Emerging role of extracellular vesicles in musculoskeletal diseases

Adipose-derived small extracellular vesicle miR-146a-5p targets Fbx32 to regulate mitochondrial autophagy and delay aging in skeletal muscle

This study investigates how miR-146a-5p, found in adipose tissue-derived small extracellular vesicles (sEV), influences mitochondrial autophagy and its impact on delaying skeletal muscle aging through the targeting of Fbx32. The findings highlight miR-146a-5p as crucial in skeletal muscle development and aging, influencing autophagy, apoptosis, differentiation, and proliferation, collectively impacting muscle atrophy. In C2C12 cells, miR-146a-5p mimics decreased apoptosis, autophagy, and reactive oxygen species (ROS) levels, while enhancing ATP production; conversely, miR-146a-5p inhibitors had the opposite effects. Furthermore, miR-146a-5p-enriched sEV from adipose tissue alleviated skeletal muscle atrophy in aged mice and promoted muscle fiber growth and repair by regulating mitochondrial autophagy and apoptosis. Mechanistically, miR-146a-5p modulated mitochondrial autophagy in myoblasts by targeting Fbx32 and impacting the FoxO3 signaling pathway. This led to a notable decrease in apoptosis-related gene expression, reduced ROS production, and elevated ATP levels. In conclusion, miR-146a-5p derived from WAT-sEV modulates myoblast autophagy, apoptosis, ROS, and differentiation through the Fbx32/FoxO3 signaling axis. This work presents a novel molecular target and theoretical framework for delaying skeletal muscle aging and developing therapies for skeletal muscle-related disorders.

Exosomes of stem cells: a potential frontier in the treatment of osteoarthritis

The aging population has led to a global issue of osteoarthritis (OA), which not only impacts the quality of life for patients but also poses a significant economic burden on society. While biotherapy offers hope for OA treatment, currently available treatments are unable to delay or prevent the onset or progression of OA. Recent studies have shown that as nanoscale bioactive substances that mediate cell communication, exosomes from stem cell sources have led to some breakthroughs in the treatment of OA and have important clinical significance. This paper summarizes the mechanism and function of stem cell exosomes in delaying OA and looks forward to the development prospects and challenges of exosomes.

The Regenerative Marriage Between High-Density Platelet-Rich Plasma and Adipose Tissue

The use of autologous biological preparations (ABPs) and their combinations fills the void in healthcare treatment options that exists between surgical procedures, like plastic reconstructive, cosmetic, and orthopedic surgeries; non-surgical musculoskeletal biological procedures; and current pharmaceutical treatments. ABPs, including high-density platelet-rich plasma (HD-PRP), bone marrow aspirate concentrates (BMACs), and adipose tissue preparations, with their unique stromal vascular fractions (SVFs), can play important roles in tissue regeneration and repair processes. They can be easily and safely prepared at the point of care. Healthcare professionals can employ ABPs to mimic the classical wound healing cascade, initiate the angiogenesis cascade, and induce tissue regenerative pathways, aiming to restore the integrity and function of damaged tissues. In this review, we will address combining autologous HD-PRP with adipose tissue, in particular the tissue stromal vascular fraction (t-SVF), as we believe that this biocellular combination demonstrates a synergistic effect, where the HD-PRP constituents enhance the regenerative potential of t-SVF and its adipose-derived mesenchymal stem cells (AD-MSCs) and pericytes, leading to improved functional tissue repair, tissue regeneration, and wound healing in variety of clinical applications. We will address some relevant platelet bio-physiological aspects, since these properties contribute to the synergistic effects of combining HD-PRP with t-SVF, promoting overall better outcomes in chronic inflammatory conditions, soft tissue repair, and tissue rejuvenation.

Engineered extracellular vesicles with sequential cell recruitment and osteogenic functions to effectively promote senescent bone repair

Senescent mandibular bone repair poses a formidable challenge without a completely satisfactory strategy. Endogenous cell recruitment and osteogenic differentiation are two sequential stages in bone regeneration, and disruptions in these two processes present significant obstacles to senescent bone repair. To address these issues, engineered extracellular vesicles (EV) with sequential stem cell recruitment and osteogenic functions were developed. This study demonstrated that Apt19s-engineered extracellular vesicles (Apt19s-EV) recognize and recruit bone marrow mesenchymal stem cells derived from old rats (O-BMSCs) specifically and effectively. MiR-376b-5p, identified by RNA sequencing and transfection, was significantly decreased in O-BMSCs, and it was selected to construct miR-376b-5p-engineered extracellular vesicles (376b-EV). 376b-EV could promote osteogenesis and alleviate senescence of O-BMSCs by targeting Camsap1. To combine the advantages of Apt19s and miR-376b-5p, dual engineered extracellular vesicles (Apt-376b-EV) comprising both Apt19s and miR-376b-5p modifications were constructed. To further validate its function, Gelatin methacryloyl (GelMA) hydrogel was used as a carrier to construct the Apt-376b-EV@GelMA delivery system. The in vitro results have demonstrated that Apt-376b-EV@GelMA could recruit O-BMSCs, alleviate senescence and promote osteogenic differentiation sequentially. Notably, the in vivo study also showed that Apt-376b-EV@GelMA could sequentially recruit endogenous stem cells and enhance new bone formation in senescent bone fracture and critical-sized defect models. In summary, the dual engineered extracellular vesicles, Apt-376b-EV, offer an appealing solution for recruiting endogenous stem cells and promoting bone repair sequentially in the senescent microenvironment, which may broaden the clinical applications of engineered EV and provide valuable strategies for treating senescent bone-related diseases in the future clinical work.

Extracellular Vesicles Derived from Human Umbilical Mesenchymal Stem Cells Transfected with miR-7704 Improved Damaged Cartilage and Reduced Matrix Metallopeptidase 13

We aimed to explore the therapeutic efficacy of miR-7704-modified extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (HUCMSCs) for osteoarthritis (OA) treatment. In vitro experiments demonstrated the successful transfection of miR-7704 into HUCMSCs and the isolation of EVs from these cells. In vivo experiments used an OA mouse model to assess the effects of the injection of miR-7704-modified EVs intra-articularly. Walking capacity (rotarod test), cartilage morphology, histological scores, and the expression of type II collagen, aggrecan, interleukin-1 beta, and matrix metalloproteinase 13 (MMP13) in the cartilage were evaluated. The EVs were characterized to confirm their suitability for therapeutic use. IL-1beta-treated chondrocytes increased type II collagen and decreased MMP13 after treatment with miR-7704-overexpressed EVs. In vivo experiments revealed that an intra-articular injection of miR-7704-overexpressed EVs significantly improved walking capacity, preserved cartilage morphology, and resulted in higher histological scores compared to in the controls. Furthermore, the decreased expression of MMP13 in the cartilage post treatment suggests a potential mechanism for the observed therapeutic effects. Therefore, miR-7704-overexpressed EVs derived from HUCMSCs showed potential as an innovative therapeutic strategy for treating OA. Further investigations should focus on optimizing dosage, understanding mechanisms, ensuring safety and efficacy, developing advanced delivery systems, and conducting early-phase clinical trials to establish the therapeutic potential of HUCMSC-derived EVs for OA management.

Extracellular derivatives for bone metabolism

BACKGROUND

Bone metabolism can maintain the normal homeostasis and function of bone tissue. Once the bone metabolism balance is broken, it will cause osteoporosis, osteoarthritis, bone defects, bone tumors, or other bone diseases. However, such orthopedic diseases still have many limitations in clinical treatment, such as drug restrictions, drug tolerance, drug side effects, and implant rejection.

AIM OF REVIEW

In complex bone therapy and bone regeneration, extracellular derivatives have become a promising research focus to solve the problems of bone metabolic diseases. These derivatives, which include components such as extracellular matrix, growth factors, and extracellular vesicles, have significant therapeutic potential. It has the advantages of good biocompatibility, low immune response, and dynamic demand for bone tissue. The purpose of this review is to provide a comprehensive perspective on extracellular derivatives for bone metabolism and elucidate the intrinsic properties and versatility of extracellular derivatives. Further discussion of them as innovative advanced orthopedic materials for improving the effectiveness of bone therapy and regeneration processes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we first listed the types and functions of three extracellular derivatives. Then, we discussed the effects of extracellular derivatives of different cell sources on bone metabolism. Subsequently, we collected applications of extracellular derivatives in the treatment of bone metabolic diseases and summarized the advantages and challenges of extracellular derivatives in clinical applications. Finally, we prospected the extracellular derivatives in novel orthopedic materials and clinical applications. We hope that the comprehensive understanding of extracellular derivatives in bone metabolism will provide new solutions to bone diseases.

Distribution and Incorporation of Extracellular Vesicles into Chondrocytes and Synoviocytes

Osteoarthritis (OA) is a chronic disease affecting over 500 million people worldwide. As the population ages and obesity rates rise, the societal burden of OA is increasing. Pro-inflammatory cytokines, particularly interleukin-1β, are implicated in the pathogenesis of OA. Recent studies suggest that crosstalk between cartilage and synovium contributes to OA development, but the mechanisms remain unclear. Extracellular vesicles (EVs) were purified from cell culture-conditioned medium via ultracentrifugation and confirmed using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. We demonstrated that EVs were taken up by human synoviocytes and chondrocytes in vitro, while in vivo experiments revealed that fluorescent-labelled EVs injected into mouse joints were incorporated into chondrocytes and synoviocytes. EV uptake was significantly inhibited by dynamin-mediated endocytosis inhibitors, indicating that endocytosis plays a major role in this process. Additionally, co-culture experiments with HEK-293 cells expressing red fluorescent protein (RFP)-tagged CD9 and the chondrocytic cell line OUMS-27 confirmed the transfer of RFP-positive EVs across a 600-nm but not a 30-nm filter. These findings suggest that EVs from chondrocytes are released into joint fluid and taken up by cells within the cartilage, potentially facilitating communication between cartilage and synovium. The results underscore the importance of EVs in OA pathophysiology.

The impact of exosomes on bone health: A focus on osteoporosis

Osteoporosis is a widespread chronic condition. Although standard treatments are generally effective, they are frequently constrained by side effects and the risk of developing drug resistance. A promising area of research is the investigation of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, which play a crucial role in bone metabolism. Exosomes, in particular, have shown significant potential in both the diagnosis and treatment of osteoporosis. EVs derived from osteoclasts, osteoblasts, mesenchymal stem cells, and other sources can influence bone metabolism, while exosomes from inflammatory and tumor cells may exacerbate bone loss, highlighting their dual role in osteoporosis pathology. This review offers a comprehensive overview of EV biogenesis, composition, and function in osteoporosis, focusing on their diagnostic and therapeutic potential. We examine the roles of various types of EVs and their cargo-proteins, RNAs, and lipids-in bone metabolism. Additionally, we explore the emerging applications of EVs as biomarkers and therapeutic agents, emphasizing the need for further research to address current challenges and enhance EV-based strategies for managing osteoporosis.

New perspectives of the role of skeletal muscle derived extracellular vesicles in the pathogenesis of amyotrophic lateral sclerosis: the 'dying back' hypothesis

Amyotrophic lateral sclerosis (ALS), is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord, and is characterized by muscle weakness, paralysis and ultimately, respiratory failure. The exact causes of ALS are not understood, though it is believed to combine genetic and environmental factors. Until now, it was admitted that motor neurons (MN) in the brain and spinal cord degenerate, leading to muscle weakness and paralysis. However, as ALS symptoms typically begin with muscle weakness or stiffness, a new hypothesis has recently emerged to explain the development of the pathology, that is, the 'dying back hypothesis', suggesting that this degeneration starts at the connections between MN and muscles, resulting in the loss of muscle function. Over time, this damage extends along the length of the MN, ultimately affecting their cell bodies in the spinal cord and brain. While the dying back hypothesis provides a potential framework for understanding the progression of ALS, the exact mechanisms underlying the disease remain complex and not fully understood. In this review, we are positioning the role of extracellular vesicles as new actors in ALS development.

Harnessing exosomes for advanced osteoarthritis therapy

Exosomes are nanosized, lipid membrane vesicles secreted by cells, facilitating intercellular communication by transferring cargo from parent to recipient cells. This capability enables biological crosstalk across multiple tissues and cells. Extensive research has been conducted on their role in the pathogenesis of degenerative musculoskeletal diseases such as osteoarthritis (OA), a chronic and painful joint disease that particularly affects cartilage. Currently, no effective treatment exists for OA. Given that exosomes naturally modulate synovial joint inflammation and facilitate cartilage matrix synthesis, they are promising candidates as next generation nanocarriers for OA therapy. Recent advancements have focused on engineering exosomes through endogenous and exogenous approaches to enhance their joint retention, cartilage and chondrocyte targeting properties, and therapeutic content enrichment, further increasing their potential for OA drug delivery. Notably, charge-reversed exosomes that utilize electrostatic binding interactions with cartilage anionic aggrecan glycosaminoglycans have demonstrated the ability to penetrate the full thickness of early-stage arthritic cartilage tissue following intra-articular administration, maximizing their therapeutic potential. These exosomes offer a non-viral, naturally derived, cell-free carrier for OA drug and gene delivery applications. Efforts to standardize exosome harvest, engineering, and property characterization methods, along with scaling up production, will facilitate more efficient and rapid clinical translation. This article reviews the current state-of-the-art, explores opportunities for exosomes as OA therapeutics, and identifies potential challenges in their clinical translation.

Cinobufagin Suppresses Lipid Peroxidation and Inflammation in Osteoporotic Mice by Promoting the Delivery of miR-3102-5p by Macrophage-Derived Exosomes

BACKGROUND

Cinobufagin, the primary active compound in toad venom, is commonly used for anti-tumor, anti-inflammatory, and analgesic purposes. However, its specific bone-protective effects remain uncertain. This research aims to ascertain the bone-protective properties of cinobufagin and investigate underlying mechanisms.

METHODS

Mice were ovariectomized to establish an osteoporosis model, followed by intraperitoneal injections of cinobufagin and cinobufagin-treated RAW.264.7-derived exosomes for therapy. MicroCT, HE staining, and TRAP staining were employed to evaluate bone mass and therapeutic outcomes, while mRNA sequencing and immunoblotting were utilized to assess markers of bone metabolism, inflammation, and lipid peroxidation. Osteoblast and osteoclast precursor cells were differentiated to observe the impact of cinobufagin-treated exosomes derived from RAW264.7 cells on bone metabolism. Exosomes characteristics were studied using transmission electron microscopy and particle size analysis, and miRNA binding targets in exosomes were determined by luciferase reporting.

RESULTS

In ovariectomized mice, cinobufagin and cinobufagin-treated exosomes from RAW264.7 cells increased trabecular bone density and mass in the femur, while also decreasing inflammation and lipid peroxidation. The effect was reversed by an exosomes inhibitor. In vitro experiments revealed that cinobufagin-treated exosomes from RAW264.7 cells enhanced osteogenic and suppressed osteoclast differentiation, possibly linked to Upregulated miR-3102-5p in RAW-derived exosomes. MiR-3102-5p targets the 3'UTR region of alox15, thereby suppressing its expression and reducing the lipid peroxidation process in osteoblasts.

CONCLUSION

Overall, this study clarified cinobufagin's bone-protective effects and revealed that cinobufagin can enhance the delivery of miR-3102-5p targeting alox15 through macrophage-derived exosomes, demonstrating anti-lipid peroxidation and anti-inflammatory effects.

Delivering Microrobots in the Musculoskeletal System

Disorders of the musculoskeletal system are the major contributors to the global burden of disease and current treatments show limited efficacy. Patients often suffer chronic pain and might eventually have to undergo end-stage surgery. Therefore, future treatments should focus on early detection and intervention of regional lesions. Microrobots have been gradually used in organisms due to their advantages of intelligent, precise and minimally invasive targeted delivery. Through the combination of control and imaging systems, microrobots with good biosafety can be delivered to the desired area for treatment. In the musculoskeletal system, microrobots are mainly utilized to transport stem cells/drugs or to remove hazardous substances from the body. Compared to traditional biomaterial and tissue engineering strategies, active motion improves the efficiency and penetration of local targeting of cells/drugs. This review discusses the frontier applications of microrobotic systems in different tissues of the musculoskeletal system. We summarize the challenges and barriers that hinder clinical translation by evaluating the characteristics of different microrobots and finally point out the future direction of microrobots in the musculoskeletal system.

The roles of extracellular vesicles released by mechanically stimulated osteocytes in regulating osteoblast and osteoclast functions

Bone adapts to mechanical loading by changing its shape and mass. Osteocytes, as major mechanosensors, are critical for bone modeling/remodeling in response to mechanical stimuli. Intracellular calcium oscillation is one of the early responses in osteocytes, and this further facilitates bone cell communication through released biochemical signals. Our previous study has found that mechanically induced calcium oscillations in osteocytes enhance the release of extracellular vesicles (EVs), and those released EVs can elevate bone formation activity. However, the mechanism of mechanically stimulated EVs' regulation of bone formation and resorption is still unclear. Here, using in vitro studies, we exposed OCY454 cells, with relatively high sclerostin expression, to steady fluid flow (SFF) and characterized the functions of rapidly released EVs in osteoblast and osteoclast regulation. Our study demonstrates that SFF stimulates intracellular calcium response in OCY454 cells and further induces sclerostin, osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL) inside or outside EVs to regulate osteoblast and osteoclast activities. This load-induced protein and EVs release is load-duration dependent. Moreover, stimulated osteocytes rapidly regulate osteoclast maturation through EVs capsulated RANKL. In contrast, other regulating proteins, OPG, and sclerostin, are mainly released directly into the medium without EV capsulation.

Exosomes in the pathogenesis and treatment of cancer-related cachexia

Cancer-related cachexia is a metabolic syndrome characterized by weight loss, adipose tissue decomposition, and progressive skeletal muscle atrophy. It is a major complication of many advanced cancers and seriously affects the quality of life and survival of cancer patients. However, the specific molecules that mediate cancer-related cachexia remain elusive, and the fundamental cellular and molecular mechanisms associated with muscle atrophy and lipidolysis in cancer patients still need to be investigated. Exosomes, a newly discovered class of small extracellular vesicles that facilitate intercellular communication, have a significant role in the onset and development of various cancers. Studies have shown that exosomes play a role in the onset and progression of cancer-related cachexia by transporting active molecules such as nucleic acids and proteins. This review aimed to provide an overview of exosome developments in cancer-induced skeletal muscle atrophy and adipose tissue degradation. More importantly, exosomes were shown to have potential as diagnostic markers or therapeutic strategies for cachexia and were prospected, providing novel strategies for the diagnosis and treatment of cancer-related cachexia.

The potential role of stem cells-derived extracellular vesicles in the treatment of musculoskeletal system diseases

The therapeutic potential of stem cells-derived extracellular vesicles (EVs) has shown a great progress in the regenerative medicine. EVs are rich in a variety of bioactive substances, which are important carriers of signal transmission and interactions between cells, and they play an important role in the processes of tissue repair and regeneration. Several studies have shown that stem cells-derived EVs regulate immunity, promote cell proliferation and differentiation, enhance bone and vascular regeneration, and play an increasingly important role in musculoskeletal system. This review aimed to describe the biological characteristics of stem cells-derived EVs and discuss their potential role in the therapy of musculoskeletal system diseases.

Muscle Progenitor Cell Fusion in the Maintenance of Skeletal Muscle

Skeletal muscle possesses a resident, multipotent stem cell population that is essential for its repair and maintenance throughout life. Here I highlight the role of this stem cell population in muscle repair and regeneration and review the genetic control of the process; the mechanistic steps of activation, migration, recognition, adhesion, and fusion of these cells; and discuss the novel recognition of the membrane signaling that coordinates myogenic cell-cell fusion, as well as the identification of a two-part fusogen system that facilitates it.

Extracellular Vesicles in Triple-Negative Breast Cancer: Immune Regulation, Biomarkers, and Immunotherapeutic Potential

Triple-negative breast cancer (TNBC) is an aggressive subtype accounting for ~10-20% of all human BC and is characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) amplification. Owing to its unique molecular profile and limited targeted therapies, TNBC treatment poses significant challenges. Unlike other BC subtypes, TNBC lacks specific molecular targets, rendering endocrine therapies and HER2-targeted treatments ineffective. The chemotherapeutic regimen is the predominant systemic treatment modality for TNBC in current clinical practice. However, the efficacy of chemotherapy in TNBC is variable, with response rates varying between a wide range of patients, and the emerging resistance further adds to the difficulties. Furthermore, TNBC exhibits a higher mutational burden and is acknowledged as the most immunogenic of all BC subtypes. Consequently, the application of immune checkpoint inhibition has been investigated in TNBC, yielding promising outcomes. Recent evidence identified extracellular vesicles (EVs) as an important contributor in the context of TNBC immunotherapy. In view of the extraordinary ability of EVs to transfer bioactive molecules, such as proteins, lipids, DNA, mRNAs, and small miRNAs, between the cells, EVs are considered a promising diagnostic biomarker and novel drug delivery system among the prospects for immunotherapy. The present review provides an in-depth understanding of how EVs influence TNBC progression, its immune regulation, and their contribution as a predictive biomarker for TNBC. The final part of the review focuses on the recent key advances in immunotherapeutic strategies for better understanding the complex interplay between EVs and the immune system in TNBC and further developing EV-based targeted immunotherapies.

Novel insights of EZH2-mediated epigenetic modifications in degenerative musculoskeletal diseases

Degenerative musculoskeletal diseases (Osteoporosis, Osteoarthritis, Degenerative Spinal Disease and Sarcopenia) are pathological conditions that affect the function and pain of tissues such as bone, cartilage, and muscles, and are closely associated with ageing and long-term degeneration. Enhancer of zeste homolog 2 (EZH2), an important epigenetic regulator, regulates gene expression mainly through the PRC2-dependent trimethylation of histone H3 at lysine 27 (H3K27me3). Increasing evidence suggests that EZH2 is involved in several biological processes closely related to degenerative musculoskeletal diseases, such as osteogenic-adipogenic differentiation of bone marrow mesenchymal stem cells, osteoclast activation, chondrocyte functional status, and satellite cell proliferation and differentiation, mainly through epigenetic regulation (H3K27me3). Therefore, the synthesis and elucidation of the role of EZH2 in degenerative musculoskeletal diseases have attracted increasing attention. In addition, although EZH2 inhibitors have been approved for clinical use, whether they can be repurposed for the treatment of degenerative musculoskeletal diseases needs to be considered. Here, we reviewed the role of EZH2 in the development of degenerative musculoskeletal diseases and brought forward prospects of its pharmacological inhibitors in the improvement of the treatment of the diseases.

Amniotic Membrane-Derived Stromal Cells Release Extracellular Vesicles That Favor Regeneration of Dystrophic Skeletal Muscles

Duchenne muscular dystrophy (DMD) is a muscle disease caused by mutations in the dystrophin gene characterized by myofiber fragility and progressive muscle degeneration. The genetic defect results in a reduced number of self-renewing muscle stem cells (MuSCs) and an impairment of their activation and differentiation, which lead to the exhaustion of skeletal muscle regeneration potential and muscle replacement by fibrotic and fatty tissue. In this study, we focused on an unexplored strategy to improve MuSC function and to preserve their niche based on the regenerative properties of mesenchymal stromal cells from the amniotic membrane (hAMSCs), that are multipotent cells recognized to have a role in tissue repair in different disease models. We demonstrate that the hAMSC secretome (CM hAMSC) and extracellular vesicles (EVs) isolated thereof directly stimulate the in vitro proliferation and differentiation of human myoblasts and mouse MuSC from dystrophic muscles. Furthermore, we demonstrate that hAMSC secreted factors modulate the muscle stem cell niche in dystrophic-mdx-mice. Interestingly, local injection of EV hAMSC in mdx muscles correlated with an increase in the number of activated Pax7+/Ki67+ MuSCs and in new fiber formation. EV hAMSCs also significantly reduced muscle collagen deposition, thus counteracting fibrosis and MuSCs exhaustion, two hallmarks of DMD. Herein for the first time we demonstrate that CM hAMSC and EVs derived thereof promote muscle regeneration by supporting proliferation and differentiation of resident muscle stem cells. These results pave the way for the development of a novel treatment to counteract DMD progression by reducing fibrosis and enhancing myogenesis in dystrophic muscles.

Beyond Macromolecules: Extracellular Vesicles as Regulators of Inflammatory Diseases

Inflammation is the defense mechanism of the immune system against harmful stimuli such as pathogens, toxic compounds, damaged cells, radiation, etc., and is characterized by tissue redness, swelling, heat generation, pain, and loss of tissue functions. Inflammation is essential in the recruitment of immune cells at the site of infection, which not only aids in the elimination of the cause, but also initiates the healing process. However, prolonged inflammation often brings about several chronic inflammatory disorders; hence, a balance between the pro- and anti-inflammatory responses is essential in order to eliminate the cause while producing the least damage to the host. A growing body of evidence indicates that extracellular vesicles (EVs) play a major role in cell-cell communication via the transfer of bioactive molecules in the form of proteins, lipids, DNA, RNAs, miRNAs, etc., between the cells. The present review provides a brief classification of the EVs followed by a detailed description of how EVs contribute to the pathogenesis of various inflammation-associated diseases and their implications as a therapeutic measure. The latter part of the review also highlights how EVs act as a bridging entity in blood coagulation disorders and associated inflammation. The findings illustrated in the present review may open a new therapeutic window to target EV-associated inflammatory responses, thereby minimizing the negative outcomes.

Mitochondrial-derived vesicles in skeletal muscle remodeling and adaptation

Mitochondrial remodeling is crucial to meet the bioenergetic demand to support muscle contractile activity during daily tasks and muscle regeneration following injury. A set of mitochondrial quality control (MQC) processes, including mitochondrial biogenesis, dynamics, and mitophagy, are in place to maintain a well-functioning mitochondrial network and support muscle regeneration. Alterations in any of these pathways compromises mitochondrial quality and may potentially lead to impaired myogenesis, defective muscle regeneration, and ultimately loss of muscle function. Among MQC processes, mitophagy has gained special attention for its implication in the clearance of dysfunctional mitochondria via crosstalk with the endo-lysosomal system, a major cell degradative route. Along this pathway, additional opportunities for mitochondrial disposal have been identified that may also signal at the systemic level. This communication occurs via inclusion of mitochondrial components within membranous shuttles named mitochondrial-derived vesicles (MDVs). Here, we discuss MDV generation and release as a mitophagy-complementing route for the maintenance of mitochondrial homeostasis in skeletal myocytes. We also illustrate the possible role of muscle-derived MDVs in immune signaling during muscle remodeling and adaptation.

Extracellular vesicles in the treatment and prevention of osteoarthritis: can horses help us translate this therapy to humans?

Osteoarthritis (OA) is a common joint disease affecting humans and horses, resulting in significant morbidity, financial expense, and loss of athletic use. While the pathogenesis is incompletely understood, inflammation is considered crucial in the development and progression of the disease. Mesenchymal stromal cells (MSCs) have received increasing scientific attention for their anti-inflammatory, immunomodulatory, and pro-regenerative effects. However, there are concerns about their ability to become a commercially available therapeutic. Extracellular vesicles (EVs) are now recognized to play a crucial role in the therapeutic efficacy observed with MSCs and offer a potentially novel cell-free therapeutic that may negate many of the concerns with MSCs. There is evidence that EVs have profound anti-inflammatory, immunomodulatory, and pro-regenerative effects equal to or greater than the MSCs they are derived from in the treatment of OA. Most of these studies are in small animal models, limiting the translation of these results to humans. However, highly translational animal models are crucial for further understanding the efficacy of potential therapeutics and for close comparisons with humans. For this reason, the horse, which experiences the same gravitational impacts on joints similar to people, is a highly relevant large animal species for testing. The equine species has well-designed and validated OA models, and additionally, therapies can be further tested in naturally occurring OA to validate preclinical model testing. Therefore, the horse is a highly suitable model to increase our knowledge of the therapeutic potential of EVs.

Osteoblasts-Derived Exosomal lncRNA-MALAT1 Promotes Osteoclastogenesis by Targeting the miR-124/NFATc1 Signaling Axis in Bone Marrow-Derived Macrophages

Objective

Emerging studies have explained the crucial role of non-coding RNA (lncRNA) in various pathological progressions. The study was designed to examine the role of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and miRNA-124 in the differentiation of osteoclasts, to provide new clues or evidences for the pathogenesis of periodontitis.

Methods

We constructed an osteoblast-osteoclast Transwell co-culture system and osteoblast-derived exosomes (OB-exo) intervention model. We assessed the osteoclastogenesis as well as the level of lncRNA-MALAT1 and miRNA-124. The mechanism for lncRNA MALAT1 targeting miR-124 modulating the differentiation of osteoclasts was investigated by cell transfection, quantitative real-time reverse transcription PCR (RT-qPCR), Western blot, and Dual-Luciferase reporter assays.

Results

Osteoblast-derived exosomes were isolated and identified. Co-culture and OB-exo intervention can promote osteoclastogenesis, also significantly up-regulate the expression of MALAT1, while the level of miR-124 is the opposite. Transfection of cells with small interfering RNA (si-MALAT1) and miR-124 mimic decreased the formation of TRAP⁺ osteoclasts and inhibited the expression of NFATc1. However, the effect was reversed when transfected with miR-124 inhibitor and si-MALAT1. The Dual-Luciferase reporter assay confirmed the binding sites between MALAT1 and miR-124, and miR-124 and NFATc1.

Conclusion

LncRNA MALAT1 functioned as an endogenous sponge by competing for miR-124 binding to regulate NFATc1 expression, accelerating the progression of osteoclastogenesis.

Soluble and EV-Associated Diagnostic and Prognostic Biomarkers in Knee Osteoarthritis Pathology and Detection

Osteoarthritis (OA) is the most common degenerative disease of the connective tissue of the human musculoskeletal system. Despite its widespread prevalence, there are many limitations in its diagnosis and treatment. OA diagnosis currently relies on the presence of clinical symptoms, sometimes accompanied by changes in joint X-rays or MRIs. Biomarkers help not only to diagnose early disease progression but also to understand the process of OA in many ways. In this article, we briefly summarize information on articular joints and joint tissues, the pathogenesis of OA and review the literature about biomarkers in the field of OA, specifically inflammatory cytokines/chemokines, proteins, miRNA, and metabolic biomarkers found in the blood, synovial fluid and in extracellular vesicles.

Synovial fibroblast-miR-214-3p-derived exosomes inhibit inflammation and degeneration of cartilage tissues of osteoarthritis rats

MicroRNAs (miRs) are regulators of number of cellular process. miRs enclosed within exosomes can be crucial regulators of intercellular signalling and could be an important biomarker of various age-associated disorders. Role of exosomal enclosed miRs in osteoarthritis (OA) chondrocytes and synovial fibroblasts (SFBs) remains poorly studied. Here, we profiled and studied the effect of synovial fluid-derived exosomal miRs on inflammation, survival, proliferation of chondrocyte in correlation with cartilage degeneration. Exosomes were isolated from synovial fluid collected from OA subjects and were analysed by transmission electron microscopy. miRs were isolated and were submitted to microarray profiling. Web-based PCR analysis was done. Chondrocyte proliferation and colony formation assay were performed. Apoptosis study was done by flow cytometer. Gene expression was done by qRT-PCR analysis and protein expression by western blot assay. Rat model of OA was created by operating the knee by anterior cruciate ligament and resection of medial menisci (ACLT + MMx) method. Micro-CT analysis, histological analysis, immunohistochemical staining, and TUNEL assay were also performed. About 17 miRs were found to be expressed differentially in the synovial fluid collected from the control and OA subjects. Microarray analysis confirmed, expression of miR-214-3p was significantly downregulated in the synovial fluid exosome of OA subjects. miR-214-3p mimic promoted proliferation of chondrocyte and suppressed apoptosis. Treatment also inhibited the levels of TNF-α, IL-1β and IL-6. SFB-miR-214-3p exosomes suppressed apoptosis and also inflammation in chondrocytes. In vivo study suggested that SFB-exosomal miR-214-3p from rats suppressed the formation of osteophytes, prevented degeneration of cartilage and exerted anti-inflammatory and anti-apoptotic effect in articular cartilage tissue. The findings suggested that SFB-miR-214-3p exosomes can ameliorate chondrocyte inflammation and degeneration of cartilage tissues. The study confirms therapeutic potential of SFB-miR-214-3p exosomes in treating OA.

Potential Value and Application of Liquid Biopsy in Tumor, Neurodegeneration, and Muscle Degenerative Diseases

Liquid biopsy provides a promising alternative for the detection of disease-specific markers due to its superior noninvasive and original tissue representativeness. Liquid biopsies have a wide range of health and disease applications involving components ranging from circulating cells to acellular nucleic acid molecules and other metabolites. Here, we review the different components of liquid biopsy and investigate the most advanced noninvasive methods for detecting these components as well as their existing problems and trends. In particular, we emphasize the importance of analyzing liquid biopsy data from extracellular vesicles and small nucleic acids in neurological and muscle degeneration, with the aim of using this technique to enhance personalized healthcare. Although previous reviews have focused on cancer, this review mainly emphasizes the potential application of extracellular vesicles and microRNAs in liquid biopsy in neurodegeneration and muscle degeneration.

Extracellular Vesicles for Muscle Atrophy Treatment

Skeletal muscle atrophy is a progressive chronic disease associated with various conditions, such as aging, cancer, and muscular dystrophy. Interleukin-6 (IL-6) is highly correlated with or plays a crucial role in inducing skeletal muscle atrophy. Extracellular vehicles (EVs), including exosomes, mediate cell-cell communication, and alterations in the genetic material contained in EVs during muscle atrophy may impair muscle cell signaling. Transplantation of muscle progenitor cell-derived EVs (MPC-EVs) is a promising approach for treating muscle diseases such as Duchenne muscular dystrophy (DMD). Moreover, stem cell-derived EVs with modification of microRNAs (e.g., miR-26 and miR-29) have been reported to attenuate muscle atrophy. Unbiased RNA-Seq analysis suggests that MPC-EVs may exert an inhibitory effect on IL-6 pathway. Here, we review the latest advances concerning the mechanisms of stem cell/progenitor cell-derived EVs in alleviating muscle atrophy, including anti-inflammatory and anti-fibrotic effects. We also discuss the clinical application of EVs in the treatment of muscle atrophy.

Atrophic skeletal muscle fibre-derived small extracellular vesicle miR-690 inhibits satellite cell differentiation during ageing

BACKGROUND

Sarcopenia is a common and progressive skeletal muscle disorder characterized by atrophic muscle fibres and contractile dysfunction. Accumulating evidence shows that the number and function of satellite cells (SCs) decline and become impaired during ageing, which may contribute to impaired regenerative capacity. A series of myokines/small extracellular vesicles (sEVs) released from muscle fibres regulate metabolism in muscle and extramuscular tissues in an autocrine/paracrine/endocrine manner during muscle atrophy. It is still unclear whether myokines/sEVs derived from muscle fibres can affect satellite cell function during ageing.

METHODS

Aged mice were used to investigate changes in the myogenic capacity of SCs during ageing-induced muscle atrophy. The effects of atrophic myotube-derived sEVs on satellite cell differentiation were investigated by biochemical methods and immunofluorescence staining. Small RNA sequencing was performed to identify differentially expressed sEV microRNAs (miRNAs) between the control myotubes and atrophic myotubes. The target genes of the miRNA were predicted by bioinformatics analysis and verified by luciferase activity assays. The effects of identified miRNA on the myogenic capacity of SCs in vivo were investigated by intramuscular injection of adeno-associated virus (AAV) to overexpress or silence miRNA in skeletal muscle.

RESULTS

Our study showed that the myogenic capacity of SCs was significantly decreased (50%, n = 6, P < 0.001) in the tibialis anterior muscle of aged mice. We showed that atrophic myotube-derived sEVs inhibited satellite cell differentiation in vitro (n = 3, P < 0.001) and in vivo (35%, n = 6, P < 0.05). We also found that miR-690 was the most highly enriched miRNA among all the screened sEV miRNAs in atrophic myotubes [Log₂ (Fold Change) = 7, P < 0.001], which was verified in the atrophic muscle of aged mice (threefold, n = 6, P < 0.001) and aged men with mean age of 71 ± 5.27 years (2.8-fold, n = 10, P < 0.001). MiR-690 can inhibit myogenic capacity of SCs by targeting myocyte enhancer factor 2, including Mef2a, Mef2c and Mef2d, in vitro (n = 3, P < 0.05) and in vivo (n = 6, P < 0.05). Specific silencing of miR-690 in the muscle can promote satellite cell differentiation (n = 6, P < 0.001) and alleviate muscle atrophy in aged mice (n = 6, P < 0.001).

CONCLUSIONS

Our study demonstrated that atrophic muscle fibre-derived sEV miR-690 may inhibit satellite cell differentiation by targeting myocyte enhancer factor 2 during ageing.

How Do Extracellular Vesicles Play a Key Role in the Maintenance of Bone Homeostasis and Regeneration? A Comprehensive Review of Literature

The maintenance of bone homeostasis includes both bone resorption by osteoclasts and bone formation by osteoblasts. These two processes are in dynamic balance to maintain a constant amount of bone for accomplishing its critical functions in daily life. Multiple cell type communications are involved in these two complex and continuous processes. In recent decades, an increasing number of studies have shown that osteogenic and osteoclastic extracellular vesicles play crucial roles in regulating bone homeostasis through paracrine, autosecretory and endocrine signaling. Elucidating the functional roles of extracellular vesicles in the maintenance of bone homeostasis may contribute to the design of new strategies for bone regeneration. Hence, we review the recent understandings of the classification, production process, extraction methods, structure, contents, functions and applications of extracellular vesicles in bone homeostasis. We highlight the contents of various bone-derived extracellular vesicles and their interactions with different cells in the bone microenvironment during bone homeostasis. We also summarize the recent advances in EV-loaded biomaterial scaffolds for bone regeneration and repair.

Myoblast-derived exosomes promote the repair and regeneration of injured skeletal muscle in mice

When skeletal muscle is damaged, satellite cells (SCs) are activated to proliferate rapidly and fuse with the damaged muscle fibers to form new muscle fibers, thereby promoting muscle growth and remodeling and repair of trauma. Exosomes from differentiating human skeletal muscle cells trigger myogenesis of stem cells and provide biochemical cues for skeletal muscle regeneration. Therefore, we hypothesized that, when muscles are injured, myoblast-derived exosomes may regulate muscle repair and regeneration. Here, we investigated the underlying mechanism by applying C2C12-derived exosomes to injured mouse skeletal muscles. The expression levels of skeletal muscle regeneration factors paired box 7 and lipid-promoting factor peroxisome proliferator-activated receptor γ were upregulated, whereas the expression levels of fibrosis factors collagen-1 and α-smooth muscle actin decreased. The expression of proliferating cell nuclear antigen was elevated after applying C2C12-derived exosomes to SCs. Application of C2C12-derived exosomes to fibro-adipogenic progenitors resulted in an increase in peroxisome proliferator-activated receptor γ expression and adipogenesis capacity, whereas α-smooth muscle actin expression and fibrosis capacity decreased. Analysis of the transcriptome and proteome of SCs after treatment with exosomes showed the involvement of multiple biological processes, including proliferation and differentiation of SCs, muscle regeneration, skeletal muscle atrophy, and the inflammatory response after muscle injury. Hence, our data suggest that C2C12-derived exosomes can promote the regeneration of skeletal muscle fibers, accelerate the production of fat from damaged muscles, inhibit the fibrosis of damaged muscles, and accelerate injury repair, which is related to exosome-mediated regulation of the proliferation of SCs, differentiation of fibro-adipogenic progenitors, and modulation of SC mRNA expression and protein formation and decomposition.

Recent advances in cell-based and cell-free therapeutic approaches for sarcopenia

Sarcopenia is a progressive loss of muscle mass and function that is connected with increased hospital expenditures, falls, fractures, and mortality. Although muscle loss has been related to aging, injury, hormonal imbalances, and diseases such as malignancies, chronic obstructive pulmonary disease, heart failure, and kidney failure, the underlying pathogenic mechanisms of sarcopenia are unclear. Exercise-based interventions and multimodal strategies are currently being considered as potential therapeutic approaches to prevent or treat these diseases. Although drug therapy research is ongoing, no drug has yet been proven to have a substantial safety and clinical value to be the first drug therapy to be licensed for sarcopenia. To better understand the molecular alterations underlying sarcopenia and effective treatments, we review leading research and available findings from the systemic change to the muscle-specific microenvironment. Furthermore, we explore possible mechanisms of sarcopenia and provide new knowledge for the development of novel cell-free and cell-based therapeutics. This review will assist researchers in developing better therapies to improve muscle health in the elderly.

Vasorin-containing small extracellular vesicles retard intervertebral disc degeneration utilizing an injectable thermoresponsive delivery system

Intervertebral disc degeneration (IDD) is the pathological reason of back pain and the therapeutic approaches are still unsatisfactory. Recently, mesenchymal stem cell-derived small extracellular vesicles (EVs) have emerged as the novel regenerative method for IDD. In this study, we intensively investigated the therapeutic mechanism of small EVs, and found that vasorin protein enriched in EVs promoted the proliferation and extracellular matrix anabolism of nucleus pulposus cells via the Notch1 signaling pathway. Then, we fabricated a thermoresponsive gel which composed of Pluronic F127 and decellularized extracellular matrix (FEC) for the delivery and sustained release of EVs. Besides, ex vivo and in vivo results showed that EVs embedded in FEC (EVs@FEC) ameliorate the disc degeneration efficiently and achieve better therapeutic effects than one-off EVs delivery. Collectively, these findings deepen the understanding of EVs mechanism in treating intervertebral disc degeneration, and also illustrate the promising capacity of sustained EVs release system for intervertebral disc regeneration.

Comparative Effects of Exosomes and Ectosomes Isolated From Adipose-Derived Mesenchymal Stem Cells on Achilles Tendinopathy in a Rat Model

BACKGROUND

Extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) have gained momentum as a treatment for tendinopathy. Multiple studies have demonstrated significant differences in cargo composition between the 2 subtypes of MSC-EVs (ie, exosomes and ectosomes), which may result in different therapeutic effects. However, the effects of the 2 EV subtypes on tendinopathy have not yet been compared.

PURPOSE

To compare the effects of adipose stem cell-derived exosomes (ASC-Exos) and ectosomes (ASC-Ectos) on Achilles tendinopathy.

STUDY DESIGN

Controlled laboratory study.

METHODS

Rats were administered collagenase injections to generate a model of Achilles tendinopathy. A week later, 36 rats were randomly assigned to 3 groups. In each group, Achilles tendons were injected with equal volumes of ASC-Exos, ASC-Ectos, or saline (12 legs/group). The healing outcomes were evaluated by magnetic resonance imaging, histology, immunohistochemistry, transmission electron microscopy, and biomechanical testing at 3 and 5 weeks after collagenase injection.

RESULTS

At 3 and 5 weeks, the ASC-Exo group had better histological scores (P = .0036 and P = .0276, respectively), a lower fibril density (P < .0001 and P = .0310, respectively), and a larger collagen diameter (P = .0052 and P < .0001, respectively) than the ASC-Ecto group. At 5 weeks, the expression of collagen type 1 and CD206 in the ASC-Exo group was significantly higher than that in the ASC-Ecto group (P = .0025 and P = .0010, respectively). Regarding biomechanical testing, the ASC-Exo group showed higher failure load (P = .0005), tensile stress (P < .0001), and elastic modulus (P < .0001) than the ASC-Ecto group.

CONCLUSION

ASC-Exos had more beneficial effects on tendon repair than ASC-Ectos in a rat model of Achilles tendinopathy.

CLINICAL RELEVANCE

Administration of ASC-EVs may have the potential to treat Achilles tendinopathy, and delivery of ASC-Exos could provide additional benefits. It is necessary to compare the healing responses caused by different EV subtypes to further understand their effects on tendinopathy and to aid clinical decision making.

Comprehensive multi-cohort transcriptional meta-analysis of muscle diseases identifies a signature of disease severity

Muscle diseases share common pathological features suggesting common underlying mechanisms. We hypothesized there is a common set of genes dysregulated across muscle diseases compared to healthy muscle and that these genes correlate with severity of muscle disease. We performed meta-analysis of transcriptional profiles of muscle biopsies from human muscle diseases and healthy controls. Studies obtained from public microarray repositories fulfilling quality criteria were divided into six categories: (i) immobility, (ii) inflammatory myopathies, (iii) intensive care unit (ICU) acquired weakness (ICUAW), (iv) congenital muscle diseases, (v) chronic systemic diseases, (vi) motor neuron disease. Patient cohorts were separated in discovery and validation cohorts retaining roughly equal proportions of samples for the disease categories. To remove bias towards a specific muscle disease category we repeated the meta-analysis five times by removing data sets corresponding to one muscle disease class at a time in a "leave-one-disease-out" analysis. We used 636 muscle tissue samples from 30 independent cohorts to identify a 52 gene signature (36 up-regulated and 16 down-regulated genes). We validated the discriminatory power of this signature in 657 muscle biopsies from 12 additional patient cohorts encompassing five categories of muscle diseases with an area under the receiver operating characteristic curve of 0.91, 83% sensitivity, and 85.3% specificity. The expression score of the gene signature inversely correlated with quadriceps muscle mass (r = -0.50, p-value = 0.011) in ICUAW and shoulder abduction strength (r = -0.77, p-value = 0.014) in amyotrophic lateral sclerosis (ALS). The signature also positively correlated with histologic assessment of muscle atrophy in ALS (r = 0.88, p-value = 1.62 × 10^-3) and fibrosis in muscular dystrophy (Jonckheere trend test p-value = 4.45 × 10^-9). Our results identify a conserved transcriptional signature associated with clinical and histologic muscle disease severity. Several genes in this conserved signature have not been previously associated with muscle disease severity.

An Overview of Current Research on Mesenchymal Stem Cell-Derived Extracellular Vesicles: A Bibliometric Analysis From 2009 to 2021

Background: Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) are important mediators of intercellular communication and participate in numerous physiological and pathological processes in the body. This study aims to introduce the research status, analyze the research hotspots, and predict the development trend through bibliometric analysis of MSC-EVs.

Methods: We searched all relevant literature on MSC-EVs from 2009 to 2021 in the Web of Science. R-bibliometrix, VOSviewer, and CiteSpace software were used to visualize the quantitative analysis of the published literature, including co-authorship, co-occurrence, citation, and co-citation, to provide objective presentation and predictions in the field.

Results: A total of 1595 articles and reviews on MSC-EVs published between 2009 and 2021 were identified. The annual publication outputs increased at an exponential rate, reaching as high as 555 publications in 2021. China contributed the most publications (n = 899, 56.36%) and had the most citations (n = 24,210). The United States had the strongest intensity of cooperation in this field. Shanghai Jiao Tong University had the maximum number of publications (n = 79). In terms of the number of publications and co-citations, the journal of Stem cell research & therapy ranked first. Camussi G was the most productive and most cited author. The top three themes in the research area were cell biology, research experimental medicine, and biochemistry molecular biology. Keyword co-occurrence and co-citation clustering analysis revealed that studies of MSC-EVs covered cellular origin (bone marrow mesenchymal stem cell, adipose-derived mesenchymal stem cell), injurious diseases (spinal cord injury, acute lung injury, ischemia/reperfusion injury, acute kidney injury, traumatic brain injury), tumor (breast cancer, tumor microenvironment), biological processes (drug delivery system, angiogenesis, inflammation, proliferation, differentiation, senescence), and molecular mechanisms (signaling pathway, signal transduction, oxidative stress, VEGF, TGF β).

Conclusions: Studies on MSC-EVs have shown a steep growth trend in recent years. Available studies mostly focused on the therapeutic effects and underlying mechanisms of MSC-EVs in aplastic diseases. Multidisciplinary integration is a development trend in this field, and senescence-related topics might be the focus of future research on MSC-EVs.

Comparative Analysis of Fat Composition in Marrow, Serum, and Muscle from Aging C57BL6 mice

Osteosarcopenia is an age-related condition characterized by fragile bone and low muscle mass and function. Fat infiltration concomitantly contributes to age-related bone and muscle decline. Fat-secreted factors could be locally secreted in the muscle and bone marrow milieu affecting cell function and survival. However, the specific fat-related secretory factors that may simultaneously affect those tissues remain unknown. Using targeted-lipidomics approach, we comprehensively quantified fat composition (lipid mediators [LMs]) in bone marrow flush, gastrocnemius and serum obtained from 6-, 24- and 42-week-old C57BL6 mice. Compared to young mice (6wks), all tissues in older mice showed significantly higher levels of arachidonic acid (AA) and AA-derived eicosanoids, PGA 2, TXB 2, and 11,12-EET, which are known to affect muscle and bone function. Moreover, Lipoxin B4, another AA product and an enhancer of bone turnover and negative regulator for muscle, showed significantly lower values in older mice compared to young mice in both genders. Furthermore, eicosapentaenoic acid and docosahexaenoic acid autoxidation products (20-HDoHE, 11-HDoHE, 7-HDoHE and 4-HDoHE), and omega-3 fatty acids that negatively regulate bone and muscle health, were significantly higher in older mice. In conclusion, these results suggest that LMs could play a role in modulating musculoskeletal function during aging.

GDF-15 in tumor-derived exosomes promotes muscle atrophy via Bcl-2/caspase-3 pathway

Tumor-derived exosomes are emerging mediators of cancer cachexia, a kind of multifactorial syndrome characterized by serious loss of skeletal muscle mass and function. Our previous study had showed that microRNAs in exosomes of C26 colon tumor cells were involved in induction of muscle atrophy. Here, we focus on studying proteins in tumor-derived exosomes which might also contribute to the development of cancer cachexia. Results of comparing the protein profiles of cachexic C26 exosomes and non-cachexic MC38 exosomes suggested that growth differentiation factor 15 (GDF-15) was rich in C26 exosomes. Western blotting analysis confirmed the higher levels of GDF-15 in C26 cells and C26 exosomes, compared with that of MC38 cells. Results of animal study also showed that GDF-15 was rich in tumor tissues, serum exosomes, and gastrocnemius (GA) muscle tissues of C26 tumor-bearing mice. GDF-15 protein could directly induce muscle atrophy of cultured C2C12 myotubes via regulating Bcl-2/caspase-3 pathways. What’s more, overexpression of GDF-15 in MC38 cells could increase the potency of MC38 conditioned medium or exosomes in inducing muscle atrophy. Knockdown of GDF-15 in C26 cells decreased the potency of C26 conditioned medium or exosomes in inducing muscle atrophy. These results suggested that GDF-15 in tumor-derived exosomes could contribute to induction of muscle atrophy and also supported the possibility of targeting GDF-15 in treatment of cancer cachexia.

Harnessing the Therapeutic Potential of Extracellular Vesicles for Biomedical Applications Using Multifunctional Magnetic Nanomaterials

Extracellular vesicles (e.g., exosomes) carrying various biomolecules (e.g., proteins, lipids, and nucleic acids) have rapidly emerged as promising platforms for many biomedical applications. Despite their enormous potential, their heterogeneity in surfaces and sizes, the high complexity of cargo biomolecules, and the inefficient uptake by recipient cells remain critical barriers for their theranostic applications. To address these critical issues, multifunctional nanomaterials, such as magnetic nanomaterials, with their tunable physical, chemical, and biological properties, may play crucial roles in next-generation extracellular vesicles (EV)-based disease diagnosis, drug delivery, tissue engineering, and regenerative medicine. As such, one aims to provide cutting-edge knowledge pertaining to magnetic nanomaterials-facilitated isolation, detection, and delivery of extracellular vesicles and their associated biomolecules. By engaging the fields of extracellular vesicles and magnetic nanomaterials, it is envisioned that their properties can be effectively combined for optimal outcomes in biomedical applications.

The Therapeutic Potential of Exosomes in Soft Tissue Repair and Regeneration

Soft tissue defects are common following trauma and tumor extirpation. These injuries can result in poor functional recovery and lead to a diminished quality of life. The healing of skin and muscle is a complex process that, at present, leads to incomplete recovery and scarring. Regenerative medicine may offer the opportunity to improve the healing process and functional outcomes. Barriers to regenerative strategies have included cost, regulatory hurdles, and the need for cell-based therapies. In recent years, exosomes, or extracellular vesicles, have gained tremendous attention in the field of soft tissue repair and regeneration. These nanosized extracellular particles (30-140 nm) can break the cellular boundaries, as well as facilitate intracellular signal delivery in various regenerative physiologic and pathologic processes. Existing studies have established the potential of exosomes in regenerating tendons, skeletal muscles, and peripheral nerves through different mechanisms, including promoting myogenesis, increasing tenocyte differentiation and enhancing neurite outgrowth, and the proliferation of Schwann cells. These exosomes can be stored for immediate use in the operating room, and can be produced cost efficiently. In this article, we critically review the current advances of exosomes in soft tissue (tendons, skeletal muscles, and peripheral nerves) healing. Additionally, new directions for clinical applications in the future will be discussed.

The Role of Extracellular Vesicles in Osteoporosis: A Scoping Review

As an insidious metabolic bone disease, osteoporosis plagues the world, with high incidence rates. Patients with osteoporosis are prone to falls and becoming disabled, and their cone fractures and hip fractures are very serious, so the diagnosis and treatment of osteoporosis is very urgent. Extracellular vesicles (EVs) are particles secreted from cells to the outside of the cell and they are wrapped in a bilayer of phospholipids. According to the size of the particles, they can be divided into three categories, namely exosomes, microvesicles, and apoptotic bodies. The diameter of exosomes is 30-150 nm, the diameter of microvesicles is 100-1000 nm, and the diameter of apoptotic bodies is about 50-5000 nm. EVs play an important role in various biological process and diseases including osteoporosis. In this review, the role of EVs in osteoporosis is systematically reviewed and some insights for the prevention and treatment of osteoporosis are provided.

Therapeutic Effects of Hyaluronic Acid Against Cytotoxic Extracellular Vesicles Released During Pseudomonas Aeruginosa Pneumonia

ABSTRACT

Extracellular vesicles (EVs) have now been recognized as important mediators of cellular communication during injury and repair. We previously found that plasma EVs isolated from ex vivo perfused human lungs injured with Escherichia coli bacterial pneumonia were inflammatory, and exogenous administration of high molecular weight (HMW) hyaluronic acid (HA) as therapy bound to these EVs, decreasing inflammation and injury. In the current study, we studied the role of EVs released during severe Pseudomonas aeruginosa (PA) pneumonia in mice and determined whether intravenous administration of exogenous HMW HA would have therapeutic effects against the bacterial pneumonia. EVs were collected from the bronchoalveolar lavage fluid (BALF) of mice infected with PA103 by ultracentrifugation and analyzed by NanoSight and flow cytometry. In a cytotoxicity assay, administration of EVs released from infected mice (I-EVs) decreased the viability of A549 cells compared to EV isolated from sham control mice (C-EVs). Either exogenous HMW HA or an anti-CD44 antibody, when co-incubated with I-EVs, significantly improved the viability of the A549 cells. In mice with PA103 pneumonia, administration of HMW HA improved pulmonary edema and bacterial count in the lungs and decreased TNF-α and caspase-3 levels in the supernatant of lung homogenates. In conclusion, EVs isolated from BALF of mice with P. aeruginosa pneumonia were cytotoxic and inflammatory, and intravenous HMW HA administration was protective against P. aeruginosa pneumonia.

Extracellular Vesicles Derived From Stem Cells in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is the leading cause of low back pain related to degradation of cartilaginous tissues, mainly resulting from oxidative stress, cell apoptosis, and extracellular matrix degradation. Extracellular vesicles (EVs) exist in all bodily fluids and can be produced by all types of cells. Stem cell-derived EVs (SC-EVs), which are the main paracrine components of stem cells, have gained significant attention in the field of regenerative medicine. Over the past years, accumulating evidence indicates the therapeutic and diagnostic potentials of EVs in IVDD. The main mechanisms involve the induction of regenerative phenotypes, apoptosis alleviation, and immune modulation. In addition, the efficiency of SC-EVs can be enhanced by choosing appropriate donor cells and cell phenotypes, optimizing cell culture conditions, or engineering EVs to deliver drugs and targeting molecules. Given the importance and novelty of SC-EVs, we give an overview of SC-EVs and discuss the roles of SC-EVs in IVDD.

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.

Therapeutic effects of high molecular weight hyaluronic acid in severe Pseudomonas aeruginosa pneumonia in ex vivo perfused human lungs

We previously reported that extracellular vesicles (EVs) released during Escherichia coli (E. coli) bacterial pneumonia were inflammatory, and administration of high molecular weight hyaluronic acid (HMW HA) suppressed several indices of acute lung injury (ALI) from E. coli pneumonia by binding to these inflammatory EVs. The current study was undertaken to study the therapeutic effects of HMW HA in ex vivo perfused human lungs injured with Pseudomonas aeruginosa (PA)103 bacterial pneumonia. For lungs with baseline alveolar fluid clearance (AFC) <10%/h, HMW HA 1 or 2 mg was injected intravenously after 1 h (n = 4-9), and EVs released during PA pneumonia were collected from the perfusate over 6 h. For lungs with baseline AFC > 10%/h, HMW HA 2 mg was injected intravenously after 1 h (n = 6). In vitro experiments were conducted to evaluate the effects of HA on inflammation and bacterial phagocytosis. For lungs with AFC < 10%/h, administration of HMW HA intravenously significantly restored AFC and numerically decreased protein permeability and alveolar inflammation from PA103 pneumonia but had no effect on bacterial counts at 6 h. However, HMW HA improved bacterial phagocytosis by human monocytes and neutrophils and suppressed the inflammatory properties of EVs released during pneumonia on monocytes. For lungs with AFC > 10%/h, administration of HMW HA intravenously improved AFC from PA103 pneumonia but had no significant effects on protein permeability, inflammation, or bacterial counts. In the presence of impaired alveolar epithelial transport capacity, administration of HMW HA improved the resolution of pulmonary edema from Pseudomonas PA103 bacterial pneumonia.

lncRNA-KCNQ1OT1: A Potential Target in Exosomes Derived from Adipose-Derived Stem Cells for the Treatment of Osteoporosis

BACKGROUND

Osteoporosis is a worldwide medical and socioeconomic burden characterized by systemic impairment of bone strength and microstructure. Exosomes derived from adipose-derived stem cells (ADSCs-Exos) have been confirmed to play effective roles in the repair of various tissues and organs. This study was aimed at investigating the role of ADSCs-Exos and a novel long noncoding RNA KCNQ1OT1 played in osteoporosis as well as the underlying mechanism.

METHODS

Primary osteoblasts were treated with different doses of tumor necrosis factor-α (TNF-α) (0, 1, 2.5, 5, and 10 ng/ml) and then cocultured with ADSCs-Exos or exosome-derived from lnc-KCNQ1OT1-modified ADSCs (KCNQ1OT1-Exos). The expression of miRNA-141-5p (miR-141-5p) and lnc-KCNQ1OT1 was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of cleaved-caspase-3, caspase-3, and Bax was determined by Western blot. Cell viability and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) and flow cytometry analysis, respectively. The binding sites between KCNQ1OT1 and miR-141-5p were validated by dual-luciferase reporter assay.

RESULTS

TNF-α dose-dependently increased miR-141-5p expression, inhibited viability, and promoted apoptosis of osteoblasts. However, miR-141-5p silencing or cocultured with ADSCs-Exos attenuated these effects. In addition, KCNQ1OT1-Exos could more significantly attenuate the induced cytotoxicity and apoptosis compared to ADSCs-Exos. Moreover, miR-141-5p was confirmed as the target of KCNQ1OT1 by luciferase reporter assay.

CONCLUSIONS

ADSCs-Exos can attenuate cytotoxicity and apoptosis of TNF-α-induced primary osteoblasts. KCNQ1OT1-Exos have a more significant inhibitory effect compared to ADSCs-Exos by the function of sponging miR-141-5p, suggesting that KCNQ1OT1-Exos can be promising agents in osteoporosis treatment.

Extracellular vesicles: mediators of intercellular communication in tissue injury and disease

Intercellular communication is a critical process that ensures cooperation between distinct cell types and maintains homeostasis. EVs, which were initially described as cellular debris and devoid of biological function, are now recognized as key components in cell-cell communication. EVs are known to carry multiple factors derived from their cell of origin, including cytokines and chemokines, active enzymes, metabolites, nucleic acids, and surface molecules, that can alter the behavior of recipient cells. Since the cargo of EVs reflects their parental cells, EVs from damaged and dysfunctional tissue environments offer an abundance of information toward elucidating the molecular mechanisms of various diseases and pathological conditions. In this review, we discuss the most recent findings regarding the role of EVs in the progression of cancer, metabolic disorders, and inflammatory lung diseases given the high prevalence of these conditions worldwide and the important role that intercellular communication between immune, parenchymal, and stromal cells plays in the development of these pathological states. We also consider the clinical applications of EVs, including the possibilities for their use as novel therapeutics. While intercellular communication through extracellular vesicles (EVs) is key for physiological processes and tissue homeostasis, injury and stress result in altered communication patterns in the tissue microenvironment. When left unchecked, EV-mediated interactions between stromal, immune, and parenchymal cells lead to the development of disease states Video Abstract.

Skeletal Muscle Regeneration by the Exosomes of Adipose Tissue-Derived Mesenchymal Stem Cells

Profound skeletal muscle loss can lead to severe disability and cosmetic deformities. Mesenchymal stem cell (MSC)-derived exosomes have shown potential as an effective therapeutic tool for tissue regeneration. This study aimed to determine the regenerative capacity of MSC-derived exosomes for skeletal muscle regeneration. Exosomes were isolated from human adipose tissue-derived MSCs (AD-MSCs). The effects of MSC-derived exosomes on satellite cells were investigated using cell viability, relevant genes, and protein analyses. Moreover, NOD-SCID mice were used and randomly assigned to the healthy control (n = 4), muscle defect (n = 6), and muscle defect + exosome (n = 6) groups. Muscle defects were created using a biopsy punch on the quadriceps of the hind limb. Four weeks after the surgery, the quadriceps muscles were harvested, weighed, and histologically analyzed. MSC-derived exosome treatment increased the proliferation and expression of myocyte-related genes, and immunofluorescence analysis for myogenin revealed a similar trend. Histologically, MSC-derived exosome-treated mice showed relatively preserved shapes and sizes of the muscle bundles. Immunohistochemical staining revealed greater expression of myogenin and myoblast determination protein 1 in the MSC-derived exosome-treated group. These results indicate that exosomes extracted from AD-MSCs have the therapeutic potential for skeletal muscle regeneration.

Prediction of the Molecular Mechanism of Eucommiae Cortex - Achyranthis Bidentatae Radix in the treatment of Osteoarthritis: Network Pharmacology and Molecular Docking

OBJECTIVE

To retrieve the core drug of osteoarthritis in clinic using Data Mining, predict the drug molecular action target through the Network Pharmacology, identify the key nodes of the interaction by combining with the related targtes of osteoarthritis, explore the pharmacological mechanism of Traditional Chinese Medicine against osteoarthritis and other possible mechanisms of actions.

METHODS

to retrieve the commonly used therapeutic formulations for osteoarthritis patients in clinical with PubMed, CNKI, VIP, CBM, WanFang Database and other databases, and screen out the core drugs through the Ancient and Modern Medical Case Cloud Platform and software Gephi, filter out the core drug molecules and targets combined with TCMSP database and the targets of osteoarthritis in Genecard and OMIM database, plunge those data into R project and Cytoscape to construct the intersection model of Drug molecule-osteoarthritis, establish PPI network and GO and conduct KEGG enrichment analysis with String database. Vina molecular docking was finally implemented to draw molecular docking diagram, and the results were analyzed after comprehensive analysis.

RESULTS

The core drug pairs were identified as "Eucommiae Cortex - Achyranthis Bidentatae Radix" through correlation analysis, complex network analysis based on the coefficient. "Eucommiae Cortex - Achyranthis Bidentatae Radix" can intervene cell behavior through multiple pathways and regulate cell metabolism, cytokine synthesis, oxidative and cellular immunity with the help of topology analysis in String Database.

CONCLUSIONS

The core molecules of Quercetin and Kaempferol derived from "Eucommia bark - achyranthes" can change the spatial conformation of PTGSs by hydrogen bonding with PTGSs, the hydrophobic bonds and van der Waals forces generated by Baicalein, Wogonin and β-carotene, thereby changing the activity of PTGSs and affecting bone properties the process of osteoarthritis.

Extracellular Vesicles in Premature Aging and Diseases in Adulthood Due to Developmental Exposures

The developmental origins of health and disease (DOHaD) is a paradigm that links prenatal and early life exposures that occur during crucial periods of development to health outcome and risk of disease later in life. Maternal exposures to stress, some psychoactive drugs and alcohol, and environmental chemicals, among others, may result in functional changes in developing fetal tissues, creating a predisposition for disease in the individual as they age. Extracellular vesicles (EVs) may be mediators of both the immediate effects of exposure during development and early childhood as well as the long-term consequences of exposure that lead to increased risk and disease severity later in life. Given the prevalence of diseases with developmental origins, such as cardiovascular disease, neurodegenerative disorders, osteoporosis, metabolic dysfunction, and cancer, it is important to identify persistent mediators of disease risk. In this review, we take this approach, viewing diseases typically associated with aging in light of early life exposures and discuss the potential role of EVs as mediators of lasting consequences.

Exosome: Function and Application in Inflammatory Bone Diseases

In the skeletal system, inflammation is closely associated with many skeletal disorders, including periprosthetic osteolysis (bone loss around orthopedic implants), osteoporosis, and rheumatoid arthritis. These diseases, referred to as inflammatory bone diseases, are caused by various oxidative stress factors in the body, resulting in long-term chronic inflammatory processes and eventually causing disturbances in bone metabolism, increased osteoclast activity, and decreased osteoblast activity, thereby leading to osteolysis. Inflammatory bone diseases caused by nonbacterial factors include inflammation- and bone resorption-related processes. A growing number of studies show that exosomes play an essential role in developing and progressing inflammatory bone diseases. Mechanistically, exosomes are involved in the onset and progression of inflammatory bone disease and promote inflammatory osteolysis, but specific types of exosomes are also involved in inhibiting this process. Exosomal regulation of the NF-κB signaling pathway affects macrophage polarization and regulates inflammatory responses. The inflammatory response further causes alterations in cytokine and exosome secretion. These signals regulate osteoclast differentiation through the receptor activator of the nuclear factor-kappaB ligand pathway and affect osteoblast activity through the Wnt pathway and the transcription factor Runx2, thereby influencing bone metabolism. Overall, enhanced bone resorption dominates the overall mechanism, and over time, this imbalance leads to chronic osteolysis. Understanding the role of exosomes may provide new perspectives on their influence on bone metabolism in inflammatory bone diseases. At the same time, exosomes have a promising future in diagnosing and treating inflammatory bone disease due to their unique properties.