Skeletal muscle-derived extracellular vesicles transport glycolytic enzymes to mediate muscle-to-bone crosstalk

Bone and muscle crosstalk in ageing and disease

Interorgan communication between bone and skeletal muscle is central to human health. A dysregulation of bone-muscle crosstalk is implicated in several age-related diseases. Ageing-associated changes in endocrine, inflammatory, nutritional and biomechanical stimuli can influence the differentiation capacity, function and survival of mesenchymal stem cells and bone-forming and muscle-forming cells. Consequently, the secretome phenotype of bone and muscle cells is altered, leading to impaired crosstalk and, ultimately, catabolism of both tissues. Adipose tissue acts as a third player in the bone-muscle interaction by secreting factors that affect bone and muscle cells. Physical exercise remains the key biological stimulus for bone-muscle crosstalk, either directly via the release of cytokines from bone, muscle or adipocytes, or indirectly through extracellular vesicles. Overall, bone-muscle crosstalk is considered an inherent process necessary to maintain the structure and function of both tissues across the life cycle. This Review summarizes the latest biomedical advances in bone-muscle crosstalk as it pertains to human ageing and disease. We also outline future research priorities to accommodate the understanding of this rapidly emerging field.

Separation and Characterization of Heterogeneity Among Various Sizes of Outer Membrane Vesicles Derived from the Probiotic Escherichia coli Nissle 1917

Outer membrane vesicles (OMVs) are extracellular vesicles secreted by Gram-negative bacteria with diameters of 20-250 nm. OMVs contain various biologically active substances from their parent bacteria, such as proteins, lipids, and nucleic acids. Escherichia coli Nissle 1917 (EcN) is a Gram-negative probiotic that resides in the human intestine. EcN-derived OMVs are pivotal in modulating intestinal immune responses. However, few studies have addressed the heterogeneity of EcN-derived OMVs in terms of size, significantly limiting the research on their clinical applications. Currently, there are a lack of feasible methods for obtaining EcN-derived OMVs of different sizes. To address this knowledge gap, we developed a membrane filtration method to isolate EcN-derived OMVs of varying sizes. In this study, we first used gradient filtration to isolate high-purity EcN-derived OMVs and conducted a proteomic analysis. Subsequently, we used membrane filtration to separate the EcN-derived OMVs by size. We successfully obtained EcN-derived OMVs of three specific sizes: <50 nm, 50-100 nm, and 100-300 nm. We then performed proteomic analyses of these EcN-derived OMVs and compared their protein profiles. Finally, we compared the ability of each EcN-derived OMV type to induce RAW264.7 macrophages to secrete the pro-inflammatory factor interleukin (IL)-1β and the anti-inflammatory factor IL-10. The EcN-derived OMVs contained 646 different proteins overall; those of different sizes contained different protein types. Among them, the EcN-derived OMVs in the <50 nm group contained significantly fewer proteins (262 different types in total) than those in the 50-100 nm (1603 types) and 100-300 nm (1568 types) groups. Furthermore, the <50 nm group had fewer membrane proteins (40) than the 50-100 nm (215) and 100-300 nm (209) groups. We also found that RAW264.7 macrophages secreted different concentrations of IL-1β and IL-10 following co-incubation with the three EcN-derived OMV types. The 50-100 nm EcN-derived OMV group showed a stronger effect in terms of inducing inflammatory cytokine secretion compared to the other two groups. This study provides direct experimental evidence that EcN-derived OMVs of different sizes exhibit heterogeneous properties.

Impact of Static Myoblast Loading on Protein Secretion Linked to Tenocyte Migration

Exercise has been shown to promote wound healing, including tendon repair. Myokines released from the exercised muscles are believed to play a significant role in this process. In our previous study, we used an in vitro coculture and loading model to demonstrate that 2% static loading of myoblasts increased the migration and proliferation of cocultured tenocytes─two crucial aspects of wound healing. IGF-1, released from myoblasts in response to 2% static loading, was identified as a contributor to the increased proliferation. However, the factors responsible for the enhanced migration remained unknown. In the current study, we subjected myoblasts in single culture conditions to 2, 5, and 10% static loading and performed proteomic analysis of the cell supernatants. Gene Ontology (GO) analysis revealed that 2% static loading induced the secretion of NBL1, C5, and EFEMP1, which is associated with cell migration and motility. Further investigation by adding exogenous recombinant proteins to human tenocytes showed that NBL1 increased tenocyte migration but not proliferation. This effect was not observed with treatments using C5 and EFEMP1.

Multi-modal microcarriers reprogram mitochondrial metabolism and activate efferocytosis in macrophages for osteoporotic bone repair

Osteoporotic bone repair remains challenging due to the ineffectiveness of traditional bone repair materials in adapting to the complex immune microenvironment of aging bone tissue. Exploiting the key role of macrophages in regulating this immune environment through the rational design of osteoimmunomodulatory biomaterials has emerged as a promising approach. However, current designs inadequately address the complexity of macrophage functions in aging environments, resulting in suboptimal regulatory effects. Hence, we explored multi-modal microcarriers for enhancing macrophage functionality. In this work, we developed a VGX-1027-loaded mesoporous silica nanosphere composite PLLA microcarrier. The dual-carrier system, featuring a micro-nano hybrid design by spatially separating the mesoporous silica nanoparticles and PLLA microspheres, enables sustained intracellular release of VGX-1027, addressing the chronic nature of osteoporotic fractures. Our studies demonstrate this VGX-1027 microcarrier (PMVGX) promotes M2 macrophage polarization by reprogramming mitochondrial metabolism. Simultaneously, it enhances efferocytosis, facilitating the clearance of dead or senescent cells and reducing inflammatory responses, thus reshaping the aging osteoimmunomodulatory. Furthermore, PMVGX induces macrophages to release osteogenic exosomes containing miR-5106 through paracrine signaling, significantly enhancing osteogenic function. In a postmenopausal osteoporosis animal model, PMVGX exhibited remarkable efficacy in repairing osteoporotic bone defects. This proof-of-concept study demonstrates that our multi-modal microcarrier effectively regulates macrophage functions via mitochondrial homeostasis, efferocytosis, and exosome content, offering great potential for osteoporotic bone repair.

The existing evidence for the use of extracellular vesicles in the treatment of osteoporosis: a review

Osteoporosis is a systemic metabolic bone disease characterized by decreased bone mass, microstructural deterioration, and increased fracture risk. The crucial role of extracellular vesicles (EVs) in the occurrence and development of osteoporosis has garnered attention, with vesicle-based treatments showing significant promise. Compared to conventional osteoporosis medications, EVs possess characteristics of naturalness, selectivity, and adaptability, and more importantly, they have negligible side effects. Hence, this review discusses the applications of natural and engineered EVs in osteoporosis are comprehensively outlined. Unfortunately, the absence of consensus on the extraction, purification, characterization, and storage of EVs has resulted in a lack of clinical evidence supporting their application in patients with osteoporosis. Although significant progress is still needed before the clinical use of EVs can be achieved, their substantial potential remains undeniable. Moreover, considering the complexity of bone metabolism in osteoporosis and the heterogeneity of EVs, further investigation into the functional subpopulations of different exosomes will facilitate their application.

Muscle-Derived Small Extracellular Vesicles Mediate Exercise-Induced Cognitive Protection in Chronic Cerebral Hypoperfusion

Physical exercise protects against cognitive impairment caused by chronic cerebral hypoperfusion (CCH). However, the mechanisms through which exercise sends signals from the periphery to the central nervous system remain incompletely understood. This study demonstrated that exercise promotes the secretion of muscle-derived small extracellular vesicles (sEVs), which facilitate interorgan communication between the muscle and the brain. Systematic delivery of muscle-derived sEVs enhances synaptic plasticity and alleviated cognitive impairment in CCH. Notably, miRNA sequencing reveal miR-17/20a-5p as key cargos in sEVs involved in the exercise-induced muscle-brain crosstalk. Muscle-derived sEVs are also identified as the primary source of swimming-induced miR-17/20a-5p in circulating sEVs. Mechanistically, miR-17/20a-5p binds to the DEP-domain containing mTOR-interacting protein (DEPTOR) and activates the mammalian target of rapamycin (mTOR) pathway in the hippocampus. Depletion of miR-17/20a-5p from muscle-derived sEVs impairs the exercise-induced enhancement of synaptic plasticity and cognitive function. Moreover, overexpression of DEPTOR in the hippocampus attenuates the cognitive benefits of exercise. Conversely, hippocampus-specific activation of mTOR reverses these effects, highlighting the crucial role of mTOR in mediating the positive effects of exercise. Collectively, these findings identify miR-17/20a-5p in muscle-derived sEVs as the exercise-induced myokine with potent effects on the brain, emphasizing the therapeutic potential of exercise in managing cognitive impairment.

Role of IL-16 in age-related skeletal muscle atrophy: an integrated study

BACKGROUND

In this study, we aim to explore the roles of IL-16 in sarcopenia based on older orthopedic patients and animal research.

METHODS

This clinical research in this study was an observational investigation and included all the older patients with orthopedic trauma admitted to our department between January 2021 and January 2022. Patients were identified with sarcopenia if they have both low hand grip strength (HGS) and low appendicular skeletal muscle mass (ASM). Propensity score matching (PSM) was performed to reduce the bias caused by the co-factors and levels of IL-16 between normal patients and patients with sarcopenia were compared. In animal research, mice were treated with IL-16 to identify the effects of IL-16 on muscle function and muscle mass. Then the sarcopenia models were established and the anti-IL-16 was performed to identify the potential therapeutical effect of targeting IL-16.

RESULTS

421 individuals were included in the clinical study, and 77 were identified as sarcopenia. In the matched populations, the serum levels of IL-16 of individuals with low HGS, ASM, and sarcopenia were significantly higher than normal individuals (all p < 0.001). The mice treated with IL-16 showed significantly impaired muscle function and physical performance and loss of muscle mass. Using anti-IL-16 antibodies may rescue the sarcopenia traits caused by botulinum toxin type A.

CONCLUSION

Individuals with high levels of IL-16 may have a significantly high risk of sarcopenia. IL-16 impairs muscle function and physical performance and leads to muscle atrophy in mice, and these effects could be reduced by targeting IL-16.

In vitro study on the promotion of osteogenic differentiation by mitochondrial-derived vesicles through activation of inflammation and reprogramming of metabolic pathways

The secretion of mitochondrial-derived vesicles (MDVs) has been found to increase during osteogenic differentiation, but their role in intercellular communication and osteogenic promotion remains unclear. In this study, we extracted translocase of outer mitochondrial membrane 20 (Tomm20) + MDVs from bone marrow stromal cells (BMSCs) at different osteogenic culture days using differential centrifugation and immunoprecipitation, then co-cultured them with BMSCs to assess osteogenic differentiation, immune response and metabolic levels. The results showed that osteogenic differentiation enhances MDVs' secretion and their mitochondrial DNA (mtDNA) content. In promoting osteogenic differentiation ability, osteogenic-induced MDVs (MDV-OMs, especially MDV-OM14 and MDV-OM21) significantly enhance mineralization with OD values 1.37-fold and 1.32-fold higher than those of MDV-OM7 (p < 0.05) after 21 days, respectively. However, these MDVs containing mtDNA activate immune responses by upregulating cGas, Sting, Caspase-9, Il-6, and Tnf-a mRNA levels, inducing cell apoptosis and oxidative stress. In addition, MDVs containing mitochondrial components also have metabolic regulatory functions. Metabolic level detection revealed that MDV-OMs downregulate lactate, promote tricarboxylic acid cycle (TCA) enzyme expression, and increase mitochondrial membrane potential. Among these MDVs, MDV-OM7, induced for 7 days, shows osteogenic function without strong immune response, possibly related to metabolic reprogramming. This study highlights the potential of osteogenic-induced MDVs for bone regeneration, cGAS-STING activation, and metabolic enhancement, and are expected to be used for the treatment of diseases such as tissue damage.

Exercise for Postmenopausal Bone Health - Can We Raise the Bar?

PURPOSE OF REVIEW

This review summarises the latest evidence on effects of exercise on falls prevention, bone mineral density (BMD) and fragility fracture risk in postmenopausal women, explores hypotheses underpinning exercise-mediated effects on BMD and sheds light on innovative concepts to better understand and harness the skeletal benefits of exercise.

RECENT FINDINGS

Multimodal exercise programs incorporating challenging balance exercises can prevent falls. Emerging clinical trial evidence indicates supervised progressive high-intensity resistance and impact training (HiRIT) is efficacious in increasing lumbar spine BMD and is safe and well-tolerated in postmenopausal women with osteoporosis/osteopenia. There remains uncertainty regarding durability of this load-induced osteogenic response and safety in patients with recent fractures. Muscle-derived myokines and small circulating extracellular vesicles have emerged as potential sources of exercise-induced muscle-bone crosstalk but require validation in postmenopausal women. Exercise has the potential for multi-modal skeletal benefits with i) HiRIT to build bone, and ii) challenging balance exercises to prevent falls, and ultimately fractures. The therapeutic effect of such exercise in combination with osteoporosis pharmacotherapy should be considered in future trials.

Muscle-derived small extracellular vesicles induce liver fibrosis during overtraining

The benefits of exercise for metabolic health occur in a dose-dependent manner. However, the adverse effects of overtraining and their underlying mechanisms remain unclear. Here, we show that overtraining induces hepatic fibrosis. Mechanistically, we find that excessive lactate accumulation in skeletal muscle leads to the lactylation of SH3 domain-containing 3 (SORBS3), triggering its liquid-liquid phase separation (LLPS). LLPS of SORBS3 enhances its interaction with flotillin 1 and selectively facilitates the sorting of F-box protein 2 (FBXO2) into small extracellular vesicles, referred to as "lactate bodies." Lactate bodies induce hepatocyte apoptosis followed by hepatic stellate cell activation via myeloid cell leukemia sequence 1 (MCL1)-BAX/BAK signaling. Inhibition of SORBS3 lactylation or FBXO2 disrupts lactate bodies formation and alleviates overtraining-triggered liver fibrosis. Likewise, reduction of muscle lactate bodies formation by salidroside attenuates overtraining-induced liver fibrosis. Collectively, we identify a process by which overtraining induces hepatic fibrosis, highlighting a potential therapeutic target for liver health.

Remote limb ischemic conditioning alleviates steatohepatitis via extracellular vesicle-mediated muscle-liver crosstalk

Metabolic dysfunction-associated steatohepatitis (MASH) is an advanced form of liver disease with adverse outcomes. Manipulating interorgan communication is considered a promising strategy for managing metabolic disease, including steatohepatitis. Here, we report that remote limb ischemic conditioning (RIC), a clinically validated therapy for distant organ protection by transient muscle ischemia, significantly alleviated steatohepatitis in different mouse models. The beneficial effect of limb ischemic conditioning was mediated by muscle-to-liver transfer of small extracellular vesicles (sEVs) and their cargo microRNAs, leading to elevation of miR-181d-5p in the liver. Hepatic miR-181d-5p overexpression faithfully mirrored the molecular and histological benefits of limb ischemic conditioning by suppressing nuclear receptor 4A3 (NR4A3). Furthermore, circulating EVs from human volunteers undergoing limb ischemic conditioning improved steatohepatitis and transcriptomic perturbations in primary human hepatocytes and animal models. Our data underscore the translational potential of limb ischemic conditioning for steatohepatitis management and extend our understanding of muscle-liver crosstalk.

Exosomes derived from FN14-overexpressing BMSCs activate the NF-κB signaling pathway to induce PANoptosis in osteosarcoma

Despite advances in treatment, the prognosis of osteosarcoma (OS) patients is unsatisfactory, and searching for possible targets is substantial. Fibroblast growth factor inducible type 14 (FN14), a plasma membrane protein, is involved in wound healing, angiogenesis, proliferation, apoptosis, and inflammation. However, its implication in OS development and progression has not been completely characterized. Herein, we explored the cell-to-cell communication of bone marrow mesenchymal stem cells (BMSCs) and OS cells mediated by FN14 in the tumor microenvironment of OS. To assess the interplay between FN14 expression levels and patient survival, FN14 expression was measured in both normal and OS tissues. The FN14 overexpressing BMSCs (OE) were constructed using lentivirus, and exosomes (EXO) were extracted. The uptake of FN14-containing EXO by OS cells was analyzed via flow cytometry and in vivo fluorescence imaging. In addition, high-throughput sequencing was performed to analyze the mechanisms by which EXO inhibits OS cell growth. Finally, the therapeutic effect of OE-EXO was evaluated in a mouse model of OS xenografts. The results showcased reduced FN14 expression in human and mouse OS tissues, suggesting its role may be involved in the malignant progression of OS. The FN14 expression was higher in BMSCs relative to OS cells, and FN14 was secreted and excreted by EXO. The OS cell progression was suppressed after the uptake of FN14-derived EXO from BMSCs. In addition, RNA sequencing revealed that FN14 in EXO activated NF-κB signaling, triggering PANoptosis in OS cells. In vivo, OE-EXO injection inhibited tumor growth in OS xenografts and significantly improved the long-term survival of mice. Our findings suggest that FN14 carried by EXO from BMSCs activates the NF-κB pathway to trigger PANoptosis in OS cells, providing a potential therapeutic strategy to inhibit OS progression.

Swimming exercise induces redox-lipid crosstalk to ameliorate osteoarthritis progression

Conventional pharmacotherapy exhibits limited efficacy in halting cartilage degeneration, whereas exercise interventions have demonstrated promising protective effects against osteoarthritis (OA), albeit with unclear underlying mechanisms. This study investigated the beneficial effects of swimming in mitigating local joint damage through the enhancement of systemic antioxidant capacity. We found that overexpression of superoxide dismutase 3 (SOD3) could promote the elimination of extracellular reactive oxygen species (ROS) and preserve the cartilage extracellular matrix (C-ECM). Conversely, genetic deletion of SOD3 accelerated the loss of C-ECM and contributed to OA due to an imbalance in extracellular oxidative stress. Further investigation revealed that SOD3 could interact with CCAAT/enhancer binding protein β (C/EBPβ), leading to the inhibition of apolipoprotein E (APOE) transcription and subsequent APOE-induced cholesterol transport. Ultimately, we developed targeted extracellular vesicles (EVs) with high cartilage affinity for efficient and precise delivery of SOD3. Overall, this study elucidated the potential of exercise for degenerative joint disorders through SOD3-mediated extracellular antioxidation and cholesterol redistribution.

In Vivo Reprogramming of Tissue-Derived Extracellular Vesicles for Treating Chronic Tissue Injury Through Metabolic Engineering

Extracellular vesicles (EVs) have emerged as promising therapeutics for regenerative medicine, but the efficacy of current exogenous EV-based therapies for treating chronic tissue injury is still unsatisfactory. Exercise can affect skeletal muscle EV secretion and that this process regulates the systemic health-promoting role of exercise, suggesting that fine-tuning of endogenous tissue EV secretion may provide a new therapeutic avenue. Here, this work reports that in vivo reprogramming of EV secretion via metabolic engineering is a promising strategy for treating chronic diseases. Briefly, exercise enhanced mitochondrial metabolism and EV production in healthy skeletal muscles, and EVs from healthy skeletal muscles subjected to exercise or metabolic engineering (boosting mitochondrial biogenesis via AAV-mediated muscle-specific TFAM overexpression) exerted cellular protective effects in vitro. In injured skeletal muscles, in vivo metabolic engineering therapy could reprogram EV secretion patterns (reducing pathological EV compositions while increasing beneficial EV compositions) by regulating multiple EV biogenesis and cargo sorting pathways. Reprogrammed muscle-derived EVs could reach major organs and tissues via the circulation and then simultaneously attenuated multiple-tissue (e.g., muscle and kidney) injury in chronic kidney disease. This study highlights that in vivo reprogramming of tissue-derived EVs via a metabolic engineering approach is a potential strategy for treating diverse chronic diseases.

Circ-ITCH promotes the ubiquitination degradation of HOXC10 to facilitate osteogenic differentiation in disuse osteoporosis through stabilizing BRCA1 mRNA via IGF2BP2-mediated m6A modification

BACKGROUND

Osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) facilitated by mechanical loading is a promising therapy for disuse osteoporosis (DOP), however, it is difficult to implement mechanical loading for a majority of patients. Our study aims to identify circ-ITCH-mediated novel approach to facilitate osteogenic differentiation in DOP.

METHODS

A rat DOP model and human BM-MSCs under microgravity condition were generated as in vivo and in vitro models of DOP, respectively. The bone mineral density (BMD) and bone parameters were examined in rats. The histological changes of bones and mineralization were monitored by H&E, Alcian blue and Alizarin red S staining. Co-IP was employed to examine the ubiquitination of HOXC10 and the interaction between HOXC10 and BRCA1. The direct associations among circ-ITCH, IGFBP2 and BRCA1 mRNA were assessed by RIP, FISH and RNA pull-down assays.

RESULTS

Circ-ITCH was downregulated in rat model of DOP and BM-MSCs under microgravity stimulation. Circ-ITCH overexpression promoted osteogenic differentiation in BM-MSCs under microgravity condition. The altered bone parameters, such as BMD, trabecular number (Tb.N), trabecular separation (Tb.Sp), trabecular thickness (Tb.Th), and bone microstructure in DOP rats were rescued by circ-ITCH overexpression. Mechanistically, circ-ITCH enhanced the ubiquitination degradation of HOXC10 through enhancing BRCA1 mRNA stability. Circ-ITCH directly bound to IGF2BP2 protein to stabilize BRCA1 mRNA via m6A modification, thus facilitating osteogenic differentiation in BM-MSCs under microgravity condition.

CONCLUSION

Circ-ITCH stabilized BRCA1 mRNA via IGF2BP2-mediated m6A modification, thereby facilitating the ubiquitination degradation of HOXC10 to promote osteogenic differentiation in DOP.

A bibliometric and visualized analysis of extracellular vesicles in degenerative musculoskeletal diseases (from 2006 to 2024)

Background

With the rapid development of extracellular vesicles (EVs) in regenerative medicine research, they have become a promising new direction in the mechanistic, diagnosis and treatment studies of degenerative musculoskeletal diseases (DMDs), and has attracted increasing attention. However, there is currently a lack of comprehensive and objective summary analysis to help researchers quickly and conveniently understand the development trajectory and future trends of this field.

Method

This study collected articles and reviews published from 2006 to 2024 on EVs in DMDs from the Web of Science database. Bibliometric and visual analysis was conducted using several tools, including Microsoft Excel Office, VOSviewer, CiteSpace, Pajek, and R packages.

Results

1,182 publications were included in the analysis from 2006 to 2024. Notably, there was a rapid increase in the number of publications starting in 2016, suggesting that this field remains in a developmental stage. Co-authorship analysis revealed that China ranked first in terms of publications, whereas the United States led in citations. The journal with the highest number of publications was International Journal of Molecular Sciences (INT J MOL SCI). The most prolific authors were Ragni, E with 23 publications, while the most cited author was Toh, WS. Additionally, nine of the top 10 institutions were from China, with Shanghai Jiao Tong University leading in the number of publications. The most cited article was "MSC exosomes mediate cartilage repair by enhancing proliferation, attenuating apoptosis and modulating immune reactivity", authored by Zhang, S, and published in BIOMATERIALS in 2018.

Conclusion

This study, through bibliometric and visual analysis, clearly illustrates the collaborative relationships among countries, authors, institutions, and journals, providing valuable insights for researchers seeking academic collaboration opportunities. Moreover, the analysis of keywords and citations allows researchers to better understand key research hotspots and frontiers in this field, and points toward promising directions for future research. The growing interest in EV research in DMDs over recent years indicates increasing attention and a dynamic progression in this field.

Tumor-derived extracellular vesicles: key drivers of immunomodulation in breast cancer

Breast cancer (BC) remains a significant global health challenge characterized by its heterogeneity and treatment complexities. Extracellular vesicles (EVs) are small membranous particles released by cells, facilitating intercellular communication by transporting bioactive molecules such as proteins, lipids, and nucleic acids. Tumor-derived EVs have emerged as pivotal regulators in the tumor microenvironment (TME) and drivers of BC progression. These EVs carry diverse cargoes of bioactive molecules, influencing critical processes such as immune modulation, angiogenesis, and metastasis. By altering the behaviors of immune cells including macrophages, dendritic cells, and T cells, tumor-derived EVs contribute to immune evasion and tumor growth. Furthermore, Tumor-derived EVs play a role in mediating drug resistance, impacting the effectiveness of therapeutic interventions. Understanding the multifaceted roles of BC tumor-derived EVs is essential for the development of innovative therapeutic strategies. Targeting pathways mediated by EVs holds promise for enhancing the efficacy of cancer treatments and improving patient outcomes. This comprehensive review provides insights into the intricate interactions of tumor-derived EVs in immune modulation and BC progression, highlighting potential therapeutic targets and avenues for novel cancer therapies.

Treatment of Denervated Muscle Atrophy by Injectable Dual-Responsive Hydrogels Loaded with Extracellular Vesicles

Denervated muscle atrophy, a common outcome of nerve injury, often results in irreversible fibrosis due to the limited effectiveness of current therapeutic interventions. While extracellular vesicles (EVs) offer promise for treating muscle atrophy, their therapeutic potential is hindered by challenges in delivery and bioactivity within the complex microenvironment of the injury site. To address this issue, an injectable hydrogel is developed that is responsive to both ultrasound and pH, with inherent anti-inflammatory and antioxidant properties, designed to improve the targeted delivery of stem cell-derived EVs. This hydrogel system allows for controlled release of EVs from human umbilical cord mesenchymal stem cells (HUC-MSCs), adapting to the specific conditions of the injury environment. In vivo studies using a rat model of nerve injury demonstrated that the EV-loaded hydrogel (EVs@UR-gel) significantly preserved muscle function. Six weeks post-nerve reconstruction, treated rats exhibited muscle strength, circumference, and wet weight reaching 89.53 ± 0.96%, 76.02 ± 7.49%, and 88.0 ± 2.65% of healthy controls, respectively, alongside an improvement in the sciatic nerve index (-0.11 ± 0.09). This platform presents a novel therapeutic approach by maintaining EV bioactivity, enabling tunable release based on the disease state, and facilitating the restoration of muscle structure and function.

Muscle-Derived Bioactive Factors: MyoEVs and Myokines

Overview of the functions and applications of myokines and MyoEVs.

Rectifying the Crosstalk between the Skeletal and Immune Systems Improves Osteoporosis Treatment by Core-Shell Nanocapsules

Contemporary osteoporosis treatment often neglects the intricate interactions among immune cells, signaling proteins, and cytokines within the osteoporotic microenvironment. Here, we developed core-shell nanocapsules composed of a cationized lactoferrin core and an alendronate polymer shell. By tuning the size of these nanocapsules and leveraging the alendronate shell, we enabled precise delivery of small interfering RNA targeting the Semaphorin 4D gene (siSema4D) to specific bone sites. This strategy integrates the antiresorptive drug alendronate with siSema4D, efficiently inhibiting osteoclast (OC) differentiation and bone resorption, while promoting osteogenesis to restore the balance between osteoblasts (OBs) and OCs. Moreover, encapsulating siSema4D within the nanocapsules helps to mitigate immunological cascades, thereby reversing the inflammatory microenvironment and restoring immune homeostasis and providing insights into the immunomodulatory effects of Sema4D in osteoporosis therapy. In both ovariectomized and senile osteoporotic mouse models, local intramuscular administration of core-shell nanocapsules effectively rectified the imbalance between the skeletal and immune systems, significantly enhancing the overall efficacy of osteoporosis treatment. Our findings underscore the therapeutic promise of addressing the multifaceted osteoporotic microenvironment through targeted interventions.

Metabolic Messengers: small extracellular vesicles

Small extracellular vesicles (sEVs) are signalling molecules and biomarkers of cell status that govern a complex intraorgan and interorgan communication system through their cargo. Initially recognized as a waste disposal mechanism, they have emerged as important metabolic regulators. They transfer biological signals to recipient cells through their cargo content, and microRNAs (miRNAs) often mediate their metabolic effects. This review provides a concise overview of sEVs, specifically in the context of obesity-associated chronic inflammation and related metabolic disorders, describing their role as metabolic messengers, identifying their key sites of action and elucidating their mechanisms. We highlight studies that have shaped our understanding of sEV metabolism, address critical questions for future exploration, discuss the use of miRNAs as disease biomarkers and provide insights into the therapeutic potential of sEVs or specific miRNAs for treating metabolic diseases and related disorders in the future.

Low-intensity pulsed ultrasound enhances the osteogenic potential of PDLSCs-derived extracellular vesicles through COMP/PI3K/AKT

The therapeutic potential of extracellular vesicles (EVs) in bone regeneration is noteworthy; however, their clinical application is impeded by low yield and limited efficacy. This study investigated the effect of low-intensity pulsed ultrasound (LIPUS) on the therapeutic efficacy of EVs derived from periodontal ligament stem cells (PDLSCs) and preliminarily explored its mechanism. PDLSCs were cultured with osteogenic media and stimulated with or without LIPUS, and then EVs and LIPUS-stimulated EVs (L-EVs) were isolated separately. We investigated the biological characteristics and effects of these two EVs on cell proliferation, migration, osteogenic differentiation, and bone regeneration in vivo and in vitro, and explored the potential mechanism by analyzing protein profiles. LIPUS significantly stimulated the secretion of PDLSCs-EVs, and L-EVs exhibited stronger efficacy in promoting cell proliferation, migration, and osteogenic differentiation, thereby enhancing new bone formation. LIPUS stimulation affected the protein profile of PDLSCs-EVs, and 42 proteins were upregulated and 4 proteins downregulated in L-EVs when compared with EVs. LIPUS significantly upregulated the level of cartilage oligomeric matrix protein (COMP) in EVs, which enhanced EVs' osteogenic ability via the PI3K/AKT pathway. This study proposes that LIPUS has potential as an optimization method for enhancing the therapeutic effects of EVs in tissue regeneration.

Proteomic Profiling Towards a Better Understanding of Genetic Based Muscular Diseases: The Current Picture and a Look to the Future

Proteomics accelerates diagnosis and research of muscular diseases by enabling the robust analysis of proteins relevant for the manifestation of neuromuscular diseases in the following aspects: (i) evaluation of the effect of genetic variants on the corresponding protein, (ii) prediction of the underlying genetic defect based on the proteomic signature of muscle biopsies, (iii) analysis of pathophysiologies underlying different entities of muscular diseases, key for the definition of new intervention concepts, and (iv) patient stratification according to biochemical fingerprints as well as (v) monitoring the success of therapeutic interventions. This review presents-also through exemplary case studies-the various advantages of mass proteomics in the investigation of genetic muscle diseases, discusses technical limitations, and provides an outlook on possible future application concepts. Hence, proteomics is an excellent large-scale analytical tool for the diagnostic workup of (hereditary) muscle diseases and warrants systematic profiling of underlying pathophysiological processes. The steady development may allow to overcome existing limitations including a quenched dynamic range and quantification of different protein isoforms. Future directions may include targeted proteomics in diagnostic settings using not only muscle biopsies but also liquid biopsies to address the need for minimally invasive procedures.

Flavonoids for gastrointestinal tract local and associated systemic effects: A review of clinical trials and future perspectives

BACKGROUND

Flavonoids are naturally occurring dietary phytochemicals with significant antioxidant effects aside from several health benefits. People often consume them in combination with other food components. Compiling data establishes a link between bioactive flavonoids and prevention of several diseases in animal models, including cardiovascular diseases, diabetes, gut dysbiosis, and metabolic dysfunction-associated steatotic liver disease (MASLD). However, numerous clinical studies have demonstrated the ineffectiveness of flavonoids contradicting rodent models, thereby challenging the validity of using flavonoids as dietary supplements.

AIM OF REVIEW

This review provides a clinical perspective to emphasize the effective roles of dietary flavonoids as well as to summarize their specific mechanisms in animals briefly.

KEY SCIENTIFIC CONCEPTS OF REVIEW

First, this review offers an in-depth elucidation of the metabolic processes of flavonoids within human, encompassing the small, large intestine, and the liver. Furthermore, the review provides a comprehensive overview of the various functions of flavonoids in the gastrointestinal tract, including hindering the breakdown and assimilation of macronutrients, such as polysaccharides and lipids, regulating gut hormone secretion as well as inhibition of mineral iron absorption. In the large intestine, an unabsorbed major portion of flavonoids interact with the gut flora leading to their biotransformation. Once absorbed and circulated in the bloodstream, bioactive flavonoids or their metabolites exert numerous beneficial systemic effects. Lastly, we examine the protective effects of flavonoids in several metabolic disorders, including endothelial dysfunction, MASLD, cardiovascular disease, obesity, hyperlipidemia, and insulin resistance. In conclusion, this review outlines the safety and future prospects of flavonoids in the field of health, especially in the prevention of metabolic syndrome (MetS).

Muscle-derived extracellular vesicles mediate crosstalk between skeletal muscle and other organs

Skeletal muscle (SKM) has crucial roles in locomotor activity and posture within the body and also functions have been recognized as an actively secretory organ. Numerous bioactive molecules are secreted by SKM and transported by extracellular vesicles (EVs), a novel class of mediators of communication between cells and organs that contain various types of cargo molecules including lipids, proteins and nucleic acids. SKM-derived EVs (SKM-EVs) are intercellular communicators with significant roles in the crosstalk between SKM and other organs. In this review, we briefly describe the biological characteristics, composition, and uptake mechanisms of EVs, particularly exosomes, comprehensively summarize the regulatory effects of SKM-EVs on the function of, which include myogenesis, muscle repair and regeneration, as well as metabolic regulation. Furthermore, we explore the impact of SKM- EVs on various organs including bone, the cardiovascular system, adipose tissue, and nervous system. As emerging evidence suggests that SKM-EVs are involved in the development and regulation of type 2 diabetes (T2D), systemic inflammation, and other chronic diseases, we also highlight the potential of SKM-EVs as therapeutic targets and diagnostic biomarkers, emphasizing the need for further research to elucidate the complex mechanisms underlying intercellular communication in physiological and pathological contexts.

Musculoskeletal Organs-on-Chips: An Emerging Platform for Studying the Nanotechnology-Biology Interface

Nanotechnology-based approaches are promising for the treatment of musculoskeletal (MSK) disorders, which present significant clinical burdens and challenges, but their clinical translation requires a deep understanding of the complex interplay between nanotechnology and MSK biology. Organ-on-a-chip (OoC) systems have emerged as an innovative and versatile microphysiological platform to replicate the dynamics of tissue microenvironment for studying nanotechnology-biology interactions. This review first covers recent advances and applications of MSK OoCs and their ability to mimic the biophysical and biochemical stimuli encountered by MSK tissues. Next, by integrating nanotechnology into MSK OoCs, cellular responses and tissue behaviors may be investigated by precisely controlling and manipulating the nanoscale environment. Analysis of MSK disease mechanisms, particularly bone, joint, and muscle tissue degeneration, and drug screening and development of personalized medicine may be greatly facilitated using MSK OoCs. Finally, future challenges and directions are outlined for the field, including advanced sensing technologies, integration of immune-active components, and enhancement of biomimetic functionality. By highlighting the emerging applications of MSK OoCs, this review aims to advance the understanding of the intricate nanotechnology-MSK biology interface and its significance in MSK disease management, and the development of innovative and personalized therapeutic and interventional strategies.

Bone aging and extracellular vesicles

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

Foxk1 promotes bone formation through inducing aerobic glycolysis

Transcription factor Foxk1 can regulate cell proliferation, differentiation, metabolism, and promote skeletal muscle regeneration and cardiogenesis. However, the roles of Foxk1 in bone formation is unknown. Here, we found that Foxk1 expression decreased in the bone tissue of aged mice and osteoporosis patients. Knockdown of Foxk1 in primary murine calvarial osteoblasts suppressed osteoblast differentiation and proliferation. Conditional knockout of Foxk1 in preosteoblasts and mature osteoblasts in mice exhibited decreased bone mass and mechanical strength due to reduced bone formation. Mechanistically, we identified Foxk1 targeted the promoter region of many genes of glycolytic enzyme by CUT&Tag analysis. Lacking of Foxk1 in primary murine calvarial osteoblasts resulted in reducing aerobic glycolysis. Inhibition of glycolysis by 2DG hindered osteoblast differentiation and proliferation induced by Foxk1 overexpression. Finally, specific overexpression of Foxk1 in preosteoblasts, driven by a preosteoblast specific osterix promoter, increased bone mass and bone mechanical strength of aged mice, which could be suppressed by inhibiting glycolysis. In summary, these findings reveal that Foxk1 plays a vital role in the osteoblast metabolism regulation and bone formation stimulation, offering a promising approach for preventing age-related bone loss.

Identification of disease-specific extracellular vesicle-associated plasma protein biomarkers for Duchenne Muscular Dystrophy and Facioscapulohumeral Muscular Dystrophy

Objective

Reliable, circulating biomarkers for Duchenne, Becker and facioscapulohumeral muscular dystrophies (DBMD and FSHD) remain unvalidated. Here, we investigated the plasma extracellular vesicle (EV) proteome to identify disease-specific biomarkers that could accelerate therapy approvals.

Methods

We extracted EVs from the plasma of DBMD and FSHD patients and healthy controls using size-exclusion chromatography, conducted mass spectrometry on the extracted EV proteins, and performed comparative analysis to identify disease-specific biomarkers. We correlated the levels of these biomarkers with clinical outcome measures and confounding factors.

Results

The muscle-associated proteins PYGM, MYOM3, FLNC, MYH2 and TTN were exclusively present in DBMD EVs. PYGM, MYOM3, and TTN negatively correlated with age. PYGM and MYOM3 levels were elevated in patients without cardiomyopathy, and PYGM levels were specifically elevated in ambulatory DMD patients. On the other hand, female FSHD patients displayed significantly higher MBL2 and lower GPLD1 levels. However, male FSHD patients exhibited higher C9 and lower C4BPB levels. Additionally, desmosome proteins JUP and DSP were uniquely found in FSHD males. MBL2 positively correlated with age and C4BPB negatively correlated with FSHD severity in male patients.

Interpretation

Our findings underscore the sensitivity of analyzing circulating EV content to identify disease-specific protein biomarkers for DBMD and FSHD. Our results also emphasize the potential of EV-based biomarker discovery as a promising approach to monitor disease progression as well as effectiveness of therapies in muscular dystrophy, potentially contributing to their approval. Further research with larger cohorts is needed to validate these biomarkers and explore their clinical implications.

Recent Advances of Exosomes Derived from Skeletal Muscle and Crosstalk with Other Tissues

Skeletal muscle plays a crucial role in movement, metabolism, and energy homeostasis. As the most metabolically active endocrine organ in the body, it has recently attracted widespread attention. Skeletal muscle possesses the ability to release adipocytokines, bioactive peptides, small molecular metabolites, nucleotides, and other myogenic cell factors; some of which have been shown to be encapsulated within small vesicles, particularly exosomes. These skeletal muscle exosomes (SKM-Exos) are released into the bloodstream and subsequently interact with receptor cell membranes to modulate the physiological and pathological characteristics of various tissues. Therefore, SKM-Exos may facilitate diverse interactions between skeletal muscle and other tissues while also serving as biomarkers that reflect the physiological and pathological states of muscle function. This review delves into the pivotal role and intricate molecular mechanisms of SKM-Exos and its derived miRNAs in the maturation and rejuvenation of skeletal muscle, along with their intercellular signaling dynamics and physiological significance in interfacing with other tissues.

Histone deacetylase inhibition enhances extracellular vesicles from muscle to promote osteogenesis via miR-873-3p

Regular physical activity is widely recognized for reducing the risk of various disorders, with skeletal muscles playing a key role by releasing biomolecules that benefit multiple organs and tissues. However, many individuals, particularly the elderly and those with clinical conditions, are unable to engage in physical exercise, necessitating alternative strategies to stimulate muscle cells to secrete beneficial biomolecules. Histone acetylation and deacetylation significantly influence exercise-induced gene expression, suggesting that targeting histone deacetylases (HDACs) could mimic some exercise responses. In this study, we explored the effects of the HDAC inhibitor Trichostatin A (TSA) on human skeletal muscle myoblasts (HSMMs). Our findings showed that TSA-induced hyperacetylation enhanced myotube fusion and increased the secretion of extracellular vesicles (EVs) enriched with miR-873-3p. These TSA-EVs promoted osteogenic differentiation in human bone marrow mesenchymal stem cells (hBMSCs) by targeting H2 calponin (CNN2). In vivo, systemic administration of TSA-EVs to osteoporosis mice resulted in significant improvements in bone mass. Moreover, TSA-EVs mimicked the osteogenic benefits of exercise-induced EVs, suggesting that HDAC inhibition can replicate exercise-induced bone health benefits. These results demonstrate the potential of TSA-induced muscle-derived EVs as a therapeutic strategy to enhance bone formation and prevent osteoporosis, particularly for individuals unable to exercise. Given the FDA-approved status of various HDAC inhibitors, this approach holds significant promise for rapid clinical translation in osteoporosis treatment.

The multifaceted roles of mitochondria in osteoblasts: from energy production to mitochondrial-derived vesicle secretion

Mitochondria in osteoblasts have been demonstrated to play multiple crucial functions in bone formation from intracellular adenosine triphosphate production to extracellular secretion of mitochondrial components. The present review explores the current knowledge about mitochondrial biology in osteoblasts, including mitochondrial biogenesis, bioenergetics, oxidative stress generation, and dynamic changes in morphology. Special attention is given to recent findings, including mitochondrial donut formation in osteoblasts, which actively generates mitochondrial-derived vesicles (MDVs), followed by extracellular secretion of small mitochondria and MDVs. We also discuss the therapeutic effects of targeting osteoblast mitochondria, highlighting their potential applications in improving bone health.

Metformin enhances the therapeutic effects of extracellular vesicles derived from human periodontal ligament stem cells on periodontitis

Metformin has shown outstanding anti-inflammatory and osteogenic abilities. Mesenchymal stem cell-derived extracellular vesicles (EVs) reveal promising therapeutic potency by carrying various biomolecules. This study explored the effects of metformin on the therapeutic potential of EVs derived from human periodontal ligament stem cells (PDLSCs) for periodontitis. PDLSCs were cultured in osteogenic medium with or without metformin, and the supernatant was then collected separately to extract EVs and metformin-treated EVs (M-EVs). After identifying the characteristics, we evaluated the anti-inflammatory and osteogenic effects of EVs and M-EVs in vivo and in vitro. Osteogenic differentiation of PDLSCs was markedly enhanced after metformin treatment, and the effect was dramatically inhibited by GW4896, an inhibitor of EVs' secretion. Metformin significantly increased EVs' yields and improved their effects on cell proliferation, migration, and osteogenic differentiation. Moreover, metformin significantly enhanced the osteogenic ability of EVs on inflammatory PDLSCs. Animal experiments revealed that alveolar bone resorption was dramatically reduced in the EVs and M-EVs groups when compared to the periodontitis group, while the M-EVs group showed the lowest levels of alveolar bone loss. Metformin promoted the osteogenic differentiation of PDLSCs partly through EVs pathway and significantly enhanced the secretion of PDLSCs-EVs with superior pro-osteogenic and anti-inflammatory potential, thus improving EVs' therapeutic potential on periodontitis.

Study protocol for the ROLEX-DUO randomised placebo-controlled trial: ROmosozumab Loaded with EXercise - DUal effects on bone and muscle in postmenopausal Osteoporosis and Osteopenia

INTRODUCTION

Novel strategies are needed to address the rising burden of osteoporosis and fragility fractures. High-intensity resistance and impact (HiRIT) exercise has shown benefit in improving bone density in postmenopausal women with osteoporosis/osteopenia. Whether HiRIT can enhance the therapeutic effects of osteoporosis pharmacotherapy has not been established. ROLEX-DUO is a randomised controlled trial designed to assess the efficacy of romosozumab on various bone and muscle outcomes in combination with different exercise interventions in women with postmenopausal osteoporosis/osteopenia.

METHODS AND ANALYSIS

ROLEX-DUO is an 8-month randomised placebo-controlled trial conducted at two tertiary referral centres for patients with osteoporosis/osteopenia in Sydney, New South Wales, Australia. The study is implementing the combination of romosozumab or placebo with different forms of exercise in postmenopausal women with osteoporosis/osteopenia without recent fragility fracture (n=102). Eligible women will be randomised 1:1:1 into one of three groups: (1) romosozumab with supervised HiRIT, (2) romosozumab with unsupervised low-intensity exercise or (3) placebo with unsupervised low-intensity exercise. Co-primary outcomes are the mean percentage change in lumbar spine bone mineral density (BMD), and mean change in five times sit-to-stand test performance (seconds) at 8 months. Secondary/exploratory outcomes include BMD changes at the femoral neck, total hip and distal radius, three-dimensional dual-energy X-ray absorptiometry (DXA) hip outcomes, DXA-derived lean and fat mass, serum markers of bone turnover (procollagen type 1 peptide, C-telopeptide of type 1 collagen) and bone biomarkers (dickkopf-1), serum extracellular vesicle analyses, 36-Item Short Form Survey (SF-36) quality-of-life scores, Menopause-Specific Quality Of Life (MENQOL) Questionnaire menopause symptom burden scores, number of falls and fractures. Mixed-effects models will be performed to compare longitudinal outcome results between groups using intention-to-treat analysis.

ETHICS AND DISSEMINATION

The trial was approved by the Northern Sydney Local Health District Human Research Ethics Committee (2022/ETH01794, protocol V.8, dated 03 July 2024). Participants will provide written informed consent prior to inclusion. Findings will be disseminated via peer-reviewed journals, scientific conferences and summary reports to funding bodies.

TRIAL REGISTRATION NUMBER

ACTRN12623000867695.

Characterization of spinal cord tissue-derived extracellular vesicles in neuroinflammation

Extracellular vesicles (EVs) are released by all cells, can cross the blood-brain barrier, and have been shown to play an important role in cellular communication, substance shuttling, and immune modulation. In recent years EVs have shifted into focus in multiple sclerosis (MS) research as potential plasma biomarkers and therapeutic vehicles. Yet little is known about the disease-associated changes in EVs in the central nervous system (CNS). To address this gap, we characterized the physical and proteomic changes of mouse spinal cord-derived EVs before and at 16 and 25 days after the induction of experimental autoimmune encephalomyelitis (EAE), a neuroinflammatory model of MS. Using various bioinformatic tools, we found changes in inflammatory, glial, and synaptic proteins and pathways, as well as a shift in the predicted contribution of immune and glial cell types over time. These results show that EVs provide snapshots of crucial disease processes such as CNS-compartmentalized inflammation, re/de-myelination, and synaptic pathology, and might also mediate these processes. Additionally, inflammatory plasma EV biomarkers previously identified in people with MS were also altered in EAE spinal cord EVs, suggesting commonalities of EV-related pathological processes during EAE and MS and overlap of EV proteomic changes between CNS and circulating EVs.

Molecular insights of exercise therapy in disease prevention and treatment

Despite substantial evidence emphasizing the pleiotropic benefits of exercise for the prevention and treatment of various diseases, the underlying biological mechanisms have not been fully elucidated. Several exercise benefits have been attributed to signaling molecules that are released in response to exercise by different tissues such as skeletal muscle, cardiac muscle, adipose, and liver tissue. These signaling molecules, which are collectively termed exerkines, form a heterogenous group of bioactive substances, mediating inter-organ crosstalk as well as structural and functional tissue adaption. Numerous scientific endeavors have focused on identifying and characterizing new biological mediators with such properties. Additionally, some investigations have focused on the molecular targets of exerkines and the cellular signaling cascades that trigger adaption processes. A detailed understanding of the tissue-specific downstream effects of exerkines is crucial to harness the health-related benefits mediated by exercise and improve targeted exercise programs in health and disease. Herein, we review the current in vivo evidence on exerkine-induced signal transduction across multiple target tissues and highlight the preventive and therapeutic value of exerkine signaling in various diseases. By emphasizing different aspects of exerkine research, we provide a comprehensive overview of (i) the molecular underpinnings of exerkine secretion, (ii) the receptor-dependent and receptor-independent signaling cascades mediating tissue adaption, and (iii) the clinical implications of these mechanisms in disease prevention and treatment.

The role of photobiomodulation in accelerating bone repair

Bone repair is faced with obstacles such as slow repair rates and limited bone regeneration capacity. Delayed healing even nonunion could occur in bone defects, influencing the life quality of patients severely. Photobiomodulation (PBM) utilizes different light sources to derive beneficial therapeutic effects with the advantage of being non-invasive and painless, providing a promising strategy for accelerating bone repair. In this review, we summarize the parameters, mechanisms, and effects of PBM regulating bone repair, and further conclude the current clinical application of PBM devices in bone repair. The wavelength of 635-980 nm, the output power of 40-100 mW, and the energy density of less than 100 J/cm2 are the most commonly used parameters. New technologies, including needle systems and biocompatible and implantable optical fibers, offer references to realize an efficient and safe strategy for bone repair. Further research is required to establish the reliability of outcomes from in vivo and in vitro studies and to standardize clinical trial protocols.