An adaptive biodegradable zinc alloy with bidirectional regulation of bone homeostasis for treating fractures and aged bone defects.

Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism. Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration. Therefore, designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge. Here, this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis, which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway. The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model. Furthermore, in an aged postmenopausal rat femoral condyle defect model, 3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism, enabling personalized bone defect repair. These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.

D-mannose alleviates intervertebral disc degeneration through glutamine metabolism.

BACKGROUND: Intervertebral disc degeneration (IVDD) is a multifaceted condition characterized by heterogeneity, wherein the balance between catabolism and anabolism in the extracellular matrix of nucleus pulposus (NP) cells plays a central role. Presently, the available treatments primarily focus on relieving symptoms associated with IVDD without offering an effective cure targeting its underlying pathophysiological processes. D-mannose (referred to as mannose) has demonstrated anti-catabolic properties in various diseases. Nevertheless, its therapeutic potential in IVDD has yet to be explored. METHODS: The study began with optimizing the mannose concentration for restoring NP cells. Transcriptomic analyses were employed to identify the mediators influenced by mannose, with the thioredoxin-interacting protein (Txnip) gene showing the most significant differences. Subsequently, small interfering RNA (siRNA) technology was used to demonstrate that Txnip is the key gene through which mannose exerts its effects. Techniques such as colocalization analysis, molecular docking, and overexpression assays further confirmed the direct regulatory relationship between mannose and TXNIP. To elucidate the mechanism of action of mannose, metabolomics techniques were employed to pinpoint glutamine as a core metabolite affected by mannose. Next, various methods, including integrated omics data and the Gene Expression Omnibus (GEO) database, were used to validate the one-way pathway through which TXNIP regulates glutamine. Finally, the therapeutic effect of mannose on IVDD was validated, elucidating the mechanistic role of TXNIP in glutamine metabolism in both intradiscal and orally treated rats. RESULTS: In both in vivo and in vitro experiments, it was discovered that mannose has potent efficacy in alleviating IVDD by inhibiting catabolism. From a mechanistic standpoint, it was shown that mannose exerts its anti-catabolic effects by directly targeting the transcription factor max-like protein X-interacting protein (MondoA), resulting in the upregulation of TXNIP. This upregulation, in turn, inhibits glutamine metabolism, ultimately accomplishing its anti-catabolic effects by suppressing the mitogen-activated protein kinase (MAPK) pathway. More importantly, in vivo experiments have further demonstrated that compared with intradiscal injections, oral administration of mannose at safe concentrations can achieve effective therapeutic outcomes. CONCLUSIONS: In summary, through integrated multiomics analysis, including both in vivo and in vitro experiments, this study demonstrated that mannose primarily exerts its anti-catabolic effects on IVDD through the TXNIP-glutamine axis. These findings provide strong evidence supporting the potential of the use of mannose in clinical applications for alleviating IVDD. Compared to existing clinically invasive or pain-relieving therapies for IVDD, the oral administration of mannose has characteristics that are more advantageous for clinical IVDD treatment.

Hypermethylation of Bmp2 and Fgfr2 Promoter Regions in Bone Marrow Mesenchymal Stem Cells Leads to Bone Loss in Prematurely Aged Mice.

Osteoporosis is an age-related, systemic skeletal disease that poses a significant public health challenge in contemporary society. Development at the epigenetic level is emerging as an important pathogenic mechanism of osteoporosis. Despite indications of a robust association between DNA methylation and osteoporosis development, a comprehensive understanding of the specific role of DNA methylation in osteoporosis remains limited. In this study, significant bone loss was detected at the beginning of eight weeks of age in mouse models of premature aging (SHJHhr mice). We identified a notable upregulation of DNA methyltransferase 3b/3l (Dnmt3b/l) and downregulation of ten eleven translocation dioxygenase 1 (Tet1) in bone marrow mesenchymal stem cells (BMSCs) isolated from SHJHhr mice, along with an increase in the overall 5-methylcytosine (5mC) levels. Moreover, methylation capture sequencing revealed genomic hypermethylation in SHJHhr mice BMSCs. Integrated methylome and transcriptome analyses revealed several crucial methylated genes and networks that are potentially associated with osteoporosis development. Notably, elevated methylation levels of genes linked to the Wnt signaling pathway, particularly bone morphogenetic protein 2 (Bmp2) and fibroblast growth factor receptor (Fgfr2), appeared to compromise the osteogenic differentiation potential of BMSCs. Concurrently, DNA methyltransferase inhibitors attenuated the methylation of the promoter regions of Bmp2 and Fgfr2 and rescued the osteogenic differentiation potential of the BMSCs from SHJHhr mice. In summary, our study provides novel insights into the role of DNA methylation in the development of osteoporosis and suggests promising prospects for employing epigenetic interventions to manage osteoporosis.

A Radiographic Analysis of Coronal Morphological Parameters of Lower Limbs in Chinese Non-knee Osteoarthritis Populations.

OBJECTIVES: Analyzing the lower limb coronal morphological parameters in populations without knee osteoarthritis (KOA) holds significant value in predicting, diagnosing, and formulating surgical strategies for KOA. This study aimed to comprehensively analyze the variability in these parameters among Chinese non-KOA populations, employing a substantial sample size. METHODS: A cross-sectional retrospective analysis was performed on the Chinese non-KOA populations (n = 407; 49.9% females). The study employed an in-house developed artificial intelligence software to meticulously assess the coronal morphological parameters of all 814 lower limbs. The parameters evaluated included the hip-knee-ankle angle (HKAA), weight-bearing line ratio (WBLR), joint line convergence angle (JLCA), mechanical lateral-proximal-femoral angle (mLPFA), mechanical lateral-distal-femoral angle (mLDFA), mechanical medial-proximal-tibial angle (mMPTA), and mechanical lateral-distal-tibial angle (mLDTA). Differences in these parameters were compared between left and right limbs, different genders, and different age groups (with 50 years as the cut-off point). RESULTS: HKAA and JLCA exhibited left-right differences (left vs. right: 178.2° ± 3.0° vs. 178.6° ± 2.9° for HKAA, p = 0.001; and 1.8° ± 1.5° vs. 1.4° ± 1.6° for JLCA, p < 0.001); except for the mLPFA, all other parameters show gender-related differences (male vs. female: 177.9° ± 2.8° vs. 179.0° ± 3.0° for HKAA, p < 0.001; 1.5° ± 1.5° vs. 1.8° ± 1.7° for JLCA, p = 0.003; 87.1° ± 2.1° vs. 88.1° ± 2.1° for mMPTA, p < 0.001; 90.2° ± 4.0° vs. 91.1° ± 3.2° for mLDTA, p < 0.001; 38.7% ± 12.9% vs. 43.6% ± 14.1% for WBLR, p < 0.001; and 87.7° ± 2.3° vs. 87.4° ± 2.7° for mLDTA, p = 0.045); mLPFA increase with age (younger vs. older: 90.1° ± 7.2° vs. 93.4° ± 4.9° for mLPFA, p < 0.001), while no statistical difference exists for other parameters. CONCLUSIONS: There were differences in lower limb coronal morphological parameters among Chinese non-KOA populations between left and right sides, different genders, and age.

Cell-free fat extract-loaded microneedles attenuate inflammation-induced apoptosis and mitochondrial damage in tendinopathy.

Existing clinical treatments for tendinopathy mainly focus on reducing pain, whereas inhibiting or reversing disease progression remains challenging. Local therapeutic drugs, such as glucocorticoids, cause adverse effects on the metabolism of tendon tissues and injection-related complications. Therefore, new administration modalities for tendinopathy need to be developed. In this study, we designed a hydrogel-based microneedle (MN) system for the long-term transdermal delivery of our novel biological cell-free fat extract (CEFFE) to treat tendinopathies. We found that CEFFE-loaded MNs (CEFFE-MNs) had good biosafety and inhibited lipopolysaccharide (LPS)-induced apoptosis and matrix degradation in Achilles tendon cells of rats. The Achilles tendons of rats returned to their maximum mechanical strength after applying CEFFE-MNs. The administration of CEFFE-MNs had better anti-apoptosis and tendon repair-promoting effects than CEFEF injections in vivo. Transcriptome sequencing indicated that the anti-apoptosis effect of CEFFE-MNs was highly related to tumor necrosis factor (TNF) signaling. CEFFE-MNs inhibited the expression of TNF, TNF receptor 1, and downstream nuclear factor-kappa B signaling. Additionally, CEFFE-MNs rescued LPS-induced mitochondrial dynamics in tendon cells via the TNF-Drp1 axis. Our study reports a novel CEFFE-MN system that exhibits long-term anti-inflammatory and anti-apoptotic effects, suggesting it as a new treatment route for tendinopathy with broad clinical translation prospects.

Cartilage morphometry and magnetic susceptibility measurement for knee osteoarthritis with automatic cartilage segmentation.

Background: Automatic segmentation of knee cartilage and quantification of cartilage parameters are crucial for the early detection and treatment of knee osteoarthritis (OA). The aim of this study was to develop an automatic cartilage segmentation method for three-dimensional water-selective (3D_WATS) cartilage magnetic resonance imaging (MRI) and conduct cartilage morphometry and magnetic susceptibility measurements such as cartilage thickness, volume, and susceptibility values for knee OA assessment. Methods: Sixty-five consecutively sampled subjects, who had undergone health checks at our hospital, were enrolled in this cross-sectional study and were divided into three groups: 20 normal, 20 mild OA, 25 severe OA. Sagittal 3D_WATS sequence was used to image cartilage at 3T. The raw magnitude images were used for cartilage segmentation and the phase images were used for quantitative susceptibility mapping (QSM)-based assessment. Manual cartilage segmentation was performed by two experienced radiologists, and the automatic segmentation model was constructed using nnU-Net. Quantitative cartilage parameters were extracted from the magnitude and phase images based on the cartilage segmentation. Pearson correlation coefficient and intra-class correlation coefficient (ICC) were then used to assess the consistency of obtained cartilage parameters between automatic and manual segmentation. Cartilage thickness, volume, and susceptibility values among different groups were compared using one-way analysis of variance (ANOVA). Support vector machine (SVM) was used to further verify the classification validity of automatically extracted cartilage parameters. Results: The constructed cartilage segmentation model based on nnU-Net achieved an average Dice score of 0.93. The consistency of cartilage thickness, volume, and susceptibility values calculated using automatic and manual segmentations ranged from 0.98 to 0.99 (95% CI: 0.89-1.00) for the Pearson correlation coefficient, and from 0.91-0.99 (95% CI: 0.86-0.99) for ICC, respectively. Significant differences were found in OA patients; including decreases in cartilage thickness, volume, and mean susceptibility values (P<0.05), and increases in standard deviation (SD) of susceptibility values (P<0.01). Moreover, the automatically extracted cartilage parameters can achieve an AUC value of 0.94 (95% CI: 0.89-0.96) for OA classification using the SVM classifier. Conclusions: The 3D_WATS cartilage MR imaging allows simultaneously automated assessment of cartilage morphometry and magnetic susceptibility for evaluating the severity of OA using the proposed cartilage segmentation method.

Forkhead box O3 attenuates osteoarthritis by suppressing ferroptosis through inactivation of NF-κB/MAPK signaling.

Background: Ferroptosis is a nonapoptotic cell death process that is characterized by lipid peroxidation and intracellular iron accumulation. As osteoarthritis (OA) progresses, inflammation or iron overload induces ferroptosis of chondrocytes. However, the genes that play a vital role in this process are still poorly studied. Methods: Ferroptosis was elicited in the ATDC5 chondrocyte cell line and primary chondrocytes by administration of the proinflammatory cytokines, interleukin (IL)-1ß and tumor necrosis factor (TNF)-α, which play key roles in OA. The effect of FOXO3 expression on apoptosis, extracellular matrix (ECM) metabolism, and ferroptosis in ATDC5 cells and primary chondrocytes was verified by western blot, Immunohistochemistry (IMHC), immunofluorescence (IF) and measuring Malondialdehyde (MDA) and Glutathione (GSH) levels. The signal cascades that modulated FOXO3-mediated ferroptosis were identified by using chemical agonists/antagonists and lentivirus. In vivo experiments were performed following destabilization of medial meniscus surgery on 8-week-old C57BL/6 mice and included micro-computed tomography measurements. Results: In vitro administration of IL-1ß and TNF-α, to ATDC5 cells or primary chondrocytes induced ferroptosis. In addition, the ferroptosis agonist, erastin, and the ferroptosis inhibitor, ferrostatin-1, downregulated or upregulated the protein expression of forkhead box O3 (FOXO3), respectively. This, suggested, for the first time, that FOXO3 may regulate ferroptosis in articular cartilage. Our results further suggested that FOXO3 regulated ECM metabolism via the ferroptosis mechanism in ATDC5 cells and primary chondrocytes. Moreover, a role for the NF-κB/mitogen-activated protein kinase (MAPK) signaling cascade in regulating FOXO3 and ferroptosis was demonstrated. In vivo experiments confirmed the rescue effect of intra-articular injection of a FOXO3-overexpressing lentivirus against erastin-aggravated OA. Conclusions: The results of our study show that the activation of ferroptosis promotes chondrocyte death and disrupts the ECM both in vivo and in vitro. In addition, FOXO3 can reduce OA progression by inhibiting ferroptosis through the NF-κB/MAPK signaling pathway. The Translational potential of this article: This study highlights the important role of chondrocyte ferroptosis regulated by FOXO3 through the NF-κB/MAPK signaling in the progression of OA. The inhibition of chondrocyte ferroptosis by activating FOXO3 is expected to be a new target for the treatment of OA.

Constitutively activated AMPKα1 protects against skeletal aging in mice by promoting bone-derived IGF-1 secretion.

Senile osteoporosis is characterized by age-related bone loss and bone microarchitecture deterioration. However, little is known to date about the mechanism that maintains bone homeostasis during aging. In this study, we identify adenosine monophosphate-activated protein kinase alpha 1 (AMPKα1) as a critical factor regulating the senescence and lineage commitment of mesenchymal stem cells (MSCs). A phospho-mutant mouse model shows that constitutive AMPKα1 activation prevents age-related bone loss and promoted MSC osteogenic commitment with increased bone-derived insulin-like growth factor 1 (IGF-1) secretion. Mechanistically, upregulation of IGF-1 signalling by AMPKα1 depends on cAMP-response element binding protein (CREB)-mediated transcriptional regulation. Furthermore, the essential role of the AMPKα1/IGF-1/CREB axis in promoting aged MSC osteogenic potential is confirmed using three-dimensional (3D) culture systems. Taken together, these results can provide mechanistic insight into the protective effect of AMPKα1 against skeletal aging by promoting bone-derived IGF-1 secretion.

Irisin promotes fracture healing by improving osteogenesis and angiogenesis.

Background: Osteogenesis and angiogenesis are important for bone fracture healing. Irisin is a muscle-derived monokine that is associated with bone formation. Methods: To demonstrate the effect of irisin on bone fracture healing, closed mid-diaphyseal femur fractures were produced in 8-week-old C57BL/6 mice. Irisin was administrated intraperitoneally every other day after surgery, fracture healing was assessed by using X-rays. Bone morphometry of the fracture callus were assessed by using micro-computed tomography. Femurs of mice from each group were assessed by the three-point bending testing. Effect of irisin on osteogenic differentiation in mesenchymal stem cells in vitro was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), alkaline phosphatase staining and alizarin red staining. Angiogenesis of human umbilical vein endothelial cells (HUVECs) were evaluated by qRT-PCR, migration tests, and tube formation assays. Results: Increased callus formation, mineralization and tougher fracture healing were observed in the irisin-treated group than in the control group, indicating the better fracture callus healing due to Irisin treatment. The vessel surface and vessel volume fraction of the callus also increased in the irisin-treated group. The expression of BMP2, CD31, and VEGF in callus were enhanced in the irisin-treated group. In mouse bone mesenchymal stem cells, irisin promoted ALP expression and mineralization, and increased the expression of osteogenic genes, including OSX, Runx2, OPG, ALP, OCN and BMP2. Irisin also promoted HUVEC migration and tube formation. Expression of angiogenic genes, including ANGPT1, ANGPT2, VEGFb, CD31, FGF2, and PDGFRB in HUVECs were increased by irisin. Conclusion: All the results indicate irisin can promote fracture healing through osteogenesis and angiogenesis. These findings help in the understanding of muscle-bone interactions during fracture healing. The Translational Potential of this Article: Irisin was one of the most important monokine secreted by skeletal muscle. Studies have found that irisin have anabolic effect one bone remodeling through affecting osteocyte and osteoblast. Based on our study, irisin could promote bone fracture healing by increasing bone mass and vascularization, which provide a potential usage of irisin to promote fracture healing and improve clinical outcomes.

[Semi-automated measurement and analysis of three-dimensional acetabular orientation in asymptomatic population and patients of developmental dysplasia of the hip].

OBJECTIVE: To evaluate the three-dimensional acetabular orientation in asymptomatic population and patients of developmental dysplasia of the hip (DDH) using a semi-automated measurement software, which provides data for the differential diagnosis, surgical planning, surgical instrument design, and postoperative evaluation of hip related diseases. METHODS: Eighty-four cases of CT data in asymptomatic population (asymptomatic group) and 47 cases of CT data in DDH patients (DDH group) were collected. There was no significant difference in gender and age (including age of male and female subgroups) between the two groups ( P<0.05). MaxTHA, a semi-automatic measurement software, was used to measure acetabular inclination and anteversion, including operative inclination (OI), radiographic inclination (RI), anatomic inclination (AI), operative anteversion (OA), radiographic anteversion (RA), and anatomic anteversion (AA). Comparisons were made between the two populations, between different Crowe classification subgroups, between different gender subgroups, and between left and right sides of acetabula. RESULTS: The comparison between asymptomatic group, healthy side of DDH group, and affected side of DDH group showed that there was no significant difference in acetabular orientation between asymptomatic group and healthy side of DDH group ( P>0.05). The OI, RI, and AI of affected side of DDH group were significantly higher than those in healthy side of DDH group and asymptomatic group, and AA was significantly lower than that in healthy side of DDH group and asymptomatic group ( P<0.05). The comparison between the normal acetabula and DDH acetabula with different Crowe classifications showed that there was no significant difference in the acetabulum orientation between Crowe Ⅰ group and the normal group ( P>0.05). The OI, RI, and AI of Crowe Ⅱ, Ⅲ, and Ⅳ groups were significantly higher than those of normal group ( P<0.05), the OI of Crowe Ⅲ group, RI and AI of Crowe Ⅳ group were significantly higher than those of Crowe Ⅰ group ( P<0.05), the AI of Crowe Ⅳ group was significantly higher than that of Crowe Ⅱ group ( P<0.05), and the OA, RA, and AA of Crowe Ⅲ group were significantly lower than other subgroups ( P<0.05) except Crowe Ⅰ group. The OA, RA, and AA in asymptomatic female group, and the OA and AI in DDH female group were significantly higher than those in all male groups ( P<0.05). The OI, RI, AI, and OA of the right acetabula in asymptomatic male group, and the RI and AI of the right acetabula in asymptomatic female group were significantly higher than those on the left side ( P<0.05). CONCLUSION: There were significant differences in acetabular orientation between asymptomatic and DDH populations, inter-group differences among Crowe classification subgroups, inter-gender differences among subgroups, and bilateral differences among asymptomatic individuals.