Circulating MiRNA-21-enriched extracellular vesicles promote bone remodeling in traumatic brain injury patients

Targeting capabilities of engineered extracellular vesicles for the treatment of neurological diseases

Recent advances in research on extracellular vesicles have significantly enhanced their potential as therapeutic agents for neurological diseases. Owing to their therapeutic properties and ability to cross the blood-brain barrier, extracellular vesicles are recognized as promising drug delivery vehicles for various neurological conditions, including ischemic stroke, traumatic brain injury, neurodegenerative diseases, glioma, and psychosis. However, the clinical application of natural extracellular vesicles is hindered by their limited targeting ability and short clearance from the body. To address these limitations, multiple engineering strategies have been developed to enhance the targeting capabilities of extracellular vesicles, thereby enabling the delivery of therapeutic contents to specific tissues or cells. Therefore, this review aims to highlight the latest advancements in natural and targeting-engineered extracellular vesicles, exploring their applications in treating traumatic brain injury, ischemic stroke, Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, glioma, and psychosis. Additionally, we summarized recent clinical trials involving extracellular vesicles and discussed the challenges and future prospects of using targeting-engineered extracellular vesicles for drug delivery in treating neurological diseases. This review offers new insights for developing highly targeted therapies in this field.

Periprosthetic osteolysis: Mechanisms and potential treatment strategies

Periprosthetic osteolysis is a common bone-related disorder that often occurs after total hip arthroplasty. The implants can cause damage to bone and bone-related cells due to mechanical stress and micromotions, resulting in the generation of a large number of wear particles. These wear particles trigger inflammation and oxidative stress in the surrounding tissues, disrupting the delicate balance maintained by osteoblasts and osteoclasts, ultimately leading to bone loss around the implant. Clinical investigations have demonstrated that Epimedium prenylflavonoids, miR-19a-3p, stem cell-derived exosomes, and certain non-PPO category pharmaceuticals have regulatory effects on bone homeostasis through distinct molecular pathways. Notably, this phenomenon reflects inherent biological rationality rather than stochastic occurrence. Extensive research has revealed that multiple natural compounds, non-coding RNAs, exosomes, and non-PPO therapeutics not only exert modulatory influences on critical pathophysiological processes including inflammatory cascades, oxidative stress responses, and tissue regeneration mechanisms, but also effectively regulate bone-related cellular functions to inhibit PPO progression. Therefore, this review comprehensively and systematically summarizes the main pathogenic mechanisms of periprosthetic osteolysis. Furthermore, it delves deeper into the research progress on the applications of currently reported natural products, ncRNAs, exosomes, and non-PPO medications in the treatment of periprosthetic osteolysis. Based on this, we hope that this paper can provide new perspectives and references for the future development of drugs targeting periprosthetic osteolysis.

MicroRNAs in adipose tissue fibrosis: Mechanisms and therapeutic potential

Adipose tissue fibrosis, characterized by abnormal extracellular matrix deposition within adipose tissue, signifies a crucial indicator of adipose tissue malfunction, potentially leading to organ tissue dysfunction. Various factors, including a high-fat diet, non-alcoholic fatty liver disease, and insulin resistance, coincide with adipose tissue fibrosis. MicroRNAs (miRNAs) represent a class of small non-coding RNAs with significant influence on tissue fibrosis through diverse signaling pathways. For instance, in response to a high-fat diet, miRNAs can modulate signaling pathways such as TGF-β/Smad, PI3K/AKT, and PPAR-γ to impact adipose tissue fibrosis. Furthermore, miRNAs play roles in inhibiting fibrosis in different contexts: suppressing corneal fibrosis via the TGF-β/Smad pathway, mitigating cardiac fibrosis through the VEGF signaling pathway, reducing wound fibrosis via regulation of the MAPK signaling pathway, and diminishing fibrosis post-fat transplantation via involvement in the PDGFR-β signaling pathway. Notably, the secretome released by miRNA-transfected adipose-derived stem cells facilitates targeted delivery of miRNAs to evade host immune rejection, enhancing their anti-fibrotic efficacy. Hence, this study endeavors to elucidate the role and mechanism of miRNAs in adipose tissue fibrosis and explore the mechanisms and advantages of the secretome released by miRNA-transfected adipose-derived stem cells in combating fibrotic diseases.

Accelerated fracture healing accompanied with traumatic brain injury: A review of clinical studies, animal models and potential mechanisms

The orthopaedic community frequently encounters polytrauma individuals with concomitant traumatic brain injury (TBI) and their fractures demonstrate accelerated fracture union, but the mechanisms remain far from clear. Animal and clinical studies demonstrate robust callus formation at the early healing process and expedited radiographical union. In humans, robust callus formation in TBI occurs independently of fracture fixation methods across multiple fracture sites. Animal studies of TBI replicate clinically relevant enlarged fracture callus as characterized by increased tissue volume and bone volume at the early stages. However, refinement and standardization of the TBI models requires further research. The quest for its underlying mechanisms began with the finding of increased osteogenesis in vitro using the serum and cerebral spinal fluid (CSF) from TBI individuals. This has led to the investigation of myriads of brain-derived factors including humoral factors, cytokines, exosomes, and mi-RNAs. Further, the emerging information of interplay between the skeletal system and central nervous system, the roles of peripheral nerves and their neuropeptides in regulating bone regeneration, offers valuable insights for future research. This review consolidates the findings from both experimental and clinical studies, elucidating the potential mechanisms underlying enhanced fracture healing in concurrent TBI scenarios that may lay down a foundation to develop innovative therapies for fracture healing enhancement and conquer fracture non-union. The translational potential of this article. This review comprehensively summarizes the observations of accelerated fracture healing in the presence of traumatic brain injury from both preclinical and clinical studies. In addition, it also delineates potential cellular and molecular mechanisms. Further detailed investigation into its underlying mechanisms may reveal innovative orthopaedic intervention strategies to improve fracture healing and thus offering promising avenues for future translational applications.

Receptor Activator of Nuclear Factor Kappa-B-Expressing Mesenchymal Stem Cells-Derived Extracellular Vesicles for Osteoporosis Therapy

The dynamic balance between bone resorption and formation is critical for maintaining healthy bone homeostasis. However, the receptor activator of the nuclear factor B ligand (RANKL) primarily stimulates mature osteoclasts to resorb bone, and its upregulation leads to osteoporosis in patients. Here, we designed RANK-expressing extracellular vesicles (EVs) derived from mesenchymal stem cells to maintain bone homeostasis in mice. This engineered EV (EV@R) effectively neutralizes excess RANKL in bone tissue due to the RANK-RANKL interaction, thereby attenuating osteoclast differentiation. Additionally, we found that miRNA-21a-5p in EV@R contributes to restoring bone metabolic homeostasis. We demonstrate the protective and therapeutic efficacy of EV@R against osteoporosis in the ovariectomy-induced osteoporosis mouse model with a lasting effect and minimal side effects. Our study provides an alternative way to use engineered EVs for bone homeostasis treatment.

Astrocyte-neuron crosstalk through extracellular vesicle-shuttled miRNA-382-5p promotes traumatic brain injury

Although astrocytes undergo functional changes in response to brain injury and may be the driving force of subsequent neuronal death, the underlying mechanisms remain incompletely elucidated. Here, we showed that extracellular vesicle (EV)-shuttled miRNA-382-5p may serve as a biomarker for the severity of traumatic brain injury (TBI), as the circulating EV-miRNA-382-5p level was significantly increased in both human patients and TBI model mice. Mechanistically, astrocyte-derived EVs delivered the shuttled miRNA-382-5p to mediate astrocyte-neuron communication, which promoted neuronal mitochondrial dysfunction by inhibiting the expression of optic atrophy-1 (OPA1). Consistent with these findings, genetic ablation of neuronal OPA1 exacerbated mitochondrial damage and neuronal apoptosis in response to TBI. Moreover, engineered RVG-miRNA-382-5p inhibitor-EVs, which can selectively deliver a miRNA-382-5p inhibitor to neurons, significantly attenuated mitochondrial damage and improved neurological function after TBI. Taken together, our data suggest that EV-shuttled miRNA-382-5p may be a critical mediator of astrocyte-induced neurotoxicity under pathological conditions and that targeting miRNA-382-5p-OPA1 signaling has potential for clinical translation in the treatment of traumatic brain injury.

Molecular Signaling Pathways and MicroRNAs in Bone Remodeling: A Narrative Review

Bone remodeling is an intricate process executed throughout one's whole life via the cross-talk of several cellular events, progenitor cells and signaling pathways. It is an imperative mechanism for regaining bone loss, recovering damaged tissue and repairing fractures. To achieve this, molecular signaling pathways play a central role in regulating pathological and causal mechanisms in different diseases. Similarly, microRNAs (miRNAs) have shown promising results in disease management by mediating mRNA targeted gene expression and post-transcriptional gene function. However, the role and relevance of these miRNAs in signaling processes, which regulate the delicate balance between bone formation and bone resorption, are unclear. This review aims to summarize current knowledge of bone remodeling from two perspectives: firstly, we outline the modus operandi of five major molecular signaling pathways, i.e.,the receptor activator of nuclear factor kappa-B (RANK)-osteoprotegrin (OPG) and RANK ligand (RANK-OPG-RANKL), macrophage colony-stimulating factor (M-CSF), Wnt/β-catenin, Jagged/Notch and bone morphogenetic protein (BMP) pathways in regards to bone cell formation and function; and secondly, the miRNAs that participate in these pathways are introduced. Probing the miRNA-mediated regulation of these pathways may help in preparing the foundation for developing targeted strategies in bone remodeling, repair and regeneration.

Exosomes: A Cellular Communication Medium That Has Multiple Effects On Brain Diseases

Exosomes, as membranous vesicles generated by multiple cell types and secreted to extracellular space, play a crucial role in a range of brain injury-related brain disorders by transporting diverse proteins, RNA, DNA fragments, and other functional substances. The nervous system's pathogenic mechanisms are complicated, involving pathological processes like as inflammation, apoptosis, oxidative stress, and autophagy, all of which result in blood-brain barrier damage, cognitive impairment, and even loss of normal motor function. Exosomes have been linked to the incidence and progression of brain disorders in recent research. As a result, a thorough knowledge of the interaction between exosomes and brain diseases may lead to the development of more effective therapeutic techniques that may be implemented in the clinic. The potential role of exosomes in brain diseases and the crosstalk between exosomes and other pathogenic processes were discussed in this paper. Simultaneously, we noted the delicate events in which exosomes as a media allow the brain to communicate with other tissues and organs in physiology and disease, and compiled a list of natural compounds that modulate exosomes, in order to further improve our understanding of exosomes and propose new ideas for treating brain disorders.

Impact of menopause-associated frailty on traumatic brain injury

Navigating menopause involves traversing a complex terrain of hormonal changes that extend far beyond reproductive consequences. Menopausal transition is characterized by a decrease in estradiol-17β (E2), and the impact of menopause resonates not only in the reproductive system but also through the central nervous system, musculoskeletal, and gastrointestinal domains. As women undergo menopausal transition, they become more susceptible to frailty, amplifying the risk and severity of injuries, including traumatic brain injury (TBI). Menopause triggers a cascade of changes leading to a decline in muscle mass, accompanied by diminished tone and excitability, thereby restricting the availability of irisin, a crucial hormone derived from muscles. Concurrently, bone mass undergoes reduction, culminating in the onset of osteoporosis and altering the dynamics of osteocalcin, a hormone originating from bones. The diminishing levels of E2 during menopause extend their influence on the gut microbiota, resulting in a reduction in the availability of tyrosine, tryptophan, and serotonin metabolites, affecting neurotransmitter synthesis and function. Understanding the interplay between menopause, frailty, E2 decline, and the intricate metabolisms of bone, gut, and muscle is imperative when unraveling the nuances of TBI after menopause. The current review underscores the significance of accounting for menopause-associated frailty in the incidence and consequences of TBI. The review also explores potential mechanisms to enhance gut, bone, and muscle health in menopausal women, aiming to mitigate frailty and improve TBI outcomes.

MicroRNAs in osteoblast differentiation and fracture healing: From pathogenesis to therapeutic implication

The term "fracture" pertains to the occurrence of bones being either fully or partially disrupted as a result of external forces. Prolonged fracture healing can present a notable danger to the patient's general health and overall quality of life. The significance of osteoblasts in the process of new bone formation is widely recognized, and optimizing their function could be a desirable strategy. Therefore, the mending of bone fractures is intricately linked to the processes of osteogenic differentiation and mineralization. MicroRNAs (miRNAs) are RNA molecules that do not encode for proteins, but rather modulate the functioning of physiological processes by directly targeting proteins. The participation of microRNAs (miRNAs) in experimental investigations has been extensive, and their control functions have earned them the recognition as primary regulators of the human genome. Earlier studies have shown that modulating the expression of miRNAs, either by increasing or decreasing their levels, can initiate the differentiation of osteoblasts. This implies that miRNAs play a pivotal function in promoting osteogenesis, facilitating bone mineralization and formation, ultimately leading to an efficient healing of fractures. Hence, focusing on miRNAs can be considered a propitious therapeutic approach to accelerate the healing of fractures and forestall nonunion. In this manner, the information supplied by this investigation has the potential to aid in upcoming clinical utilization, including its possible use as biomarkers or as resources for devising innovative therapeutic tactics aimed at promoting fracture healing.

Engineered Extracellular Vesicles in Chronic Kidney Diseases: A Comprehensive Review

Chronic kidney diseases (CKD) present a formidable global health challenge, characterized by a deficiency of effective treatment options. Extracellular vesicles (EVs), recognized as multifunctional drug delivery systems in biomedicine, have gained accumulative interest. Specifically, engineered EVs have emerged as a promising therapeutic approach for targeted drug delivery, potentially addressing the complexities of CKD management. In this review, we systematically dissect EVs, elucidating their classification, biogenesis, composition, and cargo molecules. Furthermore, we explore techniques for EV engineering and strategies for their precise renal delivery, focusing on cargo loading and transportation, providing a comprehensive perspective. Moreover, this review also discusses and summarizes the diverse therapeutic applications of engineered EVs in CKD, emphasizing their anti-inflammatory, immunomodulatory, renoprotective, and tissue-regenerating effects. It critically evaluates the challenges and limitations in translating EV therapies from laboratory settings to clinical applications, while outlining future prospects and emerging trends.

Hypoxic-preconditioned mesenchymal stem cell-derived small extracellular vesicles promote the recovery of spinal cord injury by affecting the phenotype of astrocytes through the miR-21/JAK2/STAT3 pathway

BACKGROUND

Secondary injury after spinal cord injury (SCI) is a major obstacle to their neurological recovery. Among them, changes in astrocyte phenotype regulate secondary injury dominated by neuroinflammation. Hypoxia-preconditioned mesenchymal stem cells (MSCs)-derived extracellular vesicle (H-EV) plays a multifaceted role in secondary injury by interacting with cellular components and signaling pathways. They possess anti-inflammatory properties, regulate oxidative stress, and modulate apoptotic pathways, promoting cell survival and reducing neuronal loss. Given the unique aspects of secondary injury, H-EV shows promise as a therapeutic approach to mitigate its devastating consequences. Our study aimed to determine whether H-EV could promote SCI repair by altering the phenotype of astrocytes.

METHODS

Rat bone marrow MSCs (BMSCs) and EVs secreted by them were extracted and characterized. After the SCI model was successfully constructed, EV and H-EV were administered into the tail vein of the rats, respectively, and then their motor function was evaluated by the Basso-Beattie-Bresnahan (BBB) score, Catwalk footprint analysis, and electrophysiological monitoring. The lesion size of the spinal cord was evaluated by hematoxylin-eosin (HE) staining. The key point was to use glial fibrillary acidic protein (GFAP) as a marker of reactive astrocytes to co-localize with A1-type marker complement C3 and A2-type marker S100A10, respectively, to observe phenotypic changes in astrocytes within tissues. The western blot (WB) of the spinal cord was also used to verify the results. We also compared the efficacy differences in apoptosis and inflammatory responses using terminal deoxynucleotidyl transferase dUTP terminal labeling (TUNEL) assay, WB, and enzyme-linked immunosorbent assay (ELISA). Experiments in vitro were also performed to verify the results. Subsequently, we performed microRNA (miRNA) sequencing analysis of EV and H-EV and carried out a series of knockdown and overexpression experiments to further validate the mechanism by which miRNA in H-EV plays a role in promoting astrocyte phenotypic changes, as well as the regulated signaling pathways, using WB both in vivo and in vitro.

RESULTS

Our findings suggest that H-EV is more effective than EV in the recovery of motor function, anti-apoptosis, and anti-inflammatory effects after SCI, both in vivo and in vitro. More importantly, H-EV promoted the conversion of A1 astrocytes into A2 astrocytes more than EV. Moreover, miR-21, which was found to be highly expressed in H-EV by miRNA sequencing results, was also demonstrated to influence changes in astrocyte phenotype through a series of knockdown and overexpression experiments. At the same time, we also found that H-EV might affect astrocyte phenotypic alterations by delivering miR-21 targeting the JAK2/STAT3 signaling pathway.

CONCLUSION

H-EV exerts neuroprotective effects by delivering miR-21 to promote astrocyte transformation from the A1 phenotype to the A2 phenotype, providing new targets and ideas for the treatment of SCI.

Unraveling the Emerging Niche Role of Extracellular Vesicles (EVs) in Traumatic Brain Injury (TBI)

Extracellular vesicles or exosomes, often known as EVs, have acquired significant attention in the investigations of traumatic brain injury (TBI) and have a distinct advantage in actively researching the fundamental mechanisms underlying various clinical symptoms and diagnosing the wide range of traumatic brain injury cases. The mesenchymal stem cells (MSCs) can produce and release exosomes, which offer therapeutic benefits. Exosomes are tiny membranous vesicles produced by various cellular entities originating from endosomes. Several studies have reported that administering MSC-derived exosomes through intravenous infusions improves neurological recovery and promotes neuroplasticity in rats with traumatic brain damage. The therapeutic advantages of exosomes can be attributed to the microRNAs (miRNAs), which are small non-coding regulatory RNAs that significantly impact the regulation of posttranscriptional genes. Exosome-based therapies, which do not involve cells, have lately gained interest as a potential breakthrough in enhancing neuroplasticity and accelerating neurological recovery for various brain injuries and neurodegenerative diseases. This article explores the benefits and drawbacks of exosome treatment for traumatic brain injury while emphasizing the latest advancements in this field with clinical significance.

Cellular and Molecular Connections Between Bone Fracture Healing and Exosomes

Fracture healing is a multifaceted process that requires various phases and intercellular interactions. In recent years, investigations have been conducted to assess the feasibility of utilizing exosomes, small extracellular vesicles (EVs), to enhance and accelerate the healing process. Exosomes serve as a cargo transport platform, facilitating intercellular communication, promoting the presentation of antigens to dendritic cells, and stimulating angiogenesis. Exosomes have a special structure that gives them a special function, especially in the healing process of bone injuries. This article provides an overview of cellular and molecular processes associated with bone fracture healing, as well as a survey of existing exosome research in this context. We also discuss the potential use of exosomes in fracture healing, as well as the obstacles that must be overcome to make this a viable clinical practice.

Roles of microRNA-124 in traumatic brain injury: a comprehensive review

Traumatic brain injury (TBI) is a prominent global cause of mortality due to the limited availability of effective prevention and treatment strategies for this disorder. An effective molecular biomarker may contribute to determining the prognosis and promoting the therapeutic efficiency of TBI. MicroRNA-124 (miR-124) is most abundantly expressed in the brain and exerts different biological effects in a variety of diseases by regulating pathological processes of apoptosis and proliferation. Recently, increasing evidence has demonstrated the association between miR-124 and TBI, but there is still a lack of relevant literature to summarize the current evidence on this topic. Based on this review, we found that miR-124 was involved as a regulatory factor in cell apoptosis and proliferation, and was also strongly related with the pathophysiological development of TBI. MiR-124 played an essential role in TBI by interacting with multiple biomolecules and signaling pathways, such as JNK, VAMP-3, Rela/ApoE, PDE4B/mTOR, MDK/TLR4/NF-κB, DAPK1/NR2B, JAK/STAT3, PI3K/AKT, Ras/MEK/Erk. The potential benefits of upregulating miR-124 in facilitating TBI recovery have been identified. The advancement of miRNA nanocarrier system technology presents an opportunity for miR-124 to emerge as a novel therapeutic target for TBI. However, the specific mechanisms underlying the role of miR-124 in TBI necessitate further investigation. Additionally, comprehensive large-scale studies are required to evaluate the clinical significance of miR-124 as a therapeutic target for TBI.

The Role of Microglial Exosomes and miR-124-3p in Neuroinflammation and Neuronal Repair after Traumatic Brain Injury

(1) Background: In this study, we aimed to explore the regulatory mechanism of miR-124-3p microglial exosomes, as they were previously reported to modulate neuroinflammation and promote neuronal repair following traumatic brain injury (TBI). (2) Methods: Studies investigating the impact of microglial exosomal miRNAs, specifically miR-124-3p, on injured neurons and brain microvascular endothelial cells (BMVECs) in the context of TBI were reviewed. (3) Results: Animal models of TBI, in vitro cell culture experiments, RNA sequencing analysis, and functional assays were employed to elucidate the mechanisms underlying the effects of miR-124-3p-loaded exosomes on neuroinflammation and neuronal repair. Anti-inflammatory M2 polarization of microglia, mTOR signaling suppression, and BMVECs-mediated autophagy were reported as the main processes contributing to neuroprotection, reduced blood-brain barrier leakage, and improved neurologic outcomes in animal models of TBI. (4) Conclusions: Microglial exosomes, particularly those carrying miR-124-3p, have emerged as promising candidates for therapeutic interventions in TBI. These exosomes exhibit neuroprotective effects, attenuate neuroinflammation, and promote neuronal repair and plasticity. However, further research is required to fully elucidate the underlying mechanisms and optimize their delivery strategies for effective treatment in human TBI cases.

Hmga1-overexpressing lentivirus protects against osteoporosis by activating the Wnt/β-catenin pathway in the osteogenic differentiation of BMSCs

Postmenopausal osteoporosis is associated with bone formation inhibition mediated by the impaired osteogenic differentiation potential of bone marrow mesenchymal stem cells (BMSCs). However, identifying and confirming the essential genes in the osteogenic differentiation of BMSCs and osteoporosis remain challenging. The study aimed at revealing the key gene that regulated osteogenic differentiation of BMSCs and led to osteoporosis, thus exploring its therapeutic effect in osteoporosis. In the present study, six essential genes related to the osteogenic differentiation of BMSCs and osteoporosis were identified, namely, fibrillin 2 (Fbn2), leucine-rich repeat-containing 17 (Lrrc17), heat shock protein b7 (Hspb7), high mobility group AT-hook 1 (Hmga1), nexilin F-actin-binding protein (Nexn), and endothelial cell-specific molecule 1 (Esm1). Furthermore, the in vivo and in vitro experiments showed that Hmga1 expression was increased during the osteogenic differentiation of rat BMSCs, while Hmga1 expression was decreased in the bone tissue of ovariectomized (OVX) rats. Moreover, the expression of osteogenic differentiation-related genes, the activity of alkaline phosphatase (ALP), and the number of mineralized nodules were increased after Hmga1 overexpression, which was partially reversed by a Wnt signaling inhibitor (DKK1). In addition, after injecting Hmga1-overexpressing lentivirus into the bone marrow cavity of OVX rats, the bone loss, and osteogenic differentiation inhibition of BMSCs in OVX rats were partially reversed, while osteoclast differentiation promotion of BMSCs in OVX rats was unaffected. Taken together, the present study confirms that Hmga1 prevents OVX-induced bone loss by the Wnt signaling pathway and reveals that Hmga1 is a potential gene therapeutic target for postmenopausal osteoporosis.