Diabetic and nondiabetic BMSC-derived exosomes affect bone regeneration via regulating miR-17-5p/SMAD7 axis

Protein O-GlcNAcylation reprograms macrophage-mediated bone remodeling in medication-related osteonecrosis of the jaw

O-Linked N-acetylglucosamine (O-GlcNAcylation) is an essential nutrient-sensitive post-translational modification (PTM) that has emerged as a critical regulator bridging immunometabolic reprogramming and skeletal homeostasis. Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication of anti-resorptive therapy, with limited effective treatments available. Despite four decades of research since its discovery, the therapeutic potential of targeting O-GlcNAcylation in MRONJ remains underexplored. Macrophages orchestrate a pro-inflammatory/anti-inflammatory milieu by polarization and paracrine signaling to promote bone resorption/formation. However, during MRONJ progression, metabolic alterations reshape macrophage function, leading to immune dysregulation and impaired bone remodeling. O-GlcNAcylation serves as a metabolic sensor of nutritional status and cellular stress, influences macrophage phenotype and function, making it a potential target for therapeutic intervention. Currently, extensive research on biomaterials for bone regeneration primarily focuses on enhancing osteogenesis or inhibiting osteoclast activity, often overlooking the impact of PTMs on bone remodeling. In this review, we highlight the emerging role of O-GlcNAcylation in macrophage regulation, discuss its implications in MRONJ pathogenesis, and explore its potential applications in macrophage-targeted biomaterials and nanotherapeutics.

Insights into the potential role of BMSCs-exo delivered USP14 on SIRT1 deubiquitination in Staphylococcus aureus-induced model of osteomyelitis

Osteomyelitis resulting from a traumatic fracture is a recurrent and difficult-to-treat bone infection. Ubiquitin-specific protease 14 (USP14), a deubiquitinating enzyme, and Sirtuin-1 (SIRT1), an NAD+-dependent deacetylase, both play critical roles in regulating cellular processes, including inflammation. It has been discovered that exosomes originated from bone marrow mesenchymal stem cells (BMSCs-exo) can promote the repair and regeneration of bone fractures. In this study, we aimed to investigate the role of BMSCs-exo in osteoblast differentiation in osteomyelitis and the related molecular mechanisms. MC3T3-E1 cells induced with S. aureus were used as an in vitro model of osteomyelitis. BMSCs-exo were isolated and characterized using ultracentrifugation, transmission electron microscopy (TEM), and Western blot. RT-qPCR, Western blot, CCK-8, ALP staining, ELISA, and CO-IP were utilized to evaluate USP14 and SIRT1 levels, the osteogenic differentiation ability of MC3T3-E1 cells, and the deubiquitination level of SIRT1. Low expression of USP14 and SIRT1 was observed in the bone tissue of osteomyelitis patients. BMSCs-exo could upregulate the expression of USP14 and promote the expression of SIRT1 protein in the cell model of osteomyelitis. In addition, BMSCs-exo reduced the levels of inflammatory factors TNFα and IL-6, enhanced cell viability, promoted the expression of osteogenic differentiation markers RUNX2 and OCN in MC3T3-E1 cells, and improved cell osteogenic capacity. However, these trends were significantly reversed in MC3T3-E1 cells following treatment with BMSCs-exo transfected with si-USP14. Furthermore, knockdown of USP14 promoted SIRT1 ubiquitination and degradation, the process that was reversed by the proteasome inhibitor MG132, whereas USP14 overexpression inhibited SIRT1 ubiquitination. In MC3T3-E1 cells infected with S. aureus, BMSCs-exo delivers USP14, which may enhance SIRT1 deubiquitination and increase SIRT1 protein activity. This process inhibits inflammation and promotes osteogenesis, warranting further investigation into its mechanisms and in vivo efficacy.

MicroRNA functions in osteogenic differentiation of periodontal ligament stem cells: a scoping review

This scoping review aimed to describe the differential microRNA (miRNA) functions in osteogenic differentiation of periodontal ligament stem cells (PDLSCs), and then analyze the potential of applying PDLSCs and miRNAs in bone regeneration. The databases of PubMed, Google Scholar and EBSCO search were performed by the 4 themes, including periodontal ligament stem cells, miRNA, osteogenic differentiation, and tissue regeneration. The original articles described miRNA functions in osteogenic differentiation of PDLSCs were identified and selected for content analyze. The articles suggested that PDLSCs have high potential in bone regeneration because of their multipotency and immunomodulation. PDLSCs are conveniently accessible and obtained from extracted teeth. However, recent evidence reported that PDLSCs of various origins demonstrate differential characteristics of osteogenic differentiation. Exosomal miRNAs of PDLSCs demonstrate a regulatory role in tissue regeneration. The properties of PDLSCs associated to miRNA functions are altered in differential microenvironmental conditions such as infection, inflammation, high-glucose environment, or mechanical force. Therefore, these factors must be considered when inflamed PDLSCs are used for tissue regeneration. The results suggested inflammation-free PDLSCs harvested from the middle third of root surface provide the best osteogenic potential. Alternatively, the addition of miRNA as a bioactive molecule also increases the success of PDLSCs therapy to enhance their osteogenic differentiation. In conclusion, Exosome-derived miRNAs play a key role in PDLSCs osteogenic differentiation during tissue regeneration. While the success of PDLSCs in tissue regeneration could be uncertain by many factors, the use of miRNAs as an adjunct is beneficial for new bone regeneration.

Role of microRNA in Diabetic Osteoporosis

Diabetic osteoporosis (DOP), a complication associated with diabetes mellitus (DM), is a metabolic bone disorder characterized by a reduction in bone mass per unit volume, impaired bone tissue microarchitecture, heightened bone fragility, and increased susceptibility to fractures. Individuals with diabetes exhibit a significantly greater incidence of osteoporosis and related fractures than those without diabetes. These fractures present a significant challenge in terms of the healing process and can result in severe consequences, including fatalities. MicroRNAs (miRNAs), a class of noncoding RNAs, play a pivotal role in numerous human diseases and are implicated in the pathogenesis of DOP. This review initially elucidates the essential role of miRNAs in the pathogenesis of DOP. Next, we emphasize the potential significance of miRNAs as valuable biomarkers for diagnosing DOP and predicting DOP-related fractures. Furthermore, we explore the involvement of miRNAs in managing DOP through various pathways, including conventional pharmaceutical interventions and exercise therapy. Importantly, miRNAs exhibit potential as targeted therapeutic agents for effectively treating DOP. Finally, we highlight the use of novel materials and exosomes for miRNA delivery, which has significant advantages in the treatment of DOP and overcomes the limitations associated with miRNA delivery.

Exosomes to exosome-functionalized scaffolds: a novel approach to stimulate bone regeneration

Bone regeneration is a complex biological process that relies on the orchestrated interplay of various cellular and molecular events. Bone tissue engineering is currently the most promising method for treating bone regeneration. However, the immunogenicity, stable and cell quantity of seed cells limited their application. Recently, exosomes, which are small extracellular vesicles released by cells, have been found to effectively address these problems and better induce bone regeneration. Meanwhile, a growing line of research has shown the cargos of exosomes may provide effective therapeutic and biomarker tools for bone repair, including miRNA, lncRNA, and proteins. Moreover, engineered scaffolds loaded with exosomes can offer a cell-free bone repair strategy, addressing immunogenicity concerns and providing a more stable functional performance. Herein, we provide a comprehensive summary of the role played by scaffolds loaded with exosomes in bone regeneration, drawing on a systematic analysis of relevant literature available on PubMed, Scopus, and Google Scholar database.

The interactions of macrophages, lymphocytes, and mesenchymal stem cells during bone regeneration

Bone regeneration and repair are crucial to ambulation and quality of life. Factors such as poor general health, serious medical comorbidities, chronic inflammation, and ageing can lead to delayed healing and nonunion of fractures, and persistent bone defects. Bioengineering strategies to heal bone often involve grafting of autologous bone marrow aspirate concentrate (BMAC) or mesenchymal stem cells (MSCs) with biocompatible scaffolds. While BMAC shows promise, variability in its efficacy exists due to discrepancies in MSC concentration and robustness, and immune cell composition. Understanding the mechanisms by which macrophages and lymphocytes - the main cellular components in BMAC - interact with MSCs could suggest novel strategies to enhance bone healing. Macrophages are polarized into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, and influence cell metabolism and tissue regeneration via the secretion of cytokines and other factors. T cells, especially helper T1 (Th1) and Th17, promote inflammation and osteoclastogenesis, whereas Th2 and regulatory T (Treg) cells have anti-inflammatory pro-reconstructive effects, thereby supporting osteogenesis. Crosstalk among macrophages, T cells, and MSCs affects the bone microenvironment and regulates the local immune response. Manipulating the proportion and interactions of these cells presents an opportunity to alter the local regenerative capacity of bone, which potentially could enhance clinical outcomes.

Analysis of Circulating miRNA Expression Profiles in Type 2 Diabetes Patients with Diabetic Foot Complications

Type 2 diabetes mellitus (T2DM) is associated with various complications, including diabetic foot, which can lead to significant morbidity and mortality. Non-healing foot ulcers in diabetic patients are a major risk factor for infections and amputations. Despite conventional treatments, which have limited efficacy, there is a need for more effective therapies. MicroRNAs (miRs) are small non-coding RNAs that play a role in gene expression and have been implicated in diabetic wound healing. miR expression was analyzed through RT-qPCR in 41 diabetic foot Mexican patients and 50 controls. Diabetic foot patients showed significant increases in plasma levels of miR-17-5p (p = 0.001), miR-191-5p (p = 0.001), let-7e-5p (p = 0.001), and miR-33a-5p (p = 0.005) when compared to controls. Elevated levels of miR-17, miR-191, and miR-121 correlated with higher glucose levels in patients with diabetic foot ulcers (r = 0.30, p = 0.004; r = 0.25, p = 0.01; and r = 0.21, p = 0.05, respectively). Levels of miR-17 showed the highest diagnostic potential (AUC 0.903, p = 0.0001). These findings underscore the possible role of these miRs in developing diabetes complications. Our study suggests that high miR-17, miR-191, and miR-121 expression is strongly associated with higher glucose levels and the development of diabetic foot ulcers.

Engineering extracellular vesicles for ROS scavenging and tissue regeneration

Stem cell therapy holds promise for tissue regeneration, yet significant challenges persist. Emerging as a safer and potentially more effective alternative, extracellular vesicles (EVs) derived from stem cells exhibit remarkable abilities to activate critical signaling cascades, thereby facilitating tissue repair. EVs, nano-scale membrane vesicles, mediate intercellular communication by encapsulating a diverse cargo of proteins, lipids, and nucleic acids. Their therapeutic potential lies in delivering cargos, activating signaling pathways, and efficiently mitigating oxidative stress-an essential aspect of overcoming limitations in stem cell-based tissue repair. This review focuses on engineering and applying EVs in tissue regeneration, emphasizing their role in regulating reactive oxygen species (ROS) pathways. Additionally, we explore strategies to enhance EV therapeutic activity, including functionalization and incorporation of antioxidant defense proteins. Understanding these molecular mechanisms is crucial for optimizing EV-based regenerative therapies. Insights into EV and ROS signaling modulation pave the way for targeted and efficient regenerative therapies harnessing the potential of EVs.

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

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