M2 exosomes modified by hydrogen sulfide promoted bone regeneration by moesin mediated endocytosis

Pretreated exosomes by electrical stimulation accelerate bone regeneration

Bone tissue engineering has attracted significant attention from both the research and clinical communities. Inspired by the inherent bioelectric properties of bone tissue, electrical stimulation is widely recognized as an external intervention that can induce osteogenesis, mineralization, and accelerate bone regeneration. However, the clinical application of electrical stimulation is limited by the complexity of the procedures and the use of cumbersome, invasive equipment. Exosomes, as an alternative to seed cells, can overcome many of the limitations associated with stem cell transplantation. Researchers aim to enhance exosomes' therapeutic potential for bone regeneration. While various pretreatments have been studied, there is currently no research investigating the role of exosomes pretreated with electrical stimulation in bone tissue regeneration. In this study, we pretreated bone marrow mesenchymal stem cells (BMSCs) with electrical stimulation and isolated the resulting exosomes (Elec-exo). A series of in vitro experiments determined that 150 μA is the optimal condition for electrical stimulation. Mechanistically, proteomic analysis revealed an enrichment of proteins involved in "Oxidative Phosphorylation" regulation within Elec-exo, and transcriptomic analysis indicated the activation of Pl3k-Akt and MAPK bone formation-related signaling pathways in the effector cells. Hydrogels, as a sustained-release scaffold, were used to deliver Elec-exo in vivo. In a rat femur defect model, Elec-exo loaded into chondroitin sulfate methacrylate (CSMA) hydrogel accelerated early bone tissue regeneration. In summary, our study explores the mechanisms by which electrical stimulation pretreatment enhances bone tissue regeneration and broadens the therapeutic application of exosomes in accelerating bone regeneration.

Gas-powered extracellular vesicles promote bone regeneration

The signaling gas hydrogen sulfide (H2S) has recently been implicated in the regulation of bone remodeling and the maintenance of periodontal health. Exploring the underlying mechanisms for this regulation holds promise for the development of new treatment strategies to block bone resorption and stimulate bone regeneration. A recent study by Zhou et al. (Bioactive Materials, 2024) showed that treatment with H2S stimulated changes in the extracellular vesicles (EVs) released by M2 macrophages, enhancing their capacity to promote the osteogenic differentiation of mesenchymal stem cells in vitro. The H2S-stimulated EVs, given together with mesenchymal stem cells (MSCs), also promoted bone regeneration in vivo in a mouse calvarial critical-size defect model. This activity was linked to augmented expression of moesin, a membrane-cytoskeletal linkage protein, which was found at increased levels in EVs from cells stimulated by H2S. The study identifies a new strategy for generating EVs that are pro-osteogenic. It also uncovers a surprising role for moesin in stimulating osteogenesis in MSCs.

Bibliometric and visualized analysis of the applications of exosomes for bone regeneration

Background

Bone defect, a common orthopedic condition, is characterized by a lengthy and impactful treatment period, posing a considerable challenge in clinical settings. Medical technology has advanced notably, and has effectively treated an increasing number of patients with bone defects. Consequently, there has been an explosion of research articles on bone regeneration, including a substantial number on the application of exosomes. Exosomes, especially those derived from stem cells, have been confirmed to be effective in bone regeneration and have garnered widespread attention in the last decade. Therefore, this study conducted a bibliometric analysis on publications related to the application of exosomes for bone regeneration. The objectives are to explore the development history and research hotspots in this field over the past 10 years, predict future development trends, and provide guidance for subsequent research.

Methods

The Web of Science Core Collection (WoSCC) database was searched for articles related to exosomes and bone regeneration published from 1 January 2014, to 31 December 2023. The collected literature was analyzed using software such as Microsoft Excel, CiteSpace 6.3R1, VOSviewer 1.6.20, and the bibliometric online platform (https://bibliometric.com).

Results

A total of 3,004 articles published by 2,729 institutions from 68 countries were included in this study. The number of articles on the application of exosomes for bone regeneration has increased annually over the last decade. China was the most prolific country in this field, with a total of 1,468 papers; Shanghai Jiao Tong University (China) was the institution with the highest number of publications (117 publications). In terms of authors, Xin Wang, Yi Zhang, and Yang Wang were the three who published the highest number of papers, with 14 papers each. Co-citation analysis revealed that the article published by Valadi H in 2007 has the highest number of co-citations (270 times of quotation). Additionally, most research hotspots focused on the function of exosomes and the mechanism of action. Furthermore, the importance of osteoblast differentiation and angiogenesis in bone regeneration has also garnered significant attention from scholars in this field.

Conclusion

This study reviewed the research achievements on the application of exosomes for bone regeneration over the past 10 years, utilizing bibliometric analysis tools. It visualized the countries, institutions, authors, and journals that have made significant contributions to this field, revealed current research hotspots, and finally explored future development trends.

Static Topographical Cue Combined with Dynamic Fluid Stimulation Enhances the Macrophage Extracellular Vesicle Yield and Therapeutic Potential for Bone Defects

Extracellular vesicles (EVs) hold promise for tissue regeneration, but their low yield and limited therapeutic efficacy hinder clinical translation. Bioreactors provide a larger culture surface area and stable environment for large-scale EV production, yet their ability to enhance EV therapeutic efficacy is limited. Physical stimulation, by inducing cell differentiation and modulating EV cargo composition, offers a more efficient, cost-effective, and reproducible approach compared to the cargo loading of EVs and biochemical priming of parental cells. Herein, the effects of a 3D-printed perfusion bioreactor with a topographical cue on the macrophage EV yield and bioactivity were assessed. The results indicate that the bioreactor increased the EV yield 12.5-fold and enhanced bioactivity in promoting osteogenic differentiation and angiogenesis via upregulated miR-210-3p. Mechanistically, fluid shear stress activates Piezo1, triggering Ca2+ influx and Yes-associated protein (YAP) nuclear translocation, promoting EV secretion and enhancing macrophage M2 polarization in conjunction with morphological changes guided by aligned topography. Moreover, a porous electrospun membrane-hydrogel composite scaffold loaded with bioreactor-derived EVs exhibited outstanding efficacy in promoting osteogenic differentiation and angiogenesis in a rat cranial defect model. This study presents a scalable, cost-effective, and stable platform for the production of therapeutic EVs, potentially overcoming key challenges in translating EV-based therapies to the clinic.

Study on the mechanism of Shuanghe decoction against steroid-induced osteonecrosis of the femoral head: insights from network pharmacology, metabolomics, and gut microbiota

BACKGROUND

Steroid-induced osteonecrosis of the femoral head (SONFH) is a challenging and debilitating orthopedic condition with a rising incidence in recent years. Shuanghe Decoction (SHD), a traditional Chinese medicine formula, has shown significant efficacy in treating SONFH, though its underlying mechanisms remain unclear.

PURPOSE

This study aims to elucidate the therapeutic effects and potential mechanisms of SHD on SONFH through in vivo experiments, combined with network pharmacology, metabolomics, and gut microbiota analysis.

MATERIALS AND METHODS

Forty male Sprague-Dawley rats (300 ± 20 g) were randomly assigned to four groups: Control, Model, SHD-L, and SHD-H, with 10 rats each. SONFH was induced in all groups except the Control group using lipopolysaccharide and methylprednisolone. The SHD-L and SHD-H groups were treated with Shuanghe decoction at doses of 4.86 g/kg/day and 9.72 g/kg/day, respectively, for eight weeks. Bone morphology, pathological changes, and osteogenic factors were evaluated using Micro-CT, histological staining, and immunohistochemistry. Network pharmacology, metabolomics, and gut microbiota analyses were conducted to explore SHD's mechanisms.

RESULTS

SHD improved bone morphology and increased osteogenic factor expression (RUNX2, OCN, COL-I). Network pharmacology indicated that metabolic pathways play a key role in SHD's therapeutic effects. Metabolomic analysis identified 14 differential metabolites, including 21-hydroxypregnenolone and tyramine, which were restored to normal levels by SHD. Gut microbiota analysis revealed that SHD modulated bacterial abundance, particularly Verrucomicrobia, Allobaculum, and Burkholderiales. A comprehensive network identified two key metabolites (tyramine, 21-hydroxypregnenolone), seven targets (CYP19A1, CYP1A2, CYP1B1, CYP2C9, CYP3A4, MIF, and HSD11B1), two metabolic pathways (tyrosine metabolism, steroid hormone biosynthesis), and four bacterial taxa (Jeotgalicoccus, Clostridium, Corynebacterium, rc4-4) as central to SHD against SONFH.

CONCLUSION

SHD alleviates SONFH by reshaping gut microbiota, reversing metabolic imbalances, and enhancing osteogenesis. Our findings provide novel insights into the pharmacological mechanisms of SHD, laying a foundation for its clinical application in treating SONFH.

Exosomes derived from liver failure patients' plasma stimulated mesenchymal stem cells alleviate acute liver failure

BACKGROUND

Exosomes derived from pre-stimulated mesenchymal stem cells (MSCs) have improved therapeutic effects in disease-associated microenvironments. In this study, we investigated the therapeutic potential of exosomes from MSCs stimulated with plasma from patients with liver failure (LF-Exos).

METHODS

Untreated exosomes (NC-Exos) and LF-Exos were extracted and characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), western blotting, and miRNA sequencing. We then examined the protective effects of LF-Exos on hepatocytes acutely injured by D-galactosamine (D-GalN)/lipopolysaccharide (LPS) co-treatment and on a mouse model of acute liver failure (ALF). Apoptosis was assessed using the CCK-8 assay and flow cytometry. Liver tissue damage was examined by hematoxylin and eosin staining and immunohistochemistry. The levels of signaling pathway proteins were determined by western blotting.

RESULTS

Stimulation with plasma from patients with liver failure significantly altered the morphology of MSCs and reduced their proliferative activity. Gene chip analysis identified 31 differentially expressed miRNAs, and further analysis showed that these differentially expressed miRNAs may affect the PI3K-AKT signaling pathway. Compared to NC-Exos, LF-Exos induced AKT phosphorylation in hepatocytes and liver tissues, inhibited D-GalN/LPS-induced apoptosis in hepatocytes, and reduced pathological liver injury in the mouse model of ALF.

CONCLUSION

The biological effects of Exos were improved after stimulation with plasma from patients with liver failure. LF-Exos may inhibit the activity of the NLRP3 inflammasome and activate the PI3K-AKT signaling pathway to exert protective effects on acutely injured hepatocytes and a mouse model of ALF.

Research Advances and Application Progress on miRNAs in Exosomes Derived From M2 Macrophage for Tissue Injury Repairing

Tissue injury repair is a multifaceted and dynamic process characterized by complex interactions among various immune cells, with M2 macrophages assuming a crucial role. Exosomes derived from M2-type macrophages (M2-Exos) significantly influence the injury repair process through intercellular communication mediated by enriched microRNAs (miRNAs). This review aims to elucidate the biological processes underlying exosome formation, the synthesis and function of miRNAs, and the diverse methodologies employed for exosome extraction. Furthermore, we provide a comprehensive summary of the established multifarious functions and mechanisms of M2-Exos miRNAs in tissue injury repair across different systems, while also exploring their potential applications in disease prevention, diagnosis, and clinical practice. Despite the challenges encountered, the therapeutic use of M2-Exos in clinical contexts appears promising, prompting research efforts to focus on improving the efficiency of exosome extraction and application, as well as ensuring the safety of their clinical utilization.

M2 macrophage-derived exosomes enable osteogenic differentiation and inhibit inflammation in human periodontal ligament stem cells through promotion of CXCL12 expression

BACKGROUND

Periodontitis is a dental disease characterized by inflammation of periodontal tissues and loss of the periodontal ligaments and alveolar bone. Exosomes are a class of extracellular vesicles that are involved in a variety of diseases by releasing active substances. In this study, we aimed to investigate the effect and mechanism of exosomes from M2 polarized macrophages (M2-exos) on osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs).

METHODS

M2-exos were isolated from IL-4-induced RAW264.7 cells (M2 macrophages) and then treated on hPDLSCs. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, measurement of osteogenic differentiation-related genes and proteins, and inflammation was evaluated by measuring the levels of inflammatory factors. The mechanism of M2-exo was confirmed through qPCR, western blot, ALP and ARS staining.

RESULTS

Results suggested that M2-exo improved osteogenic differentiation and inhibited inflammation in LPS-induced hPDLSCs. CXCL12 expression was elevated in M2 macrophages, but decreased in LPS-induced hPDLSCs. Moreover, the effect of M2-exo on osteogenic differentiation and inflammation in LPS-induced hPDLSCs was reversed by CXCL12 knockdown.

CONCLUSION

We demonstrated that M2-exo facilitated osteogenic differentiation and suppressed inflammation in LPS-induced hPDLSCs through promotion of CXCL12 expression. These results suggested the potential of M2-exo in the treatment of periodontitis, which may provide a new theoretical basis for M2-exo treatment of periodontitis.

Hydrogen Sulfide can Scavenge Free Radicals to Improve Spinal Cord Injury by Inhibiting the p38MAPK/mTOR/NF-κB Signaling Pathway

Spinal cord injury (SCI) causes irreversible cell loss and neurological dysfunctions. Presently, there is no an effective clinical treatment for SCI. It can be the only intervention measure by relieving the symptoms of patients such as pain and fever. Free radical-induced damage is one of the validated mechanisms in the complex secondary injury following primary SCI. Hydrogen sulfide (H2S) as an antioxidant can effectively scavenge free radicals, protect neurons, and improve SCI by inhibiting the p38MAPK/mTOR/NF-κB signaling pathway. In this report, we analyze the pathological mechanism of SCI, the role of free radical-mediated the p38MAPK/mTOR/NF-κB signaling pathway in SCI, and the role of H2S in scavenging free radicals and improving SCI.

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

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

Macrophage exosomes modified by miR-365-2-5p promoted osteoblast osteogenic differentiation by targeting OLFML1

In the bone immune microenvironment, immune cells can regulate osteoblasts through a complex communication network. Macrophages play a central role in mediating immune osteogenesis, exosomes derived from them have osteogenic regulation and can be used as carriers in bone tissue engineering. However, there are problems with exosomal therapy alone, such as poor targeting, and the content of loaded molecules cannot reach the therapeutic concentration. In this study, macrophage-derived exosomes modified with miR-365-2-5p were developed to accelerate bone healing. MC3T3-E1 cells were incubated with the culture supernatants of M0, M1 and M2 macrophages, and it was found that the culture medium of M2 macrophages had the most significant effects in contributing to osteogenesis. High-throughput sequencing identified that miR-365-2-5p was significantly expressed in exosomes derived from M2 macrophages. We incubated MC3T3-E1 with exosomes overexpressing or knocking down miR-365-2-5p to examine the biological function of exosome miR-365-2-5p on MC3T3-E1 differentiation. These findings suggested that miR-365-2-5p secreted by exosomes increased the osteogenesis of MC3T3-E1. Moreover, miR-365-2-5p had a direct influence over osteogenesis for MC3T3-E1. Sequencing analysis combined with dual luciferase detection indicated that miR-365-2-5p binded to the 3'-UTR of OLFML1. In summary, exosomes secreted by M2 macrophages targeted OLFML1 through miR-365-2-5p to facilitate osteogenesis.

Engineered Extracellular Vesicles: A potential treatment for regeneration

Extracellular vesicles (EVs) play a critical role in various physiological and pathological processes. EVs have gained recognition in regenerative medicine due to their biocompatibility and low immunogenicity. However, the practical application of EVs faces challenges such as limited targeting ability, low yield, and inadequate therapeutic effects. To overcome these limitations, engineered EVs have emerged. This review aims to comprehensively analyze the engineering methods utilized for modifying donor cells and EVs, with a focus on comparing the therapeutic potential between engineered and natural EVs. Additionally, it aims to investigate the specific cell effects that play a crucial role in promoting repair and regeneration, while also exploring the underlying mechanisms involved in the field of regenerative medicine.