Bone Marrow Mesenchymal Stem Cells Research Articles

Injectable acellular matrix microgel assembly with stem cell recruitment and chondrogenic differentiation functions promotes microfracture-based articular cartilage regeneration

Articular cartilage repair and regeneration is still a significant challenge despite years of research. Although microfracture techniques are commonly used in clinical practice, the newborn cartilage is usually fibrocartilage rather than hyaline cartilage, which is mainly attributed to the inadequate microenvironment for effectively recruiting, anchoring, and inducing bone marrow mesenchymal stem cells (BMSCs) to differentiate into hyaline cartilage. This paper introduces a novel cartilage acellular matrix (CACM) microgel assembly with excellent microporosity, injectability, tissue adhesion, BMSCs recruitment and chondrogenic differentiation capabilities to improve the microfracture-based articular cartilage regeneration. Specifically, the sustained release of simvastatin (SIM) from the SIM@CACM microgel assembly efficiently recruits BMSCs in the early stage of cartilage regeneration, while the abundant interconnected micropores and high specific area assure the quick adhesion, proliferation and infiltration of BMSCs. Additionally, the active factors within the CACM matrix, appropriate mechanical properties of the microgel assembly, and excellent tissue adhesion provide a conductive environment for the continuous chondrogenic differentiation of BMSCs into hyaline cartilage. Owing to the synergistic effect of the above-mentioned factors, good articular cartilage repair and regeneration is achieved.

Construction of an interactome network among circRNA-miRNA-mRNA reveals new biomarkers in hBMSCs osteogenic differentiation

Human bone marrow mesenchymal stem cells (hBMSCs) are adult stem cells residing in the bone marrow, characterized by their capacity for multi-directional differentiation, self-renewal, migration, and engraftment. Serving as seed cells, BMSCs play a pivotal role in the regeneration of bone defects. Hence, investigating the transcription factors and signaling pathways involved in the regulation of osteogenic differentiation in BMSCs holds significant importance. Recent research has unveiled that certain circular RNAs (circRNAs) can function as molecular sponges, influencing the osteogenic differentiation process of mesenchymal stem cells. However, many circRNAs remain undiscovered, and their precise mechanisms remain elusive. Therefore, the objective of this study is to construct an osteogenic differentiation-related circRNA-miRNA-mRNA network in hBMSCs. Subsequently, through bioinformatics analysis, we constructed a ceRNA network related to the osteogenic differentiation ability of hBMSCs, comprising 22 circRNAs, 17 miRNAs, and 15 mRNAs. The potential circRNA-miRNA-mRNA axes, including the role of hsa_circ_0001600 in promoting the osteogenic differentiation of hBMSCs through the targeted regulation of hsa-miR-542-3p, were validated through in vitro experiments.

A MnO2 nanosheets doping double crosslinked hydrogel for cartilage defect repair through alleviating inflammation and guiding chondrogenic differentiation

The inflammatory microenvironment and inferior chondrogenesis are major symptoms after cartilage defect. Although various modifications strategies associated with hydrogels exhibit remarkable capacity of pro-cartilage regeneration, the adverse effect by prolonging inflammation is still formidable to hamper potential biomedical applications of different hydrogel implants. Herein, inspired by the repair microenvironment of articular cartilage defects, an injectable, immunomodulatory, and chondrogenic L-MNS-CMDA hydrogel is prepared through grafting vinyl and catechol groups to chitosan macromolecules using amide reaction, then further loading MnO2 nanosheets (MNS). The double crosslinking of photopolymerization and catechol oxidative polymerization endows L-MNS-CMDA hydrogel with preferable mechanical property, affording a suitable mechanical support for cartilage defect repair. Additionally, the robust tissue adhesion capability stemming from catechol groups guarantees the long-term retention of the hydrogel in the defect site. Meanwhile, L-MNS-CMDA hydrogel decomposes exogenous and intracellular H2O2 into O2 and H2O, to effectively alleviate cellular oxidative stress caused by long-term hypoxia. Under the synergies of catechol groups and MNS, L-MNS-CMDA hydrogel not only inhibits macrophages polarizing into M1 phenotype, but encourages them turn into M2 phenotype, thereby, reconstructing an immunization friendly microenvironment to ultimately enhance cartilage regeneration. Predictably, the hydrogel markedly induces rat bone marrow mesenchymal stem cells differentiating into chondrocytes by expressing abundant glycosaminoglycan and type II collagen. A cartilage defect model of rat knee joint indicates that L-MNS-CMDA hydrogel visually regulate the early inflammatory response of post-implantation, and facilitate cartilage regeneration and recovery of joint function after 12 weeks of post-implantation. All in all, this multifunctional L-MNS-CMDA hydrogel exhibits superior immunomodulatory and chondrogenic properties, holding immense clinical potential in the treatment of cartilage defects.

Dual-Function Femtosecond Laser: β-TCP Structuring and AgNP Synthesis via Photoreduction with Azorean Green Tea for Enhanced Osteointegration and Antibacterial Properties.

β-Tricalcium phosphate (β-TCP) is a well-established biomaterial for bone regeneration, highly regarded for its biocompatibility and osteoconductivity. However, its clinical efficacy is often compromised by susceptibility to bacterial infections. In this study, we address this limitation by integrating femtosecond (fs)-laser processing with the concurrent synthesis of silver nanoparticles (AgNPs) mediated by Azorean green tea leaf extract (GTLE), which is known for its rich antioxidant and anti-inflammatory properties. The fs laser was employed to modify the surface of β-TCP scaffolds by varying scanning velocities, fluences, and patterns. The resulting patterns, formed at lower scanning velocities, display organized nanostructures, along with enhanced roughness and wettability, as characterized by Scanning Electron Microscopy (SEM), optical profilometry, and contact angle measurements. Concurrently, the femtosecond laser facilitated the photoreduction of silver ions in the presence of GTLE, enabling the efficient synthesis of small, spherical AgNPs, as confirmed by UV-vis spectroscopy, Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). The resulting AgNP-embedded β-TCP scaffolds exhibited a significantly improved cell viability and elongation of human bone marrow mesenchymal stem cells (hBM-MSCs), alongside significant antibacterial activity against Staphylococcus aureus (S. aureus). This study underscores the transformative potential of combining femtosecond laser surface modification with GTLE-mediated AgNP synthesis, presenting a novel and effective strategy for enhancing the performance of β-TCP scaffolds in bone-tissue engineering.

A monoallelic variant in CCN2 causes an autosomal dominant spondyloepimetaphyseal dysplasia with low bone mass

Cellular communication network factor 2 (CCN2) is a secreted extracellular matrix-associated protein, and its aberrantly increased expression has been implicated in a diversity of diseases involving pathological processes of fibrosis, chronic inflammation, or tissue injury, which has promoted the evaluation of CCN2 as therapeutic targets for multiple disorders. However, human phenotypes associated with CCN2 deficiency have remained enigmatic; variants in CCN2 have not yet been associated with a human phenotype. Here, we collected families diagnosed with spondyloepimetaphyseal dysplasia (SEMD), and screened candidate pathogenic genes for families without known genetic causes using next-generation sequencing. We identified a monoallelic variant in signal peptide of CCN2 (NM_001901.2: c.65 G > C [p.Arg22Pro]) as the cause of SEMD in 14 subjects presenting with different degree of short stature, premature osteoarthritis, and osteoporosis. Affected subjects showed decreased serum CCN2 levels. Cell lines harboring the variant displayed decreased amount of CCN2 proteins in culture medium and an increased intracellular retention, indicating impaired protein secretion. And the variant weakened the stimulation effect of CCN2 on osteogenesis of bone marrow mesenchymal stem cells. Zebrafish ccn2a knockout model and osteoblast lineage-specific Ccn2-deficient mice (Ccn2fl/fl;Prx1Cre) partially recapitulated the phenotypes including low bone mass observed in affected subjects. Pathological mechanism implicated in the skeletal abnormality in Ccn2fl/fl;Prx1Cre mice involved decreased bone formation, increased bone resorption, and abnormal growth plate formation. Collectively, our study indicate that monoallelic variants in CCN2 lead to a human inherited skeletal dysplasia, and highlight the critical role of CCN2 in osteogenesis in human.

Low-intensity pulsed ultrasound regulates bone marrow mesenchymal stromal cells differentiation and inhibits bone loss by activating the IL-11-Wnt/β-catenin signaling pathway

BackgroundOsteoporosis (OP) is a common metabolic bone disease. Low-intensity pulsed ultrasound (LIPUS) can effectively promote bone formation and fracture healing. The Wnt/β-catenin signaling pathway is crucial for regulating bone homeostasis and bone diseases, and its downregulation is one of the main mechanisms of osteoporosis pathogenesis. Interleukin-11 (IL-11), which is regulated by mechanical stress, is a key factor in bone remodeling. Here, we investigated the optimal intervention parameters for LIPUS, the relationships among LIPUS, IL-11, and the Wnt/β-catenin signaling pathway, and the effects of LIPUS on bone loss and potential molecular mechanisms in ovariectomized (OVX) mice. MethodsBone marrow mesenchymal stromal cells (BMSCs) were subjected to LIPUS intervention for 0, 10, or 20 min to determine the optimal intervention time. The mediating role of IL-11 in LIPUS intervention was explored through IL-11 knockdown and overexpression. Finally, animal experiments were conducted to investigate the in vivo therapeutic effects of LIPUS. ResultsThe optimal intervention time for LIPUS was 20 min. LIPUS promoted IL-11 expression and upregulated the Wnt/β-catenin signaling pathway, thereby promoting osteogenic differentiation and inhibiting adipogenic differentiation of BMSCs. IL-11 mediates the regulation of the Wnt/β-catenin signaling pathway by LIPUS. Additionally, LIPUS effectively improved the bone microstructure in ovariectomized mice, inhibited bone loss, promoted IL-11 expression in bone tissue, and activated the Wnt/β-catenin signaling pathway in the femur. ConclusionLow-intensity pulsed ultrasound can regulate BMSCs differentiation and inhibit bone loss by promoting IL-11 expression and activating the Wnt/β-catenin signaling pathway.

IL-4 promotes chondrogenesis of bone marrow mesenchymal stem cellsand blockade of IL-4Rα retards the endochondral ossification during rat embryonic bone development.

Interleukin-4 (IL-4)/IL-4 receptor alpha (IL-4Rα) signalling pathways play important roles in the complex process of bone formation and bone remodelling. However, whether IL-4/IL-4Rα participates in skeletogenesis during embryonic development is not completely understood. We used the anti-IL-4Rα monoclonal antibody (anti-IL-4Rα mAb) as a powerful investigational tool to evaluate the potential roles of IL-4/IL-4Rα in the chondrogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) in vitro. Simultaneously, we explored the effect of IL-4/IL-4Rα on bone ossification during rat embryo-fetal development. In this study, we found that, compared to the control group, IL-4 can significantly promote the chondrogenic differentiation of BMSCs. Furthermore, following exposure to anti-IL-4Rα mAb in pregnant rats, unexpected phenomena were observed in fetal bone development, including non-ossification of the fetal sternum, an incomplete ossification centre in long bones and a reduced number of ossification points in digit (toe) bones. To further investigate the underlying mechanism of the phenotype, we studied the rat sternum as the target organ, starting from different time points of sternum development in the embryonic stage. The results indicated that the retardation mainly occurred in the middle and late stages of embryonic development. This retardation was characterized by the inhibition of the differentiation process of mesenchymal stem cells into chondrocytes, resulting in reduced angiogenesis near the ossification centre, failure of osteoblasts to invade the centre of the cartilage body with the blood vessels and delayed formation of the primary ossification centre (POC). Overall, our study demonstrated the significant function of IL-4/IL-4Rα in chondrogenic differentiation of BMSCs and bone ossification during embryo-fetal development.

Preliminary study of the role of histone deacetylase (HDAC) in steroid-induced avascular necrosis of the femoral head induced by BMSC adipogenic differentiation

Our previous research revealed a close association between the acetylation of peroxisome proliferator-activated receptor γ (PPARγ) histone H3K27 and the adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). We preliminarily explored the epigenetic mechanism of steroid-induced avascular necrosis of the femoral head (SANFH) development, but the specific histone deacetylase (HDAC) involved in this regulatory process remains unknown. In this study, we combined cell, animal, and clinical specimen experiments to screen for specific HDAC genes that could regulate BMSC adipogenic differentiation and to explore their roles. The results showed that dexamethasone (DEX) significantly exacerbated the imbalance between the adipogenic and osteogenic differentiation of BMSCs, and there were differences in HDAC expression in the adipogenic differentiation cell models, with histone deacetylase 10 (HDAC10) showing the most significant decrease in expression. Subsequent use of a chromatin immunoprecipitation assay kit and quantitative polymerase chain reaction (ChIP‒qPCR) revealed a decrease in HDAC10 expression at predicted potential sites within the PPARγ promoter, indicating a significant decrease in HDAC10 enrichment in the PPARγ promoter region of BMSCs, thereby promoting sustained PPARγ expression. Additionally, immunohistochemistry of samples collected from mice and humans with SANFH and normal femoral heads revealed an imbalance between adipogenic and osteogenic differentiation in the necrotic area of femoral heads, with a significant decrease in the relative expression of HDAC10 in the necrotic area of femoral heads with SANFH. In summary, we speculate that HDAC10 affects the progression of SANFH by regulating BMSC adipogenic differentiation, a process possibly related to PPARγ histone acetylation. These findings provide a promising direction for the treatment of SANFH.Graphical abstract

Research on silk fibroin composite materials for wet environment applications

Silk fibroin material has good mechanical properties and excellent biocompatibility as a natural biomaterial with broad application prospects. However, by applying regenerated silk fibroin in biomaterials with high mechanical strength requirements, such as bone materials, there are problems, such as insufficient mechanical properties and a significant decline in mechanical properties in the wet state. In this report, a silk fibroin composite that maintains high strength in the wet state was prepared by adding nano-SiO2 as a nano-strengthening filler to the silk protein material and employing an epoxy-based silane coupling agent KH560 as an interfacial reinforcing agent. The results showed that the dry compressive strength of the composite material was substantially increased compared with that of the pure silk protein material; the wet compressive strength was significantly increased compared with that of the pure silk fibroin material, and the decrease of the mechanical properties in the wet state was low. The cytotoxicity test results of the composites showed that the materials were not cytotoxic. Rat bone marrow mesenchymal stem cells were cultured on the surface of the composites, and the results indicated that the composites could support the proliferation of bone marrow mesenchymal stem cells. The silk fibroin nanocomposites developed in this work can be applied as bone repair materials.

Extracellular vesicles from human cardiac stromal cells up-regulate cardiomyocyte protective responses to hypoxia

BackgroundCell therapy can protect cardiomyocytes from hypoxia, primarily via paracrine secretions, including extracellular vesicles (EVs). Since EVs fulfil specific biological functions based on their cellular origin, we hypothesised that EVs from human cardiac stromal cells (CMSCLCs) obtained from coronary artery bypass surgery may have cardioprotective properties.ObjectivesThis study characterises CMSCLC EVs (C_EVs), miRNA cargo, cardioprotective efficacy and transcriptomic modulation of hypoxic human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). C_EVs are compared to bone marrow mesenchymal stromal cell EVs (B_EVs) which are a known therapeutic EV type.MethodsCells were characterised for surface markers, gene expression and differentiation potential. EVs were compared for yield, phenotype, and ability to protect hiPSC-CMs from hypoxia/reoxygenation injury. EV dose was normalised by both protein concentration and particle count, allowing direct comparison. C_EV and B_EV miRNA cargo was profiled and RNA-seq was performed on EV-treated hypoxic hiPSC-CMs, then data were integrated by multi-omics. Confirmatory experiments were carried out using miRNA mimics.ResultsAt the same dose, C_EVs were more effective than B_EVs at protecting CM integrity, reducing apoptotic markers, and cell death during hypoxia. While C_EVs and B_EVs shared 70–77% similarity in miRNA content, C_EVs contained unique miRNAs, including miR-202-5p, miR-451a and miR-142-3p. Delivering miRNA mimics confirmed that miR-1260a and miR-202/451a/142 were cardioprotective, and the latter upregulated protective pathways similar to whole C_EVs.ConclusionsThis study demonstrates the potential of cardiac tissues, routinely discarded following surgery, as a valuable source of EVs for myocardial infarction therapy. We also identify miR-1260a as protective of CM hypoxia.

The Biomimetic Electrical Stimulation System Inducing Osteogenic Differentiations of BMSCs.

Electrical stimulation has been used clinically as an adjunct therapy to accelerate the healing of bone defects, and its mechanism requires further investigations. The complexity of the physiological microenvironment makes it challenging to study the effect of electrical signal on cells alone. Therefore, an artificial system mimicking cell microenvironment in vitro was developed to address this issue. In this work, a novel electrical stimulation system was constructed based on polypyrrole nanowires (ppyNWs) with a high aspect ratio. Synthesized ppyNWs formed a conductive network in the composited hydrogel which contained modified gelatin with methacrylate, providing a conductive cell culture matrix for bone marrow mesenchymal stem cells. The dual-network conductive hydrogel had improved mechanical, electrical, and hydrophilic properties. It was able to imitate the three-dimensional structure of the cell microenvironment and allowed adjustable electrical stimulations in the following system. This hydrogel was integrated with cell culture plates, platinum electrodes, copper wires, and external power sources to construct the artificial electrical stimulation system. The optimum voltage of the electrical stimulation system was determined to be 2 V, which exhibited remarkable biocompatibility. Moreover, this system had significant promotion in cell spreading, osteogenic makers, and bone-related gene expression of stem cells. RNA-seq analysis revealed that osteogenesis was correlated to Notch, BMP/Smad, and calcium signal pathways. It was proven that this biomimetic system could regulate the osteogenesis procedure, and it provided further information about how the electrical signal regulates osteogenic differentiations.

Angiogenesis-osteogenesis coupling and anti-osteoclastogenesis zoledronate intermixed calcium silicate metal-organic/inorganic hybrid coating on biodegradable zinc-based intramedullary nails for osteoporotic fracture healing

Osteoporotic (OP) fractures remain a tough clinical challenge owing to their impaired healing outcome, which requires novel biomaterials with osteogenicity for effective healing. Metallic zinc (Zn) is attracting increasing attention for biodegradable intramedullary nails (IMNs) for OP fracture healing thanks to their comprehensive mechanical properties, biosafety, and bioactivity. However, the multiple biofunctions required for OP fracture healing have not been fully met by Zn. Herein, a zoledronate (ZA)-mediated calcium-zinc silicate (Ca(Zn)Si) metal-organic/inorganic hybrid coating was fabricated on Zn-based IMN by coordination chemistry driven via interactions between ZA and Ca2+/Zn2+ as well as in-situ directional growth of Ca(Zn)Si phase. The ZA&Ca(Zn)Si hybrid coating exhibited a homogeneous micro/nanostructure with a granular morphology, which prevented premature fracture failure of IMN in rat femur by ameliorating corrosion mode and decreasing degradation rate of the Zn matrix. More importantly, this hybrid coating enabled sustained release of Zn2+/Ca2+/Si4+ and ZA in the long term, achieving a remarkable effect on vascularized bone regeneration. The coated IMN enhanced angiogenesis–osteogenesis coupling through autocrine and paracrine effects between endothelial cells and bone marrow mesenchymal stem cells. Osteoclastogenesis was repressed by Zn2+ and ZA. This approach offers a new strategy for surface-engineering of biodegradable metals for bone fracture healing.

Biologic Correlates of Radiologic Features of Systemic Sclerosis Interstitial Lung Disease

Background and objectivesThe extent and pattern of radiological features (e.g., fibrosis, ground glass) can influence treatment approaches for systemic sclerosis-related interstitial lung disease (SSc-ILD). However, the pathobiology underlying these radiologic features is poorly understood and warrants further investigation.MethodsSixty-eight proteins were measured in bronchoalveolar lavage (BAL) fluid from 103 SSc-ILD participants in Scleroderma Lung Study I. Quantitative image analysis calculated the extent of fibrosis (QLF) and ground glass opacity (QGG) from concurrent high-resolution computerized tomography (HRCT) scans. The relationship between BAL proteins and quantitative HRCT scores was assessed by univariate and multivariate analyses.ResultsQLF scores correlated weakly with the extent of QGG, suggesting two distinct processes. In a univariate analysis, 25 proteins from several biologic pathways correlated with QLF scores, including pro-fibrotic factors, tissue remodeling proteins, proteins involved in monocyte/macrophage migration and activation, and proteins linked to inflammation and immune regulation. In contrast, QGG scores correlated with only 6 proteins of which four were unique and related to granulocyte activation, mobilization of bone marrow mesenchymal stem cells, and activation of T cells, B cells, macrophages and eosinophils. In the multivariate models, IL-4, CCL7, receptor activator of NF-κB, and tumor necrosis factor alpha were independently associated with QLF, whereas, IFN-γ was independently associated with QGG.InterpretationQLF and QGG represent distinct radiologic features of SSc-ILD, a conclusion reinforced by the presence of different biologic pathways present within BAL fluid that associate with each. The identified proteins and related biologic pathways may represent important therapeutic targets.

Exosomal therapy mitigates silver nanoparticles-induced neurotoxicity in rats

Introduction Our investigation aims to appraise the neuroprotective impact of Bone Marrow-Mesenchymal Stem Cells (BM-MSCs) derived exosomes against Ag NPs-inducing neurotoxicity in rats. Materials and Methods Twenty-four albino rats were divided into 3 groups. Group I (control negative), Group II (intraperitoneally injected with Ag NPs for 28 days, whereas Group III (intraperitoneally injected with Ag NP and BM-MSCs derived exosomes. Results There was a marked elevation of Malondialdehyde (MDA) along with a reduction of brain antioxidants, Gamma-aminobutyric acid (GABA) and Monoamine Oxidase (MAO) in the Ag NPs receiving group. Ag NPs upregulated c-Jun N-terminal Kinases (JNK) genes and c-Myc and downregulated the tissue inhibitors of metalloproteinases (TIMP-1) and Histone deacetylase 1 (HDAC1) genes. Otherwise, the co-treatment of BM-MSCs derived exosomes with Ag NPs could markedly increase the rat’s body weight, activity and learning while, decreasing anxiety, restoring all the toxicological parameters and improving the microscopic appearance of different brain areas. Conclusion BM-MSCs-derived exosomes downregulated both apoptotic and inflammatory mediators and upregulated the antiapoptotic genes. BM-MSCs-derived exosomes exhibit a great therapeutic effect against the neurotoxic effects of Ag NPs.

Biomimetic mineralization of collagen from fish scale to construct a functionally gradient lamellar bone-like structure for guided bone regeneration

Wide used guided bone regeneration (GBR) membrane materials, such as collagen, Teflon, and other synthesized polymers, present a great challenge in term of integrating the mechanical property and degradation rate when addressing critical bone defects. Therefore, inspired by the distinctive architecture of fish scales, this study utilized epigallocatechin gallate to modify decellularized fish scales following biomimetic mineralization to fabricate a GBR membrane that mimics the structure of lamellar bone. The structure, physical and chemical properties, and biological functions of the novel GBR membrane were evaluated. Results indicate that the decellularized fish scale with 5 remineralization cycles (5R-E-DCFS) exhibited a composite and structure similar to natural bone and had a special functionally gradient mineral contents character, demonstrating excellent mechanical properties, hydrophilicity, and degradation properties. In vitro, the 5R-E-DCFS membrane exhibited excellent cytocompatibility promoting Sprague-Dawley (SD) rat bone marrow mesenchymal stem cell proliferation and differentiation up-regulating the expression of osteogenic-related genes and proteins. Furthermore, in vivo, the 5R-E-DCFS membrane promoted the critical skull bone defects of SD rats repairment and regeneration. Therefore, this innovative biomimetic membrane holds substantial clinical potential as an ideal GBR membrane with mechanical properties for space-making and suitable degradation rate for bone regeneration to manage bone defects.

Extracellular vesicles from inflammatory-stimulated BMSCs ameliorate osteoarthritis via Rpl14 mediated synovial macrophage polarization

Bone marrow mesenchymal stem cells (BMSCs) and extracellular vesicles (EVs) were considered promising methods for the treatment of diverse diseases, including osteoarthritis (OA). However, the role of inflammatory-stimulated BMSCs driven EVs (iBMSC-EVs) in OA remains unclear. This study aims to investigate the potential function of iBMSC-EVs in ameliorating OA and its underlying molecular mechanism. In this study, EVs were isolated from inflammatory-stimulated BMSCs and destabilization of the medial meniscus (DMM) surgery was performed to induce knee OA model in mice. Micro-CT, H&E Staining, Safranin O-Fast Green Staining and immunofluorescence were used to examine the in vivo therapeutic effect of iBMSC-EVs on OA. Public single-cell RNA-seq data was downloaded and bulk RNA-seq data was acquired to identify critical genes promoted by iBMSC-EVs in macrophage polarization during OA. Real-time quantitative polymerase chain reaction (RT-qPCR), western blot, enzyme-linked immunosorbent assay (ELISA), cell counting kit-8 (CCK-8), transwell and scratch assays were used to further confirm the in vitro effect of iBMSC-EVs on macrophage polarization and chondrocyte proliferation, migration, as well as ECM anabolism and catabolism. In vivo experiments demonstrated that iBMSC-EVs could alleviate OA in mice and promote the reprogramming of M1 macrophages towards an M2 phenotype. RNA-Seq and scRNA-Seq analyses indicated that iBMSC-EVs altered the expression profiles of OA-related genes, with Rpl14 identified as a critical gene regulating macrophage reprogramming in OA. In vivo and in vitro experiments further confirmed that iBMSC-EVs, by downregulating Rpl14 expression, promoted M1 macrophage reprogramming to M2, facilitating chondrocyte proliferation and migration, inhibiting ECM degradation and ultimately alleviating OA progression. In conclusion, our data revealed the substantive role of iBMSC-EVs in ameliorating OA progression via Rpl14 mediated synovial macrophage polarization, presenting a promising therapeutic method for the treatment of OA.

Alendronate-functionalized polymeric micelles target icaritin to bone for mitigating osteoporosis in a rat model

Formulating drugs into nanoparticles that target sites of disease can lead to strong therapeutic effects with lower doses of drugs and lower rates of off-target adverse effects. Few ways to target drugs to bone have been described, hampering the treatment of osteoporosis. Here we exploit the ability of alendronate to bind tightly to hydroxyapatite in bone as a tactic to target polymeric micelles loaded with the plant flavonoid icaritin to osteoporotic lesions. The traditional Chinese medicine icaritin, from Herba Epimedii, has previously been shown to inhibit adipogenesis and enhance osteogenesis by bone mesenchymal stem cells, but the compound on its own persists only briefly in the bloodstream. Our delivery system led to stronger inhibition of adipogenesis and activation of osteogenesis in a rat model of osteoporosis than when the icaritin-loaded micelles lacked alendronate. These results establish the feasibility of using alendronate to target osteogenic phytomolecules to sites of bone injury, which may guide the development of effective therapies against osteoporosis and, by extension, other bone disorders.

USP26 Combats Age-Related Declines in Self-Renewal and Multipotent Differentiation of BMSC by Maintaining Mitochondrial Homeostasis.

Age-related declines in self-renewal and multipotency of bone marrow mesenchymal stem cells (BMSCs) limit their applications in tissue engineering and clinical therapy. Thus, understanding the mechanisms behind BMSC senescence is crucial for maintaining the rejuvenation and multipotent differentiation capabilities of BMSCs. This study reveals that impaired USP26 expression in BMSCs leads to mitochondrial dysfunction, ultimately resulting in aging and age-related declines in the self-renewal and multipotency of BMSCs. Specifically, decreased USP26 expression results in decreased protein levels of Sirtuin 2 due to its ubiquitination degradation, which leads to mitochondrial dysfunction in BMSCs and ultimately resulting in aging and age-related declines in self-renewal and multilineage differentiation potentials. Additionally, decreased USP26 expression in aging BMSCs is a result of dampened hypoxia-inducible factor 1α (HIF-1α) expression. HIF-1α facilitates USP26 transcriptional expression by increasing USP26 promoter activity through binding to the -191 - -198 bp and -262 - -269 bp regions on the USP26 promoter. Therefore, the identification of USP26 as being correlated with aging and age-related declines in self-renewal and multipotency of BMSCs, along with understanding its expression and action mechanisms, suggests that USP26 represents a novel therapeutic target for combating aging and age-related declines in the self-renewal and multipotent differentiation of BMSCs.

SLAMF8 regulates osteogenesis and adipogenesis of bone marrow mesenchymal stem cells via S100A6/Wnt/β-catenin signaling pathway

BackgroundThe inflammatory microenvironment plays an essential role in bone healing after fracture. The signaling lymphocytic activation molecule family (SLAMF) members deeply participate in inflammatory response and make a vast difference.MethodsWe identified SLAMF8 in GEO datasets (GSE129165 and GSE176086) and co-expression analyses were performed to define the relationships between SLAMF8 and osteogenesis relative genes (RUNX2 and COL1A1). In vitro, we established SLAMF8 knockdown and overexpression mouse bone marrow mesenchymal stem cells (mBMSCs) lines. qPCR, Western blot, ALP staining, ARS staining, Oil Red O staining and Immunofluorescence analyses were performed to investigate the effect of SLAMF8 in mBMSCs osteogenesis and adipogenesis. In vivo, mice femoral fracture model was performed to explore the function of SLAMF8.ResultsSLAMF8 knockdown significantly suppressed the expression of osteogenesis relative genes (RUNX2, SP7 and COL1A1), ALP activity and mineral deposition, but increased the expression of adipogenesis relative genes (PPARγ and C/EBPα). Additionally, SLAMF8 overexpression had the opposite effects. The role SLAMF8 played in mBMSCs osteogenic and adipogenic differentiation were through S100A6 and Wnt/β-Catenin signaling pathway. Moreover, SLAMF8 overexpression mBMSCs promoted the healing of femoral fracture.ConclusionsSLAMF8 promotes osteogenesis and inhibits adipogenesis of mBMSCs via S100A6 and Wnt/β-Catenin signaling pathway. SLAMF8 overexpression mBMSCs effectively accelerate the healing of femoral fracture in mice.

Mechanism research of elastic fixation promoting fracture healing based on proteomics and fracture microenvironment.

This study aimed to demonstrate the promoting effect of elastic fixation on fracture, and further explore its mechanism at the gene and protein expression levels. A closed tibial fracture model was established using 12 male Japanese white rabbits, and divided into elastic and stiff fixation groups based on different fixation methods. Two weeks after the operation, a radiograph and pathological examination of callus tissue were used to evaluate fracture healing. Then, the differentially expressed proteins (DEPs) were examined in the callus using proteomics. Finally, in vitro cell experiments were conducted to investigate hub proteins involved in this process. Mean callus volume was larger in the elastic fixation group (1,755 mm3 (standard error of the mean (SEM) 297)) than in the stiff fixation group (258 mm3 (SEM 65)). Pathological observation found that the expression levels of osterix (OSX), collagen, type I, alpha 1 (COL1α1), and alkaline phosphatase (ALP) in the callus of the elastic fixation group were higher than those of the stiff fixation group. The protein sequence of the callus revealed 199 DEPs, 124 of which were highly expressed in the elastic fixation group. In the in vitro study, it was observed that a stress of 200 g led to upregulation of thrombospondin 1 (THBS1) and osteoglycin (OGN) expression in bone marrow mesenchymal stem cells (BMSCs). Additionally, these genes were found to be upregulated during the osteogenic differentiation process of the BMSCs. Elastic fixation can promote fracture healing and osteoblast differentiation in callus, and the ability of elastic fixation to promote osteogenic differentiation of BMSCs may be achieved by upregulating genes such as THBS1 and OGN.