the presence of AS-exosomes reduced the proliferation of FOXP3+ Treg cells and decreased the frequency of FOXP3+IRF4+ Treg cells. miRNA sequencing identified 24 differentially expressed miRNAs found in circulating exosomes of patients with AS compared with HC; 22 of which were upregulated and 2 were downregulated.

CONCLUSIONS

Individuals with AS have different immunological and genetic profiles, as determined by evaluating the exosomes of these patients. The inhibitory effect of exosomes on Treg in AS suggests a mechanism contributing to chronically activated T cells in this disease.

Impact of immune regulation and differentiation dysfunction of mesenchymal stem cells on the disease process in ankylosing spondylitis and prospective analysis of stem cell transplantation therapy

Ankylosing spondylitis (AS) is a rheumatic bone and joint disease caused by inflammation, erosion, and pathological bone formation. The pathological features of chronic inflammation, bone destruction, and pathological ossification occur due to the disruption of the body's immune regulation and altered bone remodeling balance. Mesenchymal stem cells (MSCs) have multidirectional differentiation potential and immunomodulatory functions and play an important role in immune regulation and bone formation. The immune regulation and osteogenic capacity of MSCs in AS are altered by factors such as genetic background, internal environment, infection, and mechanical forces that drive disease development. This review further evaluates the role of MSCs dysfunction in inflammation and pathological bone formation by analyzing the effects of the above-mentioned factors on MSCs function and also looks forward to the prospects of MSCs in treating AS, providing some ideas for an in-depth study of inflammation and ectopic ossification.

KEY MESSAGES

microRNAs delivered by small extracellular vesicles in MSCs as an emerging tool for bone regeneration

Bone regeneration is a dynamic process that involves angiogenesis and the balance of osteogenesis and osteoclastogenesis. In bone tissue engineering, the transplantation of mesenchymal stem cells (MSCs) is a promising approach to restore bone homeostasis. MSCs, particularly their small extracellular vesicles (sEVs), exert therapeutic effects due to their paracrine capability. Increasing evidence indicates that microRNAs (miRNAs) delivered by sEVs from MSCs (MSCs-sEVs) can alter gene expression in recipient cells and enhance bone regeneration. As an ideal delivery vehicle of miRNAs, MSCs-sEVs combine the high bioavailability and stability of sEVs with osteogenic ability of miRNAs, which can effectively overcome the challenge of low delivery efficiency in miRNA therapy. In this review, we focus on the recent advancements in the use of miRNAs delivered by MSCs-sEVs for bone regeneration and disorders. Additionally, we summarize the changes in miRNA expression in osteogenic-related MSCs-sEVs under different microenvironments.

Biomimetic synthesis and optimization of extracellular vesicles for bone regeneration

Critical-size bone defect repair is in high demand but is difficult to treat. Modern therapies, such as autograft and cell-based treatments, face limitations, including potential immunological rejection and tumorigenesis. Therefore, extracellular vesicle (EV)-based strategies have been proposed as a novel approach for tissue regeneration owing to EVs' complex composition of lipids, proteins, and nucleic acids, as well as their low immunogenicity and congenital cell-targeting features. Despite these remarkable features of EVs, biomimetic synthesis and optimization of natural EVs can lead to enhanced bioactivity, increased cellular uptake, and specific cell targeting, aiming to achieve optimal therapeutic efficacy. To maximize their function, these nanoparticles can be integrated into bone graft biomaterials for superior bone regeneration. Herein, we summarize the role of naturally occurring EVs from distinct cell types in bone regeneration, the current strategies for optimizing biomimetic synthetic EVs in bone regeneration, and discuss the recent advances in applying bone graft biomaterials for the delivery of EVs to bone defect repair. We focused on distinct strategies for optimizing EVs with different functions and the most recent research on achieving time-controlled release of nanoparticles from EV-loaded biomaterials. Furthermore, we thoroughly discuss several current challenges and proposed solutions, aiming to provide insight into current progress, inspiration for future development directions, and incentives for clinical application in this field.

In situ detection of exosomal RNAs for cancer diagnosis

Exosomes are considered as biomarkers reflecting the physiological state of the human body. Studies have revealed that the expression levels of specific exosomal RNAs are closely associated with certain cancers. Thus, detection of exosomal RNA offers a new avenue for liquid biopsy of cancers. Many exosomal RNA detection methods based on various principles have been developed, and most of the methods detect the extracted RNAs after lysing exosomes. Besides complex and time-consuming extraction steps, a major drawback of this approach is the degradation of the extracted RNAs in the absence of plasma membrane and cytosol. In addition, there is considerable loss of RNAs during their extraction. In situ detection of exosomal RNAs can avoid these drawbacks, thus allowing higher diagnostic reliability. In this paper, in situ detection of exosomal RNAs was systematically reviewed from the perspectives of detection methods, transport methods of the probe systems, probe structures, signal amplification strategies, and involved functional materials. Furthermore, the limitations and possible improvements of the current in situ detection methods for exosomal RNAs towards the clinical diagnostic application are discussed. This review aims to provide a valuable reference for the development of in situ exosomal RNA detection strategies for non-invasive diagnosis of cancers. STATEMENT OF SIGNIFICANCE: Certain RNAs have been identified as valuable biomarkers for some cancers, and sensitive detection of cancer-related RNAs is expected to achieve better diagnostic efficacy. Currently, the detection of exosomal RNAs is receiving increasing attention due to their high stability and significant concentration differences between patients and healthy individuals. In situ detection of exosomal RNAs has greater diagnostic reliability due to the avoidance of RNA degradation and loss. However, this mode is still limited by some factors such as detection methods, transport methods of the probe systems, probe structures, signal amplification strategies, etc. This review focuses on the progress of in situ detection of exosomal RNAs and aims to promote the development of this field.

Extracellular vesicles rejuvenate the microenvironmental modulating function of recipient tissue-specific mesenchymal stem cells in osteopenia treatment

Systemic transplantation of mesenchymal stem cells (MSCs), such as bone marrow MSCs (BMMSCs) and stem cells from human exfoliated deciduous teeth (SHED), is considered a prominent treatment for osteopenia. However, the mechanism of action of the transplanted MSCs has been poorly elucidated. In the recipient target tissue, including bone and bone marrow, only a few donor MSCs can be detected, suggesting that the direct contribution of donor MSCs may not be expected for osteopenia treatment. Meanwhile, secretomes, especially contents within extracellular vesicles (EVs) released from donor MSCs (MSC-EVs), play key roles in the treatment of several diseases. In this context, administrated donor MSC-EVs may affect bone-forming function of recipient cells. In this review, we discuss how MSC-EVs contribute to bone recovery recipient tissue in osteopenia. We also summarize a novel mechanism of action of systemic administration of SHED-derived EVs (SHED-EVs) in osteopenia. We found that reduced telomerase activity in recipient BMMSCs caused the deficiency of microenvironmental modulating function, including bone and bone marrow-like niche formation and immunomodulation in estrogen-deficient osteopenia model mice. Systemic administration of SHED-EVs could exert therapeutic effects on bone reduction via recovering the telomerase activity, leading to the rejuvenation of the microenvironmental modulating function in recipient BMMSCs, as seen in systemic transplantation of SHED. RNase-preconditioned donor SHED-EVs diminished the therapeutic benefits of administrated SHED-EVs in the recipient osteopenia model mice. These facts suggest that MSC-EV therapy targets the recipient BMMSCs to rejuvenate the microenvironmental modulating function via telomerase activity, recovering bone density. We then introduce future challenges to develop the reproducible MSC-EV therapy in osteopenia.

Novel regulatory role of non-coding RNAs in ankylosing spondylitis

Ankylosing spondylitis (AS) is a type of arthritis that primarily affects the spine and involves disorders of the immune and skeletal systems. However, the exact pathogenesis of AS is not fully understood. Non-coding RNAs (ncRNAs), particularly, long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and micro RNAs (miRNAs) and their interactions have been shown to influence many biological processes such as inflammatory responses, osteogenic differentiation and apoptosis, pyroptosis, and proliferation. In addition, ncRNAs reflect the disease activity of AS. In this review, we discuss the regulatory roles of ncRNAs in AS cell functions (inflammatory responses, cellular osteogenic differentiation and apoptosis, pyroptosis, and proliferation) and their potential applications in AS diagnosis and treatment. Understanding the role of ncRNAs in the pathogenesis of AS will lay the foundation for exploring potential new therapeutic approaches for AS.