Extracellular vesicles from adipose tissue-derived stem cells alleviate osteoporosis through osteoprotegerin and miR-21-5p

Highly sensitive electrochemical Osteoprotegerin (OPG) immunosensor for assessing fracture healing and evaluating drug efficacy

Tibial fractures are common long bone injuries requiring effective monitoring for optimal healing. Osteoprotegerin (OPG), as a key marker of bone formation, is closely related to the degree of fracture healing. However, existing detection methods have certain limitations in sensitivity and specificity. This study successfully crafted an exceptionally sensitive electrochemical immunosensor based on COOH-CNFs/Ti3C2Tx MXene/PANI-AgNPs nanocomposite material for the quantitative analysis of OPG in serum, providing a methodological basis for auxiliary diagnosis of fracture healing degree and evaluation of drug efficacy. A one-pot hydrothermal method was employed to synthesize and modify the nanocomposite material on gold electrode surfaces, which exhibit high electrochemical activity, low charge transfer resistance, and a large electroactive surface area, thereby enhancing the immunosensor's conductivity and stability, with a wide linear range (10-17 to 10-12 g/mL) and a low detection limit (1.94 × 10-18 g/mL). Methodological validation further confirmed the immunosensor's excellent performance in specificity, reproducibility, and stability. Moreover, the successful application of this immunosensor in detecting OPG in serum samples from actual tibial fracture patients before and after medication demonstrates significant potential for clinical application in assisting the assessment of fracture healing and evaluating the efficacy of orthopedic drugs.

Therapeutic potential of stem cell-derived exosomes for bone tissue regeneration around prostheses

Artificial joint replacement is a widely recognized treatment for arthritis and other severe joint conditions. However, one of the primary causes of failure in joint replacements is the loosening of the prosthesis. After implantation, wear particles between the implant and the adjacent bone tissue are the principal contributors to this loosening. Recently, exosomes have garnered significant interest due to their low immunogenicity and effective membrane binding. They have shown potential in promoting bone regeneration via the paracrine pathway. This review examines the role and mechanisms of exosomes derived from mesenchymal stem cells (MSCs) in bone regeneration, their impact on the integration of various implants into surrounding bone tissue and current challenges and future directions for the clinical application of exosomes. The Translational Potential of this Article: Emerging evidence suggests that mesenchymal stem cell-derived exosomes may offer a promising therapeutic strategy for aseptic prosthesis loosening, potentially mediated through mechanisms such as modulation of inflammatory responses, suppression of osteoclastogenesis, enhancement of osteogenic differentiation and facilitation of bone regeneration. Preclinical studies further indicate that the therapeutic potential of these extracellular vesicles could be optimized through bioengineering strategies, including surface modification and cargo-loading techniques, warranting further investigation to advance their clinical translation.

Molecular mechanisms and treatment strategies for estrogen deficiency-related and glucocorticoid-induced osteoporosis: a comprehensive review

Osteoporosis, a debilitating condition characterized by reduced bone mass and increased fracture risk, is notably influenced by estrogen deficiency and glucocorticoid treatment. This comprehensive review elucidates the molecular mechanisms underpinning estrogen deficiency-related osteoporosis (EDOP) and glucocorticoid-induced osteoporosis (GIOP). The role of estrogen in bone metabolism is critically examined, highlighting its regulatory effects on bone turnover and formation through various signaling pathways. Conversely, this review explores how glucocorticoids disrupt bone homeostasis, focusing on their impact on osteoclast and osteoblast function and the subsequent alteration of bone remodeling processes. The pathogenesis of both conditions is intertwined, with estrogen receptor signaling pathways and the role of inflammatory cytokines being pivotal in driving bone loss. A detailed analysis of pathogenetic and risk factors associated with EDOP and GIOP is presented, including lifestyle and genetic factors contributing to disease progression. Modern therapeutic approaches emphasize pharmacologic, non-pharmacologic, and herbal treatments for managing EDOP and GIOP. In summary, current therapeutic strategies highlight the efficacy and the safety of various interventions. This review concludes with future directions for research, suggesting a need for novel treatment modalities and a deeper understanding of the underlying mechanisms of osteoporosis. By addressing the multifaceted nature of EDOP and GIOP, this work aims to provide insights into developing targeted therapeutic strategies and improving patient outcomes in osteoporosis management.

hnRNPA2B1 facilitates ovarian carcinoma metastasis by sorting cargoes into small extracellular vesicles driving myofibroblasts activation

BACKGROUND

Ovarian carcinoma (OvCa) metastasis is initiated and boosted by tumor-stroma interactions mediated by small extracellular vesicles (sEVs) containing microRNAs (miRNAs). However, the mechanisms of sorting relevant miRNAs into tumoral sEVs remain elusive.

RESULTS

In this study, among the RNA-binding proteins, hnRNPA2B1 was identified as the most significant factor associated with survival in OvCa patients, and its expression was higher in omental metastases compared to paired ovarian lesions. Based on the CRISPR-Cas9 technique, orthotopic xenograft mice revealed a remarkable metastasis-inhibiting effect of hnRNPA2B1-knockdown, accompanied by diminished myofibroblast signals in the omentum. Meanwhile, after hnRNPA2B1-knockdown, OvCa-sEVs largely lost the ability to promote omental metastasis and myofibroblast activation in vivo and in vitro. High-throughput miRNA sequencing of sEV cargoes revealed that UAG motif-containing miRNAs were significantly affected by hnRNPA2B1, and RNA immunoprecipitation (RIP) verified their direct binding to hnRNPA2B1. In pull down assays, the miRNAs with mutated UAG motif exhibited decreased binding capacity to hnRNPA2B1. The myofibroblasts activated by OvCa-sEVs could promote tumor metastasis, and this effect was notably impacted by manipulating hnRNPA2B1, related sEV-miRNAs, and PI3K/AKT signaling.

CONCLUSIONS

These findings highlight the miRNA sorting to sEVs mediated by hnRNPA2B1 as an important mechanism involved in OvCa metastasis, which may illuminate new therapeutic strategies.

Advances in Tracing Techniques: Mapping the Trajectory of Mesenchymal Stem-Cell-Derived Extracellular Vesicles

Mesenchymal stem-cell-derived extracellular vesicles (MSC-EVs) are nanoscale lipid bilayer vesicles secreted by mesenchymal stem cells. They inherit the parent cell's attributes, facilitating tissue repair and regeneration, promoting angiogenesis, and modulating the immune response, while offering advantages like reduced immunogenicity, straightforward administration, and enhanced stability for long-term storage. These characteristics elevate MSC-EVs as highly promising in cell-free therapy with notable clinical potential. It is critical to delve into their pharmacokinetics and thoroughly elucidate their intracellular and in vivo trajectories. A detailed summary and evaluation of existing tracing strategies are needed to establish standardized protocols. Here, we have summarized and anticipated the research progress of MSC-EVs in various biomedical imaging techniques, including fluorescence imaging, bioluminescence imaging, nuclear imaging (PET, SPECT), tomographic imaging (CT, MRI), and photoacoustic imaging. The challenges and prospects of MSC-EV tracing strategies, with particular emphasis on clinical translation, have been analyzed, with promising solutions proposed.

Hydrogels empowered mesenchymal stem cells and the derived exosomes for regenerative medicine in age-related musculoskeletal diseases

As the population ages, musculoskeletal diseases (MSK) have emerged as a significant burden for individuals, healthcare systems, and social care systems. Recently, regenerative medicine has exhibited vast potential in age-related MSK, with mesenchymal stromal cells (MSCs) and their derived exosomes (Exos) therapies showing distinct advantages. However, these therapies face several limitations, including issues related to ensuring stability and effective distribution within the body. Hydrogels, acting as an ideal carrier, can enhance the therapeutic effects and application range of MSCs and Exos derived from MSCs (MSC-Exos). Therefore, this review comprehensively summarizes the application progress of MSCs and MSC-Exos combined with hydrogels in age-related MSK disease research. It aims to provide a detailed perspective, showcasing the functional enhancement of MSCs and MSC-Exos when incorporated into hydrogels. Additionally, this review explores their potential and challenges in treating age-related MSK diseases, offering references for future research directions and potential innovative strategies.

Grem1 inhibits osteogenic differentiation of MBMSCs in OVX rats through BMP/Smad1/5 signaling pathway

Objective

This study aims to explore how Grem1 regulates the differentiation and signaling activity of mandibular bone marrow mesenchymal stem cells (MBMSCs), affecting their osteogenic differentiation capacity and participating in the pathophysiological mechanism of postmenopausal mandibular osteoporosis.

Materials and methods

A postmenopausal osteoporosis (POP) rat model was constructed via bilateral ovariectomy. Techniques such as Western Blot (WB) and Real-Time Quantitative PCR (RT-qPCR) were employed to determine changes in Grem1 expression in MBMSCs of postmenopausal rats and its effect on osteogenic differentiation. Plasmids for Grem1 overexpression and siRNA for Grem1 knockdown were transfected into MBMSCs, and WB was used to assess the regulatory role of Grem1 on MBMSCs osteogenic differentiation.

Results

Grem1 expression was significantly elevated in the MBMSCs and mandibular tissues of POP rats, accompanied by inhibited osteogenic differentiation. Grem1 levels were inversely proportional to osteogenic capacity and BMP/Smad1/5 signaling activity. BMP-2 alleviated Grem1's inhibitory effects on the BMP/Smad1/5 pathway, influencing MBMSCs' osteogenic differentiation. Upregulating Grem1 in MBMSCs suppressed BMP/Smad1/5 pathway activity and osteogenic differentiation, while Grem1 knockdown restored these processes in the OVX group.

Conclusion

Grem1 reduces osteogenic capacity in mandibular POP rats by inhibiting the BMP/Smad1/5 signaling pathway. Targeting Grem1 or enhancing BMP/Smad1/5 signaling activity may improve mandibular bone health in osteoporosis patients.

Mapk7 enhances osteogenesis and suppresses adipogenesis by activating Lrp6/β-catenin signaling axis in mesenchymal stem cells

The lineage commitment and differentiation of mesenchymal stem cells (MSCs) play a crucial role in bone homeostasis. MAPK7 (Mitogen-activated protein kinase 7), a member of MAPK family, controls cell differentiation, proliferation and survival. However, the specific role of Mapk7 in regulating osteogenic and adipogenic differentiation of MSCs remains to be determined. In this study, depletion of Mapk7 in MSCs by crossing Prx1-Cre mice to Mapk7flox/flox resulted in severe low bone mass and accumulation of fat in bone marrow exhibiting osteoporosis (OP) in mice. Mapk7 promoted osteogenic differentiation and inhibited adipogenic differentiation of MSCs after knocking out and over-expressing Mapk7 in vitro. Mechanistically, Mapk7 activated Wnt/β-catenin signaling by phosphorylating Lrp6 at Ser1490, which ultimately enhanced osteogenesis and suppressed adipogenesis of MSCs. This is of great clinical and scientific significance for understanding biological function of Mapk7 and developing potential therapeutic targets for treatment of MSCs differentiation imbalance related bone diseases, such as, osteoporosis.

Pyroptosis: candidate key targets for mesenchymal stem cell-derived exosomes for the treatment of bone-related diseases

Bone-related diseases impact a large portion of the global population and, due to their high disability rates and limited treatment options, pose significant medical and economic challenges. Mesenchymal stem cells (MSCs) can differentiate into multiple cell types and offer strong regenerative potential, making them promising for treating various diseases. However, issues with the immune response and cell survival limit the effectiveness of cell transplantation. This has led to increased interest in cell-free stem cell therapy, particularly the use of exosomes, which is the most studied form of this approach. Exosomes are extracellular vesicles that contain proteins, lipids, and nucleic acids and play a key role in cell communication and material exchange. Pyroptosis, a form of cell death involved in innate immunity, is also associated with many diseases. Studies have shown that MSC-derived exosomes have therapeutic potential for treating a range of conditions by regulating inflammation and pyroptosis. This study explored the role of MSC-derived exosomes in modulating pyroptosis to improve the treatment of bone-related diseases.

New Insights on the miRNA Role in Diabetic Tendinopathy: Adipose-Derived Mesenchymal Stem Cell Conditioned Medium as a Potential Innovative Epigenetic-Based Therapy for Tendon Healing

BACKGROUND

Adipose-derived mesenchymal stem cell conditioned medium (ASC-CM) improved the viability and wound closure of human tenocytes (HTCN) exposed to high glucose (HG) by activating the transforming growth factor beta 1 (TGF-β1) pathway.

OBJECTIVES

Since ASC-CM can also modulate microRNAs (miRNAs) in recipient cells, this study investigated the effects of ASC-CM on the miRNAs regulating tendon repair (miR-29a-3p, miR-210-3p and miR-21-5p) in HG-HTNC.

METHODS

ASC-CM was obtained by ASCs isolated from the abdominal fat tissue of seven non-diabetic patients. HTNC were cultured in HG for 20 days, then scratched and exposed for 24 h to ASC-CM. qRT-PCR and ELISAs assessed miRNA and target levels.

RESULTS

HG-HTNC exhibited a significant downregulation of miRNAs. ASC-CM restored the levels of miRNAs and their related targets involved in tendon repair.

CONCLUSIONS

The epigenetic modulation observed in HG-HTNC exposed to ASC-CM could be an innovative option in the management of diabetic tendinopathy.

hBMSC-EVs alleviate weightlessness-induced skeletal muscle atrophy by suppressing oxidative stress and inflammation

BACKGROUND

Muscle disuse and offloading in microgravity are likely the primary factors mediating spaceflight-induced muscle atrophy, for which there is currently no effective treatment other than exercise. Extracellular vesicles derived from bone marrow mesenchymal stem cells (BMSC-EVs) possess anti-inflammatory and antioxidant properties, offering a potential strategy for combating weightless muscular atrophy.

METHODS

In this study, human BMSCs-EVs (hBMSC-EVs) were isolated using super-centrifugation and characterized. C2C12 myotube nutrition-deprivation and mice tail suspension models were established. Subsequently, the diameter of C2C12 myotubes, Soleus mass, cross-sectional area (CSA) of muscle fibers, and grip strength in mice were assessed to investigate the impact of hBMSC-EVs on muscle atrophy. Immunostaining, transmission electron microscopy observation, and western blot analysis were employed to assess the impact of hBMSC-EVs on muscle fiber types, ROS levels, inflammation, ubiquitin-proteasome system activity, and autophagy lysosome pathway activation in skeletal muscle atrophy.

RESULTS

The active hBMSC-EVs can be internalized by C2C12 myotubes and skeletal muscle. hBMSC-EVs can effectively reduce C2C12 myotube atrophy caused by nutritional deprivation, with a concentration of 10 × 108 particles/mL showing the best effect (P < 0.001). Additionally, hBMSC-EVs can down-regulate the protein levels associated with UPS and oxidative stress. Moreover, intravenous administration of hBMSC-EVs at a concentration of 1 × 1010 particles/mL can effectively reverse the reduction in soleus mass (P < 0.001), CSA (P < 0.01), and grip strength (P < 0.001) in mice caused by weightlessness. They demonstrate the ability to inhibit protein degradation mediated by UPS and autophagy lysosome pathway, along with the suppression of oxidative stress and inflammatory responses. Furthermore, hBMSC-EVs impede the transition of slow muscle fibers to fast muscle fibers via upregulation of Sirt1 and PGC-1α protein levels.

CONCLUSIONS

Our findings indicate that hBMSC-EVs are capable of inhibiting excessive activation of the UPS and autophagy lysosome pathway, suppressing oxidative stress and inflammatory response, reversing muscle fiber type transformation, effectively delaying hindlimb unloading-induced muscle atrophy and enhancing muscle function. Our study has further advanced the understanding of the molecular mechanism underlying muscle atrophy in weightlessness and has demonstrated the protective effect of hBMSC-EVs on muscle atrophy.

Aflatoxin B1 contamination reduces the saponins content and anti-osteoporosis efficacy of the traditional medicine Radix Dipsaci

ETHNOPHARMACOLOGICAL RELEVANCE

The Radix Dipsaci, a traditional Chinese medicine with a history spanning over 2000 years in China, is widely recognized for its hepatorenal tonic properties, musculoskeletal fortifying effects, fracture healing capabilities, and its frequent application in the treatment of osteoporosis. Like many traditional Chinese herbal medicines, preparations from Radix Dipsaci are at risk of contamination by harmful mycotoxins such as aflatoxin B1.

AIMS OF THE STUDY

This study aims to evaluate the impact of aflatoxin B1 contamination on Radix Dipsaci in terms of changes in quality, efficacy of anti-osteoporosis and hepatorenal toxicity.

MATERIALS AND METHODS

The contamination rates and levels of major mycotoxins were determined in 45 batches of Radix Dipsaci samples using UPLC-MS/MS analysis. The total saponin content and the levels of akebia saponin D in Radix Dipsaci and its decoctions were evaluated through high-performance liquid chromatography (HPLC) analysis. Differences in secondary metabolites between samples without any mycotoxin contamination (N-RD) and those contaminated solely by aflatoxin B1 (AFB1-RD) were compared using metabolomics sequencing and analysis. The anti-osteoporotic efficacy of Radix Dipsaci contaminated with aflatoxin B1 was assessed in a murine model of retinoic acid-induced osteoporosis by quantifying bone mineral content and bone mineral density using dual-energy X-ray absorptiometry. Additionally, the hepatorenal toxicity of Radix Dipsaci contaminated with aflatoxin B1 was evaluated using hematoxylin-eosin staining and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The results indicated that aflatoxin B1 (AFB1) was the most frequently detected mycotoxin, found in 37.7% of the Radix Dipsaci samples. AFB1 contamination significantly altered the secondary metabolites of Radix Dipsaci. Specifically, there was a notable decrease in the levels of total saponins and akebia saponin D in the AFB1-contaminated samples, which exhibited a negative correlation with the levels of AFB1 contamination. However, the administration of a water decoction from AFB1-contaminated Radix Dipsaci did not result in significant improvements in bone mineral density, bone mineral salt content, the trabecular number, trabecular area, proportion of trabecular bone volume/tissue volume and trabecular separation in an osteoporosis mouse model. Additionally, we observed that approximately 16.04% of AFB1 could migrate from the raw herbs into the decoction, leading to hepatocyte and kidney cell damage, as well as increased levels of the oxidative stress molecule malondialdehyde and pro-inflammatory cytokines in the liver and kidney tissues of the osteoporosis model mice.

CONCLUSION

In summary, Radix Dipsaci is highly susceptible to mycotoxin contamination, particularly aflatoxin B1. The contamination of Radix Dipsaci with AFB1 not only impacts their saponin content and anti-osteoporosis effect but also induces hepatotoxicity and nephrotoxicity.

Extracellular vesicles: essential agents in critical bone defect repair and therapeutic enhancement

Bone serves as a fundamental structural component in the body, playing pivotal roles in support, protection, mineral supply, and hormonal regulation. However, critical-sized bone injuries have become increasingly prevalent, necessitating extensive medical interventions due to limitations in the body's capacity for self-repair. Traditional approaches, such as autografts, allografts, and xenografts, have yielded unsatisfactory results. Stem cell therapy emerges as a promising avenue, but challenges like immune rejection and low cell survival rates hinder its widespread clinical implementation. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) have garnered attention for their regenerative capabilities, which surpass those of MSCs themselves. EVs offer advantages such as reduced immunogenicity, enhanced stability, and simplified storage, positioning them as a promising tool in stem cell-based therapies. This review explores the potential of EV-based therapy in bone tissue regeneration, delving into their biological characteristics, communication mechanisms, and preclinical applications across various physiological and pathological conditions. The mechanisms underlying EV-mediated bone regeneration, including angiogenesis, osteoblast proliferation, mineralization, and immunomodulation, are elucidated. Preclinical studies demonstrate the efficacy of EVs in promoting bone repair and neovascularization, even in pathological conditions like osteoporosis. EVs hold promise as a potential alternative for regenerating bone tissue, particularly in the context of critical-sized bone defects, offering new avenues for effective bone defect repair and management.

Adipose-Derived Stromal Cell Conditioned Medium on Bone Remodeling: Insights from a 3D Osteoblast-Osteoclast Co-Culture Model

This study describes the potential of the conditioned medium (CM) from adipose-derived mesenchymal stromal cells (ASCs) to affect the response of bone cells and support bone remodeling. This was in particular assessed by an in vitro model represented by a 3D human osteoblast-osteoclast co-culture. It has been reported that the effects of ASCs are predominantly attributable to the paracrine effects of their secreted factors, that are present as soluble factors or loaded into extracellular vesicles. They may affect various biological processes, including bone turnover. Our interest was to provide further evidence to support ASC-CM as a promising cell-free therapeutic agent for the treatment of bone loss. ASC-CM was characterized using nanoparticle tracking analysis (NTA), cytofluorimetry, and proteomic analysis. Human osteoblasts (hOBs) from vertebral lamina were cultured with monocytes, as osteoclasts (hOCs) precursors, in a Rotary cell culture system for 14 days. Histochemical analysis was performed to evaluate the effect of ASC-CM on bone-specific markers such as tartrate-resistant acid phosphatase (TRAP), osteopontin (OPN), RUNX2, Collagen 1 (COL1), and mineral matrix. ASC-CM characterization confirmed the content of CD63/CD81/CD9 positive extracellular vesicles. Proteomic dataset considering bone-remodeling-related keywords identified 16 processes significantly enriched. The exposure of hOBs/hOCs aggregates to ASC-CM induced increase of OPN, COL I, and RUNX2, and significantly induced mineral matrix deposition, while significantly reducing TRAP expression. These data demonstrated that CM from ASCs contains a complex of secreted factors able to control either bone resorption or bone formation and requires further investigations to deeply analyze their potential therapeutic effects.

Polyphenols and Functionalized Hydrogels for Osteoporotic Bone Regeneration

Osteoporosis induces severe oxidative stress and disrupts bone metabolism, complicating the treatment of bone defects. Current therapies often have side effects and require lengthy bone regeneration periods. Hydrogels, known for their flexible mechanical properties and degradability, are promising carriers for drugs and bioactive factors in bone tissue engineering. However, they lack the ability to regulate the local pathological environment of osteoporosis and expedite bone repair. Polyphenols, with antioxidative, anti-inflammatory, and bone metabolism-regulating properties, have emerged as a solution. Combining hydrogels and polyphenols, polyphenol-based hydrogels can regulate local bone metabolism and oxidative stress while providing mechanical support and tissue adhesion, promoting osteoporotic bone regeneration. This review first provides a brief overview of the types of polyphenols and the mechanisms of polyphenols in facilitating adhesion, antioxidant, anti-inflammatory, and bone metabolism modulation in modulating the pathological environment of osteoporosis. Next, this review examines recent advances in hydrogels for the treatment of osteoporotic bone defects, including their use in angiogenesis, oxidative stress modulation, drug delivery, and stem cell therapy. Finally, it highlights the latest research on polyphenol hydrogels in osteoporotic bone defect regeneration. Overall, this review aims to facilitate the clinical application of polyphenol hydrogels for the treatment of osteoporotic bone defects.

Osterix mRNA Enrichment in Small Extracellular Vesicles Derived From Osteogenically Induced ADSCs: A Promoter of Osteogenic Differentiation in BMSCs

Osteogenic differentiation of bone marrow stem cells (BMSCs) is essential for bone tissue regeneration and repair. However, this process is often hindered by an unstable differentiation influenced by local microenvironmental factors. While small extracellular vesicles (sEVs) derived from osteogenically induced adipose mesenchymal stem cells (ADSCs) reportedly can promote osteogenic differentiation of BMSCs, the underlying molecular mechanisms remain incompletely understood. In this study, we investigated the mRNA expression profile of ADSC-sEVs+ and explored the role of specific mRNAs in the osteogenic differentiation of BMSCs. We first validated the osteogenic induction activity of ADSC-sEVs+ through both in vitro and in vivo experiments. Using reverse transcription polymerase chain reaction, we compared mRNA expression between ADSC-sEVs+ and ADSC-sEVs and further assessed the impact of specific mRNAs on the differentiation of BMSCs through a series of in vitro experiments. One of our key findings was that osterix mRNA was highly enriched in ADSC-sEVs+, which significantly enhanced alkaline phosphatase staining and upregulated downstream osteoblastic markers in BMSCs. Both overexpression and knockdown experiments confirmed that osterix mRNA is a critical signalling molecule that facilitates the differentiation of BMSCs into osteoblasts through ADSC-sEVs+. This finding expands our understanding of the molecular mechanisms underlying the osteogenic differentiation of BMSCs and offers a promising strategy for targeted osteoblastic differentiation in clinical applications.

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.

Unlocking the Therapeutic Potential of Adipose-Derived Stem Cell Secretome in Oral and Maxillofacial Medicine: A Composition-Based Perspective

The adipose-derived stem cell (ADSC) secretome is widely studied for its immunomodulatory and regenerative properties, yet its potential in maxillofacial medicine remains largely underexplored. This review takes a composition-driven approach, beginning with a list of chemokines, cytokines, receptors, and inflammatory and growth factors quantified in the ADSC secretome to infer its potential applications in this medical field. First, a review of the literature confirmed the presence of 107 bioactive factors in the secretome of ADSCs or other types of mesenchymal stem cells. This list was then analyzed using the Search Tool for Retrieval of Interacting Genes/Proteins (STRING) software, revealing 844 enriched biological processes. From these, key processes were categorized into three major clinical application areas: immunoregulation (73 factors), bone regeneration (13 factors), and wound healing and soft tissue regeneration (27 factors), with several factors relevant to more than one area. The most relevant molecules were discussed in the context of existing literature to explore their therapeutic potential based on available evidence. Among these, TGFB1, IL10, and CSF2 have been shown to modulate immune and inflammatory responses, while OPG, IL6, HGF, and TIMP1 contribute to bone regeneration and tissue repair. Although the ADSC secretome holds great promise in oral and maxillofacial medicine, further research is needed to optimize its application and validate its clinical efficacy.

Exploration of Key Regulatory Factors in Mesenchymal Stem Cell Continuous Osteogenic Differentiation via Transcriptomic Analysis

BACKGROUND/OBJECTIVES

Mesenchymal stem cells (MSCs) possess the remarkable ability to differentiate into various cell types, including osteoblasts. Understanding the molecular mechanisms governing MSC osteogenic differentiation is crucial for advancing clinical applications and our comprehension of complex disease processes. However, the key biological molecules regulating this process remain incompletely understood.

METHODS

In this study, we conducted systematic re-analyses of published high-throughput transcriptomic datasets to identify and validate key biological molecules that dynamically regulate MSC osteogenic differentiation. Our approach involved a comprehensive analysis of gene expression patterns across human tissues, followed by the rigorous experimental validation of the identified candidates.

RESULTS

Through integrated analytical and experimental approaches, we utilized high-throughput transcriptomics to identify four critical regulators of MSC osteogenic differentiation: PTBP1, H2AFZ, BCL6, and TTPAL (C20ORF121). Among these, PTBP1 and H2AFZ functioned as positive regulators, while BCL6 and TTPAL acted as negative regulators in osteogenesis. The regulatory roles of these genes in osteogenesis were further validated via overexpression experiments.

CONCLUSIONS

Our findings advance our understanding of MSC differentiation fate determination and open new therapeutic possibilities for bone-related disorders. The identification of these regulators provides a foundation for developing targeted interventions in regenerative medicine.

The role of miRNAs as biomarkers in heterotopic ossification

Fibrodysplasia ossificans progressiva and progressive osseous heteroplasia are genetic forms of heterotopic ossification (HO). Fibrodysplasia ossificans progressiva is caused by ACVR1 gene mutations, while progressive osseous heteroplasia is caused by GNAS gene mutations. Nongenetic HO typically occurs after trauma or surgery, with an occurrence rate of 20-60%. It can also be observed in conditions such as diffuse idiopathic skeletal hyperostosis, spinal ligament ossification, ankylosing spondylitis, and skeletal fluorosis. The exact cause of nongenetic HO is not entirely clear. More than 100 types of miRNAs have been identified as being linked to the development of HO. Some miRNAs are promising potential biomarkers for traumatic HO and ossification of the posterior longitudinal ligament. These findings further emphasize the significant role miRNAs play in the pathogenesis and progression of bone disorders. Repeated investigations into the function of a specific miRNA are infrequent and yield inconsistent results, possibly because of variable experimental conditions. It is hypothesized that miRNAs can enhance osteogenesis for the management of fractures and bone defects. However, further research is required to validate this hypothesis.

3D-printed constructs deliver bioactive cargos to expedite cartilage regeneration

Cartilage is solid connective tissue that recovers slowly from injury, and pain and dysfunction from cartilage damage affect many people. The treatment of cartilage injury is clinically challenging and there is no optimal solution, which is a hot research topic at present. With the rapid development of 3D printing technology in recent years, 3D bioprinting can better mimic the complex microstructure of cartilage tissue and thus enabling the anatomy and functional regeneration of damaged cartilage. This article reviews the methods of 3D printing used to mimic cartilage structures, the selection of cells and biological factors, and the development of bioinks and advances in scaffold structures, with an emphasis on how 3D printing structure provides bioactive cargos in each stage to enhance the effect. Finally, clinical applications and future development of simulated cartilage printing are introduced, which are expected to provide new insights into this field and guide other researchers who are engaged in cartilage repair.

Dopamine-conjugated extracellular vesicles induce autophagy in Parkinson's disease

The application of extracellular vesicles (EVs) as vehicles for anti-Parkinson's agents represents a significant advance, yet their clinical translation is hampered by challenges in efficient brain delivery and complex blood-brain barrier (BBB) targeting strategies. In this study, we engineered dopamine onto the surface of adipose-derived stem cell EVs (Dopa-EVs) utilizing a facile, two-step cross-linking approach. This engineering enhanced neuronal uptake of the EVs in primary neurons and neuroblastoma cells, a process shown to be competitively inhibited by dopamine pretreatment and dopamine receptor antibodies. Notably, Dopa-EVs demonstrated increased brain accumulation in mouse Parkinson's disease (PD) models. Therapeutically, Dopa-EVs administration led to the rescue of dopaminergic neuronal loss and amelioration of behavioural deficits in both 6-hydroxydopamine (6-OHDA) and α-Syn PFF-induced PD models. Furthermore, we observed that Dopa-EVs stimulated autophagy evidenced by the upregulation of Beclin-1 and LC3-II. These findings collectively indicate that surface modification of EVs with dopamine presents a potent strategy for targeting dopaminergic neurons in the brain. The remarkable therapeutic potential of Dopa-EVs, demonstrated in PD models, positions them as a highly promising candidate for PD treatment, offering a significant advance over current therapeutic modalities.

Enrichment protocols for human conjunctival extracellular vesicles and their characterization

The understanding of the role played by extracellular vesicles (EVs) in different tissues has improved significantly in the last years, but remains limited concerning the conjunctiva, a complex eye tissue whose role is pivotal for corneal protection. Here, we conducted a comparative study to isolate and characterize EVs from human conjunctival epithelial (IM-HConEpiC) and human conjunctival mesenchymal stromal cell (Conj-MSCs) secretomes using different isolation methods: differential ultracentrifugation (UC), and a combination of ultrafiltration (UF) with precipitation or size exclusion chromatography (SEC). EVs were characterized by total protein content, size, morphology, and expression of protein markers. EV functional effect was tested in an in vitro oxidative stress model. We successfully recovered EVs with the three methods, although significantly higher yields were obtained with UF-precipitation. Dynamic light scattering analysis confirmed the presence of nano-sized particles, being UC-isolated EVs larger than those isolated by UF-precipitation and UF-SEC. Atomic Force Microscopy showed EVs with a slightly ellipsoidal morphology. EVs enriched with UF-precipitation method were further analyzed, confirming the expression of Alix, CD63, TSG101, and Syntenin-1 by Western blotting and showing that Conj-MSC-derived EVs significantly reduced oxidative stress on IM-HConEpiC. Therefore, we conclude that UF-precipitation is the most efficient method for conjunctival EV enrichment.

Role of mir-32-3p in the diagnosis and risk assessment of osteoporotic fractures

BACKGROUND

Osteoporotic fractures (OPF) are fractures that occur with low-energy injuries or during daily activities, representing a serious consequence of osteoporosis (OP). With the worsening of population aging, the number of OPF patients continues to expand, causing a significant burden on families and society. Consequently, it is significant to diagnose and analyze OPF at the molecular level.

OBJECTIVE

The aim of this research was to explore the diagnostic value of miR-32-3p in OPF patients and to exploit new biomarkers for clinical applications.

METHODS

The miR-32-3p expression level of patients was detected by RT-qPCR. Diagnostic accuracy of miR-32-3p analyzed adopting ROC curve. Additionally, the risk factors correlation with the occurrence of OPF were assessed by logistic analysis. The effect of miR-32-3p on BMSCs was verified by in vitro transfection experiments.

RESULTS

miR-32-3p expression was lower in OPF patients than in OP patients. ROC curve implied that miR-32-3p exhibits commendable sensitivity (88.9%) and specificity (75.6%) to differentiate between OP and OPF patients (AUC = 0.905, P < 0.001). Furthermore, miR-32-3p was correlated with the development of OPF and was a risk factor for OPF (P < 0.001). Functional assays revealed that transfection with miR-32-3p mimic could promote proliferation and inhibit apoptosis, whereas transfection with miR-32-3p inhibitor had the opposite effect.

CONCLUSION

miR-32-3p demonstrates significant diagnostic potential for OPF patients. It is likely that miR-32-3p probably is a new diagnosis biomarker for OPF, offering promising therapeutic avenues through targeted interventions.

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

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

Recent trends of stem cell therapies in the management of orthopedic surgical challenges

Emerged health-related problems especially with increasing population and with the wider occurrence of these issues have always put the utmost concern and led medicine to outgrow its usual mode of treatment, to achieve better outcomes. Orthopedic interventions are one of the most concerning hitches, requiring advancement in several issues, that show complications with conventional approaches. Advanced studies have been undertaken to address the issue, among which stem cell therapy emerged as a better area of growth. The capacity of the stem cells to renovate themselves and adapt into different cell types made it possible to implement its use as a regenerative slant. Harvesting the stem cells, particularly mesenchymal stem cells (MSCs) is easier and can be further grown in vitro . In this review, we have discussed orthopedic-related issues including bone defects and fractures, nonunions, ligament and tendon injuries, degenerative changes, and associated conditions, which require further approaches to execute better outcomes, and the advanced strategies that can be tagged along with various ways of application of MSCs. It aims to objectify the idea of stem cells, with a major focus on the application of MSCs from different sources in various orthopedic interventions. It also discusses the limitations, and future scopes for further approaches in the field of regenerative medicine. The involvement of MSCs may transition the procedures in orthopedic interventions from predominantly surgical substitution and reconstruction to bio-regeneration and prevention. Nevertheless, additional improvements and evaluations are required to explore the effectiveness and safety of mesenchymal stem cell treatment in orthopedic regenerative medicine.

Apoptotic vesicles rescue impaired mesenchymal stem cells and their therapeutic capacity for osteoporosis by restoring miR-145a-5p deficiency

Apoptotic vesicles (apoVs) play a vital role in various physiological and pathological conditions. However, we have yet to fully understand their precise biological effects in rescuing impaired mesenchymal stem cells (MSCs). Here, we proved that systemic infusion of MSCs derived from wild-type (WT) mice rather than from ovariectomized (OVX) mice effectively improved the osteopenia phenotype and rescued the impaired recipient MSCs in osteoporotic mice. Meanwhile, apoVs derived from WT MSCs (WT apoVs) instead of OVX apoVs efficiently restored the impaired biological function of OVX MSCs and their ability to improve osteoporosis. Mechanistically, the reduced miR-145a-5p expression hindered the osteogenic differentiation and immunomodulatory capacity of OVX MSCs by affecting the TGF-β/Smad 2/3-Wnt/β-catenin signaling axis, resulting in the development of osteoporosis. WT apoVs directly transferred miR-145a-5p to OVX MSCs, which were then reused to restore their impaired biological functions. The differential expression of miR-145a-5p is responsible for the distinct efficacy between the two types of apoVs. Overall, our findings unveil the remarkable potential of apoVs, as a novel nongenetic engineering approach, in rescuing the biological function and therapeutic capability of MSCs derived from patients. This discovery offers a new avenue for exploring apoVs-based stem cell engineering and expands the application scope of stem cell therapy, contributing to the maintenance of bone homeostasis through a previously unrecognized mechanism.

Harnessing Engineered Extracellular Vesicles from Mesenchymal Stem Cells as Therapeutic Scaffolds for Bone‐Related Diseases

Mesenchymal stem cells (MSCs) play a crucial role in maintaining bone homeostasis and are extensively explored for cell therapy in various bone‐related diseases. In addition to direct cell therapy, the secretion of extracellular vesicles (EVs) by MSCs has emerged as a promising alternative approach. MSC‐derived EVs (MSC‐EVs) offer equivalent therapeutic efficacy to MSCs while mitigating potential risks. These EVs possess unique properties that enable them to traverse biological barriers and deliver bioactive cargos to target cells. Furthermore, by employing modification and engineering strategies, the therapeutic effects and tissue targeting specificity of MSC‐EVs can be further enhanced to meet specific therapeutic needs. In this review, the mechanisms and advantages of MSC‐EV therapy in diseased bone tissues are highlighted. Through simple isolation and modification techniques, MSC‐EV‐based biomaterials have demonstrated great promise for bone regeneration. Finally, future perspectives on MSC‐EV therapy are presented, envisioning the development of next‐generation regenerative materials and bioactive agents for clinical translation in the field of bone regeneration.

Mesenchymal stem cells and their extracellular vesicles in bone and joint diseases: targeting the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a cytosolic multi-subunit protein complex, and recent studies have demonstrated the vital role of the NLRP3 inflammasome in the pathological and physiological conditions, which cleaves gasdermin D to induce inflammatory cell death called pyroptosis and mediates the release of interleukin-1 beta and interleukin-18 in response to microbial infection or cellular injury. Over-activation of the NLRP3 inflammasome is associated with the pathogenesis of many disorders affecting bone and joints, including gouty arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis, and periodontitis. Moreover, mesenchymal stem cells (MSCs) have been discovered to facilitate the inhibition of NLRP3 and maybe ideal for treating bone and joint diseases. In this review, we implicate the structure and activation of the NLRP3 inflammasome along with the detail on the involvement of NLRP3 inflammasome in bone and joint diseases pathology. In addition, we focused on MSCs and MSC-extracellular vesicles targeting NLRP3 inflammasomes in bone and joint diseases. Finally, the existing problems and future direction are also discussed.

Oral microbiome, periodontal disease and systemic bone-related diseases in the era of homeostatic medicine

BACKGROUND

Homeostasis is a state of self-regulation and dynamic equilibrium, maintaining the good physiological functions of each system in living organisms. In the oral cavity, the interaction between the host and the oral microbiome forms oral microbial homeostasis. Physiological bone remodeling and renewal can occur under the maintenance of oral microbial homeostasis. The imbalance of bone homeostasis is a key mechanism leading to the occurrence of systemic bone-related diseases. Considering the importance of oral microbial homeostasis in the maintenance of bone homeostasis, it still lacks a complete understanding of the relationship between oral microbiome, periodontal disease and systemic bone-related diseases.

AIM OF REVIEW

This review focuses on the homeostatic changes, pathogenic routes and potential mechanisms in the oral microbiome in periodontal disease and systemic bone-related diseases such as rheumatoid arthritis, osteoarthritis, osteoporosis and osteomyelitis. Additionally, this review discusses oral microbiome-based diagnostic approaches and explores probiotics, mesenchymal stem cells, and oral microbiome transplantation as promising treatment strategies.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review highlights the association between oral microbial homeostasis imbalance and systemic bone-related diseases, and highlights the possibility of remodeling oral microbial homeostasis for the prevention and treatment of systemic bone-related diseases.

Long non-coding TRPM2-AS regulates fracture healing by targeting miR-545-3p/Bmp2

OBJECTIVE

Delayed fracture healing increases the suffering of patients. An in-depth investigation of the pathogenesis of delayed fracture healing may offer new direction for the prevention and treatment.

METHODS

The study included 63 normal healing tibial fractures and 58 delayed healing tibial fractures patients. Long non-coding RNA (lncRNA)TRPM2-AS, microRNA-545-3p (miR-545-3p), bone morphogenetic protein 2 (Bmp2) mRNA and osteogenic differentiation markers, including runt-related transcription factor 2 (Runx2), osteocalcin (Ocn), and alkaline phosphatase (Alp) mRNA expression were determined by Real-time quantitative reverse transcription-polymerase chain reaction in serum and MC3T3-E1 cells. The prediction potential of TRPM2-AS in delayed healing fracture patients was verified by receiver operating characteristic curves. The binding relationship of TRPM2-AS/miR-545-3p/Bmp2 was evaluated by dual luciferase reporter gene assay. Cell proliferation and apoptosis were detected by CCK-8 and flow cytometry.

RESULTS

TRPM2-AS was remarkably down-regulated in patients with delayed fracture healing and could better predict the fracture healing status. TRPM2-AS downregulation inhibited osteogenic markers mRNA expression, restrained proliferation, and promoted apoptosis of MC3T3-E1 cells (p < 0.05). In delayed fracture healing, miR-545-3p was dramatically up-regulated and was negatively regulated by TRPM2-AS. Reducing miR-545-3p eliminate the negative effect of TRPM2-AS down-regulation on osteoblast proliferation and differentiation (p < 0.05). miR-545-3p targets Bmp2, which plays a positive role in osteoblast differentiation (p < 0.05).

CONCLUSION

This study found that TRPM2-AS has the potential to be a diagnostic marker for delayed fracture healing and revealed that the TRPM2-AS/miR-545-3p/Bmp2 axis affects fracture healing by regulating osteoblast.

Engineered exosomes with a photoinducible protein delivery system enable CRISPR-Cas-based epigenome editing in Alzheimer's disease

Effective intracellular delivery of therapeutic proteins can potentially treat a wide array of diseases. However, efficient delivery of functional proteins across the cell membrane remains challenging. Exosomes are nanosized vesicles naturally secreted by various types of cells and may serve as promising nanocarriers for therapeutic biomolecules. Here, we engineered exosomes equipped with a photoinducible cargo protein release system, termed mMaple3-mediated protein loading into and release from exosome (MAPLEX), in which cargo proteins can be loaded into the exosomes by fusing them with photocleavable protein (mMaple3)-conjugated exosomal membrane markers and subsequently released from the exosomal membrane by inducing photocleavage with blue light illumination. Using this system, we first induced transcriptional regulation by delivering octamer-binding transcription factor 4 and SRY-box transcription factor 2 to fibroblasts in vitro. Second, we induced in vivo gene recombination in Cre reporter mice by delivering Cre recombinase. Last, we achieved targeted epigenome editing in the brains of 5xFAD and 3xTg-AD mice, two models of Alzheimer's disease. Administration of MAPLEXs loaded with β-site amyloid precursor protein cleaving enzyme 1 (Bace1)-targeting single guide RNA-incorporated dCas9 ribonucleoprotein complexes, coupled with the catalytic domain of DNA methyltransferase 3A, resulted in successful methylation of the targeted CpG sites within the Bace1 promoter. This approach led to a significant reduction in Bace1 expression, improved recognition memory impairment, and reduced amyloid pathology in 5xFAD and 3xTg-AD mice. These results suggest that MAPLEX is an efficient intracellular protein delivery system that can deliver diverse therapeutic proteins for multiple diseases.

Extracellular Vesicles Derived from Adipose Stem Cells Alleviate Systemic Sclerosis by Inhibiting TGF-β Pathway

Systemic sclerosis is an autoimmune disease characterized by inflammatory reactions and fibrosis. Myofibroblasts are considered therapeutic targets for preventing and reversing the pathogenesis of fibrosis in systemic sclerosis. Although the mechanisms that differentiate into myofibroblasts are diverse, transforming growth factor β (TGF-β) is known to be a key mediator of fibrosis in systemic sclerosis. This study investigated the effects of extracellular vesicles derived from human adipose stem cells (ASC-EVs) in an in vivo systemic sclerosis model and in vitro TGF-β1-induced dermal fibroblasts. The therapeutic effects of ASC-EVs on the in vivo systemic sclerosis model were evaluated based on dermal thickness and the number of α-smooth muscle actin (α-SMA)-expressing cells using hematoxylin and eosin staining and immunohistochemistry. Administration of ASC-EVs decreased both the dermal thickness and α-SMA expressing cell number as well as the mRNA levels of fibrotic genes, such as Acta2, Ccn2, Col1a1 and Comp. Additionally, we discovered that ASC-EVs can decrease the expression of α-SMA and CTGF and suppress the TGF-β pathway by inhibiting the activation of SMAD2 in dermal fibroblasts induced by TGF-β1. Finally, TGF-β1-induced dermal fibroblasts underwent selective death through ASC-EVs treatment. These results indicate that ASC-EVs could provide a therapeutic approach for preventing and reversing systemic sclerosis.

Cardiac-derived extracellular vesicles improve mitochondrial function to protect the heart against ischemia/reperfusion injury by delivering ATP5a1

BACKGROUND

Numerous studies have confirmed the involvement of extracellular vesicles (EVs) in various physiological processes, including cellular death and tissue damage. Recently, we reported that EVs derived from ischemia-reperfusion heart exacerbate cardiac injury. However, the role of EVs from healthy heart tissue (heart-derived EVs, or cEVs) on myocardial ischemia-reperfusion (MI/R) injury remains unclear.

RESULTS

Here, we demonstrated that intramyocardial administration of cEVs significantly enhanced cardiac function and reduced cardiac damage in murine MI/R injury models. cEVs treatment effectively inhibited ferroptosis and maintained mitochondrial homeostasis in cardiomyocytes subjected to ischemia-reperfusion injury. Further results revealed that cEVs can transfer ATP5a1 into cardiomyocytes, thereby suppressing mitochondrial ROS production, alleviating mitochondrial damage, and inhibiting cardiomyocyte ferroptosis. Knockdown of ATP5a1 abolished the protective effects of cEVs. Furthermore, we found that the majority of cEVs are derived from cardiomyocytes, and ATP5a1 in cEVs primarily originates from cardiomyocytes of the healthy murine heart. Moreover, we demonstrated that adipose-derived stem cells (ADSC)-derived EVs with ATP5a1 overexpression showed much better efficacy on the therapy of MI/R injury compared to control ADSC-derived EVs.

CONCLUSIONS

These findings emphasized the protective role of cEVs in cardiac injury and highlighted the therapeutic potential of targeting ATP5a1 as an important approach for managing myocardial damage induced by MI/R injury.

Therapeutic potential of extracellular vesicles from diverse sources in cancer treatment

Cancer, a prevalent and complex disease, presents a significant challenge to the medical community. It is characterized by irregular cell differentiation, excessive proliferation, uncontrolled growth, invasion of nearby tissues, and spread to distant organs. Its progression involves a complex interplay of several elements and processes. Extracellular vesicles (EVs) serve as critical intermediaries in intercellular communication, transporting critical molecules such as lipids, RNA, membrane, and cytoplasmic proteins between cells. They significantly contribute to the progression, development, and dissemination of primary tumors by facilitating the exchange of information and transmitting signals that regulate tumor growth and metastasis. However, EVs do not have a singular impact on cancer; instead, they play a multifaceted dual role. Under specific circumstances, they can impede tumor growth and influence cancer by delivering oncogenic factors or triggering an immune response. Furthermore, EVs from different sources demonstrate distinct advantages in inhibiting cancer. This research examines the biological characteristics of EVs and their involvement in cancer development to establish a theoretical foundation for better understanding the connection between EVs and cancer. Here, we discuss the potential of EVs from various sources in cancer therapy, as well as the current status and future prospects of engineered EVs in developing more effective cancer treatments.

Recent advances in the use of extracellular vesicles from adipose-derived stem cells for regenerative medical therapeutics

Adipose-derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs) isolated from adipose tissue. They possess remarkable properties, including multipotency, self-renewal, and easy clinical availability. ADSCs are also capable of promoting tissue regeneration through the secretion of various cytokines, factors, and extracellular vesicles (EVs). ADSC-derived EVs (ADSC-EVs) act as intercellular signaling mediators that encapsulate a range of biomolecules. These EVs have been found to mediate the therapeutic activities of donor cells by promoting the proliferation and migration of effector cells, facilitating angiogenesis, modulating immunity, and performing other specific functions in different tissues. Compared to the donor cells themselves, ADSC-EVs offer advantages such as fewer safety concerns and more convenient transportation and storage for clinical application. As a result, these EVs have received significant attention as cell-free therapeutic agents with potential future application in regenerative medicine. In this review, we focus on recent research progress regarding regenerative medical use of ADSC-EVs across various medical conditions, including wound healing, chronic limb ischemia, angiogenesis, myocardial infarction, diabetic nephropathy, fat graft survival, bone regeneration, cartilage regeneration, tendinopathy and tendon healing, peripheral nerve regeneration, and acute lung injury, among others. We also discuss the underlying mechanisms responsible for inducing these therapeutic effects. We believe that deciphering the biological properties, therapeutic effects, and underlying mechanisms associated with ADSC-EVs will provide a foundation for developing a novel therapeutic approach in regenerative medicine.

Apoptotic vesicles rescue impaired mesenchymal stem cells and their therapeutic capacity for osteoporosis by restoring miR-145a-5p deficiency

Apoptotic vesicles (apoVs) play a vital role in various pathological conditions; however, we have yet to fully understand their precise biological effects in rescuing impaired mesenchymal stem cells (MSCs) and regulating tissue homeostasis. Here, we proved that systemic infusion of bone marrow MSCs derived from wild-type (WT) mice effectively improved the osteopenia phenotype and hyperimmune state in ovariectomized (OVX) mice. Importantly, the WT MSCs rescued the impairment of OVX MSCs both in vivo and in vitro, whereas OVX MSCs did not show the same efficacy. Interestingly, treatment with apoVs derived from WT MSCs (WT apoVs) restored the impaired biological function of OVX MSCs and their ability to improve osteoporosis. This effect was not observed with OVX MSCs-derived apoVs (OVX apoVs) treatment. Mechanistically, the reduced miR-145a-5p expression hindered the osteogenic differentiation and immunomodulatory capacity of OVX MSCs by affecting the TGF-β/Smad 2/3-Wnt/β-catenin signaling axis, resulting in the development of osteoporosis. WT apoVs directly transferred miR-145a-5p to OVX MSCs, which were then reused to restore their impaired biological functions. Conversely, treatment with OVX apoVs did not produce significant effects due to their limited expression of miR-145a-5p. Overall, our findings unveil the remarkable potential of apoVs in rescuing the biological function and therapeutic capability of MSCs derived from individuals with diseases. This discovery offers a new avenue for exploring apoVs-based MSC engineering and expands the application scope of stem cell therapy, contributing to the maintenance of bone homeostasis through a previously unrecognized mechanism.

Adipose exosomal noncoding RNAs: Roles and mechanisms in metabolic diseases

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

Engineering approaches to manipulate osteoclast behavior for bone regeneration

Extensive research has delved into the multifaceted roles of osteoclasts beyond their traditional function in bone resorption in recent years, uncovering their significant influence on bone formation. This shift in understanding has spurred investigations into engineering strategies aimed at leveraging osteoclasts to not only inhibit bone resorption but also facilitate bone regeneration. This review seeks to comprehensively examine the mechanisms by which osteoclasts impact bone metabolism. Additionally, it explores various engineering methodologies, including the modification of bioactive material properties, localized drug delivery, and the introduction of exogenous cells, assessing their potential and mechanisms in aiding bone repair by targeting osteoclasts. Finally, the review proposes current limitations and future routes for manipulating osteoclasts through biological and material cues to facilitate bone repair.

[miRNA Is Involved in the Pathogenesis of Multiple Diseases by Targeting Osteoprotegerin]

As a member of the tumor necrosis factor receptor family, osteoprotegerin (OPG) is highly expressed in adults in the lung, heart, kidney, liver, spleen, thymus, prostate, ovary, small intestines, thyroid gland, lymph nodes, trachea, adrenal gland, the testis, and bone marrow. Together with the receptor activator of nuclear factor-κB (RANK) and the receptor activator of nuclear factor-κB ligand (RANKL), it forms the RANK/RANKL/OPG pathway, which plays an important role in the molecular mechanism of the development of various diseases. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs performing regulatory functions in eukaryotes, with a size of about 20-25 nucleotides. miRNA genes are transcribed into primary transcripts by RNA polymerase, bind to RNA-induced silencing complexes, identify target mRNAs through complementary base pairing, with a single miRNA being capable of targeting hundreds of mRNAs, and influence the expression of many genes through pathways involved in functional interactions. In recent years, a large number of studies have been done to explore the mechanism of action of miRNA in diseases through miRNA isolation, miRNA quantification, miRNA spectrum analysis, miRNA target detection, in vitro and in vivo regulation of miRNA levels, and other technologies. It was found that miRNA can play a key role in the pathogenesis of osteoporosis, rheumatoid arthritis, and other diseases by targeting OPG. The purpose of this review is to explore the interaction between miRNA and OPG in various diseases, and to propose new ideas for studying the mechanism of action of OPG in diseases.

The Impact of Non-alcohol Fatty Liver Disease on Bone Mineral Density is Mediated by Sclerostin by Mendelian Randomization Study

Non-alcoholic fatty liver disease (NAFLD) has been found to be associated with osteoporosis (OP) in observational studies. However, the precise causal relationship between NAFLD and OP remains unclear. Here, we used Mendelian randomization (MR) to explore the causal relationship. We selected NAFLD-related single-nucleotide polymorphisms from a genome-wide meta-analysis (8434 cases and 434,770 controls) as instrumental variants. We used inverse variance weighted analysis for the primary MR analysis. Furthermore, we used similar methodologies in parallel investigations of other chronic liver diseases (CLDs). We performed sensitivity analyses to ensure the reliability of the results. We observed a causality between NAFLD and forearm bone mineral density (FABMD) (beta-estimate [β]: - 0.212; p-value: 0.034). We also found that sclerostin can act as a mediator to influence the NAFLD and FABMD pathways to form a mediated MR network (mediated proportion = 8.8%). We also identified indications of causal relationships between other CLDs and OP. However, we were unable to establish any associated mediators. Notably, our analyses did not yield any evidence of pleiotropy. Our findings have implications in the development of preventive and interventional measures aimed at managing low bone mineral density in patients with NAFLD.

Synthetic biology-based bacterial extracellular vesicles displaying BMP-2 and CXCR4 to ameliorate osteoporosis

Osteoporosis (OP) is a systematic bone disease characterized by low bone mass and fragile bone microarchitecture. Conventional treatment for OP has limited efficacy and long-term toxicity. Synthetic biology makes bacterial extracellular vesicle (BEVs)-based therapeutic strategies a promising alternative for the treatment of OP. Here, we constructed a recombinant probiotics Escherichia coli Nissle 1917-pET28a-ClyA-BMP-2-CXCR4 (ECN-pClyA-BMP-2-CXCR4), in which BMP-2 and CXCR4 were overexpressed in fusion with BEVs surface protein ClyA. Subsequently, we isolated engineered BEVs-BMP-2-CXCR4 (BEVs-BC) for OP therapy. The engineered BEVs-BC exhibited great bone targeting in vivo. In addition, BEVs-BC had good biocompatibility and remarkable ability to promote osteogenic differentiation of BMSCs. Finally, the synthetic biology-based BEVs-BC significantly prevented the OP in an ovariectomized (OVX) mouse model. In conclusion, we constructed BEVs-BC with both bone-targeting and bone-forming in one-step using synthetic biology, which provides an effective strategy for OP and has great potential for industrialization.

Exosome MiR-21-5p Upregulated by HIF-1α Induces Adipose Stem Cell Differentiation to Promote Ectopic Bone Formation

Heterotopic bone occurs after burns, trauma and major orthopedic surgery, which cannot be completely cured by current treatments. The development of new treatments requires more in-depth research into the mechanism of HO. Available evidence suggests that miR-21-5p plays an important role in bone formation. However, its mechanism in traumatic HO is still unclear. First, we identified exosomes extracted from L6 cells using TEM observation of the structure and western blotting detection of the surface marker CD63. Regulation effect of HIF-1α to miR-21-5p was confirmed by q-PCR assay. Then we co-cultured L6 cells with ASCs and performed alizarin red staining and ALP detection. Overexpression of miR-21-5p upregulated BMP4, p-smad1/5/8, OCN and OPN, which suggests the BMP4-smad signaling pathway may be involved in miR-21-5p regulation of osteogenic differentiation of ASCs. Finally in vivo experiments showed that miR-21-5p exosomes promoted ectopic formation in traumatized mice. This study confirms that HIF-1α could modulate miR-21-5p exosomes to promote post-traumatic ectopic bone formation by inducing ASCs cell differentiation. Our study reveals the mechanisms of miR-21-5p in ectopic ossification formation after trauma.

Nerve Growth Factor-Preconditioned Mesenchymal Stem Cell-Derived Exosome-Functionalized 3D-Printed Hierarchical Porous Scaffolds with Neuro-Promotive Properties for Enhancing Innervated Bone Regeneration

The essential role of the neural network in enhancing bone regeneration has often been overlooked in biomaterial design, leading to delayed or compromised bone healing. Engineered mesenchymal stem cells (MSCs)-derived exosomes are becoming increasingly recognized as potent cell-free agents for manipulating cellular behavior and improving therapeutic effectiveness. Herein, MSCs are stimulated with nerve growth factor (NGF) to regulate exosomal cargoes to improve neuro-promotive potential and facilitate innervated bone regeneration. In vitro cell experiments showed that the NGF-stimulated MSCs-derived exosomes (N-Exos) obviously improved the cellular function and neurotrophic effects of the neural cells, and consequently, the osteogenic potential of the osteo-reparative cells. Bioinformatic analysis by miRNA sequencing and pathway enrichment revealed that the beneficial effects of N-Exos may partly be ascribed to the NGF-elicited multicomponent exosomal miRNAs and the subsequent regulation and activation of the MAPK and PI3K-Akt signaling pathways. On this basis, N-Exos were delivered on the micropores of the 3D-printed hierarchical porous scaffold to accomplish the sustained release profile and extended bioavailability. In a rat model with a distal femoral defect, the N-Exos-functionalized hierarchical porous scaffold significantly induced neurovascular structure formation and innervated bone regeneration. This study provided a feasible strategy to modulate the functional cargoes of MSCs-derived exosomes to acquire desirable neuro-promotive and osteogenic potential. Furthermore, the developed N-Exos-functionalized hierarchical porous scaffold may represent a promising neurovascular-promotive bone reparative scaffold for clinical translation.

Micro Trojan horses: Engineering extracellular vesicles crossing biological barriers for drug delivery

The biological barriers of the body, such as the blood-brain, placental, intestinal, skin, and air-blood, protect against invading viruses and bacteria while providing necessary physical support. However, these barriers also hinder the delivery of drugs to target tissues, reducing their therapeutic efficacy. Extracellular vesicles (EVs), nanostructures with a diameter ranging from 30 nm to 10 μm secreted by cells, offer a potential solution to this challenge. These natural vesicles can effectively pass through various biological barriers, facilitating intercellular communication. As a result, artificially engineered EVs that mimic or are superior to the natural ones have emerged as a promising drug delivery vehicle, capable of delivering drugs to almost any body part to treat various diseases. This review first provides an overview of the formation and cross-species uptake of natural EVs from different organisms, including animals, plants, and bacteria. Later, it explores the current clinical applications, perspectives, and challenges associated with using engineered EVs as a drug delivery platform. Finally, it aims to inspire further research to help bioengineered EVs effectively cross biological barriers to treat diseases.

Porcine Mandibular Bone Marrow-Derived Mesenchymal Stem Cell (BMSC)-Derived Extracellular Vesicles Can Promote the Osteogenic Differentiation Capacity of Porcine Tibial-Derived BMSCs

OBJECTIVE

Existing research suggests that bone marrow-derived mesenchymal stem cells (BMSCs) may promote endogenous bone repair. This may be through the secretion of factors that stimulate repair processes or directly through differentiation into osteoblast-progenitor cells. However, the osteogenic potential of BMSCs varies among different tissue sources (e.g., mandibular versus long BMSCs). The main aim of this study was to investigate the difference in osteogenic differentiation capacity between mandibular BMSCs (mBMSCs) and tibial BMSCs (tBMSCs).

MATERIALS AND METHODS

Bioinformatics analysis of the GSE81430 dataset taken from the Gene Expression Omnibus (GEO) database was performed using GEO2R. BMSCs were isolated from mandibular and tibial bone marrow tissue samples. Healthy pigs (n = 3) (registered at the State Office for Nature, Environment, and Consumer Protection, North Rhine-Westphalia (LANUV) 81-02.04.2020.A215) were used for this purpose. Cell morphology and osteogenic differentiation were evaluated in mBMSCs and tBMSCs. The expression levels of toll-like receptor 4 (TLR4) and nuclear transcription factor κB (NF-κB) were analyzed using quantitative polymerase chain reaction (qPCR) and Western blot (WB), respectively. In addition, mBMSC-derived extracellular vesicles (mBMSC-EVs) were gained and used as osteogenic stimuli for tBMSCs. Cell morphology and osteogenic differentiation capacity were assessed after mBMSC-EV stimulation.

RESULTS

Bioinformatic analysis indicated that the difference in the activation of the TLR4/NF-κB pathway was more pronounced compared to all other examined genes. Specifically, this demonstrated significant downregulation, whereas only 5-7 upregulated genes displayed significant variances. The mBMSC group showed stronger osteogenic differentiation capacity compared to the tBMSC group, confirmed via ALP, ARS, and von Kossa staining. Furthermore, qPCR and WB analysis revealed a significant decrease in the expression of the TLR4/NF-κB pathway in the mBMSC group compared to the tBMSC group (TLR4 fold changes: mBMSCs vs. tBMSCs p < 0.05; NF-κB fold changes: mBMSCs vs. tBMSCs p < 0.05). The osteogenic differentiation capacity was enhanced, and qPCR and WB analysis revealed a significant decrease in the expression of TLR4 and NF-κB in the tBMSC group with mBMSC-EVs added compared to tBMSCs alone (TLR4 fold changes: p < 0.05; NF-κB fold changes: p < 0.05).

CONCLUSION

Our results indicate that mBMSC-EVs can promote the osteogenic differentiation of tBMSCs in vitro. The results also provide insights into the osteogenic mechanism of mBMSCs via TLR4/NF-κB signaling pathway activation. This discovery promises a fresh perspective on the treatment of bone fractures or malunions, potentially offering a novel therapeutic method.

Advances in the research and application of neurokinin-1 receptor antagonists

Recently, the substance P (SP)/neurokinin-1 receptor (NK-1R) system has been found to be involved in various human pathophysiological disorders including the symptoms of coronavirus disease 2019 (COVID-19). Besides, studies in the oncological field have demonstrated an intricate correlation between the upregulation of NK-1R and the activation of SP/NK-1R system with the progression of multiple carcinoma types and poor clinical prognosis. These findings indicate that the modulation of SP/NK-1R system with NK-1R antagonists can be a potential broad-spectrum antitumor strategy. This review updates the latest potential and applications of NK-1R antagonists in the treatment of human diseases and cancers, as well as the underlying mechanisms. Furthermore, the strategies to improve the bioavailability and efficacy of NK-1R antagonist drugs are summarized, such as solid dispersion systems, nanonization, and nanoencapsulation. As a radiopharmaceutical therapeutic, the NK-1R antagonist aprepitant was originally developed as radioligand receptor to target NK-1R-overexpressing tumors. However, combining NK-1R antagonists with other drugs can produce a synergistic effect, thereby enhancing the therapeutic effect, alleviating the symptoms, and improving patients quality of life in several diseases and cancers.

Enhancing osteoporosis treatment with engineered mesenchymal stem cell-derived extracellular vesicles: mechanisms and advances

As societal aging intensifies, the incidence of osteoporosis (OP) continually rises. OP is a skeletal disorder characterized by reduced bone mass, deteriorated bone tissue microstructure, and consequently increased bone fragility and fracture susceptibility, typically evaluated using bone mineral density (BMD) and T-score. Not only does OP diminish patients' quality of life, but it also imposes a substantial economic burden on society. Conventional pharmacological treatments yield limited efficacy and severe adverse reactions. In contemporary academic discourse, mesenchymal stem cells (MSCs) derived extracellular vesicles (EVs) have surfaced as auspicious novel therapeutic modalities for OP. EVs can convey information through the cargo they carry and have been demonstrated to be a crucial medium for intercellular communication, playing a significant role in maintaining the homeostasis of the bone microenvironment. Furthermore, various research findings provide evidence that engineered strategies can enhance the therapeutic effects of EVs in OP treatment. While numerous reviews have explored the progress and potential of EVs in treating degenerative bone diseases, research on using EVs to address OP remains in the early stages of basic experimentation. This paper reviews advancements in utilizing MSCs and their derived EVs for OP treatment. It systematically examines the most extensively researched MSC-derived EVs for treating OP, delving not only into the molecular mechanisms of EV-based OP therapy but also conducting a comparative analysis of the strengths and limitations of EVs sourced from various cell origins. Additionally, the paper emphasizes the technical and engineering strategies necessary for leveraging EVs in OP treatment, offering insights and recommendations for future research endeavors.

Non-bone-derived exosomes: a new perspective on regulators of bone homeostasis

Accumulating evidence indicates that exosomes help to regulate bone homeostasis. The roles of bone-derived exosomes have been well-described; however, recent studies have shown that some non-bone-derived exosomes have better bone targeting ability than bone-derived exosomes and that their performance as a drug delivery vehicle for regulating bone homeostasis may be better than that of bone-derived exosomes, and the sources of non-bone-derived exosomes are more extensive and can thus be better for clinical needs. Here, we sort non-bone-derived exosomes and describe their composition and biogenesis. Their roles and specific mechanisms in bone homeostasis and bone-related diseases are also discussed. Furthermore, we reveal obstacles to current research and future challenges in the practical application of exosomes, and we provide potential strategies for more effective application of exosomes for the regulation of bone homeostasis and the treatment of bone-related diseases. Video Abstract.