Pro-angiognetic and pro-osteogenic effects of human umbilical cord mesenchymal stem cell-derived exosomal miR-21-5p in osteonecrosis of the femoral head

Matrix-bound nanovesicles recapitulate tissue-specific angiogenic properties of parent extracellular matrix with distinct miRNA profiles

Decellularized extracellular matrix (dECM) exhibits tissue-specific pro- or anti-angiogenic effects. Previous studies have demonstrated that matrix-bound nanovesicles (MBVs) act as key bioactive components of dECM, replicating various biological functions such as anti-inflammatory and immunomodulatory effects. Building on this evidence, this study hypothesized that MBVs derived from cartilage and small intestinal submucosa (SIS) modulate angiogenesis through the selective packaging of miRNAs. Cartilage-derived MBVs (cMBVs) and SIS-derived MBVs (sMBVs) were isolated, characterized, and analyzed for their miRNA profiles using RNA sequencing and RT-qPCR validation. The interactions between MBVs and human umbilical vein endothelial cells (HUVECs) were assessed by examining proliferation, adhesion, migration, and tube formation in comparison to the parent ECM. Angiogenic modulation was further evaluated using a mouse Matrigel plug assay and a rabbit corneal neovascularization (NV) model. Our results demonstrated that anti-angiogenic miRNAs (e.g., miR-140-3p, miR-455-5p, and miR-148a-5p) were predominant in cMBVs, suppressing endothelial cell activity and angiogenesis, while pro-angiogenic miRNAs (e.g., miR-143-3p, miR-181a, and miR-21-5p) were prevalent in sMBVs, enhancing vessel formation. In vivo, cMBVs significantly inhibited vascular invasion and neovessel formation, whereas sMBVs promoted angiogenesis in both models. These findings confirm that MBVs reflect the tissue-specific angiogenic regulatory functions of their parent ECM, and highlight their potential as therapeutic tools for targeted modulation of angiogenesis in regenerative medicine and tissue engineering.

Knowledge mapping of core decompression in osteonecrosis of the femoral head: a bibliometric analysis

Background

Osteonecrosis of the femoral head (ONFH), caused by disrupted blood supply leading to bone cell death and joint collapse, remains a critical orthopedic challenge. While core decompression has advanced significantly in ONFH treatment, no bibliometric analysis has mapped its research landscape.

Method

We analyzed 854 articles from the Web of Science Core Collection (1986-2023) using VOSviewer, CiteSpace, and bibliometrix.

Results

Publications surged from 5.4/year (1986-2001) to 52.3/year (2015-2023), reflecting intensified interest. China (253 articles, 29.6%) and the United States (232, 27.2%) dominated contributions, with Stanford University and Johns Hopkins University as top institutions. International collaborations linked China to the United States, Germany, and England. Clinical Orthopaedics and Related Research was the most cited journal (4708 citations). Keyword analysis revealed emerging hotspots: mesenchymal stem cells (19 occurrences), cell therapy, and angiogenesis. Citation bursts highlighted Mont MA's seminal work (burst strength: 19.67) on joint-preserving strategies and stem cell-enhanced core decompression.

Conclusion

This first bibliometric study delineates trends, collaborations, and frontiers in core decompression for ONFH, emphasizing the translational potential of stem cell therapies.

The multifaceted roles of extracellular vesicles in osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is a severe disease characterized by bone tissue necrosis due to vascular impairment, often leading to joint collapse and requiring surgical intervention. Extracellular vesicles (EVs) serve as crucial mediators of intercellular communication, influencing osteogenesis, angiogenesis, and immune regulation. This review summarizes the dual role of EVs in both the pathogenesis of ONFH and post-necrosis bone repair, highlighting the impact of various EV-mediated signaling pathways on bone regeneration and the potential crosstalk among these pathways. Additionally, EVs hold promise as diagnostic biomarkers or contrast agents to complement conventional imaging techniques for ONFH detection. By elucidating the role of EVs in osteonecrosis and addressing the current challenges, we aspire to establish a foundation for the timely identification and treatment of ONFH. The translational potential of this article: This review comprehensively discusses the role of EVs in ONFH, providing innovative and promising insights for its diagnosis and treatment, which also establishes a theoretical foundation for the future clinical application of EVs in ONFH.

Small extracellular vesicles: the origins, current status, future prospects, and applications

Small extracellular vesicles (sEVs) are membrane-bound vesicles with a size of less than 200 nm, released by cells. Due to their relatively small molecular weight and ability to participate in intercellular communication, sEVs can serve not only as carriers of biomarkers for disease diagnosis but also as effective drug delivery agents. Furthermore, these vesicles are involved in regulating the onset and progression of various diseases, reflecting the physiological and functional states of cells. This paper introduces the classification of extracellular vesicles, with a focus on the extraction and identification of sEVs and their significant role in repair, diagnosis, and intercellular communication. Additionally, the paper addresses the engineering modification of sEVs to provide a reference for enhanced understanding and application.

Exosomal RNAs and EZH2: unraveling the molecular dialogue driving tumor progression

The EZH2 gene encodes an enzyme that is part of the epigenetic factor Polycomb Repressive Complex 2 (PRC2). In order to control gene expression, PRC2 mainly modifies chromatin structure. In this complex process, EZH2 methylates histone proteins, which in turn suppresses further RNA transcriptions. As a result, EZH2 dysregulations can occasionally induce abnormal gene expression patterns, which can aid in the development and progression of cancer. Non-coding RNAs significantly impact the expression of EZH2 through epigenetic mechanisms. Meanwhile, normal and cancerous cells frequently release vesicles into the extracellular matrix, also known as exosomes, that occasionally carry RNA molecules from their origin cells, including messenger RNAs, microRNAs, and other non-coding RNAs. Thus exosomes are granted the ability to regulate numerous physiological functions and act as crucial messengers between cells by influencing gene expression in the recipient cell. We conducted this review to focus on EZH2's substantial biological role and the mechanisms that regulate it, driven by the desire to understand the possible impact of exosomal RNAs on EZH2 expression.

Exosomes in cartilage microenvironment regulation and cartilage repair

Osteoarthritis (OA) is a debilitating disease that predominantly impacts the hip, hand, and knee joints. Its pathology is defined by the progressive degradation of articular cartilage, formation of bone spurs, and synovial inflammation, resulting in pain, joint function limitations, and substantial societal and familial burdens. Current treatment strategies primarily target pain alleviation, yet improved interventions addressing the underlying disease pathology are scarce. Recently, exosomes have emerged as a subject of growing interest in OA therapy. Numerous studies have investigated exosomes to offer promising therapeutic approaches for OA through diverse in vivo and in vitro models, elucidating the mechanisms by which exosomes from various cell sources modulate the cartilage microenvironment and promote cartilage repair. Preclinical investigations have demonstrated the regulatory effects of exosomes originating from human cells, including mesenchymal stem cells (MSC), synovial fibroblasts, chondrocytes, macrophages, and exosomes derived from Chinese herbal medicines, on the modulation of the cartilage microenvironment and cartilage repair through diverse signaling pathways. Additionally, therapeutic mechanisms encompass cartilage inflammation, degradation of the cartilage matrix, proliferation and migration of chondrocytes, autophagy, apoptosis, and mitigation of oxidative stress. An increasing number of exosome carrier scaffolds are under development. Our review adopts a multidimensional approach to enhance comprehension of the pivotal therapeutic functions exerted by exosomes sourced from diverse cell types in OA. Ultimately, our aim is to pinpoint therapeutic targets capable of regulating the cartilage microenvironment and facilitating cartilage repair in OA.

Huc-MSC-derived exosomes alleviates alcohol-induced osteonecrosis of the femoral head through targeting the miR-25-3p/GREM1 axis

Osteonecrosis of the femoral head (ONFH) is a destructive bone disease, and overuse of alcohol is one of the major contributing factors. Although mesenchymal stem cells (MSCs) and their exosomes have been reported to attenuate ONFH, the potential mechanisms of alcohol-induced ONFH (AONFH) are unclear. Here, we isolated and identified human umbilical cord MSCs-derived exosomal (hucMSCs-exos) miR-25-3p. We observed that hucMSCs-exos transferred miR-25-3p into bone marrow stem cells (BMSCs). HucMSCs-exos miR-25-3p increased cell viability, osteogenic differentiation, and inhibited apoptosis of alcohol-treated BMSCs and AONFH rat model. Mechanically, hucMSCs-exos upregulated miR-25-3p expression in BMSCs by repressing miR-25-3p DNA methylation, and DNA methylation inhibitor 5-Aza-2-deoxycytidine (DAC) ameliorated AONFH. Besides, miR-25-3p suppressed gremlin 1 (GREM1) expression, and upregulation of GREM1 restored the inhibition of hucMSCs-exos on AONFH. Therefore, we determined that hucMSCs-exos miR-25-3p alleviated AONFH by inhibiting miR-25-3p DNA methylation and GREM1 expression, which may help identify novel biomarkers, diagnostic and therapeutic targets.

Critical roles of miR-21 in promotions angiogenesis: friend or foe?

MiRNAs are small RNA strands that are managed following transcription and are of substantial importance in blood vessel formation. It is essential to oversee the growth, differentiation, death, movement and construction of tubes by angiogenesis-affiliated cells. If miRNAs are not correctly regulated in regard to angiogenesis, it can deteriorate the health and lead to various illnesses, which include cancer, cardiovascular disorder, critical limb ischemia, Crohn's disease, ocular diseases, diabetic microvascular complications, and more. Consequently, it is vital to understand the crucial part that miRNAs play in the development of blood vessels, so we can develop reliable treatment plans for vascular diseases. This write-up will assess the critical role of miR-21/exosomal miR-21 in managing angiogenesis associated with bone growth, wound recovery, and other pathological conditions like tumor growth, ocular illnesses, diabetes, and other diseases connected to formation of blood vessels. Previous investigations have demonstrated that miR-21 is present at higher amounts in certain cancerous cells, and it influences a multitude of genes that moderate the increased creation of blood vessels. Furthermore, studies demonstrated that exosomal miR-21 has the capacity to interact with endothelial cells to foster tumor angiogenesis. For that reason, this review explains the critical importance of miR-21/exosomal miR-21 in managing both healthy and diseased states of angiogenesis.

Bioengineering strategies targeting angiogenesis: Innovative solutions for osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is a prevalent orthopedic disorder characterized primarily by compromised blood supply. This vascular deficit results in cell apoptosis, trabecular bone loss, and structural collapse of the femoral head at late stage, significantly impairing joint function. While MRI is a highly effective tool for diagnosing ONFH in its early stages, challenges remain due to the limited availability and high cost of MRI, as well as the absence of routine MRI screening in asymptomatic patients. . In addition, current therapeutic strategies predominantly only relieve symptoms while disease-modifying ONFH drugs are still under investigation/development. Considering that blood supply of the femoral head plays a key role in the pathology of ONFH, angiogenic therapies have been put forward as promising treatment options. Emerging bioengineering interventions targeting angiogenesis hold promising potential for ONFH treatment. In this review, we introduce the advances in research into the pathology of ONFH and summarize novel bioengineering interventions targeting angiogenesis. This review sheds light upon new directions for future research into ONFH.

Advances in mechanism and management of bone homeostasis in osteonecrosis: a review article from basic to clinical applications

Osteonecrosis, characterized by bone cell death leading to impaired bone recovery, causes challenges in bone homeostasis maintenance. Bone homeostasis relies on the delicate balance between osteoclasts and osteoblasts, encompassing a series of complex and strictly regulated biological functions. Current treatments, including conservative therapies and surgeries, often fall short of expected outcomes, necessitating a reorientation towards more effective therapeutic strategies according to the pathogenesis. In this review, the authors hierarchically outlined risk factors, emerging mechanisms, and last-decade treatment approaches in osteonecrosis. By connecting mechanisms of bone homeostasis, the authors proposed future research directions should be focused on elucidating risk factors and key molecules, performing high-quality clinical trial, updating practice, and accelerating translational potential.

Biomimetic Extracellular Vesicles Based on Composite Bioactive Ions for the Treatment of Ischemic Bone Disease

Extracellular vesicles (EVs) have demonstrated considerable potential in the treatment of ischemic bone diseases, such as glucocorticoid-induced osteonecrosis of the femoral head (GIONFH). However, the clinical application of EVs faces challenges such as low yield, poor bioactivity, and lack of targeting. Herein, we have developed a platform of multiengineered extracellular vesicle mimetics (EVMs) to address these challenges. By stimulating mesenchymal stem cells (MSCs) with multibioactive ions from TS (Trisilicate, a mixture of calcium silicate, magnesium silicate, and strontium silicate), we obtained endogenously modified TS-MSCs. From these, we further prepared a large quantity of bioactive EVMTS-MSCs through a straightforward extrusion method. Moreover, by integrating metabolic glycoengineering with click chemistry strategies, alendronate (ALN) was surface-modified on EVMTS-MSCs to further prepare ALN-EVMTS-MSCs. The engineered ALN-EVMTS-MSCs demonstrated bone-targeting effects, promoting osteogenesis and angiogenesis. This promoting effect is attributed to the rich presence of miR-21 in the TS-modified EVM, which further silences PTEN to activate the PI3K/AKT signaling pathway, thereby enhancing osteogenesis and angiogenesis. Our treatment strategy for ischemic bone diseases is based on a multiengineered, biomaterial-inspired, metabolic glycoengineering, and click chemistry-based platform of EVM. This study also provides an enhanced understanding of the development and application of engineered vesicles in disease treatment.

DNA Tetrahedron Delivering miR-21-5p Promotes Senescent Bone Defects Repair through Synergistic Regulation of Osteogenesis and Angiogenesis

Compromised osteogenesis and angiogenesis is the character of stem cell senescence, which brought difficulties for bone defects repairing in senescent microenvironment. As the most abundant bone-related miRNA, miRNA-21-5p plays a crucial role in inducing osteogenic and angiogenic differentiation. However, highly efficient miR-21-5p delivery still confronts challenges including poor cellular uptake and easy degradation. Herein, TDN-miR-21-5p nanocomplex is constructed based on DNA tetrahedral (TDN) and has great potential in promoting osteogenesis and alleviating senescence of senescent bone marrow stem cells (O-BMSCs), simultaneously enhancing angiogenic capacity of senescent endothelial progenitor cells (O-EPCs). Of note, the activation of AKT and Erk signaling pathway may direct regulatory mechanism of TDN-miR-21-5p mediated osteogenesis and senescence of O-BMSCs. Also, TDN-miR-21-5p can indirectly mediate osteogenesis and senescence of O-BMSCs through pro-angiogenic growth factors secreted from O-EPCs. In addition, gelatin methacryloyl (GelMA) hydrogels are mixed with TDN and TDN-miR-21-5p to fabricate delivery scaffolds. TDN-miR-21-5p@GelMA scaffold exhibits greater bone repair with increased expression of osteogenic- and angiogenic-related markers in senescent critical-size cranial defects in vivo. Collectively, TDN-miR-21-5p can alleviate senescence and induce osteogenesis and angiogenesis in senescent microenvironment, which provides a novel candidate strategy for senescent bone repair and widen clinical application of TDNs-based gene therapy.

Endothelial cell-derived exosomes trigger a positive feedback loop in osteogenesis-angiogenesis coupling via up-regulating zinc finger and BTB domain containing 16 in bone marrow mesenchymal stem cell

The close spatial and temporal connection between osteogenesis and angiogenesis around type H vasculature is referred as "osteogenesis-angiogenesis coupling", which is one of the basic mechanisms of osteogenesis. Endothelial cells (ECs), bone marrow mesenchymal stem cells (BMSCs), and their specific lineage constitute important cluster that participate in the regulation of osteogenesis and angiogenesis in bone microenvironment. However, the regulatory mechanism of osteogenesis-angiogenesis coupling under the condition of bone healing has not been unveiled. In this study, we demonstrated that the exosome derived from ECs (EC-exo) is an initiator of type H blood vessels formation, and EC-exo acts as a mediator in orchestrating osteogenesis-angiogenesis coupling by enhancing BMSC osteogenic differentiation and EC angiogenesis both in monolayer and stereoscopic co-culture system of primary human cells. The transcriptome array indicated that zinc finger and BTB domain containing 16 (ZBTB16) is a key gene in EC-exo-mediated osteogenesis, and ZBTB16 is indispensable in EC-exo-initiated osteogenesis-angiogenesis coupling. Mechanistically, EC-exo up-regulated the expression of ZBTB16 in BMSCs, thereby promoting osteoprogenitor phenotype transformation; the osteoprogenitors further promote ECs which constitute type H vessel (H-ECs) generation by activating HIF-1α pathway; and the H-ECs conversely promotes osteogenic differentiation of BMSCs. The crosstalk between BMSCs and ECs triggered by EC-exo constitutes a positive feedback loop that enhances osteogenesis-angiogenesis coupling. This study demonstrates that EC-exo can become an effective therapeutic tool to promote bone regeneration and repair.

Adipose-derived stem cell exosomal miR-21-5p enhances angiogenesis in endothelial progenitor cells to promote bone repair via the NOTCH1/DLL4/VEGFA signaling pathway

BACKGROUND

Angiogenesis is essential for repairing critical-sized bone defects. Although adipose-derived stem cell (ADSC)-derived exosomes have been shown to enhance the angiogenesis of endothelial progenitor cells (EPCs), the underlying mechanisms remain unclear. This study aims to explore the effects and mechanisms of ADSC-derived exosomes in enhancing bone repair by promoting EPC angiogenesis.

METHODS

Transmission electron microscopy, nanoparticle tracking analysis, and Dil reagent kit were employed to identify ADSC-derived exosomes and their internalization by EPCs. Micro-CT analysis, H&E staining, and Masson staining were used to assess bone mineral density (BMD), bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N), as well as the pathological changes and fibrosis at defect sites. Cell viability, migration, invasion, and tube formation of EPCs were evaluated using CCK-8, wound healing, Transwell, and tube formation assays. Immunohistochemical staining, RT-PCR, and Western blotting were utilized to measure the gene and protein expression of markers such as CD31, VEGFA, OCN, RUNX2, NOTCH1, and DLL4. Gene sequencing and bioinformatics analyses were conducted to identify the most highly expressed miRNA in exosomes, while miRDB and dual-luciferase reporter assays were used to explore the interaction between miR-21-5p and NOTCH1.

RESULTS

The ADSC-derived exosomes, averaging 126 nm in diameter, were internalized by EPCs. In vivo, these exosomes promoted new bone formation, increased BMD, BV/TV, Tb.Th, and Tb.N, reduced pathological damage to cranial defect tissues, enhanced vascular and bone tissue regeneration, and upregulated OCN and RUNX2 expression. In vitro, ADSC-derived exosomes enhanced EPC viability, migration, invasion, and tube formation. Both in vivo and in vitro experiments demonstrated that ADSC-derived exosomes upregulated CD31 and VEGFA expression. miR-21-5p, the most highly expressed miRNA in ADSC-derived exosomes, was found to target NOTCH1. Overexpression of miR-21-5p in these exosomes facilitated EPC migration, tube formation, and VEGFA expression while downregulating NOTCH1 and DLL4 expression. Inhibition of miR-21-5p produced opposite effects on EPCs.

CONCLUSIONS

These findings indicate that miR-21-5p in ADSC-derived exosomes promotes angiogenesis in EPCs to accelerate bone repair by targeting the NOTCH1/DLL4/VEGFA signaling pathway, offering a potential therapeutic strategy for bone defect treatment.

Mesenchymal stem cell-derived extracellular vesicles in joint diseases: Therapeutic effects and underlying mechanisms

Joint diseases greatly impact the daily lives and occupational functioning of patients globally. However, conventional treatments for joint diseases have several limitations, such as unsatisfatory efficacy and side effects, necessitating the exploration of more efficacious therapeutic strategies. Mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) have demonstrated high therapeutic efficacyin tissue repair and regeneration, with low immunogenicity and tumorigenicity. Recent studies have reported that EVs-based therapy has considerable therapeutic effects against joint diseases, including osteoarthritis, tendon and ligament injuries, femoral head osteonecrosis, and rheumatoid arthritis. Herein, we review the therapeutic potential of various types of MSC-EVs in the aforementioned joint diseases, summarise the mechanisms underlying specific biological effects of MSC-EVs, and discuss future prospects for basic research on MSC-EV-based therapeutic modalities and their clinical translation. In general, this review provides an in-depth understanding of the therapeutic effects of MSC-EVs in joint diseases, as well as the underlying mechanisms, which may be beneficial to the clinical translation of MSC-EV-based treatment. The translational potential of this article: MSC-EV-based cell-free therapy can effectively promote regeneration and tissue repair. When used to treat joint diseases, MSC-EVs have demonstrated desirable therapeutic effects in preclinical research. This review may supplement further research on MSC-EV-based treatment of joint diseases and its clinical translation.

A novel approach in biomedical engineering: The use of polyvinyl alcohol hydrogel encapsulating human umbilical cord mesenchymal stem cell-derived exosomes for enhanced osteogenic differentiation and angiogenesis in bone regeneration

Developing effective methods for alveolar bone defect regeneration is a significant challenge in orthopedics. Exosomes from human umbilical cord mesenchymal stem cells (HUMSC-Exos) have shown potential in bone repair but face limitations due to undefined application methods and mechanisms. To address this, HUMSC-Exos were encapsulated in polyvinyl alcohol (PVA) hydrogel (Exo@PVA) to create a novel material for alveolar bone repair. This combination enhanced the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) more effectively than Exos alone. Additionally, Exo@PVA significantly improved alveolar bone regeneration and defect repair in rats. The microRNA-21-5p (miR-21-5p) in Exo@PVA, identified through the GEO database and analyzed via in silico methods, played a crucial role. miR-21-5p promoted BMSC osteogenic differentiation by inhibiting WWP1-mediated KLF5 ubiquitination and enhanced HUVEC angiogenesis by targeting ATP2B4. These findings underscore the potential of an Exo-based approach with PVA hydrogel scaffolds for bone defect repair, operating through the miR-21-5p/WWP1/ATP2B4 signaling axis.

Exosomes: A New Hope for Angiogenesis-Mediated Bone Regeneration

Bone is a metabolically dynamic structure that is generally remodeled throughout the lifetime of an individual but often causes problems with increasing age. A key player for bone development and homeostasis, but also under pathological conditions, is the bone vasculature. This complex system of arteries, veins, and capillaries forms distinct structures where each subset of endothelial cells has important functions. Starting with the basic process of angiogenesis and bone-specific blood vessel formation, coupled with initial bone formation, the importance of different vascular structures is highlighted with respect to how these structures are maintained or changed during homeostasis, aging, and pathological conditions. After exemplifying the current knowledge on bone vasculature, this review will move on to exosomes, a novel hotspot of scientific research. Exosomes will be introduced starting from their discovery via current isolation procedures and state-of-the-art characterization to their role in bone vascular development, homeostasis, and bone regeneration and repair while summarizing the underlying signal transduction pathways. With respect to their role in these processes, especially mesenchymal stem cell-derived extracellular vesicles are of interest, which leads to a discussion on patented applications and an update on ongoing clinical trials. Taken together, this review provides an overview of bone vasculature and bone regeneration, with a major focus on how exosomes influence this intricate system, as they might be useful for therapeutic purposes in the near future.

PBX/Knotted 1 homeobox-2 (PKNOX2) is a novel regulator of myocardial fibrosis

Much effort has been made to uncover the cellular heterogeneities of human hearts by single-nucleus RNA sequencing. However, the cardiac transcriptional regulation networks have not been systematically described because of the limitations in detecting transcription factors. In this study, we optimized a pipeline for isolating nuclei and conducting single-nucleus RNA sequencing targeted to detect a higher number of cell signal genes and an optimal number of transcription factors. With this unbiased protocol, we characterized the cellular composition of healthy human hearts and investigated the transcriptional regulation networks involved in determining the cellular identities and functions of the main cardiac cell subtypes. Particularly in fibroblasts, a novel regulator, PKNOX2, was identified as being associated with physiological fibroblast activation in healthy hearts. To validate the roles of these transcription factors in maintaining homeostasis, we used single-nucleus RNA-sequencing analysis of transplanted failing hearts focusing on fibroblast remodelling. The trajectory analysis suggested that PKNOX2 was abnormally decreased from fibroblast activation to pathological myofibroblast formation. Both gain- and loss-of-function in vitro experiments demonstrated the inhibitory role of PKNOX2 in pathological fibrosis remodelling. Moreover, fibroblast-specific overexpression and knockout of PKNOX2 in a heart failure mouse model induced by transverse aortic constriction surgery significantly improved and aggravated myocardial fibrosis, respectively. In summary, this study established a high-quality pipeline for single-nucleus RNA-sequencing analysis of heart muscle. With this optimized protocol, we described the transcriptional regulation networks of the main cardiac cell subtypes and identified PKNOX2 as a novel regulator in suppressing fibrosis and a potential therapeutic target for future translational studies.

Exosomes derived from M2 macrophages prevent steroid-induced osteonecrosis of the femoral head by modulating inflammation, promoting bone formation and inhibiting bone resorption

Inflammatory reactions are involved in the development of steroid-induced osteonecrosis of the femoral head(ONFH). Studies have explored the therapeutic efficacy of inhibiting inflammatory reactions in steroid-induced ONFH and revealed that inhibiting inflammation may be a new strategy for preventing the development of steroid-induced ONFH. Exosomes derived from M2 macrophages(M2-Exos) display anti-inflammatory properties. This study aimed to examine the preventive effect of M2-Exos on early-stage steroid-induced ONFH and explore the underlying mechanisms involved. In vitro, we explored the effect of M2-Exos on the proliferation and osteogenic differentiation of bone marrow-derived mesenchymal stem cells(BMMSCs). In vivo, we investigated the role of M2-Exos on inflammation, osteoclastogenesis, osteogenesis and angiogenesis in an early-stage rat model of steroid-induced ONFH. We found that M2-Exos promoted the proliferation and osteogenic differentiation of BMMSCs. Additionally, M2-Exos effectively attenuated the osteonecrotic changes, inhibited the expression of proinflammatory mediators, promoted osteogenesis and angiogenesis, reduced osteoclastogenesis, and regulated the polarization of M1/M2 macrophages in steroid-induced ONFH. Taken together, our data suggest that M2-Exos are effective at preventing steroid-induced ONFH. These findings may be helpful for providing a potential strategy to prevent the development of steroid-induced ONFH.

HWJMSC-EVs promote cartilage regeneration and repair via the ITGB1/TGF-β/Smad2/3 axis mediated by microfractures

The current first-line treatment for repairing cartilage defects in clinical practice is the creation of microfractures (MF) to stimulate the release of mesenchymal stem cells (MSCs); however, this method has many limitations. Recent studies have found that MSC-derived extracellular vesicles (MSC-EVs) play an important role in tissue regeneration. This study aimed to verify whether MSC-EVs promote cartilage damage repair mediated by MFs and to explore the repair mechanisms. In vitro experiments showed that human umbilical cord Wharton's jelly MSC-EVs (hWJMSC-EVs) promoted the vitality of chondrocytes and the proliferation and differentiation ability of bone marrow-derived MSCs. This was mainly because hWJMSC-EVs carry integrin beta-1 (ITGB1), and cartilage and bone marrow-derived MSCs overexpress ITGB1 after absorbing EVs, thereby activating the transforming growth factor-β/Smad2/3 axis. In a rabbit knee joint model of osteochondral defect repair, the injection of different concentrations of hWJMSC-EVs into the joint cavity showed that a concentration of 50 µg/ml significantly improved the formation of transparent cartilage after MF surgery. Extraction of regenerated cartilage revealed that the changes in ITGB1, transforming growth factor-β, and Smad2/3 were directly proportional to the repair of regenerated cartilage. In summary, this study showed that hWJMSC-EVs promoted cartilage repair after MF surgery.

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.

Exosomal non-coding RNAs: Emerging insights into therapeutic potential and mechanisms in bone healing

Exosomes are nano-sized extracellular vesicles (EVs) released by diverse types of cells, which affect the functions of targeted cells by transporting bioactive substances. As the main component of exosomes, non-coding RNA (ncRNA) is demonstrated to impact multiple pathways participating in bone healing. Herein, this review first introduces the biogenesis and secretion of exosomes, and elucidates the role of the main cargo in exosomes, ncRNAs, in mediating intercellular communication. Subsequently, the potential molecular mechanism of exosomes accelerating bone healing is elucidated from the following four aspects: macrophage polarization, vascularization, osteogenesis and osteoclastogenesis. Then, we systematically introduce construction strategies based on modified exosomes in bone regeneration field. Finally, the clinical trials of exosomes for bone healing and the challenges of exosome-based therapies in the biomedical field are briefly introduced, providing solid theoretical frameworks and optimization methods for the clinical application of exosomes in orthopedics.

Extracellular vesicles and their engineering strategies, delivery systems, and biomedical applications

Extracellular vesicles are nanoscale vesicles that can be secreted by all cell types, are intracellular in origin and have the same composition as their parent cells, play a key role in intercellular communication in organismal health and disease, and are now often used as biomarkers of disease and therapeutic agents in biomedical research. When injected locally or systemically, they have the ability to provide a variety of therapeutic effects, for example, regeneration of skin damage or restoration of cardiac function. However, direct injection of extracellular vesicles may result in their rapid clearance from the injection site.In order to maintain the biological activity of extracellular vesicles and to control the release of effective concentrations for better therapeutic efficacy during long-term disease treatment, the design of an optimized drug delivery system is necessary and different systems for the continuous delivery of extracellular vesicles have been developed. This paper first provides an overview of the biogenesis, composition and physiological function of extracellular vesicles, followed by a review of different strategies for extracellular vesicle isolation and methods for engineering extracellular vesicles. In addition, this paper reviews the latest extracellular vesicle delivery platforms such as micro-nanoparticles, injectable hydrogels, microneedles and scaffold patches. At the same time, the research progress and key cases of extracellular vesicle delivery systems in the field of biomedical therapeutics are described. Finally, the challenges and future trends of extracellular vesicle delivery are discussed.

PLGA nanoparticles engineering extracellular vesicles from human umbilical cord mesenchymal stem cells ameliorates polyethylene particles induced periprosthetic osteolysis

The wear particle-induced dissolution of bone around implants is a significant pathological factor in aseptic loosening, and controlling prosthetic aseptic loosening holds crucial social significance. While human umbilical cord mesenchymal stem cell-derived exosomes (HucMSCs-Exos, Exos) have been found to effectively promote osteogenesis and angiogenesis, their role in periprosthetic osteolysis remains unexplored. To enhance their in vivo application, we engineered HucMSCs-Exos-encapsulated poly lactic-co-glycolic acid (PLGA) nanoparticles (PLGA-Exos). In our study, we demonstrate that PLGA-Exos stimulate osteogenic differentiation while inhibiting the generation of reactive oxygen species (ROS) and subsequent osteoclast differentiation in vitro. In vivo imaging revealed that PLGA-Exos released exosomes slowly and maintained a therapeutic concentration. Our in vivo experiments demonstrated that PLGA-Exos effectively suppressed osteolysis induced by polyethylene particles. These findings suggest that PLGA-Exos hold potential as a therapeutic approach for the prevention and treatment of periprosthetic osteolysis. Furthermore, they provide novel insights for the clinical management of osteolysis.

Vascular wall microenvironment: exosomes secreted by adventitial fibroblasts induced vascular calcification

Vascular calcification often occurs in patients with chronic renal failure (CRF), which significantly increases the incidence of cardiovascular events in CRF patients. Our previous studies identified the crosstalk between the endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and the paracrine effect of VSMCs, which regulate the calcification of VSMCs. Herein, we aim to investigate the effects of exosomes secreted by high phosphorus (HPi) -induced adventitial fibroblasts (AFs) on the calcification of VSMCs and the underlying mechanism, which will further elucidate the important role of AFs in high phosphorus vascular wall microenvironment. The conditioned medium of HPi-induced AFs promotes the calcification of VSMCs, which is partially abrogated by GW4869, a blocker of exosomes biogenesis or release. Exosomes secreted by high phosphorus-induced AFs (AFsHPi-Exos) show similar effects on VSMCs. miR-21-5p is enriched in AFsHPi-Exos, and miR-21-5p enhances osteoblast-like differentiation of VSMCs by downregulating cysteine-rich motor neuron 1 (Crim1) expression. AFsHPi-Exos and exosomes secreted by AFs with overexpression of miR-21-5p (AFsmiR21M-Exos) significantly accelerate vascular calcification in CRF mice. In general, AFsHPi-Exos promote the calcification of VSMCs and vascular calcification by delivering miR-21-5p to VSMCs and subsequently inhibiting the expression of Crim1. Combined with our previous studies, the present experiment supports the theory of vascular wall microenvironment.

microRNAs delivered by small extracellular vesicles in MSCs as an emerging tool for bone regeneration

Bone regeneration is a dynamic process that involves angiogenesis and the balance of osteogenesis and osteoclastogenesis. In bone tissue engineering, the transplantation of mesenchymal stem cells (MSCs) is a promising approach to restore bone homeostasis. MSCs, particularly their small extracellular vesicles (sEVs), exert therapeutic effects due to their paracrine capability. Increasing evidence indicates that microRNAs (miRNAs) delivered by sEVs from MSCs (MSCs-sEVs) can alter gene expression in recipient cells and enhance bone regeneration. As an ideal delivery vehicle of miRNAs, MSCs-sEVs combine the high bioavailability and stability of sEVs with osteogenic ability of miRNAs, which can effectively overcome the challenge of low delivery efficiency in miRNA therapy. In this review, we focus on the recent advancements in the use of miRNAs delivered by MSCs-sEVs for bone regeneration and disorders. Additionally, we summarize the changes in miRNA expression in osteogenic-related MSCs-sEVs under different microenvironments.

The Potential of miR-21 in Stem Cell Differentiation and its Application in Tissue Engineering and Regenerative Medicine

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two important types of non-coding RNAs that are not translated into protein. These molecules can regulate various biological processes, including stem cell differentiation and self-renewal. One of the first known miRNAs in mammals is miR-21. Cancer-related studies have shown that this miRNA has proto-oncogene activity and is elevated in cancers. However, it is confirmed that miR-21 inhibits stem cell pluripotency and self-renewal and induces differentiation by targeting various genes. Regenerative medicine is a field of medical science that tries to regenerate and repair damaged tissues. Various studies have shown that miR-21 plays an essential role in regenerative medicine by affecting stem cell proliferation and differentiation. In this review, we will discuss the function of miR-21 in regenerative medicine of the liver, nerve, spinal cord, wound, bone, and dental tissues. In addition, the function of natural compounds and lncRNAs will be analyzed as potential regulators of miR-21 expression in regenerative medicine.

Research Progress on the Osteogenesis-Related Regulatory Mechanisms of Human Umbilical Cord Mesenchymal Stem Cells

In recent years, research on human umbilical cord mesenchymal stem cells (hUCMSCs) derived from human umbilical cord tissue has accelerated and entered clinical application research. Compared with mesenchymal stem cells (MSCs) from other sources, hUCMSCs can be extracted from different parts of umbilical cord or from the whole umbilical cord. It has the characteristics of less ethical controversy, high differentiation potential, strong proliferation ability, efficient expansion in vitro, avoiding immune rejection and immune privilege, and avoids the limitations of lack of embryonic stem cells, heterogeneity, ethical and moral constraints. hUCMSCs avoid the need for embryonic stem cell sources, heterogeneity, and ethical and moral constraints. Bone defects are very common in clinical practice, but completely effective bone tissue regeneration treatment is challenging. Currently, autologous bone transplantation and allogeneic bone transplantation are main treatment approaches in clinical work, but each has different shortcomings, such as limited sources, invasiveness, immune rejection and insufficient osteogenic ability. Therefore, to solve the bottleneck of bone tissue regeneration and repair, a great amount of research has been carried out to explore the clinical advantages of hUCMSCs as seed cells to promote osteogenesis.However, the regulation of osteogenic differentiation of hUCMSCs is an extremely complex process. Although a large number of studies have demonstrated that the role of hUCMSCs in enhancing local bone regeneration and repair through osteogenic differentiation and transplantation into the body involves multiple signaling pathways, there is no relevant article that summarize the findings. This article discusses the osteogenesis-related regulatory mechanisms of hUCMSCs, summarizes the currently known related mechanisms, and speculates on the possible signals.

miRNA-Guided Regulation of Mesenchymal Stem Cells Derived from the Umbilical Cord: Paving the Way for Stem-Cell Based Regeneration and Therapy

The human body is an abundant source of multipotent cells primed with unique properties that can be exploited in a multitude of applications and interventions. Mesenchymal stem cells (MSCs) represent a heterogenous population of undifferentiated cells programmed to self-renew and, depending on their origin, differentiate into distinct lineages. Alongside their proven ability to transmigrate toward inflammation sites, the secretion of various factors that participate in tissue regeneration and their immunoregulatory function render MSCs attractive candidates for use in the cytotherapy of a wide spectrum of diseases and conditions, as well as in different aspects of regenerative medicine. In particular, MSCs that can be found in fetal, perinatal, or neonatal tissues possess additional capabilities, including predominant proliferation potential, increased responsiveness to environmental stimuli, and hypoimmunogenicity. Since microRNA (miRNA)-guided gene regulation governs multiple cellular functions, miRNAs are increasingly being studied in the context of driving the differentiation process of MSCs. In the present review, we explore the mechanisms of miRNA-directed differentiation of MSCs, with a special focus on umbilical cord-derived mesenchymal stem cells (UCMSCs), and we identify the most relevant miRNAs and miRNA sets and signatures. Overall, we discuss the potent exploitations of miRNA-driven multi-lineage differentiation and regulation of UCMSCs in regenerative and therapeutic protocols against a range of diseases and/or injuries that will achieve a meaningful clinical impact through maximizing treatment success rates, while lacking severe adverse events.

Biology and therapeutic potential of mesenchymal stem cell extracellular vesicles in axial spondyloarthritis

Axial spondyloarthritis (AxSpA) is a chronic, inflammatory, autoimmune disease that predominantly affects the joints of the spine, causes chronic pain, and, in advanced stages, may result in spinal fusion. Recent developments in understanding the immunomodulatory and tissue-differentiating properties of mesenchymal stem cell (MSC) therapy have raised the possibility of applying such treatment to AxSpA. The therapeutic effectiveness of MSCs has been shown in numerous studies spanning a range of diseases. Several studies have been conducted examining acellular therapy based on MSC secretome. Extracellular vesicles (EVs) generated by MSCs have been proven to reproduce the impact of MSCs on target cells. These EVs are associated with immunological regulation, tissue remodeling, and cellular homeostasis. EVs' biological effects rely on their cargo, with microRNAs (miRNAs) integrated into EVs playing a particularly important role in gene expression regulation. In this article, we will discuss the impact of MSCs and EVs generated by MSCs on target cells and how these may be used as unique treatment strategies for AxSpA.

Human umbilical cord mesenchymal stem cells accelerate and increase implant osseointegration in diabetic rats

OBJECTIVE

This study was conducted to assess the effect of hUCMSCs injection on the osseointegration of dental implant in diabetic rats via Runt-related Transcription Factor 2 (Runx2), Osterix (Osx), osteoblasts, and Bone Implant Contact (BIC).

METHODOLOGY

The research design was a true experimental design using Rattus norvegicus Wistar strain. Rattus norvegicus were injected with streptozotocin to induce experimental diabetes mellitus. The right femur was drilled and loaded with titanium implant. Approximately 1 mm from proximal and distal implant site were injected with hUCMSCs. The control group was given only gelatin solvent injection. After 2 and 4 weeks of observation, the rats were sacrificed for further examination around implant site using immunohistochemistry staining (RUNX2 and Osterix expression), hematoxylin eosin staining, and bone implant contact area. Data analysis was done using ANOVA test.

RESULTS

Data indicated a significant difference in Runx2 expression (p<0.001), osteoblasts (p<0.009), BIC value (p<0.000), and Osterix expression (p<0.002). In vivo injection of hUCMSCs successfully increased Runx2, osteoblasts, and BIC value significantly, while decreased Osterix expression, indicating an acceleration of the bone maturation process.

CONCLUSION

The results proved hUCMSCs to accelerate and enhance implant osseointegration in diabetic rat models.

Biomimetic synthesis and optimization of extracellular vesicles for bone regeneration

Critical-size bone defect repair is in high demand but is difficult to treat. Modern therapies, such as autograft and cell-based treatments, face limitations, including potential immunological rejection and tumorigenesis. Therefore, extracellular vesicle (EV)-based strategies have been proposed as a novel approach for tissue regeneration owing to EVs' complex composition of lipids, proteins, and nucleic acids, as well as their low immunogenicity and congenital cell-targeting features. Despite these remarkable features of EVs, biomimetic synthesis and optimization of natural EVs can lead to enhanced bioactivity, increased cellular uptake, and specific cell targeting, aiming to achieve optimal therapeutic efficacy. To maximize their function, these nanoparticles can be integrated into bone graft biomaterials for superior bone regeneration. Herein, we summarize the role of naturally occurring EVs from distinct cell types in bone regeneration, the current strategies for optimizing biomimetic synthetic EVs in bone regeneration, and discuss the recent advances in applying bone graft biomaterials for the delivery of EVs to bone defect repair. We focused on distinct strategies for optimizing EVs with different functions and the most recent research on achieving time-controlled release of nanoparticles from EV-loaded biomaterials. Furthermore, we thoroughly discuss several current challenges and proposed solutions, aiming to provide insight into current progress, inspiration for future development directions, and incentives for clinical application in this field.

Magnetofection of miR-21 promoted by electromagnetic field and iron oxide nanoparticles via the p38 MAPK pathway contributes to osteogenesis and angiogenesis for intervertebral fusion

BACKGROUND

Magnetofection-mediated gene delivery shows great therapeutic potential through the regulation of the direction and degree of differentiation. Lumbar degenerative disc disease (DDD) is a serious global orthopaedic problem. However, even though intervertebral fusion is the gold standard for the treatment of DDD, its therapeutic effect is unsatisfactory. Here, we described a novel magnetofection system for delivering therapeutic miRNAs to promote osteogenesis and angiogenesis in patients with lumbar DDD.

RESULTS

Co-stimulation with electromagnetic field (EMF) and iron oxide nanoparticles (IONPs) enhanced magnetofection efficiency significantly. Moreover, in vitro, magnetofection of miR-21 into bone marrow mesenchymal stem cells (BMSCs) and human umbilical endothelial cells (HUVECs) influenced their cellular behaviour and promoted osteogenesis and angiogenesis. Then, gene-edited seed cells were planted onto polycaprolactone (PCL) and hydroxyapatite (HA) scaffolds (PCL/HA scaffolds) and evolved into the ideal tissue-engineered bone to promote intervertebral fusion. Finally, our results showed that EMF and polyethyleneimine (PEI)@IONPs were enhancing transfection efficiency by activating the p38 MAPK pathway.

CONCLUSION

Our findings illustrate that a magnetofection system for delivering miR-21 into BMSCs and HUVECs promoted osteogenesis and angiogenesis in vitro and in vivo and that magnetofection transfection efficiency improved significantly under the co-stimulation of EMF and IONPs. Moreover, it relied on the activation of p38 MAPK pathway. This magnetofection system could be a promising therapeutic approach for various orthopaedic diseases.