Exosomal miR-186 derived from BMSCs promote osteogenesis through hippo signaling pathway in postmenopausal osteoporosis

Dysregulation of miR-106a-5p/PTEN axis associated with progression and diagnostic of postmenopausal osteoporosis

OBJECTIVE

Postmenopausal osteoporosis (PMOP) is a bone disorder in postmenopausal women and a significant risk factor for fragility fractures. This study aims to explore the role of miR-106a-5p in the pathogenesis of PMOP and its potential as a diagnostic biomarker.

METHODS

220 postmenopausal women were recruited. The levels of miR-106a-5p, PTEN, and osteogenic-related genes were quantified using qRT-PCR. The relative protein of PTEN was detected using Western blotting. ROC curve and Pearson correlation were employed to evaluate the diagnostic value and relationships between variables. To model iron accumulation, hFOB1.19 osteoblasts were treated with ferric ammonium citrate (FAC). Cell proliferation and apoptosis were assessed using the CCK-8 and flow cytometry. The target relationship was verified using dual-luciferase assays.

RESULTS

miR-106a-5p levels were reduced, while PTEN levels were increased in PMOP. miR-106a-5p was positively correlated with bone mineral density and negatively correlated with ferritin. In the FAC-treated cells, miR-106a-5p decreased, and PTEN increased. Dual-luciferase assays confirmed that miR-106a-5p targets PTEN. Successful transfection was confirmed by observing the corresponding changes in miR-106a-5p and PTEN expression. Up-regulated miR-106a-5p increased the PTEN protein level, mRNA expression of RUNX2, OPN, and OCN, promoted cell proliferation, and decreased cell apoptosis under iron accumulation conditions. These effects were reversed by the upregulation of PTEN.

CONCLUSION

miR-106a-5p has the potential to diagnose osteoporosis in postmenopausal women and is linked to ferritin levels. miR-106a-5p plays a protective role in PMOP by regulating PTEN under conditions of iron accumulation, suggesting its potential as a promising biomarker for PMOP.

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

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

The Hippo pathway in bone and cartilage: implications for development and disease

Bone is the main structure of the human body; it mainly plays a supporting role and participates in metabolic processes. The Hippo signaling pathway is composed of a series of protein kinases, including the mammalian STE20-like kinase MST1/2 and the large tumor suppressor LATS1/2, which are widely involved in pathophysiological processes, including cell proliferation, differentiation, apoptosis and death, especially those related to biomechanical transduction in vivo. However, the role of it in regulating skeletal system development and the evolution of bone-related diseases remains poorly understood. The pathway can intervene in and regulate the physiological activities of bone-related cells such as osteoclasts and chondrocytes through its own or other bone-related signaling pathways, such as the Wnt pathway, the Notch pathway, and receptor activator of nuclear factor-κB ligand (RANKL), thereby affecting the occurrence and development of bone diseases. This article discusses the role of the Hippo signaling pathway in bone development and disease to provide new insights into the treatment of bone-related diseases by targeting the Hippo signaling pathway.

Exosomal non-coding RNAs in the regulation of bone metabolism homeostasis: Molecular mechanism and therapeutic potential

Bone metabolism is a dynamic balance between bone formation and absorption regulated by osteoblasts/osteoclasts. Bone metabolic disorders can lead to metabolic bone disease. Osteoporosis (OP), osteoarthritis (OA) and femoral head necrosis (ONFH) are common metabolic bone diseases. At present, the treatment of metabolic bone disease is still mainly to relieve pain and improve joint function. However, surgical treatment does not apply to the vast majority of high-risk groups, including postmenopausal women, patients with diabetes, cirrhosis, etc. Exosomes (Exos) are nanoscale membrane vesicles that are released by almost all cells. Exos are rich in a variety of bioactive substances, such as non-coding RNAs, nucleic acids, proteins and lipids. In view of the structure of Exos, it can protect the biologically active molecules can be smoothly delivered to the target cells and involved in the regulation of cell function. In this review, we focus on the regulation mechanism and function of bone homeostasis mediated by exosomal ncRNAs (Exos-ncRNAs), including macrophage polarization, autophagy, angiogenesis, signal transduction and competing endogenous RNA (ceRNA). We summarized the therapeutic strategies and potential drugs of Exos-ncRNAs in metabolic bone disease. Moreover, we discussed the shortcomings and potential research directions of Exos as carrier to deliver ncRNAs to play a role.

Osseointegration-Related Exosomes for Surface Functionalization of Titanium Implants

Despite that the clinical application of titanium-based implants has achieved great success, patients' own diseases and/or unhealthy lifestyle habits often lead to implant failure. Many studies have been carried out to modify titanium implants to promote osseointegration and implant success. Recent studies showed that exosomes, proactively secreted extracellular vesicles by mammalian cells, could selectively target and modulate the functions of recipient cells such as macrophages, nerve cells, endothelial cells, and bone marrow mesenchymal stem cells that are closely involved in implant osseointegration. Accordingly, using exosomes to functionalize titanium implants has been deemed as a novel and effective way to improve their osseointegration ability. Herein, recent advances pertaining to surface functionalization of titanium implants with exosomes are analyzed and discussed, with focus on the role of exosomes in regulating the functions of osseointegration-related cells, and their immobilization strategies as well as resultant impact on osseointegration ability.

Advancements in Research on Mesenchymal Stem-Cell-Derived Exosomal miRNAs: A Pivotal Insight into Aging and Age-Related Diseases

Mesenchymal stem cells (MSCs) are capable of differentiating into various cell types and play a crucial role in repairing aging tissues and diseased organs. Aging manifests as a gradual loss of cellular, tissue, and organ function, leading to the progression of pathologies. Exosomes (Exos) are extracellular vesicles secreted by cells, which maintain cellular homeostasis, clear cellular debris, and facilitate communication between cells and organs. This review provides a comprehensive summary of the mechanisms for the synthesis and sorting of MSC-Exo miRNAs and summarizes the current research status of MSCs-Exos in mitigating aging and age-related diseases. It delves into the underlying molecular mechanisms, which encompass antioxidative stress, anti-inflammatory response, and the promotion of angiogenesis. Additionally, this review also discusses potential challenges in and future strategies for advancing MSC-Exo miRNA-based therapies in the treatment of aging and age-related diseases.

Age-related alveolar bone maladaptation in adult orthodontics: finding new ways out

Compared with teenage patients, adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment, indicating the maladaptation of alveolar bone homeostasis under orthodontic force. However, this phenomenon is not well-elucidated to date, leading to increased treatment difficulties and unsatisfactory treatment outcomes in adult orthodontics. Aiming to provide a comprehensive knowledge and further inspire insightful understanding towards this issue, this review summarizes the current evidence and underlying mechanisms. The age-related abatements in mechanosensing and mechanotransduction in adult cells and periodontal tissue may contribute to retarded and unbalanced bone metabolism, thus hindering alveolar bone reconstruction during orthodontic treatment. To this end, periodontal surgery, physical and chemical cues are being developed to reactivate or rejuvenate the aging periodontium and restore the dynamic equilibrium of orthodontic-mediated alveolar bone metabolism. We anticipate that this review will present a general overview of the role that aging plays in orthodontic alveolar bone metabolism and shed new light on the prospective ways out of the impasse.

Towards an enhanced understanding of osteoanabolic effects of PTH-induced microRNAs on osteoblasts using a bioinformatic approach

In this study, we used a bioinformatic approach to construct a miRNA-target gene interaction network potentially involved in the anabolic effect of parathyroid hormone analogue teriparatide [PTH (1-34)] on osteoblasts. We extracted a dataset of 26 microRNAs (miRNAs) from previously published studies and predicted miRNA target interactions (MTIs) using four software tools: DIANA, miRWalk, miRDB, and TargetScan. By constructing an interactome of PTH-regulated miRNAs and their predicted target genes, we elucidated signaling pathways regulating pluripotency of stem cells, the Hippo signaling pathway, and the TGF-beta signaling pathway as the most significant pathways in the effects of PTH on osteoblasts. Furthermore, we constructed intersection of MTI networks for these three pathways and added validated interactions. There are 8 genes present in all three selected pathways and a set of 18 miRNAs are predicted to target these genes, according to literature data. The most important genes in all three pathways were BMPR1A, BMPR2 and SMAD2 having the most interactions with miRNAs. Among these miRNAs, only miR-146a-5p and miR-346 have validated interactions in these pathways and were shown to be important regulators of these pathways. In addition, we also propose miR-551b-5p and miR-338-5p for further experimental validation, as they have been predicted to target important genes in these pathways but none of their target interactions have yet been verified. Our wet-lab experiment on miRNAs differentially expressed between PTH (1-34) treated and untreated mesenchymal stem cells supports miR-186-5p from the literature obtained data as another prominent miRNA. The meticulous selection of miRNAs outlined will significantly support and guide future research aimed at discovering and understanding the crucial pathways of osteoanabolic PTH-epigenetic effects on osteoblasts. Additionally, they hold potential for the discovery of new PTH target genes, innovative biomarkers for the effectiveness and safety of osteoporosis-affected treatment, as well as novel therapeutic targets.

Therapeutic potential of mesenchymal stem cell-derived exosomes in skeletal diseases

Skeletal diseases impose a considerable burden on society. The clinical and tissue-engineering therapies applied to alleviate such diseases frequently result in complications and are inadequately effective. Research has shifted from conventional therapies based on mesenchymal stem cells (MSCs) to exosomes derived from MSCs. Exosomes are natural nanocarriers of endogenous DNA, RNA, proteins, and lipids and have a low immune clearance rate and good barrier penetration and allow targeted delivery of therapeutics. MSC-derived exosomes (MSC-exosomes) have the characteristics of both MSCs and exosomes, and so they can have both immunosuppressive and tissue-regenerative effects. Despite advances in our knowledge of MSC-exosomes, their regulatory mechanisms and functionalities are unclear. Here we review the therapeutic potential of MSC-exosomes for skeletal diseases.

Understanding molecular characteristics of extracellular vesicles derived from different types of mesenchymal stem cells for therapeutic translation

Mesenchymal stem cells (MSCs) have been studied for decades as candidates for cellular therapy, and their secretome, including secreted extracellular vesicles (EVs), has been identified to contribute significantly to regenerative and reparative functions. Emerging evidence has suggested that MSC-EVs alone, could be used as therapeutics that emulate the biological function of MSCs. However, just as with MSCs, MSC-EVs have been shown to vary in composition, depending on the tissue source of the MSCs as well as the protocols employed in culturing the MSCs and obtaining the EVs. Therefore, the importance of careful choice of cell sources and culture environments is receiving increasing attention. Many factors contribute to the therapeutic potential of MSC-EVs, including the source tissue, isolation technique, and culturing conditions. This review illustrates the molecular landscape of EVs derived from different types of MSC cells along with culture strategies. A thorough analysis of publicly available omic datasets was performed to advance the precision understanding of MSC-EVs with unique tissue source-dependent molecular characteristics. The tissue-specific protein and miRNA-driven Reactome ontology analysis was used to reveal distinct patterns of top Reactome ontology pathways across adipose, bone marrow, and umbilical MSC-EVs. Moreover, a meta-analysis assisted by an AI technique was used to analyze the published literature, providing insights into the therapeutic translation of MSC-EVs based on their source tissues.

Unlocking the potential of exosomes: a breakthrough in the theranosis of degenerative orthopaedic diseases

Degenerative orthopaedic diseases pose a notable worldwide public health issue attributable to the global aging population. Conventional medical approaches, encompassing physical therapy, pharmaceutical interventions, and surgical methods, face obstacles in halting or reversing the degenerative process. In recent times, exosome-based therapy has gained widespread acceptance and popularity as an effective treatment for degenerative orthopaedic diseases. This therapeutic approach holds the potential for "cell-free" tissue regeneration. Exosomes, membranous vesicles resulting from the fusion of intracellular multivesicles with the cell membrane, are released into the extracellular matrix. Addressing challenges such as the rapid elimination of natural exosomes in vivo and the limitation of drug concentration can be effectively achieved through various strategies, including engineering modification, gene overexpression modification, and biomaterial binding. This review provides a concise overview of the source, classification, and preparation methods of exosomes, followed by an in-depth analysis of their functions and potential applications. Furthermore, the review explores various strategies for utilizing exosomes in the treatment of degenerative orthopaedic diseases, encompassing engineering modification, gene overexpression, and biomaterial binding. The primary objective is to provide a fresh viewpoint on the utilization of exosomes in addressing bone degenerative conditions and to support the practical application of exosomes in the theranosis of degenerative orthopaedic diseases.

The Potential of Exosomes for Osteoporosis Treatment: A Review

As a continuous process comprising bone resorption and formation, bone remodeling, plays an essential role in maintaining the balance of bone metabolism. One type of metabolic osteopathy is osteoporosis, which is defined by low bone mass and deteriorating bone microstructure. Osteoporosis patients are more likely to experience frequent osteoporotic fractures, which makes osteoporosis prevention and treatment crucial. A growing body of research has revealed that exosomes, which are homogenous vesicles released by most cell types, play a major role in mediating a number of pathophysiological processes, including osteoporosis. Exosomes may act as a mediator in cell-to-cell communication and offer a fresh perspective on information sharing. This review discusses the characteristics of exosomes and outlines the exosomes' underlying mechanism that contributes to the onset of osteoporosis. Recent years have seen a rise in interest in the role of exosomes in osteoporosis, which has given rise to innovative therapeutic approaches for the disease prevention and management.

Mesoporous bioactive glass scaffolds for the delivery of bone marrow stem cell-derived osteoinductive extracellular vesicles lncRNA promote senescent bone defect repair by targeting the miR-1843a-5p/Mob3a/YAP axis

Bone repair in elderly patients poses a huge challenge due to the age-related progressive decline in regenerative abilities attributed to the senescence of bone marrow stem cells (BMSCs). Bioactive scaffolds have been applied in bone regeneration due to their various biological functions. In this study, we aimed to fabricate functionalized bioactive scaffolds through loading osteoinductive extracellular vesicles (OI-EVs) based on mesoporous bioactive glass (MBG) scaffolds (1010 particles/scaffold) and to investigate its effects on osteogenesis and senescence of BMSCs. The results suggested that OI-EVs upregulate the proliferative and osteogenic capacities of senescent BMSCs. More importantly, The results showed that loading OI-EVs into MBG scaffolds achieved better bone regeneration. Furthermore, OI-EVs and BMSCs RNAs bioinformatics analysis indicated that OI-EVs play roles through transporting pivotal lncRNA acting as a "sponge" to compete with Mob3a for miR-1843a-5p to promote YAP dephosphorylation and nuclear translocation, ultimately resulting in elevated proliferation and osteogenic differentiation and reduced senescence-related phenotypes. Collectively, these results suggested that the OI-EVs lncRNA ceRNA regulatory networks might be the key point for senescent osteogenesis. More importantly, the study indicated the feasibility of loading OI-EVs into scaffolds and provided novel insights into biomaterial design for facilitating bone regeneration in the treatment of senescent bone defects. STATEMENT OF SIGNIFICANCE: Constructing OI-EVs/MBG delivering system and verification of its bone regeneration enhancement in senescent defect repair. Aging bone repair poses a huge challenge due to the age-related progressive degenerative decline in regenerative abilities attributed to the senescence of BMSCs. OI-EVs/MBG delivering system were expected as promising treatment for senescent bone repair, which could provide an effective strategy for bone regeneration in elderly patients. Clarification of potential OI-EVs lncRNA ceRNA regulatory mechanism in senescent bone regeneration OI-EVs play important roles through transferring lncRNA-ENSRNOG00000056625 sponging miR-1843a-5p that targeted Mob3a to activate YAP translocation into nucleus, ultimately alleviate senescence, promote proliferation and osteogenic differentiation in O-BMSCs, which provides theoretical basis for EVs-mediated therapy in future clinical works.

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.

Understanding exosomes: Part 2-Emerging leaders in regenerative medicine

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of diseases/conditions. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be developed. Today exosomes have been applied in numerous contexts including neurodegenerative disorders (Alzheimer's disease, central nervous system, depression, multiple sclerosis, Parkinson's disease, post-traumatic stress disorders, traumatic brain injury, peripheral nerve injury), damaged organs (heart, kidney, liver, stroke, myocardial infarctions, myocardial infarctions, ovaries), degenerative processes (atherosclerosis, diabetes, hematology disorders, musculoskeletal degeneration, osteoradionecrosis, respiratory disease), infectious diseases (COVID-19, hepatitis), regenerative procedures (antiaging, bone regeneration, cartilage/joint regeneration, osteoarthritis, cutaneous wounds, dental regeneration, dermatology/skin regeneration, erectile dysfunction, hair regrowth, intervertebral disc repair, spinal cord injury, vascular regeneration), and cancer therapy (breast, colorectal, gastric cancer and osteosarcomas), immune function (allergy, autoimmune disorders, immune regulation, inflammatory diseases, lupus, rheumatoid arthritis). This scoping review is a first of its kind aimed at summarizing the extensive regenerative potential of exosomes over a broad range of diseases and disorders.

miR-155-5p/Bmal1 Modulates the Senescence and Osteogenic Differentiation of Mouse BMSCs through the Hippo Signaling Pathway

BACKGROUND

The core clock gene brain and muscle ARNT like-1 (Bmal1) is involved in the regulation of bone tissue aging. However, current studies are mostly limited to the establishment of the association between Bmal1 and bone senescence, without in-depth exploration of its main upstream and downstream regulatory mechanisms.

METHODS

The luciferase reporter assay, RT-qPCR and Western blotting were performed to detect the interaction between miR-155-5p and Bmal1. The effects of miR-155-5p and Bmal1 on the aging and osteogenic differentiation ability of mouse bone marrow mesenchymal stem cells (BMSCs) were investigated by cell counting kit-8 (CCK-8) assay, flow cytometry, β-gal staining, alkaline phosphatase quantitative assay and alizarin red staining in vitro. The potential molecular mechanism was identified by ChIP-Seq, RNA-seq database analysis and immunofluorescence staining.

RESULTS

The expression of Bmal1 declined with age, while the miR-155-5p was increased. miR-155-5p and Bmal1 repressed each other's expression, and miR-155-5p targeted the Bmal1. Besides, miR-155-5p inhibited the proliferation and osteogenic differentiation of BMSCs, promoted cell apoptosis and senescence, inhibited the expression and nuclear translocation of YAP and TAZ. However, Bmal1 facilitated the osteogenic differentiation and suppressed the aging of BMSCs, meanwhile inactivated the Hippo pathway. Moreover, YAP inhibitors abrogated the positive regulation of aging and osteogenic differentiation in BMSCs by miR-155-5p and Bmal1.

CONCLUSION

In mouse BMSCs, miR-155-5p and Bmal1 regulated the aging and osteogenic differentiation ability of BMSCs mainly through the Hippo signaling pathway. Our findings provide new insights for the interventions in bone aging.

Mesenchymal Stem Cells‐Derived Extracellular Vesicles in Orthopedic Diseases: Recent Advances and Therapeutic Potential

Ever since the first application of mesenchymal stem cell (MSC) transplantation treating human hematologic malignancies in 1995, MSC‐based treatments have demonstrated great therapeutic potential in clinical settings. However, only a few MSC‐based cell therapy products have been clinically approved. Accumulating evidence suggests that the beneficial effects of MSCs are mainly attributed to the release of paracrine factors or extracellular vesicles (EVs) rather than their mesodermal differentiation potential. Therefore, MSC‐derived EVs (MSC‐EVs), such as exosomes and microvesicles, have merged as promising alternatives to traditional cell‐based therapeutics in clinical practice. They offer several advantages such as better safety, lower immunogenicity, protection of cargoes from degradation, and the ability to overcome biological barriers. Moreover, there have been multiple clinical studies exploring the potential of MSC‐EVs for treating various diseases, including orthopedic disorders. However, there is no definitive “cure” for conditions such as osteoporosis and other bone disorders, but MSC‐EVs have displayed significant therapeutic potential for these orthopedic ailments. Therefore, the objective of this study is to conduct a systematic review of current knowledge related to MSC‐EVs and emphasize their potential application in treating orthopedic diseases, such as bone defects, osteoarthritis, osteoporosis, intervertebral disc degeneration, osteosarcoma, and osteoradionecrosis.

Long non-coding RNA Homeobox D gene cluster antisense growth-associated long noncoding RNA/microRNA-182-5p/Homeobox protein A10 alleviates postmenopausal osteoporosis via accelerating osteoblast differentiation of bone marrow mesenchymal stem cells

BACKGROUND

Studies have illuminated that long non-coding RNA (lncRNA) influences bone cell differentiation and formation. Nevertheless, whether lncRNA Homeobox D gene cluster antisense growth-associated long noncoding RNA (HAGLR) was implicated in postmenopausal osteoporosis (PMOP) was yet uncertain.

PURPOSE

The research was to explore HAGLR's role in the osteogenic differentiation (OD) process of bone marrow mesenchymal stem cells (BMSCs).

METHODS

BMSCs were isolated from mouse bone marrow tissues and identified by electron microscope and flow cytometry. HAGLR, microRNA (miR)-182-5p, and homeobox protein A10 (Hoxa10) levels in BMSCs were detected. Mouse BMSC OD process was induced, and calcium deposition and alkaline phosphatase content were analyzed, as well as expressions of runt-related transcription factor 2, osteopontin, and osteocalcin, and cell apoptosis. Bilateral ovaries were resected from mice to construct the ovariectomized model and bone mineral density, maximum bending stress, maximum load, and elastic modulus of the femur were tested, and the femur was histopathologically evaluated. Chondrocyte apoptosis in the articular cartilage of mice was analyzed. Analysis of the interaction of HAGLR, miR-182-5p with Hoxa10 was conducted.

RESULTS

HAGLR and Hoxa10 were down-regulated and miR-182-5p was elevated in PMOP patients. During the BMSC OD process, HAGLR and Hoxa10 levels were suppressed, while miR-182-5p was elevated. Promotion of HAGLR or suppression of miR-182-5p accelerated OD of BMSCs. Inhibition of miR-182-5p reversed the inhibitory effect of HAGLR on BMSC OD. In in vivo experiments, up-regulating HAGLR alleviated PMOP, while silencing Hoxa10 reversed the effects of upregulating HAGLR. HAGLR performed as a sponge for miR-182-5p, while miR-182-5p targeted Hoxa10.

CONCLUSION

In general, HAGLR boosted the OD process of BMSCs and relieved PMOP via the miR-182-5p/Hoxa10 axis. These data preliminarily reveal the key role of HAGLR in PMOP, and the research results have a certain reference for the treatment of PMOP.

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.

Identification and evaluation of circulating exosomal miRNAs for the diagnosis of postmenopausal osteoporosis

BACKGROUND

Postmenopausal osteoporosis (PMOP) is a common condition that leads to a loss of bone density and an increased risk of fractures in women. Recent evidence suggests that exosomal miRNAs are involved in regulating bone development and osteogenesis. However, exosomal miRNAs as biomarkers for PMOP diagnosis have not been systematically evaluated. In this study, we aim to identify PMOP-associated circulating exosomal miRNAs and evaluate their diagnostic performance.

METHODS

We performed next-generation sequencing and bioinformatics analysis of plasma exosomal miRNAs from 12 PMOP patients and 12 non-osteoporosis controls to identify PMOP-associated exosomal miRNAs, and then validated them in an independent natural community cohort with 26 PMOP patients and 21 non-osteoporosis controls. Exosomes were isolated with the size exclusion chromatography method from the plasma of elder postmenopausal women. The plasma exosomal miRNA profiles were characterized in PMOP paired with controls with next-generation sequencing. Potential plasma exosomal miRNAs were validated by qRT-PCR in the validation cohort, and their performance in diagnosing PMOP was systematically evaluated with the receiver operating characteristic curve.

RESULTS

Twenty-seven miRNAs were identified as differentially expressed in PMOP versus controls in sequencing data, of which six exosomal miRNAs (miR-196-5p, miR-224-5p, miR320d, miR-34a-5p, miR-9-5p, and miR-98-5p) were confirmed to be differentially expressed in PMOP patients by qRT-PCR in the validation cohort. The three miRNAs combination (miR-34a-5p + miR-9-5p + miR-98-5p) demonstrated the best diagnostic performance, with an AUC = 0.734. In addition, the number of pregnancies was found to be an independent risk factor that can improve the performance of exosomal miRNAs in diagnosing PMOP.

CONCLUSIONS

These results suggested that the plasma exosomal miRNAs had the potential to serve as noninvasive diagnostic biomarkers for PMOP.

Differential Expression of Non-Coding RNAs in Stem Cell Development and Therapeutics of Bone Disorders

Stem cells' self-renewal and multi-lineage differentiation are regulated by a complex network consisting of signaling factors, chromatin regulators, transcription factors, and non-coding RNAs (ncRNAs). Diverse role of ncRNAs in stem cell development and maintenance of bone homeostasis have been discovered recently. The ncRNAs, such as long non-coding RNAs, micro RNAs, circular RNAs, small interfering RNA, Piwi-interacting RNAs, etc., are not translated into proteins but act as essential epigenetic regulators in stem cells' self-renewal and differentiation. Different signaling pathways are monitored efficiently by the differential expression of ncRNAs, which function as regulatory elements in determining the fate of stem cells. In addition, several species of ncRNAs could serve as potential molecular biomarkers in early diagnosis of bone diseases, including osteoporosis, osteoarthritis, and bone cancers, ultimately leading to the development of new therapeutic strategies. This review aims to explore the specific roles of ncRNAs and their effective molecular mechanisms in the growth and development of stem cells, and in the regulation of osteoblast and osteoclast activities. Furthermore, we focus on and explore the association of altered ncRNA expression with stem cells and bone turnover.

Osteoporosis treatment using stem cell-derived exosomes: a systematic review and meta-analysis of preclinical studies

BACKGROUND

The increasing incidence of osteoporosis in recent years has aroused widespread public concern; however, existing effective treatments are limited. Therefore, new osteoporosis treatment methods, including stem cell transplantation and exosome therapy, have been proposed and are gaining momentum. Exosomes are considered to have greater potential for clinical application owing to their immunocompatibility. This study summarises the latest evidence demonstrating the efficacy of exosomes in improving bone loss in the treatment of osteoporosis.

MAIN TEXT

This systematic review and meta-analyses searched PubMed, Embase, and Cochrane Library databases from inception to 26 March 2022 for osteoporosis treatment studies using stem cell-derived exosomes. Six endpoints were selected to determine efficacy: bone mineral density, trabecular bone volume/tissue volume fraction, trabecular number, trabecular separation, trabecular thickness, and cortical thickness. The search generated 366 citations. Eventually, 11 articles that included 15 controlled preclinical trials and 242 experimental animals (rats and mice) were included in the meta-analysis.

CONCLUSION

The results were relatively robust and reliable despite some publication biases, suggesting that exosome treatment increased bone mass, improved bone microarchitecture, and enhanced bone strength compared with placebo treatments. Moreover, stem cell-derived exosomes may favour anabolism over catabolism, shifting the dynamic balance towards bone regeneration.

The expression of NOTUM in replantation of severed fingers may be an important treatment factor

BACKGROUND

After years of development, digital replantation has become a mature treatment. Although the NOTUM gene has been shown to be involved in the formation of vertebrate nerves, whether it contributes to the osteogenic mechanism of severed finger replantation remains unknown. In response to this, this study investigates the specific details of NOTUM involvement in replantation of severed fingers.

METHODS

The experimental subjects are patients with replantation of severed fingers from Shulan International Medical College of Shulan (Hangzhou) Hospital affiliated to Zhejiang Shuren University. In addition to using bone marrow mesenchymal stem cells (BMSCs) as an in vitro system, this experiment also involves quantitative polymerase chain reaction, microarray analysis, cell counting Kit-8, ethynyl deoxyuridine staining and Western blot analysis.

RESULTS

The expression level of NOTUM in the severed finger replantation group is lower than that in the normal group. NOTUM inhibits cell growth and cell transfer, osteogenic differentiation and β-catenin gene expression in BMSCs. Luciferase reporter assay illustrated that β-catenin wild type closely correlated with NOTUM. The inhibition of β-catenin increases the effects of NOTUM on cell growth, cell transfer and osteogenic differentiation of BMSCs.

CONCLUSIONS

Considering that NOTUM can inhibit cell growth, cell transfer, osteogenic differentiation of BMSCs, as well as the gene expression of β-catenin, it may be a biomarker of osteogenic differentiation and a potential therapeutic target for replantation of severed fingers.

Extracellular vesicles rejuvenate the microenvironmental modulating function of recipient tissue-specific mesenchymal stem cells in osteopenia treatment

Systemic transplantation of mesenchymal stem cells (MSCs), such as bone marrow MSCs (BMMSCs) and stem cells from human exfoliated deciduous teeth (SHED), is considered a prominent treatment for osteopenia. However, the mechanism of action of the transplanted MSCs has been poorly elucidated. In the recipient target tissue, including bone and bone marrow, only a few donor MSCs can be detected, suggesting that the direct contribution of donor MSCs may not be expected for osteopenia treatment. Meanwhile, secretomes, especially contents within extracellular vesicles (EVs) released from donor MSCs (MSC-EVs), play key roles in the treatment of several diseases. In this context, administrated donor MSC-EVs may affect bone-forming function of recipient cells. In this review, we discuss how MSC-EVs contribute to bone recovery recipient tissue in osteopenia. We also summarize a novel mechanism of action of systemic administration of SHED-derived EVs (SHED-EVs) in osteopenia. We found that reduced telomerase activity in recipient BMMSCs caused the deficiency of microenvironmental modulating function, including bone and bone marrow-like niche formation and immunomodulation in estrogen-deficient osteopenia model mice. Systemic administration of SHED-EVs could exert therapeutic effects on bone reduction via recovering the telomerase activity, leading to the rejuvenation of the microenvironmental modulating function in recipient BMMSCs, as seen in systemic transplantation of SHED. RNase-preconditioned donor SHED-EVs diminished the therapeutic benefits of administrated SHED-EVs in the recipient osteopenia model mice. These facts suggest that MSC-EV therapy targets the recipient BMMSCs to rejuvenate the microenvironmental modulating function via telomerase activity, recovering bone density. We then introduce future challenges to develop the reproducible MSC-EV therapy in osteopenia.

Exosomes: A new option for osteoporosis treatment

Osteoporosis is a systemic bone disease characterized by reduced bone mass and destruction of bone microarchitecture, leading to increased bone fragility and susceptibility to fracture. However, the pathogenesis and molecular mechanisms of this disease remain unclear. Extracellular vesicles, structures originating from the plasma membrane and ranging from 30 nm to 5 µm in diameter, play an important role in intercellular communication in the bone microenvironment. Exosomes are extracellular vesicles that deliver cargo molecules, including endogenous proteins, lipids and nucleic acids. These cargo molecules are encapsulated in a lipid bilayer and internalized by target cells through receptor-ligand interactions or lipid membrane fusion. With the advancement of exosome research, exosome therapy for osteoporosis is fast becoming a research hotspot for researchers. This review aims to discuss the role of exosomes in the pathogenesis of osteoporosis. In addition, emerging diagnostic and therapeutic properties of exosomes are described to highlight the potential role of exosomes in osteoporosis.

Aging and aging-related diseases: from molecular mechanisms to interventions and treatments

Aging is a gradual and irreversible pathophysiological process. It presents with declines in tissue and cell functions and significant increases in the risks of various aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. Although the development of modern medicine has promoted human health and greatly extended life expectancy, with the aging of society, a variety of chronic diseases have gradually become the most important causes of disability and death in elderly individuals. Current research on aging focuses on elucidating how various endogenous and exogenous stresses (such as genomic instability, telomere dysfunction, epigenetic alterations, loss of proteostasis, compromise of autophagy, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing) participate in the regulation of aging. Furthermore, thorough research on the pathogenesis of aging to identify interventions that promote health and longevity (such as caloric restriction, microbiota transplantation, and nutritional intervention) and clinical treatment methods for aging-related diseases (depletion of senescent cells, stem cell therapy, antioxidative and anti-inflammatory treatments, and hormone replacement therapy) could decrease the incidence and development of aging-related diseases and in turn promote healthy aging and longevity.

Application and Molecular Mechanisms of Extracellular Vesicles Derived from Mesenchymal Stem Cells in Osteoporosis

Osteoporosis (OP) is a chronic bone disease characterized by decreased bone mass, destroyed bone microstructure, and increased bone fragility. Accumulative evidence shows that extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) (MSC-EVs), especially exosomes (Exos), exhibit great potential in the treatment of OP. However, the research on MSC-EVs in the treatment of OP is still in the initial stage. The potential mechanism has not been fully clarified. Therefore, by reviewing the relevant literature of MSC-EVs and OP in recent years, we summarized the latest application of bone targeted MSC-EVs in the treatment of OP and further elaborated the potential mechanism of MSC-EVs in regulating bone formation, bone resorption, bone angiogenesis, and immune regulation through internal bioactive molecules to alleviate OP, providing a theoretical basis for the related research of MSC-EVs in the treatment of OP.

Bioinformatic analysis of the RNA expression patterns in microgravity-induced bone loss

Researchers have linked microgravity in space to the significant imbalance between bone formation and bone resorption that induces persistent bone loss in load-bearing bones. However, the underlying molecular mechanisms are still unclear, which hinders the development of therapeutic measures. The aim of this study was to identify hub genes and explore novel molecular mechanisms underlying microgravity-induced bone loss using transcriptome datasets obtained from the GEO and SRA databases. In summary, comparative RNA expression pattern studies that differ in species (Homo or Mus), models (in vitro or in vivo), microgravity conditions (real microgravity or ground-based simulators) and microgravity duration showed that it is difficult to reach a consistent conclusion about the pathogenesis of microgravity-induced bone loss across these studies. Even so, we identified 11 hub genes and some miRNA-mRNA interactions mainly based on the GSE100930 dataset. Also, the expression of CCL2, ICAM1, IGF1, miR-101-3p and miR-451a markedly changed under clinorotation-microgravity condition. Remarkedly, ICAM1 and miR-451a were key mediators of the osteogenesis of hMSCs under clinorotation-microgravity condition. These findings provide novel insights into the molecular mechanisms of bone loss during microgravity and could indicate potential targets for further countermeasures against this condition.

Advances of Mesenchymal Stem Cells Released Extracellular Vesicles in Periodontal Bone Remodeling

Extracellular vesicles (EVs) are nanoparticles that include exosomes, microvesicles, and apoptotic bodies; they interact with target cell surface receptors and transport contents, including mRNA, proteins, and enzymes into the cytoplasm of target cells to function. The biological fingerprints of EVs practically mirror those of the parental cells they originated from. In the bone remodeling microenvironment, EVs could act on osteoblasts to regulate the bone formation, promote osteoclast differentiation, and regulate bone resorption. Therefore, there have been many attempts wherein EVs were used to achieve targeted therapy in bone-related diseases. Periodontitis, a common bacterial infectious disease, could cause severe alveolar bone resorption, resulting in tooth loss, whereas research on periodontal bone regeneration is also an urgent question. Therefore, EVs-related studies are important for periodontal bone remodeling. In this review, we summarize the current knowledge of mesenchymal stem cell-EVs involved in periodontal bone remodeling and explore the functional gene expression through a comparative analysis of transcriptomic content.

Application of exosome-derived noncoding RNAs in bone regeneration: Opportunities and challenges

With advances in the fields of regenerative medicine, cell-free therapy has received increased attention. Exosomes have a variety of endogenous properties that provide stability for molecular transport across biological barriers to cells, as a form of cell-to-cell communication that regulates function and phenotype. In addition, exosomes are an important component of paracrine signaling in stem-cell-based therapy and can be used as a stand-alone therapy or as a drug delivery system. The remarkable potential of exosomes has paved the pathway for cell-free treatment in bone regeneration. Exosomes are enriched in distinct noncoding RNAs (ncRNAs), including microRNAs, long ncRNAs and circular RNAs. Different ncRNAs have multiple functions. Altered expression of ncRNA in exosomes is associated with the regenerative potential and development of various diseases, such as femoral head osteonecrosis, myocardial infarction, and cancer. Although there is increasing evidence that exosome-derived ncRNAs (exo-ncRNAs) have the potential for bone regeneration, the detailed mechanisms are not fully understood. Here, we review the biogenesis of exo-ncRNA and the effects of ncRNAs on angiogenesis and osteoblast- and osteoclast-related pathways in different diseases. However, there are still many unsolved problems and challenges in the clinical application of ncRNA; for instance, production, storage, targeted delivery and therapeutic potency assessment. Advancements in exo-ncRNA methods and design will promote the development of therapeutics, revolutionizing the present landscape.

Bone mesenchymal stem cells (BMSCs)-derived exosomal microRNA-21-5p regulates Kruppel-like factor 3 (KLF3) to promote osteoblast proliferation in vitro

Bone mesenchymal stem cells (BMSCs)-derived exosomes (Exos) play important roles in osteoporosis, while the regulation of microRNA (miR)-21-5p remains unclear. The BMSCs-derived exosomes were isolated from femoral bone marrow of trauma patients, which were then used to stimulate human osteoblasts (hFOB1.19 cells). The miR-21-5p mimic or inhibitor was transfected into BMSCs to overexpress or knockdown miR-21-5p. The functions of miR-21-5p in osteoporosis were assessed by cell counting kit-8 (CCK-8) assay, alkaline phosphatase (ALP) staining and alizarin red staining assays. We found that BMSCs-derived exosomes could enhance proliferation, osteoblastic differentiation and ALP activity of hFOB1.19 cells. BMSCs-derived exosomes with upregulated miR-21-5p could further enhance these protective impacts compared with that in BMSCs-derived exosomes, while BMSCs-derived exosomes with downregulated miR-21-5p reduced these cell phenotypes. MiR-21-5p could directly bind to the 3’-untranslated region (UTR) of Kruppel-like factor 3 (KLF3), and knockdown of KLF3 obviously attenuated these inhibitory effects of BMSCs-derived exosomes with downregulated miR-21-5p on osteoblastic differentiation and ALP activity of hFOB1.19 cells. In summary, BMSCs-derived exosomal miR-21-5p improved osteoporosis through regulating KLF3, providing a potential therapeutic strategy for osteoporosis.

Effects of BMSC-Derived EVs on Bone Metabolism

Extracellular vesicles (EVs) are small membrane vesicles that can be secreted by most cells. EVs can be released into the extracellular environment through exocytosis, transporting endogenous cargo (proteins, lipids, RNAs, etc.) to target cells and thereby triggering the release of these biomolecules and participating in various physiological and pathological processes. Among them, EVs derived from bone marrow mesenchymal stem cells (BMSC-EVs) have similar therapeutic effects to BMSCs, including repairing damaged tissues, inhibiting macrophage polarization and promoting angiogenesis. In addition, BMSC-EVs, as efficient and feasible natural nanocarriers for drug delivery, have the advantages of low immunogenicity, no ethical controversy, good stability and easy storage, thus providing a promising therapeutic strategy for many diseases. In particular, BMSC-EVs show great potential in the treatment of bone metabolic diseases. This article reviews the mechanism of BMSC-EVs in bone formation and bone resorption, which provides new insights for future research on therapeutic strategies for bone metabolic diseases.

The Role of Extracellular Vesicles in Osteoporosis: A Scoping Review

As an insidious metabolic bone disease, osteoporosis plagues the world, with high incidence rates. Patients with osteoporosis are prone to falls and becoming disabled, and their cone fractures and hip fractures are very serious, so the diagnosis and treatment of osteoporosis is very urgent. Extracellular vesicles (EVs) are particles secreted from cells to the outside of the cell and they are wrapped in a bilayer of phospholipids. According to the size of the particles, they can be divided into three categories, namely exosomes, microvesicles, and apoptotic bodies. The diameter of exosomes is 30-150 nm, the diameter of microvesicles is 100-1000 nm, and the diameter of apoptotic bodies is about 50-5000 nm. EVs play an important role in various biological process and diseases including osteoporosis. In this review, the role of EVs in osteoporosis is systematically reviewed and some insights for the prevention and treatment of osteoporosis are provided.

Exosome-Derived LncRNA TCONS_00072128 Mediated Osteogenic Differentiation and Inflammation by Caspase 8 Regulation

Postmenopausal osteoporosis (PMOP) is a systemic metabolic bone disease in postmenopausal women. It has been known that long non-coding RNAs (lncRNAs) play a regulatory role in the progression of osteoporosis. However, the mechanism underlying the effects of exosome-derived lncRNA on regulating the occurrence and development of PMOP remains unclear. Exosomes in the serum of patients PMOP were collected and identified. RNA sequencing was performed to obtain the expression profile of exosome-derived lncRNAs in the serum of PMOP patients. RNA sequencing identified 26 differentially expressed lncRNAs from the exosomes between healthy people and PMOP patients. Among them, the expression of TCONS_00072128 was dramatically down-regulated. A co-location method was employed and searched its potential target gene caspase 8. TCONS_00072128 knockdown notably decreased the expression of caspase 8, while the osteogenic differentiation of BMSCs was also reduced. Reversely, TCONS_00072128 overexpression enhanced caspase 8 expression and osteogenic differentiation of BMSCs. Moreover, the continuous expression of caspase 8 regulated by TCONS_00072128 significantly activated inflammation pathways including NLRP3 signaling and NF-κB signaling. Simultaneously, RIPK1 which has emerged as a promising therapeutic target for the treatment of a wide range of human neurodegenerative, autoimmune, and inflammatory diseases, was also phosphorylated. The results of the present study suggested that exosome-derived lncRNA TCONS_00072128 could promote the progression of PMOP by regulating caspase 8. In addition, caspase 8 expression in BMSCs was possible to be a key regulator that balanced cell differentiation and inflammation activation.

Role of Exosomal Non-Coding RNAs in Bone-Related Diseases

Bone-related diseases seriously affect the lives of patients and carry a heavy economic burden on society. Treatment methods cannot meet the diverse clinical needs of affected patients. Exosomes participate in the occurrence and development of many diseases through intercellular communication, including bone-related diseases. Studies have shown that exosomes can take-up and “package” non-coding RNAs and “deliver” them to recipient cells, thereby regulating the function of recipient cells. The exosomal non-coding RNAs secreted by osteoblasts, osteoclasts, chondrocytes, and other cells are involved in the regulation of bone-related diseases by inhibiting osteoclasts, enhancing chondrocyte activity and promoting angiogenesis. Here, we summarize the role and therapeutic potential of exosomal non-coding RNAs in the bone-related diseases osteoporosis, osteoarthritis, and bone-fracture healing, and discuss the clinical application of exosomes in patients with bone-related diseases.

TGF-Beta Induced Key Genes of Osteogenic and Adipogenic Differentiation in Human Mesenchymal Stem Cells and MiRNA-mRNA Regulatory Networks

Background: The clinical efficacy of osteoporosis therapy is unsatisfactory. However, there is currently no gold standard for the treatment of osteoporosis. Recent studies have indicated that a switch from osteogenic to adipogenic differentiation in human bone marrow mesenchymal stem cells (hMSCs) induces osteoporosis. This study aimed to provide a more comprehensive understanding of the biological mechanisms involved in this process and to identify key genes involved in osteogenic and adipogenic differentiation in hMSCs to provide new insights for the prevention and treatment of osteoporosis.

Methods: Microarray and bioinformatics approaches were used to identify the differentially expressed genes (DEGs) involved in osteogenic and adipogenic differentiation, and the biological functions and pathways of these genes were analyzed. Hub genes were identified, and the miRNA–mRNA interaction networks of these hub genes were constructed.

Results: In an optimized microenvironment, transforming growth factor-beta (TGF-beta) could promote osteogenic differentiation and inhibit adipogenic differentiation of hMSCs. According to our study, 98 upregulated genes involved in osteogenic differentiation and 66 downregulated genes involved in adipogenic differentiation were identified, and associated biological functions and pathways were analyzed. Based on the protein–protein interaction (PPI) networks, the hub genes of the upregulated genes (CTGF, IGF1, BMP2, MMP13, TGFB3, MMP3, and SERPINE1) and the hub genes of the downregulated genes (PPARG, TIMP3, ANXA1, ADAMTS5, AGTR1, CXCL12, and CEBPA) were identified, and statistical analysis revealed significant differences. In addition, 36 miRNAs derived from the upregulated hub genes were screened, as were 17 miRNAs derived from the downregulated hub genes. Hub miRNAs (hsa-miR-27a/b-3p, hsa-miR-128-3p, hsa-miR-1-3p, hsa-miR-98-5p, and hsa-miR-130b-3p) coregulated both osteogenic and adipogenic differentiation factors.

Conclusion: The upregulated hub genes identified are potential targets for osteogenic differentiation in hMSCs, whereas the downregulated hub genes are potential targets for adipogenic differentiation. These hub genes and miRNAs play important roles in adipogenesis and osteogenesis of hMSCs. They may be related to the prevention and treatment not only of osteoporosis but also of obesity.

Mesenchymal Stem Cell-Derived Extracellular Vesicle: A Promising Alternative Therapy for Osteoporosis

Osteoporosis is the chronic metabolic bone disease caused by the disturbance of bone remodeling due to the imbalance of osteogenesis and osteoclastogenesis. A large population suffers from osteoporosis, and most of them are postmenopausal women or older people. To date, bisphosphonates are the main therapeutic agents in the treatment of osteoporosis. However, limited therapeutic effects with diverse side effects caused by bisphosphonates hindered the therapeutic applications and decreased the quality of life. Therefore, an alternative therapy for osteoporosis is still needed. Stem cells, especially mesenchymal stem cells, have been shown as a promising medication for numerous human diseases including many refractory diseases. Recently, researchers found that the extracellular vesicles derived from these stem cells possessed the similar therapeutic potential to that of parental cells. To date, a number of studies demonstrated the therapeutic applications of exogenous MSC-EVs for the treatment of osteoporosis. In this article, we reviewed the basic back ground of EVs, the cargo and therapeutic potential of MSC-EVs, and strategies of engineering of MSC-EVs for osteoporosis treatment.

Recent Insight on the Non-coding RNAs in Mesenchymal Stem Cell-Derived Exosomes: Regulatory and Therapeutic Role in Regenerative Medicine and Tissue Engineering

Advances in the field of regenerative medicine and tissue engineering over the past few decades have paved the path for cell-free therapy. Numerous stem cell types, including mesenchymal stem cells (MSCs), have been reported to impart therapeutic effects via paracrine secretion of exosomes. The underlying factors and the associated mechanisms contributing to these MSC-derived exosomes' protective effects are, however, poorly understood, limiting their application in the clinic. The exosomes exhibit a diversified repertoire of functional non-coding RNAs (ncRNAs) and have the potential to transfer these biologically active transcripts to the recipient cells, where they are found to modulate a diverse array of functions. Altered expression of the ncRNAs in the exosomes has been linked with the regenerative potential and development of various diseases, including cardiac, neurological, skeletal, and cancer. Also, modulating the expression of ncRNAs in these exosomes has been found to improve their therapeutic impact. Moreover, many of these ncRNAs are expressed explicitly in the MSC-derived exosomes, making them ideal candidates for regenerative medicine, including tissue engineering research. In this review, we detail the recent advances in regenerative medicine and summarize the evidence supporting the altered expression of the ncRNA repertoire specific to MSCs under different degenerative diseases. We also discuss the therapeutic role of these ncRNA for the prevention of these various degenerative diseases and their future in translational medicine.

Role of Exosomal MicroRNAs and Their Crosstalk with Oxidative Stress in the Pathogenesis of Osteoporosis

Osteoporosis (OP) is an aging-related disease involving permanent bone tissue atrophy. Most patients with OP show high levels of oxidative stress (OS), which destroys the microstructure of bone tissue and promotes disease progression. Exosomes (exos) help in the delivery of microRNAs (miRNAs) and allow intercellular communication. In OP, exosomal miRNAs modulate several physiological processes, including the OS response. In the present review, we aim to describe how exosomal miRNAs and OS contribute to OP. We first summarize the relationship of OS with OP and then detail the features of exos along with the functions of exo-related miRNAs. Further, we explore the interplay between exosomal miRNAs and OS in OP and summarize the functional role of exos in OP. Finally, we identify the advantages of exo-based miRNA delivery in treatment strategies for OP. Our review seeks to improve the current understanding of the mechanism underlying OP pathogenesis and lay the foundation for the development of novel theranostic approaches for OP.

Neohesperidin promotes the osteogenic differentiation of bone mesenchymal stem cells by activating the Wnt/β-catenin signaling pathway

Background

Osteoporosis is a common disease in aging populations. However, osteoporosis treatment is still challenging. Here, we aimed to investigate the role of neohesperidin (NEO) in osteoporosis progression and the potential mechanism.

Methods

Bone mesenchymal stem cells (BMSCs) were isolated and treated with different concentrations of NEO (0, 10, 30, 100 M). Cell proliferation was analyzed by cell count kit-8 (CCK-8) assay. RNA-sequencing was performed on the isolated BMSCs with control and NEO treatment. Differentially expressed genes were obtained by R software. Alkaline phosphatase (ALP) staining and Alizarin red staining (ARS) were performed to assess the osteogenic capacity of the NEO. qRT-PCR was used to detect the expression of osteoblast markers.

Western blot was used to evaluate the protein levels in BMSCs.

Results

NEO treatment significantly improved hBMSC proliferation at different time points, particularly when cells were incubated with 30 M NEO (P < 0.05). NEO dose-dependently increased the ALP activity and calcium deposition than the control group (P < 0.05). A total of 855 differentially expressed genes were identified according to the significance criteria of log₂ (fold change) > 1 and adj P < 0.05. DKK1 partially reversed the promotion effects of NEO on osteogenic differentiation of BMSCs. NEO increased levels of the -catenin protein in BMSCs.

Conclusion

NEO plays a positive role in promoting osteogenic differentiation of BMSCs, which was related with activation of Wnt/-catenin pathway.

Exosomes: A Friend or Foe for Osteoporotic Fracture?

The clinical need for effective osteoporotic fracture therapy and prevention remains urgent. The occurrence and healing of osteoporotic fracture are closely associated with the continuous processes of bone modeling, remodeling, and regeneration. Accumulating evidence has indicated a prominent role of exosomes in mediating multiple pathophysiological processes, which are essential for information and materials exchange and exerting pleiotropic effects on neighboring or distant bone-related cells. Therefore, the exosomes are considered as important candidates both in the occurrence and healing of osteoporotic fracture by accelerating or suppressing related processes. In this review, we collectively focused on recent findings on the diagnostic and therapeutic applications of exosomes in osteoporotic fracture by regulating osteoblastogenesis, osteoclastogenesis, and angiogenesis, providing us with novel therapeutic strategies for osteoporotic fracture in clinical practice.