Mesenchymal stem cell-derived exosomes and the Wnt/β-catenin pathway: Unifying mechanisms of multi-organ regeneration and the path to precision clinical translation

Abstract

In this editorial, we discuss the article by Fu Y et al, indicating that hair development is influenced by exosomes from human adipose-derived stem/stromal cell-mediated cell-to-cell communication via the Wnt/β-catenin pathway. In recent years, mesenchymal stem cells (MSCs) and MSC-derived exosomes (MSC-Exos) have emerged as a promising cell-free therapeutic strategy due to their robust regenerative capabilities across multiple tissues. MSC-Exos are enriched with bioactive molecules, including proteins, microRNAs, and growth factors, which activate critical signaling pathways, notably the Wnt/β-catenin pathway, to promote cell proliferation, differentiation, and tissue repair. This editorial systematically examines the application of MSC-Exos in regenerating diverse tissues such as hair follicles and kidney, lung, and cardiac muscle tissue. Central to their mechanism is the activation of the Wnt/β-catenin pathway, which drives cell cycle progression (via cyclin B1/cyclin-dependent kinase 1), suppresses apoptosis (through Bcl-2/Bax modulation), and attenuates fibrosis (by inhibiting transforming growth factor-β/alpha-smooth muscle actin). The challenges related to the clinical translation of exosome-based therapies, including standardization of isolation protocols, optimization of dosing and delivery methods, and safety evaluation, are discussed. The most important challenge is standardizing isolation protocols because exosomes obtained from different sources or treatment methods are different, which leads to differences in the therapeutic effects of exosomes. Overall, MSC-Exos provide an effective cell-free strategy for tissue repair and offer a robust foundation to develop personalized regenerative medicine.

Key Words: Mesenchymal stem cell; Wnt/β-catenin pathway; Exosomes; Clinical translation; Regenerative medicine

Core Tip: Mesenchymal stem cell-derived exosomes represent a novel form of cell-free therapy that operates through the activation of the Wnt/β-catenin pathway using the substances they contain, including proteins, microRNAs, and growth factors. These exosomes can stimulate cell proliferation, elicit anti-inflammatory responses, and promote the repair of multiple organs and tissues. However, the translation of these findings into clinical practice remains challenging. This is due to the need for standardization in exosome production and purification and the development of effective administration and storage methods. Additionally, concerns regarding immunogenicity and tumorigenicity complicate the translation of exosome therapy into clinical practice. Therefore, further exploration is necessary to fully assess the potential of exosome therapy as a personalized regenerative medicine approach.

INTRODUCTION

In the ongoing development of regenerative medicine, mesenchymal stem cells (MSCs) are of particular interest to researchers due to their pluripotent differentiation ability, strong paracrine signaling, low immunogenicity, and wide tissue availability[1]. In recent years, as research has progressed, the inherent characteristics of MSCs and the limitations of transplantation technology have become more apparent[2]. MSC-derived exosomes (MSC-Exos), as a cell-free therapy, contain many of the healing effects of their parent MSCs without the complexity of cell transplantation, thus giving them an advantage[3].

Exosomes (30-150 nm in diameter) are a type of extracellular vesicle that can be naturally released by all living cells, along with microvesicles (150-1000 nm in diameter) and apoptosomes (> 1000 nm in diameter)[4,5]. MSC-Exos are nanoscale vesicles that exert reparative and regenerative effects in multiple organs and tissues. These vesicles contain various biologically active substances, including proteins, microRNA (miRNA), and growth factors[6].

The mechanisms by which MSC-Exos promote tissue regeneration are associated with their ability to modulate the Wnt/β-catenin pathway, which plays a crucial role in stem cell proliferation and tissue regeneration[7]. The Wnt/β-catenin signaling pathway, a well-characterized family of glycoproteins, is associated with various physiological and pathological processes, including growth and development, physiological homeostasis, and tissue repair[8]. MSC-Exos dynamically regulate β-catenin stability, nuclear translocation, and downstream gene activation, thereby exerting a reparative effect on target tissues[9,10]. The regenerative potential of MSC-Exos has been demonstrated in various organs and tissues, including the skin, heart, kidneys, lungs, brain, and bone[11], offering a novel approach to regenerative medicine. This editorial explores the mechanisms by which MSC-Exos promote regeneration in these organ systems, highlighting shared Wnt/β-catenin-mediated mechanisms, and discusses a translational roadmap to integrate exosome-based therapies into precision medicine.

SHARED REGENERATIVE MECHANISMS OF MSC EXOSOMES ACROSS TISSUES

A salient feature of MSC-Exos is their capacity to elicit analogous regenerative responses across diverse tissular environments. Irrespective of the target organ, these vesicles promote cell survival, proliferation, and differentiation while attenuating pathological processes such as apoptosis and inflammation[12]. They carry a sophisticated cargo of cytokines, mRNAs, and miRNAs that modulate signal pathways in recipient cells, effectively reactivating the developmental program for repair. In hair follicles, MSC-Exos derived from skin papillae or adipose tissue prolong the active growth phase of hair follicles, increase the number of proliferating cells (Ki67+), and increase the level of β-catenin[13-15]. In the context of kidney injury, whether ischemic or toxic, MSC-Exos stimulate tubular epithelial cells to re-enter the cell cycle, facilitating the regeneration of damaged structures[16].

Additionally, these exosomes transfer pro-survival molecules and reduce oxidative stress. In the context of lung and heart tissue, MSC-Exos convey antifibrotic[17] and proangiogenic signals[18], respectively, contributing to creating a healing microenvironment. The broad anti-inflammatory and antifibrotic properties of MSC-Exos have been demonstrated, along with their capacity to enhance the regenerative capacity of resident cells. This cross-organ sharing of therapeutic effects can be attributed to activating the paracrine pathway of the body’s repair by these vesicles[19].

EXOSOMES AS ACTIVATORS OF WNT/Β-CATENIN SIGNALING FOR REPAIR

Examples of the role of exosomes in various organs

A unifying biochemical mechanism by which MSC-Exos promote regeneration activates the Wnt/β-catenin signaling pathway in target cells. Wnt/β-catenin is a key regulator of stem cell self-renewal and tissue repair, and MSC-Exos excel at acting on this pathway. The proteins contained within MSC-Exos function and the exosome particles carry Wnt ligands directly[20]. For example, studies have demonstrated that human umbilical cord MSC exosome particles can transport the Wnt4 protein to receptor cells, stabilizing β-catenin and activating downstream genes. In addition, experiments have demonstrated that the ability of these exosome particles to trigger β-catenin nuclear translocation depends on the presence of functional Wnt4, thereby confirming the critical role of the delivered Wnt as the active constituent of the exosome[21].

In other cases, the function of exosomes is facilitated by the miRNAs they carry. For instance, miR-181a-5p, a miRNA in skin papilla cells, targets and inhibits the activity of Wnt inhibitory factor 1 and secreted frizzled-related protein 2, two Wnt antagonists. The exosome silencing of these endogenous Wnt inhibitors effectively releases Wnt/β-catenin activity, increases the expression of pro-growth genes (Bcl2, cyclin D1, etc.), and protects hair follicle stem cells from apoptosis[22].

A study on Alzheimer’s disease (AD) found that bone marrow MSC-EVs carry miR-29c-3p, and AD neurons can internalize bone marrow MSC-EVs and release the miR-29c-3p contained therein. This results in an upregulation of the miR-29c-3p level in AD neurons, leading to the inhibition of beta-site amyloid precursor protein cleaving enzyme 1, the activation of the Wnt/β-catenin pathway, a reduction in the levels of Aβ1-42 and inflammatory cytokines, an increase in neuronal viability, and a reduction in apoptosis[23].

In a mouse model of ischemia-reperfusion acute kidney injury, human MSC exosome accumulation in damaged renal tubules is preferential, attenuating cell death and cycle arrest in these cells. A key factor is the shuttling of miR-125b-5p into tubular cells by the exosome, which directly inhibits p53. This results in an upregulation of cyclin B1/cyclin-dependent kinase 1, which promotes cell cycle progression, and a decrease in the Bcl-2/Bax ratio, which reduces apoptosis. This prevents irreversible kidney damage[16].

In silica-dust-induced lung fibrosis, the Wnt/β-catenin pathway is abnormally activated, leading to the accumulation and nuclear translocation of β-catenin. MSC-Exos alleviate the progression of silica-induced lung fibrosis by inhibiting the expression of glycogen synthase kinase 3β and β-catenin. Furthermore, MSC-Exos impede the production of pro-fibrotic transforming growth factor-β1 (TGF-β1) in lung-infiltrating immune cells and concurrently reduce the expression levels of the fibrosis marker protein alpha-smooth muscle actin[24].

In cardiac repair following myocardial infarction, MSC-Exos promote angiogenesis and significantly enrich the proangiogenic miRNA miR-125b-5p. Additionally, the enrichment of another miRNA, miR-21-5p, increases expression of the TGF-β signaling pathway, thereby promoting angiogenesis. The expression of vascular endothelial growth factor-α, angiopoietin-1, atrial natriuretic factor, and brain natriuretic peptide also increases[25-27]. MSC-Exos contain galectin-1, ezrin, and p195, which are cell adhesion proteins associated with angiogenesis and cell proliferation. Furthermore, MSC-Exos have demonstrated the capacity to reduce apoptosis by upregulating miR-24 in target cells following acute myocardial infarction and inhibiting the translation of Bcl-2-like protein-11 (BIM) in mouse cutaneous mast cells (CMC) cells[28].

Commonalities of the role of exosomes in various organs

The regenerative mechanisms mediated by MSC-Exos through the Wnt/β-catenin pathway exhibit high conservation across multiple organ systems, with three core commonalities.

Unified molecular mechanisms: MSC-Exos activate β-catenin stabilization and nuclear translocation by delivering Wnt ligands (e.g., Wnt4) or inhibiting Wnt antagonists (e.g., Wnt inhibitory factor 1/secreted frizzled-related protein 2), thereby upregulating proliferation genes (e.g., cyclin D1, Bcl2) and suppressing apoptosis (via Bax/Bcl-2 modulation) in Figure 1. This mechanism is the central repair logic in the hair follicles, kidneys, lungs, and heart.

Figure 1 Schematic diagram of exosome action.

Universal pathological regulation: Regardless of the target tissue type, MSC-Exos consistently inhibit inflammatory factors (e.g. TGF-β1, interleukin-6) and fibrosis markers (e.g., alpha-smooth muscle actin) while promoting angiogenesis (viavascular endothelial growth factor, angiopoietin-1) and cell cycle re-entry (via cyclin B1/cyclin-dependent kinase 1), thereby remodeling the regenerative microenvironment.

Synergistic signal transduction: The miRNAs (e.g., miR-125b-5p, miR-29c-3p) and proteins (e.g., galectin-1) within MSC-Exos act synergistically on multiple targets to balance Wnt pathway activity, restoring tissue homeostasis dynamically. These shared features highlight the potential of MSC-Exos as a cross-organ regenerative tool. Their core logic lies in integrating proliferation, anti-inflammatory responses, and repair functions through a unified pathway, providing a molecular foundation for clinical translation.

TRANSLATIONAL CHALLENGES AND FUTURE DIRECTIONS

Challenges

Despite noteworthy advancements in using MSC-Exo therapy for diverse organ and tissue diseases, considerable challenges and issues persist. A notable challenge pertains to the standardization of exosome production and purification methods, given their inherent origin heterogeneity. Exosomes derived from different MSC sources exhibit distinct compositional profiles. For instance, bone marrow MSC-Exos are enriched with proteins associated with collagen synthesis, extracellular matrix remodeling, bone regeneration, and muscle regeneration, such as Notch2 (which enhances skeletal remodeling in osteoprogenitor cells) and ADAM10 (involved in neurodevelopment)[29]. In contrast, adipose-derived MSC exosomes carry elevated anti-inflammatory factors and specific miRNAs (e.g., miR-31, miR-146a), demonstrating pronounced efficacy in skin repair and anti-fibrotic applications[30]. A study further revealed functional differences in exosomes derived from MSCs at varying passages[31]. This tissue specificity drives researchers to meticulously select MSC sources to optimize therapeutic outcomes, advancing personalized exosome-based therapies. However, it also poses challenges in standardized production and quality control, as batch-to-batch variability must be minimized to ensure clinical reproducibility. Parameters such as culture medium, cell density, oxygen levels, and temperature can influence the yield and composition of exosome populations.

Furthermore, many exosome isolation techniques exist, complicating the selection of a suitable method. Ultracentrifugation, for instance, is a cost-effective method based on differences in density and particle size; however, it is essential to note that high shear forces may damage the exosome membrane and affect its drug-carrying stability[32]. Size exclusion chromatography (SEC) is another example of a separation technique based on the size of biomolecules; however, removing protein aggregates such as lipoprotein particles altogether is challenging[33]. Conversely, microfluidic technology has high purity and sensitivity; however, it is expensive and may miss specific subpopulations of exosomes[34].

Another salient issue pertains to the administration and delivery of exosome therapy. Exosomes have emerged as promising drug carriers, capable of effectively delivering therapeutic agents. The administration methods employed depend on the specific therapeutic purpose of the exosome. For instance, drugs can be delivered to the central nervous system through intranasal administration, skin malignancies can be treated, wound healing can be promoted through subcutaneous injection, and visceral adipose tissue can be reached through intraperitoneal injection[35]. However, the mononuclear phagocytic system (e.g., absorption by the liver and spleen) expedites the clearance of exogenously administered vesicles, potentially limiting their retention at the target site. Additionally, there exists a possibility of immune response.

Regarding regulation, relevant authorities must strictly oversee the content, potency determination, and safety of exosomes and establish guidelines to ensure the safe and effective use of exosome-based therapies in clinical settings[36]. Most trials are still in the early stages, with inadequate long-term safety data. The experimental subjects are primarily rodents, and the transition to primates has not yet occurred[37].

Current efforts and future directions

Many researchers have attempted to overcome these issues through technological optimization and combined strategies to address the challenges of exosome production and purification standardization. One study improved the overall purity and isolation efficiency of small extracellular vesicles by combining ultracentrifugation with polymer precipitation, explicitly using two ultracentrifugation cycles with a 30% sucrose cushion. Another recent study demonstrated that combining tangential flow filtration with SEC significantly enhanced the purity and yield of exosomes compared to using SEC alone, while also preserving their biological functionality[38]. Various microfluidic systems integrated with immunoaffinity capture (e.g., CD63/CD9 antibody-modified chips) have improved the enrichment efficiency of specific subpopulations. Developing low-cost microfluidic chip materials (e.g., polydimethylsiloxane as an alternative to silicon-based materials) has also reduced production costs[39].

Regarding exosome delivery, engineered surface modifications have enhanced targeted localization at lesion sites[40]. Exosomes can be engineered to carry therapeutic payloads, including small molecules, nucleic acids, or proteins. Electroporation, sonication, or transfection methods enable the encapsulation of chemotherapeutic agents or regulatory miRNAs to synergize with endogenous exosomal cargo. Moreover, lyophilization or liposome encapsulation has extended storage stability[35].

To enhance vesicle retention, engineered exosome surface modifications, such as PEGylation (polyethylene glycol coating) or incorporating targeting antibodies and Arginylglycylaspartic acid (RGD) peptides, can be employed. These modifications reduce non-specific uptake by the mononuclear phagocyte system and enhance enrichment in target tissues[35]. Additionally, studies have optimized delivery systems by utilizing hydrogel-based sustained-release systems, enabling the slow and continuous release of exosomes and extending their bioavailability and therapeutic effects while maintaining excellent biocompatibility[37,41].

For standardization and quality control, it is essential to establish a batch consistency evaluation system based on multi-omics (proteomics, miRNA profiling) combined with nanoscale flow cytometry and atomic force microscopy to achieve dual standardization of physical properties (size, morphology) and biomarkers. Furthermore, international consensus guidelines [e.g., International Society for Extracellular Vesicles-Minimal Information for Studies of Extracellular Vesicles (ISEV-MISEV) standards] should be established to regulate the culture conditions (oxygen levels, medium composition) of MSCs from different sources, thereby reducing exosome heterogeneity[42].

According to data on ClinicalTrials.gov, there are dozens of clinical trials related to MSC-Exos, with most in phase I or II stages. These trials cover indications in the nervous system, cardiovascular system, tissue repair, and more. For example, some studies are investigating the safety and efficacy of umbilical cord MSC-Exos in treating chronic cough post-coronavirus disease 2019 (NCT05808400)[43], where 15% of patients experienced transient fever. Most trials, such as the study on exosome-based ointment for psoriasis treatment (NCT05523011)[44], have short follow-up periods, and the risks of chronic exposure remain unverified. Therefore, longer-term follow-up and observation are still necessary.

Economic costs and health system implications

We recognize that one of the critical barriers to clinical translation is the high cost associated with the production and quality control of MSC-Exos. Our discussion now addresses the following points.

Production and isolation: Current isolation methods (e.g., ultracentrifugation, SEC, and microfluidics) are expensive and difficult to scale up[29,30]. Recent studies have shown that automation, process optimization, and integrating combined methodologies (e.g., tangential flow filtration coupled with SEC) can significantly reduce production costs and enhance yield[38].

Quality control and standardization: Ensuring batch-to-batch consistency and meeting stringent regulatory criteria increase overall expenses. The development of standardized protocols and adherence to international guidelines (e.g., the ISEV-MISEV standards) is critical to streamlining these processes[42].

Storage, distribution, and delivery: Maintaining the stability and integrity of exosomes during storage and transport is challenging and costly. Optimization techniques such as lyophilization and encapsulation have been proposed to improve stability and reduce distribution costs[35]. Additionally, advanced engineering for targeted delivery, including surface modifications and sustained-release formulations, has been explored to enhance therapeutic efficacy while potentially reducing dosing requirements[40,41].

Economic feasibility for public and private health systems: The high production costs may initially limit the accessibility of these therapies. However, if robust clinical evidence confirms their efficacy, diverse funding models—from government subsidies and insurance reimbursements to private investments—could be developed to ensure broad accessibility[36]. To further clarify these economic considerations, please refer to the Table 1. With advancements in nano drug delivery technologies and immune engineering, developing exosome-based therapies that combine targeting specificity, long circulation, and low immunogenicity will become feasible.

Table 1 Economic considerations for mesenchymal stem cell-derived exosome therapies.

Cost driver	Description	Potential strategies for cost reduction	Implications for public/private health systems
Production and isolation	High cost and complexity in isolating exosomes using techniques such as ultracentrifugation and microfluidics[29,30]	Scale-up manufacturing, automation, and integration of combined methods (e.g., TFF + SEC)[38]	Reduced production costs could enable large-scale manufacturing, improving affordability and access[36]
Quality control and standardization	Ensuring batch-to-batch consistency and meeting strict regulatory criteria increases costs[42]	Development and adoption of standardized protocols and international guidelines (e.g., ISEV-MISEV)[42]	Enhanced safety and reproducibility may facilitate better insurance coverage and reimbursement prospects[36]
Storage and distribution	Maintaining exosome stability and integrity during storage and transport adds to the cost[35]	Optimization of lyophilization and encapsulation techniques to improve shelf-life[35]	Improved logistics and reduced overall treatment costs enhance the feasibility of widespread clinical use[36]
Regulatory compliance and safety	Extensive preclinical and clinical testing, along with the regulatory approval process, drive up expenses[36]	Streamlined regulatory pathways and early-phase collaborative trials to reduce development timelines[36]	Faster market entry could encourage both public and private investments, boosting therapeutic adoption[36]
Delivery methods and dosing optimization	Complexities in ensuring targeted delivery and optimal dosing further add to the cost challenges[40,41]	Advanced engineering for targeted delivery (e.g., surface modifications and sustained-release systems)[40,41]	Improved therapeutic efficacy may justify initial investments and support diverse funding models[36]

TFF: Tangential flow filtration; SEC: Size exclusion chromatography; ISEV: International Society for Extracellular Vesicles; MISEV: Minimal Information for Studies of Extracellular Vesicles.

INTEGRATION INTO PRECISION MEDICINE

In the era of precision medicine, using exosomes as molecular markers facilitates precise detection of disease-causing genes, thereby enabling targeted gene therapy to treat diseases accurately[45]. Clinicians analyze patients’ diseases and injuries at the molecular level to develop a treatment plan tailored to the individual patient. For instance, the injection of exosome-carrying Wnt agonists can promote wound healing in cases of Wnt signaling deficiency. Patients with diabetic foot ulcers often exhibit downregulated Wnt/β-catenin signaling due to hyperglycemia-induced oxidative stress. Personalized MSC-Exos therapy can be designed by selecting umbilical cord-derived exosomes enriched with Wnt4 and miR-29c-3p, synergistically activating β-catenin and suppressing inflammatory cytokines. A pilot trial (NCT06812637)[46] demonstrated that umbilical cord-derived exosomes accelerated wound closure by 40% in patients with low baseline β-catenin levels, as identified via skin biopsy RNA sequencing. In addition, the efficacy of exosome therapy can be predicted, and the dosage can be optimized by constructing personalized organoid models of patients.

The integration of interdisciplinary technologies, including machine learning and artificial intelligence, has significantly impacted the field of precision medicine, particularly in rapid disease screening[47]. Machine learning algorithms can analyze comprehensive patient data from MSC-Exos therapy, including genetic information, disease characteristics, treatment responses, and dynamically monitored in vivo signaling molecule levels. Through integrated processing, these algorithms generate personalized treatment plans for individual patients, optimizing dosage regimens, treatment duration, and identification of key signaling molecules to be incorporated into exosomes. By comparing protein expression profiles between healthy populations and patients, the algorithms can predict disease risks in susceptible populations and conduct personalized risk assessments.

A recent landmark study employed MSC proteomics to predict bladder cancer prognosis and treatment response, clinically validating the correlation between MSC characteristics and disease progression markers[48]. This research demonstrates how machine learning extracts clinically actionable insights from MSC-derived data, bridging the gap between experimental research and practical therapeutic applications—representing a significant advancement in artificial intelligence-driven precision medicine.

Engineering modified exosome surfaces by integrating targeting peptides or magnetic nanoparticles has enabled precise lesion localization[49]. Researchers created an exosome-based system (Exo-DOX-Fe₃O₄@PDA-MB) for targeted cancer therapy by electroporation-loading doxorubicin and surface-coating with magnetic nanoparticles and miR-21-targeting beacons. Experimental results confirm that this platform significantly enhances tumor cell-killing efficiency through spatiotemporally controlled drug release and synergistic therapeutic effects[50]. The study provides important technical support to develop novel exosome-based precision cancer treatment paradigms. The development of exosome-based precision medicine is intricately linked to numerous other disciplines, including nanotechnology and materials science.

CONCLUSION

MSC-Exos represent a novel domain in regenerative medicine, offering cell-free therapies that deliver precise molecular instructions to injured tissues, activating intrinsic repair programs, such as Wnt/β-catenin signaling, to facilitate organ regeneration. In hair follicles and the kidneys, lungs, and heart, these vesicles stimulate the body’s regenerative potential, whether by promoting hair growth, restoring kidney function, addressing lung fibrosis, or healing heart muscle. The common mechanisms regulating Wnt/β-catenin and related pathways offer a unifying framework to comprehend and leverage their impact. However, as this editorial discusses, realizing the full therapeutic potential of MSC exosomes necessitates overcoming translation challenges and ensuring consistent quality, appropriate delivery, and regulatory approval. Advances in precision medicine—such as engineered exosomes for targeted delivery, machine learning-driven therapeutic customization, and integration with biomaterial-based sustained-release systems—are paving the way for personalized regenerative therapies. By bridging universal molecular logic with patient-specific needs, MSC-Exos herald a transformative era in regenerative medicine. Microvesicles, once regarded as mere byproducts of cellular processes, have emerged as potent mediators of regeneration. Continued research and technological advancements promise to establish microvesicles as the fundamental building blocks for future therapeutic modalities, potentially leading to novel and effective healing methods for patients.