Exosome-mediated muscle-bone crosstalk: mechanisms and therapeutic potential

Abstract

Background

Muscle and bone maintain homeostasis through biomechanical and molecular crosstalk. Disruption of this interaction leads to osteosarcopenia, a condition marked by concurrent muscle and bone loss. Exosomes carry proteins and nucleic acids between tissues and are now recognized as key mediators of intercellular communication. Clarifying the role of exosomes in muscle-bone crosstalk is essential for identifying new biomarkers and therapeutic targets for musculoskeletal diseases.

Main body

This review first summarizes the biogenesis and molecular composition of exosomes. It then examines the regulatory effects of skeletal muscle-derived exosomes on bone metabolism, focusing on how myogenic miRNAs and proteins influence osteoblast and osteoclast activity. The review also addresses the reverse pathway, describing how bone-derived exosomes, particularly those from BMSCs, affect myogenesis and muscle atrophy. We further assess their translational potential as circulating biomarkers, therapeutic delivery vehicles, and engineered platforms, while considering current limitations in isolation and characterization, biodistribution, manufacturing, safety, and regulatory oversight.

Conclusion

Exosomes are critical mediators of muscle-bone crosstalk, with their cargo reflecting the physiological state of source cells. While exosome-based tools show promise for the diagnosis and treatment of conditions like osteosarcopenia, challenges remain in standardizing preparation methods and achieving tissue-specific delivery. Future work integrating multi-omics and artificial intelligence will be necessary to translate these findings into clinical applications for musculoskeletal health.

Introduction

Skeletal muscle and bone collectively constitute the locomotor system, and there is a close bidirectional regulatory relationship between them [1]. Biomechanically, bone provides mechanical attachment points for skeletal muscle, while the mechanical loads generated by muscle contraction, in turn, modulate bone metabolism [2]. From a molecular perspective, skeletal muscle and bone function as endocrine organs, secreting myokines (such as irisin and myostatin) and osteokines (such as osteocalcin and bone morphogenetic proteins), respectively, to achieve inter-organ signaling via paracrine and endocrine pathways [3]. When the equilibrium of this muscle-bone crosstalk is disrupted, muscle atrophy and bone loss typically occur in tandem [4]. A hallmark of this dysregulation is osteosarcopenia—a condition that has gained significant attention in recent years. It is characterized by the concurrent decline in muscle mass, muscle function, and bone mass, significantly increasing the risks of falls, fractures, disability, and death, thereby posing a “dual burden” on patients’ quality of life [5, 6]. Consequently, elucidating the complex and precise crosstalk mechanisms between muscle and bone, and mapping their specific molecular regulatory networks, has become a pivotal scientific endeavor. These efforts are essential for understanding the pathogenesis of musculoskeletal comorbidities, such as osteosarcopenia, and for developing integrated synergistic intervention strategies.

In recent years, extracellular vesicles (EVs), as a novel type of biological delivery vehicle, have provided an important breakthrough for unraveling the molecular mechanisms of muscle-bone crosstalk [7, 8]. EVs are subcellular particles that are naturally secreted by healthy, diseased, and virus-infected cells [9]. They have a lipid bilayer similar to their parent cells and carry functional molecules such as nucleic acids and proteins [10]. EVs are categorized based on their biogenesis and physical dimensions: exosomes (30–150 nm), microvesicles (50–1000 nm), and apoptotic bodies (> 1000 nm) [11]. While microvesicles and apoptotic bodies are formed by the direct outward budding of the plasma membrane from living or dying cells, exosomes originate from the endosomal pathway and are released upon the fusion of multivesicular bodies (MVBs) with the plasma membrane [12]. It should be noted that exosomes overlap with other small EVs in size and molecular composition; therefore, particle size or commonly used EV-associated markers such as CD9, CD63, and CD81 alone are generally insufficient to establish their endosomal origin [13, 14]. In accordance with the MISEV2023 guidelines, vesicles of unconfirmed endosomal origin are more appropriately referred to as sEVs (small extracellular vesicles) [15]. Accordingly, the term “exosomes” used in this review may also encompass exosome-enriched sEV populations that were identified in previous studies on the basis of conventional size, morphological, and EV-marker criteria. Notably, exosomes can protect their cargo from clearance by the mononuclear phagocyte system, which gives them an advantage in intercellular communication [16]. Intriguingly, skeletal muscle-derived exosomes can enter the circulation to influence bone cell function. Similarly, bone-derived exosomes can regulate skeletal muscle regeneration [17, 18].

In recent years, several reviews have explored the roles of exosomes in muscle-bone crosstalk. However, some have focused primarily on the unidirectional effects of skeletal muscle-derived exosomes on bone metabolism [17, 19, 20], whereas others have emphasized exercise-related regulation [21–23] or exosomal miRNAs in specific diseases [24, 25]. Notably, a recent review systematically summarized exosomal miRNA-mediated muscle-bone crosstalk and its implications for sarcopenia, osteoporosis, and osteosarcopenia, but devoted relatively limited attention to other functional cargoes, including proteins [26]. Overall, an integrated analysis encompassing exosome-mediated bidirectional muscle-bone crosstalk, diverse molecular cargoes, and clinical translation remains limited. To address this gap, we provide a comprehensive and critical synthesis of the available evidence, with particular emphasis on the functional changes in exosomal cargoes under physiological and pathological conditions. We further evaluate the translational potential and current barriers associated with exosomes as biomarkers, therapeutic delivery vehicles, and engineered therapeutic platforms. This review aims to advance understanding of the molecular mechanisms underlying muscle-bone crosstalk and provide a theoretical basis for developing exosome-based strategies for the coordinated management of musculoskeletal disorders.

Composition and biogenesis of exosomes

Exosomes are a class of bilayer lipid nanoscale membrane vesicles with a diameter of approximately 30–150 nm. In 1983, Harding et al. first observed exosomes in the supernatant of cultured sheep reticulocytes [27]. In 1987, Johnstone named them “exosomes” [28]. Early research suggested that exosomes were a type of “cellular debris” responsible for the excretion of cellular waste [29], and as a result, they were long overlooked. As research has progressed, scientists have discovered that exosomes can mediate specific intercellular signaling by carrying bioactive molecules, making them a focal point of research in the field of intercellular communication [30].

Exosomes carry bioactive molecules, including proteins, lipids, and nucleic acids [31]. Exosomal proteins can be classified into constitutive proteins and specific proteins. Constitutive proteins include adhesion molecules, annexins, and the tetraspanin family (notably CD9, CD63 and CD81), alongside molecular chaperones such as heat shock proteins (Hsp70, Hsp90) and endosomal sorting complexes required for transport (ESCRT)-related proteins like Alix and TSG101 [32]. Specific proteins are primarily determined by the parental cell of origin and fluctuate according to distinct physiological or pathological states [33]. Regarding lipids, exosomes are enriched in cholesterol, sphingomyelin, sphingosine, phosphatidylserine, and ceramide, which are essential for maintaining exosome structure, biogenesis, and regulating the homeostasis of recipient cells [34]. Furthermore, exosomes carry a large amount of nucleic acids, primarily including mRNA, miRNA, siRNA, and lncRNAs [35]. These RNA molecules exert their biological functions by being transferred from donor cells to recipient cells via exosomes. Notably, one study suggested that miRNAs may mediate approximately 70% of the regulatory effects exerted by exosomes on target cells, far surpassing the contribution of proteins, which account for only about 10% [36].

The biogenesis of exosomes is a highly regulated process involving endocytosis, sorting, and exocytosis [37](Fig. 1). First, cells internalize extracellular substances via endocytosis, forming early endosomes; subsequently, early endosomes undergo membrane sorting and maturation to evolve into late endosomes, whose membranes bud into the cytoplasm to form intraluminal vesicles (ILVs), and a large number of ILVs aggregate to form multivesicular bodies (MVBs); Finally, some MVBs fuse with lysosomes, and their contents are degraded into metabolic waste; others fuse with the plasma membrane, releasing ILVs into the extracellular space to form mature exosomes [38–40]. This process is regulated by both the ESCRT pathway and the ESCRT-independent pathway [41]. Specifically, ESCRT-0 recognizes and isolates ubiquitinated proteins in the endosomal membrane; ESCRT-I and ESCRT-II work together to induce budding of the endosomal membrane and encapsulate specific cargo; and ESCRT-III assembles at the bud neck, where it is assisted by the ATPase VPS4 in cleaving the membrane to drive vesicle fission [42]. Concurrently, the ATPase VPS4 also assists in the dissociation and recycling of ESCRT components from the membrane, ensuring their reuse [43]. The ESCRT-independent pathway is primarily driven by lipid microdomains and specific membrane proteins [44]. Lipid microdomains rich in ceramide and cholesterol on the endosomal membrane spontaneously generate negative membrane curvature, which drives inward budding of the membrane and promotes the formation of ILVs [45]. Tetrameric transmembrane proteins such as CD9, CD63, and CD81 are part of a highly conserved family of transmembrane proteins and are widely used as biomarkers [46, 47]. One study has indicated that they can form specific domains on the membrane through oligomerization, thereby directly promoting the formation of ILVs and the accumulation of specific cargo [48]. Furthermore, membrane transport and fusion proteins, such as RAB family GTPases and SNARE proteins, can collaborate to facilitate the fusion of MVBs with the plasma membrane and the release of exosomes [49, 50].

Fig. 1.

Biogenesis and cargo composition of exosomes. The biogenesis of exosomes begins with the invagination of the plasma membrane, leading to the formation of early endosomes. As these endosomes gradually mature, the endosomal membrane undergoes a second invagination, generating MVBs that contain ILVs. Subsequently, MVBs can either be transported to lysosomes for degradation or fuse with the plasma membrane, releasing their internal vesicles as exosomes into the extracellular space. Exosomes carry a diverse array of bioactive molecules, including tetraspanins, adhesion molecules, cytoskeleton-associated proteins, heat shock proteins, membrane transport proteins, as well as nucleic acids such as mRNA, miRNA, and DNA, in addition to various lipids and enzymes

Effects of skeletal muscle-derived exosomes on bone metabolism

In 2010, Guescini et al. [51] first demonstrated that C2C12 myoblasts can secrete exosomes, opening a new perspective for studying the communication mechanism between muscle and bone. Skeletal muscle-derived exosomes can travel through the circulation to the bone marrow cavity, cancellous bone, and cortical bone, where they are taken up by osteoblasts and osteoclasts, consequently influencing bone formation and resorption [52, 53]. In this section, we will summarize the roles of miRNAs and proteins carried by skeletal muscle-derived exosomes in mediating muscle-to-bone signaling and discuss the underlying molecular mechanisms(Table 1).

Table 1.

Effects of skeletal muscle-derived exosomes on bone metabolism

Exosome Source	Experimental Models	Cargo	Target Cell	Effect	Main Mechanism	Refs
C2C12 myoblast cell line	In vitro	miR-27a-3p	Pre-osteoblasts MC3T3–E1	Promotes bone formation	Inhibits APC and activates β-catenin signaling	[54]
Mechanically stimulated C2C12 myoblasts cell line	In vitro and in vivo (glucocorticoid-induced osteoporosis mice)	miR-92a-3p	BMSCs	Promotes bone formation	Suppresses PTEN and activates AKT signaling	[55]
Starvation-induced atrophic C2C12 myotubes and skeletal muscle of aged C57BL/6J mice	In vitro and in vivo (aged skeletal muscle-specific CD63-positive vesicle-tracing transgenic mice)	miR-125a-5p	Pre-osteoblasts MC3T3–E1	Inhibits bone formation	Downregulates Sirt7/Sp7 axis	[56]
C2C12 myoblast cell line	In vitro (H₂O₂-induced oxidative stress in C2C12 myoblasts)	miR-34a	BMSCs	Inhibits bone formation	Downregulates Sirt1	[57]
C2C12 myoblasts with slo1 knockdown	In vitro and in vivo (muscle-specific slo1-knockout mice)	miR-222-3p	Pre-osteoblasts MC3T3–E1	Inhibits bone formation	Inhibits STAT3 and downregulates Runx2, ALP, OPN	[58]
C2C12 myoblast cell line	In vivo and in vitro(FFSS-treated C2C12 myoblasts)	miR-196a-5p, miR-155-5p	Osteoclast precursors	Inhibits bone resorption	Downregulates NFATc1, DC-STAMP, CTSK	[59]
Skeletal muscle of C57BL/6J mice	In vitro and in vivo (disuse osteoporotic mice)	LDHA	BMSCs	Promotes bone formation	Activates glycolysis, provides energy	[53]
C2C12 myoblast cell line	In vitro and in vivo (OVX mice)	Prrx2	BMSCs	Promotes bone formation	Upregulation of MIR22HG activates Hippo/YAP1 pathway via miR-128 sponging	[60]
Circulating plasma exosomes from older adults and patients with osteoporosis	Human samples and in vitro	BAG6	Th17 cells in bone	Promotes osteoclastogenesis and bone loss	Upregulates CD6 expression in Th17 cells and promotes SPP1 expression via interaction with TREM2⁺ macrophages	[61]

Regulation of bone formation

Skeletal muscle-derived exosomes can deliver pro-osteogenic miRNAs to bone, thereby promoting osteogenic differentiation by regulating osteogenesis-related gene expression and signaling pathways. High-throughput sequencing screening revealed that miR-27a-3p is highly abundant in C2C12 myoblast exosomes [62]. Following uptake by MC3T3-E1 preosteoblasts, miR-27a-3p targets and suppresses adenomatous polyposis coli (APC), thereby activating Wnt/β-catenin signaling and promoting osteogenic differentiation [54]. In a related study, treatment of myoblasts with the traditional Chinese herbal formula Zhuang-Gu-Fang (ZGF) induced the release of exosomes enriched in miR-5100, miR-126a-3p, miR-450b-5p, and miR-669a-5p, which markedly enhanced osteoblast differentiation [63]. Notably, miR-5100 was found to target Tob2, a negative regulator of osteogenesis, thereby increasing the expression of osteogenic factors [64]. These findings suggest that miR-5100 enrichment may contribute to the pro-osteogenic effects of skeletal muscle-derived exosomes. Evidence from animal models further supports the involvement of skeletal muscle-derived exosomal miRNAs in bone homeostasis. In mice with dexamethasone-induced osteoporosis, local intramuscular administration of miR-92a-3p-enriched muscle-derived exosomes increased bone mass and improved trabecular microarchitecture [55], providing in vivo evidence for the pro-osteogenic effects of skeletal muscle-derived exosomes.

With the progressive aging of skeletal muscle, the bioactive substances of skeletal muscle-derived exosomes exhibit significant variations compared to those secreted by young skeletal muscle, consequently leading to altered effects on bone metabolism [65]. Compared with young skeletal muscle-derived exosomes, aged skeletal muscle-derived exosomes may disrupt bone homeostasis by suppressing osteogenic differentiation and bone formation. The level of miR-34a is significantly increased in aged muscle-derived exosomes. Overexpression of miR-34a in C2C12 myoblast-derived exosomes suppresses SIRT1 expression in BMSCs, reduces cell viability, and impairs bone formation [57]. More direct in vivo evidence was obtained using skeletal muscle-specific CD63-positive vesicle-tracing transgenic mice. Aging increased the release of skeletal muscle-derived exosomes, which entered the circulation, reached bone tissue, and were taken up by osteoblasts. Mechanistically, miR-125a-5p enriched in aged skeletal muscle-derived exosomes targeted and downregulated SIRT7, disrupted histone deacetylation at the Sp7 promoter, and suppressed Sp7 transcription, ultimately impairing osteogenic differentiation [56]. Muscle dysfunction can also generate exosomal signals that adversely affect bone formation. In a mouse model of sarcopenia induced by skeletal muscle-specific Slo1 knockout, miR-222-3p was markedly enriched in myoblast-derived exosomes [58]. After reaching bone tissue through the circulation, miR-222-3p suppressed STAT3 translation, thereby downregulating osteogenic markers, including Runx2, ALP, and OPN, and ultimately inhibiting bone formation. Collectively, myogenic exosomal miRNAs can be regarded as “myokine-like” trans-organ signaling molecules that transmit signals of skeletal muscle aging or dysfunction to bone tissue, thereby participating in muscle-bone crosstalk.

In addition to miRNAs, muscle-derived exosomes can regulate bone formation by delivering functional proteins. Ma et al. performed proteomic analysis and found that skeletal muscle-derived exosomes are enriched in glycolytic enzymes, including lactate dehydrogenase A (LDHA) [53]. Exosomal delivery of LDHA to bone marrow mesenchymal stem cells (BMSCs) enhances intracellular glycolysis. This metabolic activation not only provides energy for osteogenic differentiation but may also increase osteogenic gene expression through lactate-mediated epigenetic modifications, such as histone lactylation. Through this metabolic mechanism, skeletal muscle-derived exosomes promote the osteogenic differentiation of BMSCs and protect against disuse osteoporosis in mice. Paired related homeobox 2 (Prrx2) is another functional protein carried by skeletal muscle-derived exosomes. Prrx2 activates MIR22HG transcription, allowing MIR22HG to sequester miR-128 and relieve its inhibition of YAP, thereby promoting the osteogenic differentiation of BMSCs [60]. Together, these findings indicate that skeletal muscle-derived exosomes mediate muscle-to-bone signaling not only through miRNAs but also through functional protein cargoes that regulate bone formation.

Regulation of bone resorption

Muscle-to-bone crosstalk via exosomal miRNAs has both beneficial and deleterious effects on bone tissue. A representative example is miR-196a-5p. Exosomal miR-196a-5p released by murine C2C12 myoblasts suppresses RANKL-induced osteoclast formation, downregulates the osteoclast-related genes TRAP, CTSK, and NFATc1, and reduces mitochondrial biogenesis and energy metabolism in osteoclasts [66]. Inflammatory stimulation attenuates this bone-protective effect. TNF-α reduces miR-196a-5p levels in skeletal muscle-derived exosomes, thereby weakening their inhibitory effects on osteoclasts and their stimulatory effects on osteoblasts [67], which may aggravate the imbalance between bone resorption and formation. Conversely, fluid flow shear stress(FFSS) increases the levels of anti-osteoclastogenic miRNAs, including miR-196a-5p and miR-155-5p, in skeletal muscle-derived exosomes [59]. This change downregulates osteoclast-related genes and enhances the suppression of osteoclast formation. Thus, inflammatory and mechanical stimulation of skeletal muscle cells may differentially affect bone metabolism by reshaping the miRNA cargo of exosomes, highlighting the dynamic role of skeletal muscle-derived exosomes in muscle-bone crosstalk.

Skeletal muscle-derived exosomes may also regulate bone resorption by remodeling the bone immune microenvironment. During aging, dysfunctional slow-twitch muscle fibers release exosomes enriched with the BAG6 protein, which act on Th17 cells in bone through the BAG6-NCR3 axis [61]. In vitro experiments further showed that plasma exosomes with high BAG6 levels were taken up by Th17 cells and increased CD6 expression. CD6 may subsequently interact with ALCAM on TREM2⁺ macrophages, activating STAT3-SPP1 signaling and promoting osteoclastogenic responses. In line with this, plasma exosomal BAG6 levels were increased in older individuals and patients with osteoporosis. These findings suggest that exosomal BAG6 may transmit pro-resorptive signals from aged skeletal muscle to bone through a Th17 cell-TREM2⁺ macrophage immune axis. However, this pathway is supported partly by bioinformatic predictions and in vitro co-culture experiments; therefore, its causal role in vivo and clinical relevance in humans require further validation.

Overall, current evidence indicates that skeletal muscle-derived exosomes regulate bone formation and resorption through cargoes such as miRNAs and proteins. However, most supporting evidence is derived from cell-based experiments and animal models. Considerable heterogeneity in exosome sources, isolation methods, and characterization criteria also limits comparisons across studies. Moreover, direct evidence demonstrating the trafficking of skeletal muscle-derived exosomes to bone tissue in humans remains limited. Future studies should combine in vivo exosome-tracing approaches with large-scale clinical cohorts to determine the contribution of skeletal muscle-derived exosomes to human bone metabolism and evaluate their translational potential.

Effects of bone-derived exosomes on muscle metabolism

In recent years, exosomes derived from bone and bone-associated cells have emerged as potential mediators of bone-to-muscle signaling [18]. However, compared with the relatively extensive evidence on the regulation of bone metabolism by skeletal muscle-derived exosomes, the effects of bone-derived exosomes on muscle metabolism remain insufficiently explored. Current evidence is largely confined to exosomes derived from BMSCs. In this section we will summarize the roles of exosomes derived from bone and bone-associated cells in regulating myogenesis and muscle atrophy, with particular emphasis on their miRNA cargoes and underlying molecular mechanisms(Table 2).

Table 2.

Effects of bone-derived exosomes on muscle metabolism

Exosome Source	Experimental Models	Cargo	Target cell	Effect	Main Mechanism	Refs
BMSCs	In vitro and in vivo (BaCl2-induced gastrocnemius-injured mice)	miR−126−5p	C2C12 myoblasts muscle satellite cells	Promotes myogenesis	Inhibits FBXO32, reduces MyoD ubiquitination	[68]
Human fetal cartilage-derived progenitor cells	In vitro and in vivo (tail-suspension rat model of sarcopenia)	miR−145−5p	Rat myoblasts	Promotes myogenesis	Activates the Wnt signaling pathway, upregulates MyoD, MyoG, MyHC	[69]
BMSCs	In vitro and in vivo (dexamethasone-induced mouse model of muscle atrophy)	miR−486−5p	C2C12 myotubes	Inhibits muscle atrophy	Inhibits FoxO1 nuclear translocation, downregulates Atrogin−1 and MuRF1	[70]
Hypoxia-preconditioned BMSCs	In vitro and in vivo (aged rat model of sarcopenia)	miR−210−3p	Muscle satellite cells	Promotes myogenesis	Regulates KLF7, activates PI3K/AKT signaling pathway	[71]
miR−215 mimic-transfected rat BMSCs	In vitro	miR−215	L6 rat myoblasts	Promotes myogenesis	Inhibits FABP3, downregulates CDKN1A and TP53, upregulates CCNB1	[72]
Senescent BMSCs	In vitro and in vivo (aged mouse model of sarcopenia)	Surface CD81	Muscle satellite cells	Promotes muscle atrophy	Transmits senescence signals	[73]

Improvement of skeletal muscle injury and promotion of regeneration

BMSCs are an important source of exosomes. Through exosome-mediated delivery of bioactive signals to skeletal muscle, BMSCs can regulate skeletal muscle function [74]. BMSC-derived exosomes are efficiently internalized by macrophages, promoting their transition from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype, thereby optimizing the immune microenvironment for muscle regeneration [75]. In a mouse model of tibialis anterior muscle contusion, BMSC-derived exosomes reduced the expression of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, and alleviated local inflammatory infiltration and fibrosis. They also increased the expression of the myogenic regulators MyoD, MyoG, and Pax7, thereby promoting skeletal muscle regeneration and improving the biomechanical properties of the injured muscle [76]. In addition to modulating the immune microenvironment, BMSC-derived exosomes can directly regulate myogenic cells by delivering specific miRNAs. In vitro, exosomal miR-126-5p suppressed the E3 ubiquitin ligase FBXO32 and reduced the ubiquitin-mediated degradation of MyoD, thereby promoting the proliferation and differentiation of C2C12 myoblasts. Consistently, local administration of BMSC-derived exosomes increased the numbers of Pax7-positive satellite cells and newly formed myofibers in a mouse model of barium chloride-induced gastrocnemius injury, providing in vivo support for their pro-regenerative effects [68].

In addition, human fetal cartilage-derived progenitor cell exosomes (F-Exo) promoted myotube formation and increased the expression of the myogenic markers MyoD, MyoG, and MyHC by delivering miR-145-5p and activating Wnt5a/β-catenin signaling. Local administration of F-Exo increased the cross-sectional area and mass of the tibialis anterior muscle in a rat model of sarcopenia [69]. These findings provide preclinical evidence that exosomes derived from skeletal tissue-associated cells can influence skeletal muscle regeneration.

The direct effects of exosomes derived from bone-resident cells, including osteoblasts, osteocytes, and osteoclasts, on skeletal muscle remain poorly understood. Whether these exosomes can reach and be taken up by skeletal muscle cells, and whether their nucleic acid or protein cargoes directly regulate myogenesis, remain unclear. Future studies should combine cell-of-origin-specific exosome tracing with functional validation of individual cargoes to define the roles and causal mechanisms of exosomes derived from different bone cell populations in bone-muscle crosstalk.

Regulation of muscle atrophy

BMSC-derived exosomes can alleviate dexamethasone-induced myotube atrophy by delivering miR-486-5p to myogenic cells [70]. FoxO1 is a key transcription factor that promotes muscle protein degradation [77]. Exosomal miR-486-5p inhibits FoxO1 nuclear translocation and downregulates downstream atrophy-related genes, thereby protecting myotubes from catabolic signaling. In a mouse model, local administration of BMSC-derived exosomes increased muscle fiber cross-sectional area and muscle mass and improved muscle function, further supporting their protective effects against muscle atrophy.

In contrast, exosomes derived from aged BMSCs may contribute to muscle deterioration. CD81 on the surface of aged BMSC-derived exosomes facilitates their uptake by muscle satellite cells, thereby impairing myogenic differentiation and promoting muscle atrophy [73]. Knockdown of CD81 or antibody-mediated blockade of exosome uptake alleviated sarcopenia in aged mice. These findings suggest that aging may alter exosome-mediated signaling from the bone marrow microenvironment to skeletal muscle, providing a potential mechanism for pathological bone-muscle crosstalk.

Clinical observational evidence provides additional support for a possible exosomal link between abnormal bone metabolism and muscle decline. Chen et al. analyzed serum exosomal miRNAs from patients with postmenopausal osteoporosis and observed significant changes in the expression profiles of bone metabolism-related miRNAs [78]. Specifically, miR-21-5p and miR-23a-3p were upregulated, whereas miR-125b-5p was markedly downregulated. Interestingly, miR-125b-5p has been reported to suppress muscle atrophy. Therefore, its reduced levels may be associated with declines in muscle mass and function in patients with osteoporosis [79].

In summary, bone-derived exosomes can deliver beneficial molecules that support skeletal muscle function and regeneration, but may also transmit pathological signals that exacerbate muscle atrophy. These findings highlight the context-dependent roles of bone-derived exosomes as mediators of bone-to-muscle signaling within the bidirectional muscle–bone crosstalk(Fig. 2).

Fig. 2.

Exosome-mediated bidirectional regulation of bone metabolism and skeletal muscle homeostasis. Skeletal muscle-derived exosomes deliver miRNAs and proteins to bone-related cells, thereby regulating osteogenic differentiation and bone resorption; their effects vary with aging, sarcopenia, inflammation, and mechanical stimulation. Conversely, exosomes derived from bone-related cells, particularly BMSCs, modulate skeletal muscle regeneration and atrophy by regulating myogenic differentiation, satellite-cell activity, and catabolic signaling. Together, these pathways illustrate the role of exosomes in bidirectional muscle-bone crosstalk

Translational prospects of exosomes in musculoskeletal diseases

Novel biomarkers

The molecular cargoes of exosomes, including proteins, nucleic acids, and lipids, can reflect the physiological and pathological states of their cells of origin, making them attractive candidates for biomarker discovery [80]. Exosomes are present in readily accessible body fluids, including blood, urine, saliva, and synovial fluid, enabling their analysis through minimally invasive liquid biopsy [81]. Moreover, their lipid bilayer protects encapsulated cargoes from degradation by circulating nucleases and proteases [82]. These properties support the potential of exosomes as liquid biopsy biomarkers that may provide molecular information for the early detection and disease monitoring of musculoskeletal disorders, including osteoporosis and sarcopenia.

In osteoporosis, alterations in the exosomal miRNA profile may reflect an imbalance between bone formation and resorption [83]. Across three independent case–control cohorts, Xia et al. [84]consistently observed elevated plasma exosomal miR-106b-5p levels in patients with osteoporosis, which were negatively correlated with hip bone mineral density T-scores. Subsequent cellular experiments showed that miR-106b-5p suppressed osteoblast differentiation and promoted bone resorption by downregulating SMAD5, BMP2, and MAPK1. These findings suggest that miR-106b-5p may participate in the pathogenesis of osteoporosis and serve as a candidate diagnostic biomarker. A multi-miRNA signature may provide greater diagnostic performance than individual miRNAs. Using small RNA sequencing and LASSO regression in 272 postmenopausal women, Gao et al. [85] identified a panel comprising let-7d-3p, miR-24-3p, and miR-550a-3-5p. In the training cohort, the panel achieved an AUC of 0.91, outperforming the individual miRNAs (AUCs: 0.80–0.84) and the conventional bone turnover markers procollagen type I N-terminal propeptide (PINP) and β-isomer of C-terminal telopeptide of type I collagen (β-CTX). The model also showed some ability to distinguish individuals with osteopenia from healthy controls, suggesting its potential utility in the early detection and risk stratification of postmenopausal osteoporosis.

Exosomal cargoes may also provide information on muscle mass, muscle function, and physical performance. In a rat model of disuse atrophy, Van Pelt et al. [86]found that serum exosomal miR-203a-3p levels were closely associated with skeletal muscle mass. This association was subsequently observed in a human unilateral limb suspension model, suggesting that circulating miR-203a-3p may reflect skeletal muscle metabolic homeostasis.

The global prevalence of osteosarcopenia, estimated to be approximately 18.5% [87], underscores the urgency of refining these diagnostic approaches for the growing elderly population. In particular, high-risk populations, such as frail older adults, may benefit from routine screening of circulating exosomal miRNAs to detect subclinical muscle and bone loss. In postmenopausal women, bone mineral density is significantly correlated with the cross-sectional area of the paravertebral muscles. Using high-throughput sequencing of serum exosomal miRNAs combined with machine learning, researchers identified miR-92a-1-5p as a key molecule associated with both musculoskeletal phenotypes. Notably, this miRNA is specifically secreted in a muscle atrophy model and inhibits osteogenic differentiation [88]. Therefore, elevated miR-92a-1-5p levels may reflect both muscle aging and impaired osteogenesis, highlighting its potential for the early detection of osteosarcopenia. However, its diagnostic performance remains to be validated in larger, independent cohorts.

Taken together, these findings highlight the potential of exosomes and their miRNA and protein cargoes as biomarkers for musculoskeletal disorders. With advances in artificial intelligence, machine-learning approaches could integrate exosomal molecular signatures with clinical parameters, such as bone mineral density and muscle mass, to identify key variables and develop multiparametric predictive models for improved early detection and risk stratification. However, the evidence supporting most candidate biomarkers remains limited and is derived largely from preclinical studies, cross-sectional analyses, or small single-center cohorts. Their disease specificity, diagnostic performance, and clinical applicability remain to be fully established.

Therapeutic delivery vehicles

Owing to their excellent biocompatibility and intrinsic targeting capacity, exosomes have considerable potential as natural nanocarriers for therapeutic delivery [89]. For bone repair, exosomes can serve as natural delivery vehicles for osteogenic factors. Yang et al. [90]generated exosomes enriched in Bmp2 mRNA. These exosomes were efficiently taken up by BMSCs, where Bmp2 mRNA was translated into BMP2 protein, leading to increased expression of the osteogenic markers ALP, OPN, and COL1 and enhanced osteogenic differentiation. In a rat calvarial defect model, this delivery system promoted new bone formation, demonstrating its potential for bone regeneration. Exosomes can also deliver therapeutic molecules to suppress osteoclastogenesis in osteoporosis. In another study, METTL14 inhibited osteoclast-mediated bone resorption by regulating NFATc1 through m6A methylation [91]. To improve delivery efficiency, EphA2-modified exosomes were used to selectively deliver METTL14 to osteoclasts, thereby reducing bone resorption. Unlike conventional bisphosphonate treatment, this targeted strategy did not induce osteonecrosis of the jaw in animal models, providing a potential approach for developing safer osteoporosis therapies.In addition, 17β-estradiol has been loaded into BMSC-derived exosomes using incubation and sonication [92]. This study established the feasibility of exosome-mediated estrogen loading; however, its bone-targeting efficiency, anti-osteoporotic efficacy, and systemic safety in vivo remain to be determined.

Exosomes can also be used to deliver regulators of muscle growth. Ran et al. [93]fused the myostatin propeptide, a natural inhibitor of myostatin, with the exosomal membrane protein CD63, thereby displaying the propeptide on the exosome surface for in vivo delivery. In mdx mice, a model of Duchenne muscular dystrophy, this delivery system promoted muscle regeneration and improved muscle strength and motor performance. It also partially improved bone structure and enhanced bone formation, suggesting that exosome-mediated targeting of myostatin may confer benefits to both muscle and bone.

Engineered exosomes

Although exosomes possess good biocompatibility and delivery potential, native exosomes still face challenges such as nonspecific distribution, short half-life, insufficient enrichment in target tissues, and limited penetration into the pathological microenvironment [94, 95]. To overcome these limitations, engineered exosomes can be developed through parental cell modification, surface functionalization, and integration with biomaterials [96, 97]. These strategies may enhance their ability to specifically target and deliver cargo to defined cell types or tissues, thereby improving therapeutic efficacy and minimizing off-target effects.

The molecular cargo and biological functions of exosomes can be modulated by altering the state of parental cells through hypoxic preconditioning, genetic modification and physical stimulation [98]. Hypoxia-preconditioned BMSCs release miR-210-3p-enriched exosomes that promote satellite cell activation and skeletal muscle regeneration by regulating KLF7/PI3K/AKT signaling axis [71]. Transfection of BMSCs with a miR-215 mimic generates engineered exosomes enriched in miR-215. In an H₂O₂-induced injury model of L6 rat myoblasts, these exosomes improved cell viability and reduced apoptosis by delivering miR-215 and suppressing FABP3 [72]. In addition, mechanical stress induces C2C12 myoblasts to release miR-92a-3p-enriched exosomes, which promote BMSC osteogenic differentiation through PTEN/AKT signaling and ameliorate glucocorticoid-induced osteoporosis in mice [55]. These findings indicate that parental cell modulation may enhance exosome-mediated bidirectional bone–muscle signaling and therapeutic efficacy.

Surface engineering can enhance the tissue-targeting capacity and stability of exosomes through genetic or physicochemical modifications [99]. Hu et al. [100] engineered NIH-3T3 cells to produce exosomes expressing C-X-C motif chemokine receptor 4 (CXCR4) and fused them with antagomir-188-loaded liposomes to generate bone marrow-targeting hybrid nanoparticles. By suppressing adipogenic differentiation and promoting osteogenic differentiation of BMSCs, this system attenuated age-related bone loss in mice. Physicochemical engineering can also improve local exosome delivery. Muscle-derived exosomes were electrostatically immobilized on ferromagnetic nanotubes and enriched in the skeletal muscle of mdx mice under an external magnetic field [101]. This approach modulated macrophage polarization, reduced inflammation and fibrosis, and promoted muscle regeneration. Surface-engineering strategies can enhance exosome accumulation and therapeutic efficacy in muscle and bone tissues. However, their modification stability, long-term safety, and consistency in large-scale production require further validation.

Another important application involves integrating exosomes with biomaterials to construct biologically active tissue-engineering scaffolds. Porous scaffolds and hydrogels can improve exosome retention at injury sites and provide sustained release, thereby modulating the local microenvironment and promoting tissue regeneration [102]. To address the distinct regenerative requirements of bone and muscle, Jin et al. [103]developed a Janus scaffold comprising aligned and randomly oriented fibrous layers that provided myogenic and osteogenic topographical and chemical cues, respectively. Immobilization of engineered Exo^{PTGFRN/IL−4} on the scaffold promoted tissue repair in calvarial and mandibular bone defect models and a tibialis anterior muscle injury model, providing a biomaterial-based strategy for coordinated bone and muscle regeneration. In another study [104], miR-206-3p-enriched BMSC-derived exosomes were loaded into GelMA/AlgMA microspheres and incorporated into a hyaluronic acid hydrogel for sustained local release. This system enhanced angiogenesis and myogenic differentiation and improved tissue architecture and motor function following acute skeletal muscle injury in rats, providing preclinical evidence that biomaterial-mediated delivery of BMSC-derived exosomes can promote muscle regeneration and potentially facilitate bone-to-muscle signaling.

Overall, engineered exosomes show considerable potential for targeted delivery and tissue regeneration. However, current evidence is derived predominantly from in vitro studies and animal models, and their safety and therapeutic efficacy cannot yet be directly extrapolated to clinical practice(Fig. 3).

Fig. 3.

Translational applications of exosomes in musculoskeletal diseases. Exosomes have potential applications as novel biomarkers, therapeutic delivery vehicles, and engineered therapeutic platforms. Exosomal molecular profiling combined with liquid biopsy, artificial intelligence, and machine learning may facilitate biomarker discovery and early disease detection. As natural nanocarriers, exosomes can deliver therapeutic cargoes to musculoskeletal target cells, including BMSCs, osteoblasts, osteoclasts, and skeletal muscle cells. Their therapeutic performance may be further enhanced through parental cell modulation, surface engineering, and integration with biomaterials

Limitations, controversies, and unresolved issues in exosome research and clinical translation

Although research on exosome-mediated muscle-bone crosstalk has advanced rapidly, the field still faces numerous challenges in its transition to clinical applications. These include the lack of standardized production protocols, immature large-scale manufacturing technologies, insufficient delivery efficiency and targeting specificity in vivo, and undefined regulatory approval pathways. In this section, we will provide a systematic overview of these issues.

Methodological challenges

The lack of standardized protocols for exosome isolation and characterization remains a major barrier to reproducibility and cross-study comparability [105]. First, exosomes are highly heterogeneous, and their composition and biological activity can be influenced by parental cell type, donor characteristics, culture medium, oxygen tension, preconditioning, and cell passage number, complicating quality control and batch-to-batch consistency [106, 107]. Second, exosomes overlap with other EV subtypes in physicochemical properties such as size and density, making their precise separation technically challenging [108]. Common isolation methods-including ultracentrifugation, density-gradient centrifugation, size-exclusion chromatography, polymer precipitation, immunoaffinity capture, and ultrafiltration-have distinct strengths and limitations [109–111](Table 3). These methodological differences may affect not only the composition of the isolated exosomes but also the outcomes of their functional evaluation. For example, a comparative study of dental pulp stem cell-derived exosomes showed that ultracentrifugation-isolated exosomes promoted target-cell proliferation and migration but exhibited weaker osteogenic activity than size-exclusion chromatography-isolated exosomes [112]. Moreover, current isolation and purification procedures are generally time-consuming and costly, limiting large-scale production under Good Manufacturing Practice (GMP) conditions. Emerging approaches, including tangential flow filtration [113] and three-dimensional microcarrier-based cell culture [114], may improve production efficiency; however, their batch-to-batch reproducibility, quality-control requirements, and clinical applicability require further validation.

Table 3.

Isolation techniques of exosomes

Isolation Techniques	Separation principle	Advantages	Limitations	Common co-isolated contaminants
Ultracentrifugation	High-force sedimentation based on particle size, density and morphology	Widely used; reagent-free; large-volume compatible	Time-consuming; expensive equipment; potential exosome damage caused by high centrifugal forces	Lipoproteins; protein aggregates; other EV subtypes
Density gradient centrifugation	Separation by buoyant density using a sucrose or iodixanol gradient	High purity; minimal protein carryover	Time-consuming; expensive equipment; complex procedure	Particles and lipoproteins with buoyant densities overlapping those of exosomes; residual gradient medium
Size exclusion chromatography	Size-based separation through a porous gel column, with larger particles eluting first	High purity; preserves structure and function	High cost of column material and susceptibility to clogging; limited loading capacity	Large lipoproteins; viruses; non-exosomal particles
Polyethylene glycol precipitation	Hydrophilic polymers such as PEG reduce solubility	Simple operation; high yield	Low purity; residual polymers may interfere with downstream analyses	Lipoproteins; protein aggregates; residual polymers
Immunoaffinity capture	Antibody-conjugated magnetic beads binding to CD63/CD81	High specificity; high purity	High antibody cost; low yield; antibody binding may compromise exosomal integrity	Non-specifically bound proteins; antibody- or bead-associated material
Ultrafiltration	Membrane retention of large molecules	Low cost; short processing time	Low purity; membrane adsorption and clogging; possible shear-induced deformation	Proteins; lipoproteins; other particles larger than the membrane cut-off

Regulatory pathways and challenges

Differences in cellular sources, isolation techniques, and manufacturing processes have contributed to the absence of a harmonized regulatory classification and approval pathway for exosome-based products worldwide [114, 115]. In the United States, the Food and Drug Administration (FDA) generally regulates exosome-based products as biological products under Section 351 of the Public Health Service Act. Clinical investigation generally requires an Investigational New Drug (IND) application, whereas marketing authorization requires an approved Biologics License Application (BLA) [116]. The FDA has also issued safety notifications and warning letters concerning unapproved exosome products, highlighting continuing concerns regarding manufacturing quality and unauthorized clinical use. In the European Union, exosome-based products are not automatically classified as advanced therapy medicinal products (ATMPs); their regulatory status is determined on a case-by-case basis according to their composition, engineering approach, and mechanism of action [117]. In China, regulatory requirements for exosome-based products are still evolving, and detailed guidance on their classification, quality control, and clinical development has yet to be fully established [118]. Japan and South Korea are also developing regulatory approaches applicable to exosomes and other extracellular vesicle-based products; however, differences remain in product classification, quality assessment, and requirements for clinical authorization [119]. Such regulatory heterogeneity complicates the clinical translation of exosome-based therapies and underscores the need for greater international harmonization to ensure product quality and patient safety.

In vivo biodistribution and targeting challenges

The in vivo biodistribution, pharmacokinetics, and targeting efficiency of exosomes remain insufficiently characterized. Following systemic administration, a substantial proportion of exosomes are rapidly taken up and cleared by the liver, spleen, and mononuclear phagocyte system [120], leaving only a limited fraction to reach skeletal muscle or bone tissue. Their in vivo fate is also influenced by multiple factors, including parental cell source, membrane protein and glycolipid composition, administration route, and the pathological state of the recipient. Although in vivo imaging techniques are widely used to track exosome distribution, commonly used lipophilic fluorescent dyes may dissociate, aggregate, or transfer between membranes [121]. Consequently, the detected signals may not accurately represent the distribution of intact exosomes and their cargo, potentially leading to an overestimation of targeting efficiency [122]. Moreover, although engineering strategies may enhance tissue accumulation, they may also alter exosome stability, pharmacokinetics, and clearance pathways while introducing immunogenicity and off-target risks [123]. Future studies should establish standardized multimodal tracking and quantitative analysis methods to systematically evaluate circulation kinetics, target-tissue accumulation, off-target organ distribution, cargo delivery efficiency, and long-term safety, thereby providing a reliable basis for optimizing delivery strategies and designing clinical dosing regimens.

Preclinical models and clinical translation challenges

Although in vitro experiments and animal models have provided valuable mechanistic insights into exosome-mediated bidirectional muscle–bone crosstalk, evidence supporting the translation of these findings to humans remains limited. Current preclinical models cannot fully recapitulate the complex and heterogeneous pathophysiological environment of human musculoskeletal diseases. For example, differences between animal and human immune systems may influence the immunomodulatory effects of exosomes and host responses to allogeneic components [124]. Common comorbidities, including aging, diabetes, and obesity, can also alter inflammatory status, tissue microenvironments, and regenerative capacity, yet these variables are rarely incorporated simultaneously into existing models. Several clinical studies evaluating exosome-based interventions for musculoskeletal disorders have been registered on ClinicalTrials.gov(Table 4). However, most focus on individual conditions such as osteoarthritis and remain at an early exploratory stage. Their primary objectives are generally to assess safety, tolerability, and feasibility rather than to establish clinical efficacy. Moreover, the clinical use of exosomes raises ethical considerations related to informed consent, personal-data protection, and long-term safety surveillance [125]. Therefore, in the future, it will be necessary not only to conduct rigorously designed, representative clinical trials but also to establish ethical guidelines covering risk disclosure and long-term follow-up, thereby ensuring the standardized clinical translation of exosome.

Table 4.

Clinical trials for exosome-based therapy

Clinical trial ID	Study title	Phase	Diseases	Primary outcome measures	Estimated enrollment	Country
NCT07188012	Safety and Dystrophin Expression of SPOT-mRNA03 in Duchenne Muscular Dystrophy (DMD) Patients	Early Phase 1	Duchenne muscular dystrophy	Number of participants with treatment-related adverse events	9	China
NCT06937528	Use of Extracellular Vesicles (EV) for Knee Osteoarthrosis	Phase 1	Osteoarthritis	Safety and tolerability	50	Jordan
NCT06463132	Phase 1b clinical trial to evaluate PEP and EUFLEXXA for knee osteoarthritis (KOA)	Phase 1	Osteoarthritis	Primary safety	24	United States
NCT05060107	Intra-articular Injection of MSC-derived Exosomes in Knee Osteoarthritis (ExoOA−1)	Phase 1	Osteoarthritis	Adverse events	10	Chile
NCT06466850	Mesenchymal Stem Cells Derived Exosomes in Osteoarthritis Patients	N/A	Osteoarthritis	WOMAC	20	Iran
NCT04849429	Intra-discal injection of platelet‐rich plasma (PRP) enriched with exosomes in chronic low back pain	Phase 1	Degenerative Disc Disease	VAS; RDQ; FRI; SF−36 health questionnaire	30	India
NCT05261360	Clinical Efficacy of Exosome in Degenerative Meniscal Injury (KNEEXO)	Phase 2	Degenerative meniscal injury	Knee function; pain; physical activity; imaging outcomes; inflammatory markers; range of motion; treatment-related complications	30	Turkey
NCT05520125	Treatment of Patients With Bone Tissue Defects Using Mesenchymal Stem Cells Enriched by Extracellular Vesicles	Phase 2	Segmental fracture-bone loss	Adverse effects; percent of completely recovered patients	20	Belarus
NCT06431152	Intra-articular Injection of UC-MSC Exosome in Knee Osteoarthritis (EXO-OA01)	Early Phase 1	Osteoarthritis	Adverse events	12	Chile

Abbreviations N/A: Not applicable; WOMAC: Western Ontario and McMaster University Osteoarthritis index; VAS: Visual analog scale; RDQ: Roland Morris Disability Questionnaire; FRI: Functional rating index

Data are obtained from https://clinicaltrials.gov/

It should be noted that the clinical application of exosomes also requires consideration of cost-effectiveness. Donor-cell culture, large-scale purification, quality testing, and low-temperature storage may all incur substantial costs [126]. For chronic musculoskeletal diseases, it remains unclear whether exosome-based diagnostic and therapeutic strategies provide additional clinical benefits over existing pharmacological interventions. Rigorously designed clinical trials and health-economic evaluations are therefore needed to establish their safety, efficacy, cost-effectiveness, and overall clinical value.

Conclusion

Exosomes transmit signals between skeletal muscle and bone by delivering miRNAs, proteins, and other bioactive cargo, thereby contributing to the regulation of bone formation, bone resorption, myogenesis, and muscle atrophy. Current evidence further indicates that exosome function is context dependent: exosomes derived from healthy or appropriately preconditioned cells may support tissue homeostasis and regeneration, whereas those released by senescent, inflamed, or dysfunctional cells may propagate detrimental signals and exacerbate musculoskeletal degeneration. Exosomes therefore provide an important framework for understanding interorgan muscle–bone crosstalk and show potential as biomarkers and therapeutic delivery vehicles for musculoskeletal disorders.

However, the translation of exosome research from mechanistic studies to clinical applications remains hindered by major challenges in isolation, characterization, biosafety, and quality control. Several emerging technologies may help address these barriers. Advanced bioreactor systems could enable scalable production while improving exosome yield and batch-to-batch consistency [127]. Single-vesicle analysis provides unprecedented resolution for resolving exosome heterogeneity and enabling more precise characterization [128]. Integrating spatial transcriptomics with cell-specific exosome-tracing approaches may further delineate the routes of exosome-mediated communication between skeletal muscle and bone [129]. Finally, integrating transcriptomic, proteomic, lipidomic, and metabolomic data with artificial intelligence and machine-learning approaches could facilitate the identification of key molecular signatures and support biomarker discovery, disease stratification, and therapeutic-response prediction [130, 131].

Overall, exosomes provide a new molecular framework for understanding bidirectional muscle–bone crosstalk, but their clinical translation will require coordinated advances in mechanistic research, bioengineering, standardized manufacturing, and clinical validation. Future studies should prioritize long-term safety assessment, artificial intelligence-assisted rational engineering, tissue-specific delivery strategies, and personalized therapeutic platforms. By integrating bioengineering, multi-omics analysis, and artificial intelligence, exosomes may evolve from experimental nanocarriers into clinically applicable precision therapeutics for musculoskeletal disorders. Continued interdisciplinary collaboration, innovation in isolation and manufacturing technologies, and rigorous clinical investigation will be essential to realize their therapeutic potential and ultimately improve musculoskeletal health.

Abbreviations

EVs

Extracellular vesicles

sEVs

Small extracellular vesicles

MVBs

Multivesicular bodies

ESCRT

Endosomal sorting complexes required for transport

ILVs

Intraluminal vesicles

APC

Adenomatous polyposis coli

LDHA

Lactate dehydrogenase A

BMSCs

Bone marrow mesenchymal stem cells

Prrx2

Paired-related homeobox 2

FFSS

Fluid flow shear stress

F-Exo

Human fetal cartilage-derived progenitor cell exosomes

PINP

Procollagen type I N-terminal propeptide

β-CTX

β-isomer of C-terminal telopeptide of type I collagen

CXCR4

C-X-C motif chemokine receptor 4

GMP

Good Manufacturing Practice

FDA

Food and Drug Administration

IND

Investigational New Drug

BLA

Biologics License Application

ATMPs

Advanced therapy medicinal products

Author contributions

D.C. and J.L.: Investigation, Writing—original draft, Visualization, Writing—review and editing. J.L.: Funding acquisition. X.L., X.Z., L.B. and G.Q.: Investigation, Writing—review and editing. T.M., J.X. and K.L.: Investigation. D.X.: Conceptualization, Supervision, Project administration, Funding acquisition, Writing—review and editing. All authors read and approved the final manuscript.

Funding

This study was supported by the National Natural Science Foundation of China (82575204, 82609205), Jiangsu Provincial Association of Traditional Chinese Medicine and Integrated Traditional and Western Medicine “Young Eagle Soaring” Project (CYTF2026006), Key Project of Jiangsu Provincial Traditional Chinese Medicine Science and Technology Development Plan (ZD202313), Key Disease Creation Project of Jiangsu Province Hospital of Chinese Medicine (YZJ2404), Jiangsu Province Graduate Student Practice Innovation Program (SJCX25_0977), Technical Evaluation of Jiangsu Provincial Traditional Chinese Medicine Characteristic Therapies (k2025BZ02), Research on the Inheritance of Academic Experience of Renowned Senior Traditional Chinese Medicine Physicians at Jiangsu Province Hospital of Chinese Medicine (Y25020) and National Project for the Development of Advantageous Specialties in Traditional Chinese Medicine (No. 2025YL02011).

Data availability

Not applicable.

Declarations

Ethical approval and consent to participate

Not required.

Consent for publication

Not required.

Competing interests

The authors report no conflicts of interest.